Neuro Flashcards

Question

Imaging features and stages of....

Answer 1

Neurocysticerosis * Neurocysticercosis (NCC) is a neurologic infection caused by the larval stage of the tapeworm Taenia solium. In the developing world, NCC, infection of the central nervous system (CNS) with the T. solium larvae, is the most common cause of acquired epilepsy [1–3]. * Neurocysticercosis is a preventable parasitic infection of the central nervous system and is caused by the pork tapeworm Taenia solium. Humans become infected after consuming undercooked food, particularly pork, or water contaminated with tapeworm eggs, or through poor hygiene practices. * small enhancing rim lesion with a peripheral enhancing nodule (SCOLEX). * Can be large and obstruct CSF -\> hydrocephalus. * Can seed to the entire neuraxis * Significant edema * Calcifies. * 4 stages * 1: vesicular stage: thin walled vesicles \<20mm with CSF like fluid and mural nodule. No inflam response. * 2: Colloid stage: cyst dies. Cyst fluid becomes turbid. Inflammation and break down of the BBB. * 3: Nodule granular stage. Lesion undergoes involusion and begins to calcify. * 4 Calcified Stage: * Location * parenchymal * interventricula * subarachnoid * other findings: * hydrocephalus * chronic meningits * calcification of skeletal muscle (order an MRI/CT of thigh muscles).

Answer 2

CARBON MONOXIDE POISONING * Radiographic features * Changes tend to be bilateral with the globus pallidus most commonly affected 2. * CT * Classically seen as low attenuation in the globus pallidus region. Other features include diffuse hypoattenuation in cerebral white matter 4. * MRI * Regions of involvement are similar to CT. Signal characteristics include: * T1: affected areas are usually low signal, haemorrhagic areas can be high signal * T2/FLAIR: affected areas are high signal * T1 C+ (Gd): can show patchy peripheral enhancement in affected areas in the acute phase 2 * DWI: affected areas show increased diffusion signal in the acute phase * Differential diagnosis For involvement in and around the globus pallidus, consider: mitochondrial encephalopathies: tends to affect other basal ganglia regions Leigh disease Kearns-Sayre syndrome other toxic encephalopathies cyanide neurotoxicity: tends to also affect the cortex methanol neurotoxicity: tends to affect the putamen 7 organophosphate neurotoxicity other causes of anoxia metabolic disorders Wilson disease prion encephalopathies Creutzfeldt-Jakob disease

Answer 3

* fusiform aneurysm * elongated aneyrsm casued by * atheroscleorisis * kmostly located in the vertebrobasilar system * A/w * dolichoectasisa * Imaging fatures * VB arteries are elongated, tortuous and dilated * tip of basilar artery may indent 3rd vent. * aneyrysm may be thrombosed * bizarre flow voids bc turbulent flow * Complcations * brain stem infarct * because of thrombus * Mass effect * Cn palsies

Answer 4

* Intro * blood in the SA space +/- vent * 2ndary vasospasm and infection are the lading causes of death * Causes * Trauma * Aneurysm 90% most common cause after trauma * AVM, Dural AVF * co-agulop * extension of intraparenchyma hx (tumour, HTN) * Amyloid * RCVS * Idiopathic * spinal AVM * Complications * hydroceph 2ndary to obstruction/arachnoiditis * vasospasm several days after sah may lead to infact * leptomenigeal superfical siderosis secondary to iron depositing, secondary to chronic of recurrent SAH * The location of the sidderosis corresponded to the extent of the central myelin * CN I, II, VIII preferentially effectied bc they have a peripheral myelin envelope * Other CNS have their transition poist closer to the brain stem * if no causes is found MRI spine to look for a chronically bleeding spinal neoplasm * ie epndymoma or paraganglioma * perimesencephalic SAH is angiography negative * from a venous bleed

Answer 5

* case in picture * Large nidus of malformed vessels with serpigenous appearance (bag of worm) seen involving the right superior temporal and inferior frontal regions. Although large no mass effect could be detected. Arterial supply derived from the right posterior and middle cerebral arteries. venous drainage to the cortical veins and right internal cerebral vein. No haemorrhage could be detected. It displays flow void signal in T2 and SWI with homogenous contrast enhancement after contrast administration. Case Discussion Cerebral AVM may be parenchymal, dural or mixed according ot its arterial supply and venous drainage. The hallmark of the disease is the presence of nidus which is a large collection of arteries and veins that communicate with each others without capillary bed though arteriovenous shunting occur. * Points system * Eloqence * positive 1 * neg 0, * draining vein * superfiical 0, * deep 1 * Size * \<3cm 1, * 3-6cm = 2, * \> 6cm 3 * higher score is A/w increase risk of hx * other poor prognostic factors * intranidal aneurysm * aneyrsym COW * Aneysrym is a feeder * VEnous stasis * Complications * Hx * seizures * Comulative risk hx is 3% / yr Spetzler-Martin arteriovenous malformation grading system Dr Daniel J Bell◉ and Assoc Prof Frank Gaillard◉◈ et al. The Spetzler-Martin arteriovenous malformation (AVM) grading system allocates points for various angiographic features of intracranial arteriovenous malformations to give a score that predicts the morbidity/mortality risk of surgery. Grading The grade (denoted in Roman numerals) is equal to the sum of points in 3 categories, for a minimum of grade I and maximum of grade V (with a special designation of grade VI explained below) 1: size of nidus small (\<3 cm) = 1 medium (3-6 cm) = 2 large (\>6 cm) = 3 eloquence of adjacent brain non-eloquent = 0 eloquent = 1 venous drainage superficial veins only = 0 deep veins = 1 The size is defined by the largest diameter of the nidus on angiography. The following areas are considered eloquent: sensory, motor, language, or visual cortex hypothalamus or thalamus internal capsule brainstem cerebellar peduncles (superior, middle, or inferior) deep cerebellar nuclei The venous drainage pattern is considered deep if any of the drainage is to deep cerebral veins such as the internal cerebral vein, basal vein of Rosenthal, or precentral cerebellar vein. Cerebellar hemispheric veins are considered deep unless they drain directly into the straight sinus or transverse sinus. The presence of deep drainage complicates excision due to poor surgical accessibility compared to a malformation where all of the drainage is via the cortical venous system. A special category, grade VI, is defined as "inoperable," in which surgical resection would almost certainly cause total disability or death. At the time of the original grading system proposal, this category included diffuse nidus arteriovenous malformations that encompass eloquent brain structures. History and etymology The classification was proposed in 1986 by Drs Robert F Spetzler and Neil A Martin, both neurosurgeons at the Barrow Neurological Institute in Arizona, USA 1.

Answer 6

* Spinal canal * Vertebral elements * body * posterior elements * neural ring * posterior margin of vertebral body * pedicles * laminae * articulr facets * transverse processes * Recesses * subarticular recess * lateral recess * Components: * Nucleus polposus (notochordal orign) * annulus fibrosus with peripheral SHARPEY fibres * CT density 60-120 HU. * Disk periphery is slightly denser than is centre (Sharpy fibres calcify). * Disk is much denser than the thecal sac (0.30HU) * MRI * T1: hypointernse relative to marrow * PD/T2 * hyperintense relative to marrow with hypointense intranuclear cleft * Ligaments * ligamentum flavum * attaches to lamina and facets * PLL: raely seen by MRI ecept in herniations * Thecal sac * lined by dura and surrounded by epidural fat * Normal AP adiameter of thecal sac * Cx \>7mm * Lx \>10mm * MRI frequently shoes CSF flow artifacts in the thecal sac. * NEURAL STRUCTURES: * spinal cord * AP diameter 7mm * Conus medullaris: 8mm tip at L1-L2 * Filum terminale extends from L1 - S1 * Nerve roots * Ventral root * dorsal root * DRG * The dorsal and ventral nere roots join in the spinal canal to form the spinal nerve * The nerve splits into ventral and dorsal rami and short distance after exiting the neural foramen * Below T1 * spinal nerve courses UNDER the pedicle for which it is named ie L4 goes under the L4 pedicle * Above T1 * spinal nerve courses above the pedicle for which it is named. * nerve roots lie in the superior portion of the intevertebral neural foramen.

Answer 7

Clinical Findings: * Intermittant compression of Brain-stem newve palsies * Intermittant facial Pain Respiaratory depression long tract sign Rad Findings * Tonsilar hermiation, Syringo migelia, No Brain Anomalies * Downward displacement of the cerebellar tonsils below the foramen. The 4th V maybe elongated but remains in a normal position. * Chiari I is not a/w myelomeneningo sceles and is unrelated to CHIARI II & III. * Presents @20~yo Associations: * syringchydromeyelia 50% * loss of tendon reflexes * weakners of hands and feet * hydroceph 25% * Basilar Invagination. Kipple Fell Syndrome: fusion of 2 or more cervical vertibres * Atlantooccipital fusion *

Answer 8

HIV encephalopathy * WHAT * Progressive subacute subcortical dementia secondary to HIV itself * Eventually develops in 60% of AIDS patients * HOW DOES IT LOOK? * Atrophy * Increased T2 WM lesions in frontal and occipital lobes and periventricular locations * Gliosis + demyelination * Sparing of the subcortical U-fibres * no enhancement or mass effect of WM lesions

Answer 9

* Diffuse midline Gliomas * INTRO * 10-15% of paediatric Brain Tumours * Most commonly involve the brain stem * Pons \> MB \> medulla \> spinal Cord \> thalamus * many exhibit mutations in histone H3 gene affecting the K27 exon * CLINICAL FEATURES * CN VI + VII neuropathy * Long tract signs * Hydrocephalus * RAD FEATURES * enlargement of the brain stem * posterior displacement of the 4th ventricle * the floor of the 4th ventricule should be in the middle of the TWINING LINE which is between the Tuberculum sella and the toucula. * encasement of the basilar artery * Cystic formation uncommon * Hydrocephalus 30% * Enhancement in 50% (patchy and variable) * Exophyic extension into the basilar cysterns * MIMICS * brain stem encephalitis * Demyelinating disease. * Radiographic features * In tumours located within the pons, the pons is enlarged with the basilar artery displaced anteriorly against the clivus and potentially engulfed. * The floor of the fourth ventricle is flattened ("flat floor of fourth ventricle sign") and obstructive hydrocephalus may be present. * Occasionally the tumour is exophytic, either outwards into the basal cisterns or centrally in the 4th ventricle. * Usually the tumour is homogenous pre-treatment, however in a minority of patients areas of necrosis may be present. * CT * Typically hypodense with little, if any, enhancement. * MRI * T1: decreased intensity * T2: heterogeneously increased * T1 C+ (Gd): usually minimal (can enhance post radiotherapy) * DWI/ADC: usually normal, occasionally mildly restricted * The extensive spread is relatively frequent, both craniocaudally to involve the cerebral hemispheres and spinal cord, as well as leptomeningeal spread 3.

Answer 10

* Intro * Infected fluid collection in subdural (common) or epidural (uncommon) locations * Neurosurgical emergency * Causes * sinusitis (most common) * otitis * trauma * Post craniotomy * Imaging Features * DWI restriction, low on ADC * Subdural or epidural low attenuation fluid collection with enhancement of adjacent brain. * Venous infarction -\> edema -\> masseffect -\> midline shift * Thick curvilinear enhancement of empyema * Concominent signed of sinusitis/otits

Answer 11

* The baby brain has essentially the opposite signal characteristics as the adult brain * The T1 pattern of a baby is similar to a T2 pattern of an adult. * The T2 pattern of a baby is similar to the T1 pattern of an adult. * This is secondary to myelination differences. * Immature myelin has a higher water content relative to mature myelin and therefore is brighter on T2 and darker on T1. * During the matruation process water will decrease and fat will increase. * Therefore mature white matter will be brighter on T1 and darker on T1.

Answer 12

* TUMOURS * Meningioma * Hemangiopericytoma * Solitary fibrous Tumour * Dural Mets * Melanocytoma * TUMOUR LIKE * Erdheim Chester * IgG4 disease * Rosai-Dorfman * Sarcoid * TB * Symphilis

Answer 13

* Cytotoxic Oedema * Cellular Swelling due to ECF moving Intracellular space * We use to describe the mechanism of which both DWI changes and established CT changes become apparent. * vasogenic oedmea: * Increased ECF in setting of abscess or tumour that has disrupted the BBB.

Answer 14

* Intro * 30 % of astrocytomas * 40-60 year old * Cerebral hemispheres * Majority develop from lower grade Diffuse astrocytoma * Rad Features * Hererogenous mass * calc uncommon * edema common * Enhancement reflects BBB disruption.

Answer 15

* Acquired hepatocerebral degeneration is an uncommon irreversible extrapyramidal neurodegenerative condition encountered in patients with cirrhotic chronic liver disease, resulting in widespread cerebral, basal ganglia and cerebellar damage. * Terminology * Acquired hepatocerebral degeneration is a term that is restricted to patients which cirrhotic liver disease resulting from a variety of causes but specifically excluding Wilson disease; in fact this condition is often termed acquired non-Wilsonian hepatocerebral degeneration to ensure the distinction is made. * Acute neurological dysfunction from hyperammoniaema or other transient alterations in hepatic metabolism is termed hepatic encephalopathy and is discussed separately. Occasionally acquired hepatocerebral degeneration is referred to as chronic hepatic encephalopathy, although this is probably best avoided. * Clinical presentation * Patients with acquired hepatocerebral degeneration usually, but not always, have had multiple prior episodes of hepatic encephalopathy 6. * They present with gradual neurological dysfunction including dementia, rigidity, dysarthria, gait ataxia, tremor and choreoathetosis 5. * Pathology * Although the pathophysiology of acquired hepatocerebral degeneration is uncertain, manganese overload is believed to be part of the disease and responsible for the T1 shortening observed in the globus pallidus 7. * Radiographic features * MRI * T1 * intrinsic high signal intensity in the globus pallidus +/- subthalamic region, and midbrain (substantia nigra)1-5 * thought to be a reflection of increased tissue concentrations of manganese 1-4 * may reverse following liver transplantation 6 * T2 * increased signal in the middle cerebellar peduncles (MCP sign) 5

Answer 16

Huntington Disease Huntington disease is a hereditary neurodegenerative disease (autosomal dominant trait, but often de novo mutations), and can present with early onset dementia as well as choreoathetosis and psychosis. Imaging shows characteristic atrophy of the caudate nucleus and subsequent enlargement of the frontal horns of the lateral ventricles.

Answer 17

* Astrocytomas are 80% of GLIOMAS * Diffuse astrocytomas are the most common glioma in adults, * ADULTS: generally occurring in the cerberal hemispheres * Kids: brainstem diffusely infiltrating * TYPES * Diffuse astrocytoma (WHO GRADE II) * Anaplastic Astrocytoma (WHO GRADE III) * GBM (WHO GRADE IV) * Diffuse midline glioma (WHO GRADE IV)

Answer 18

* Most common vascular variant (propbably) 30% of the population. * The PCA is fed primarily as an anterior circ artery (occipital lobe is fed by the ICA). * Therefore the PCOM is large (some people define it as larger than P1. * Anatomy with a fetal PCA as the PCOM supioer/lateral to CN3, instead of superior/medial as in normal anatomy.

Answer 19

1. Haematogenous extension * Most common * IVDU * Sepsis 2. Direct extension * sinusitis * Otitis * Mastoiditis * Open injury (surgery, trauma) 3. Idiopathic

Answer 20

* Intro: * 20% of all astrocytomas * 20-40 year old * Cerebral hemispheres * IDH1 mutation present in the majority of adult and adolescent D.As * Rad features * Calcification in 20% * Hx and extensive oedema are rare * Mild enhancement * Terminology * The term diffuse astrocytoma should not be used for specific, non-infiltrative tumours of astrocyte-lineage such as pleomorphic xanthoastrocytoma, subependymal giant cell astrocytoma and pilocytic astrocytoma, as these have different prognoses, treatment and imaging features. * Diffuse astrocytomas are divided into two molecular groups according to IDH status: * IDH mutant * IDH wild-type * If IDH status is unavailable, they are known as * diffuse astrocytoma NOS (not otherwise specified). * Importantly, if IDH is shown to be mutated, then 1p19q status must be determined and shown to be not co-deleted (otherwise, even with astrocytic histology, an IDH mutated, 1p19q co-deleted tumour is now classified as an oligodendroglioma). * It is also worth noting that is it likely that the entity diffuse astrocytoma IDH wild-type will eventually vanish, as it is felt that most of these tumours harbour a variety of other distinctive genetic profiles and likely represent a collection of other tumours with astrocytic histological differentiation 13.

Answer 21

* Kids * Staph (especially after trauma) * strep * Pneumococcus * Adults * mixed aerobic and anerobic flora * Immunocompromised TAC TAC MN * **T**oxoplasma * **A**spergilosis * **C**ryptococcosis * **T**B * **A**typical mycobacteria * **c**andidiasis * **M**ucormycosis * **N**orcardiosis

Answer 22

* SAH * hyperdense CSF in basal cistens, sylvian fissue and SA space * Haematocrit effect in intravent Hx * MRI less sensitive than CT early on * dexy hb and brain are ISO INTENSE * MRI more sensitive and CT for finding * Subacture (increased FLAIR) * or Chromnic SAH (T2 hypoint,/SWI)

Answer 23

Tectal Glioma * A subcategory of Pilocytic Astrocytomas * A type of localized astrocytic tumour * Focal tumor localized to the tectal plate * A distinct subset of brain stem gliomas * Have a good prognosis and are located deep. * They are usually followed without Bx with serial imaging to document stability * if the lesion extends beyond the rectum bus is still confined to the midbrain = PRETECTAL TUMOUR which caries a worse prognosis * Pre-tectal tumours are difficult to differentiate from pineal region tumours. * Clinical presentation * Their expansion within the brainstem causes narrowing the aqueduct of Sylvius and causing obstructive hydrocephalus with presentation usually secondary to headache 3-4. * Additional symptoms may include gaze palsies, due to compression of the medial longitudinal fasciculus leading to an upgaze palsy, diplopia or **Parinaud** **syndrome**, although these are uncommon 3-4.

Answer 24

Spinal Ependymoma * Cap sign. T2 hypointense cap around tumour secondary to haemosidderin.

Answer 25

* Normal immunity * Coccidioidomycosis * histoplasmosis (Case) * Blastomycosis * Reduced Immunity * Norcadosis * Aspergillosis * Candidiasis * Cryptococcosis * Mucormycosis * https://www.cureus.com/articles/18340-disseminated-central-nervous-system-histoplasmosis-a-case-report

Answer 26

Gliomatosis Cerebri * Gliomatosis cerebri is a rare growth pattern of diffuse gliomas that involves at least three lobes by definition, have frequent bilateral growth and may extend to infratentorial structures. * There often is an important discordance between clinical and radiological findings, as it may be clinically silent while it appears as a very extensive process radiologically. * Importantly, whereas gliomatosis was previously considered a distinct entity since the 2016 update to the WHO classification of CNS tumours it is now merely thought of as a growth pattern. * Pathology * The tumour may be primary (de novo) or secondary, with the latter as a result from the spreading of a more focal glioma 5. Gliomatosis cerebri growth pattern is seen in all diffuse gliomas and can contain areas of WHO grade II or III tumours and rarely grade IV 6,7. It is most commonly encountered in anaplastic astrocytomas. * Classification * Gliomatosis cerebri can be divided into two types 7: * type 1: no discrete mass * usually IDH wild-type * type 2: discrete mass with further diffuse CNS involvement * IDH1 mutation more common in this subtype * Predominately causes expansion of WM but may also involve deep gray nuclei and cortex * Usually non-enhancing * Late in disease small foci of enhancement become visible * Leptomeningeal Gliomatosis can mimic meningeal carcinomatosis or leptomeningeal spread of primary CNS tumours with marked enhancement.

Answer 27

* **Cryptococosus** * Cystic lesions * Gelatinous pseudocysts * secondary to spread into VR spaces in basal ganglia. * Consider in HIV patients with communicating hydrocephalus. * CNS cryptococcosis results from infection of the central nervous system with the yeast-like fungus Cryptococcus neoformans. It is the most common fungal infection and second most common opportunistic infection of the central nervous system. * Epidemiology * The disease tends to be predominant in immunocompromised individuals such as those with AIDS. In immunocompetent patients, there is usually history of close contact with birds. * Pathology * Central nervous system involvement with cryptococcosis typically results from haematogenous spread from the lungs (which is usually the primary site). * In HIV/AIDS patients cryptococcal infection of the CNS usually occurs when the CD4+ count drops below 100 cells/µL. * The disease can have either meningeal or parenchymal involvement with the former being the primary manifestation 6. * With meningeal involvement, a grayish, mucinous exudate accumulates over the involved brain surface. * There are three dominant CNS forms to the disease depending on which part of the brain is affected: * meninges: meningitis * parenchyma: cryptococcomas * perivascular spaces: gelatinous pseudocysts * Radiographic features * The disease can have a variety of radiographic presentations and is influenced by the degree of immunocompromise and therapy. As a result, the literature describing features has evolved considerably in parallel to marked improvements in the management of HIV and the availability of HAART. * As a general rule, in patients who are profoundly immunocompromised (and therefore earlier literature), cryptococcosis demonstrates little enhancement. Instead, in patients who are on more effective therapy enhancement is more frequently encountered. * The range of appearances includes: * hydrocephalus * dilated perivascular spaces coalescing into gelatinous pseudocysts * leptomeningeal and pachymeningeal enhancement * cryptococcomas (or torulomas) * miliary nodules * choroid plexus (plexitis) * The most common pattern, particularly in profoundly immunocompromised patients is spread along the perivascular spaces, most commonly involving the basal ganglia but also the white matter of the cerebral hemispheres, the brainstem and cerebellum 12.

Answer 28

* **Progressive Multifocal Leukencephalopthy** **(PML)** * INTRO * Demyelinating disease casued by reactiveation of JC virus (a polyomarvirus) * The reactivated virus infects and destroys oligodendrocytes. * Imaging features * posterior centrum semiovale is the most common site * Bilateral but assymetric * Begins in Subcortical WM, spreads to deep WM. * T2 Bright lesions (parietooccipital) * Usually no enhancement * The key distinguishing features from infections and tumors. * Although there is an inflammatory variant and acute demyelinating lesions can show variable enhancement. * May cross corpus callosum * No mass effect. * Commonly effects the subcortical u-fibres

Answer 29

Frontotemporal demential 30 year old male MRI demonstrates marked frontal and temporal atrophy, more marked on the right. There is also reduction in the caudate head size, again more pronounced on the right. Hippocampal volumes appear preserved. Case courtesy of Assoc Prof Frank Gaillard, [Radiopaedia.org](https://radiopaedia.org/). From the case [rID: 14321](https://radiopaedia.org/cases/14321)

Answer 30

* Arteriovenous malformation * Intro * abnormal network of arteries and veins with no intervening capillary bed * 98% AVMs are solitary * Peak age * 20-40 years * Types * parenchymal 80% * ICA, VA supply, congential lesions * Dural * 10% * ECA supply * mostly acquired * Mixed * 10% * Imaging features * MRI study of choice * ateriography is superior of characterisation and tx planning * Serpiginous high and low signal with feeding /drfaining vessels * best seen on MRI/MRA * Replaces but des to displace brain tissue * mass effect is uncommon * unless complicated by hx and oedema * oeema occurs if hx or venous thrombus with infarction * 10% flow related aneurysm * Adjacent parenchymal atrophy * 2secondary to steal and ischameia * 25% calcify * Swi +ve if old Hx Fig. 5.1 A 47-year-old female with seizure. (a-d) Four slices of a T2-weighted MRI demonstrate an AVM with a relatively compact nidus in the left parietal lobe. There is a markedly hypertrophied left MCA branch, which feeds the AVM (white arrow). The AVM has a large venous pouch with associated surrounding edema and thrombus. (e) Left ICA cerebral angiogram shows a tortuous course of the left cervical ICA. There are proximal flow-related aneurysms of the paraophthalmic ICA and MCA bifurcation (diagonal arrows). There are feeding arterial aneurysms of the distal left MCA. There is a fistulous component to the AVM (horizontal white arrow), which dives into large venous pouches and ectasias. The draining vein is markedly dilated and has a long course. The fistulous component, thrombosed venous pouch with edema, and long course of the draining vein are all risk factors for seizures in this AVM patient. 5.1.2 Description of Imaging Findings and Diagnosis Diagnosis Fistulous type arteriovenous malformation (AVM) in the left parietal lobe with multiple feeding arterial aneurysms, a markedly hypertrophied MCA branch suggesting a fistulous component, multiple intranidal aneurysms, large venous pouches, and a long draining vein. 5.1.3 Background Brain AVMs are substantially rarer than intracranial aneurysms with an estimated prevalence of 20 per 100,000 people. These lesions are thought to form either in utero or early in life; however, there are a few reported cases of de novo AVMs developing in adult patients. AVMs can have a wide range of presentations including rupture, seizures, headache, cognitive decline, weakness, sensory changes, or bruit. The risk of rupture of a brain AVM is estimated to be 2–3% per year. A simple formula proposed for determining a patient’s lifetime risk of an AVM bleed is 105-(patient age in years). There are a variety of characteristics that need to be considered when evaluating an AVM. Perhaps, the most well-known AVM grading scheme is the Spetzler-Martin Grade, which grades AVMs on a 1–5 scale based on size, eloquence, and venous drainage to determine the patient’s risk of neurological deficit after surgical resection (Table 5.1). This scale neither evaluates natural history nor does it determine risk factors or success rates of radiosurgical or embolization treatment and thus cannot be used to characterize the risk of hemorrhage or potential success and complication rates of treatments other than surgery. Through extensive study of the imaging characteristics of brain AVMs, we now have a better understanding of which angioarchitectural characteristics are important for understanding AVM natural history, pathophysiology, and treatment decisions. In this chapter, we focus on defining various angioarchitectural terms, which will be expounded on in later chapters. These terms are summarized in Table 5.1. https://radiologykey.com/5-cerebral-arteriovenous-malformations-avms-and-dural-arteriovenous-fistulas-davfs/

Answer 31

* Child * Emboli from CHD * Venous thrombosis * Young adult * emboli * material disection * blood duscrasias (sickle cell) * Drug abuse * non-traumatic SAH * old adult * atherosclerosis * cardioembolic * vasculopathy * FMD * Vasculitis * ICH

Answer 32

Cerebral amyloid deposition diseases Dr Maxime St-Amant◉ and Assoc Prof Frank Gaillard◉◈ et al. Cerebral amyloid deposition diseases are a group of related conditions characterised by the accumulation of cerebral amyloid-β (Aβ) in various parts of the central nervous system. They lead to inflammation, neurotoxicity, and vascular friability, and are typically encountered in the elderly. Four main conditions are recognised, and these are discussed separately 1: Alzheimer disease (most common) cerebral amyloid angiopathy (common) cerebral amyloid angiopathy related inflammation (rare) cerebral amyloidoma (very rare)

Answer 33

TUBERCULOMA * rare unless reduced immunity or from endemic areas (India). Usually solitary. * Non-specific enhancing mass-like lesion. * Cerebral hemispheres and BG * Millary form: * multiple tiny parenchyma lesions. * Intracranial tuberculous granulomas, also known as CNS tuberculomas, are common in endemic areas and may occur either in isolation or along with tuberculous meningitis. * Epidemiology * The epidemiology of patients with tuberculomas is the same as that of other CNS manifestations of tuberculosis (TB) (see CNS tuberculosis). * Pathology * A tuberculoma is distinct from a tuberculous abscess in that it demonstrates evidence of granulomatous reaction and caseous necrosis histologically. In contrast, abscesses do not display a granulomatous reaction and their centres are filled with pus 5,6. Not all tuberculomas, however, have a solid granulomatous core and some may undergo liquefaction 4. Tuberculous organisms may not necessarily be identified in tuberculomas, whereas they are necessary to make the diagnosis of tuberculous abscess 6. * Radiographic features * CT * On CT, tuberculomas may appear as a round or lobulated nodule with moderate to marked oedema. Either solid or ring enhancement is typical post-contrast. A central focus of calcification with a ring of peripheral enhancement (the "target sign") is described but is not specific to tuberculosis 7. When calcification is present (the minority of cases) it tends to be larger than that calcification seen in neurocysticercosis. * MRI * MRI is the modality of choice in assessing potential tuberculomas which have fairly solid caseous necrosis centrally on the background of granulomatous reaction. In some instances, however, liquefactive necrosis centrally can occur, and the imaging appearances are then essentially indistinguishable from a tuberculous abscess, which in turn is similar to pyogenic cerebral abscesses 4. * T1 isointense to grey matter 1 may have a central region of hyperintensity representing caseation * T2 * isointense to grey matter may have a central region of hypointensity representing gliosis and abundant monocyte infiltration 1 lesions are surrounded by vasogenic oedema T1 C+ (Gd) usually appears as ring-enhancement may appear as a conglomerate enhancing mass * DWI typically central low signal (i.e. no restricted diffusion) 3 but if liquid necrosis is present centrally may be high signal * MR spectroscopy decrease in NAA/Cr slight decrease in NAA/Cho lipid-lactate peaks are usually elevated (86%) 2 * Differential diagnosis The differential of tuberculomas is primarily the differential of ring-enhancing lesions, and includes: * other infection * neurocysticercosis * cerebral toxoplasmosis * CNS cryptococcosis * bacterial cerebral abscesses * neurosarcoidosis * cerebral metastases * CNS lymphoma * **Central isointensity or hypointensity compared to grey matter seen centrally on T2 is helpful, as it is not seen in most other causes 1.**

Answer 34

* Stroke is a term that describes an acute episode of neurologic deficit * 80% are due to cerebral ischaemia. embolic or thrombotic * TIAs are focal neorlogic events that resolve within 24hours * Those that resolve after 24 hours are called reversible ischaemic neurologic deficits (RINDS)

Answer 35

* Cavum septum pelucidum * 100% of preterm infants * 15% of adults * rarely can cause hydrocephalus * Anterior to the foramen of munro * Betwen the Frontal horns * Cavum vergae * Posterior sontinuation of the vaum septum pellucidium * posterior to the foraemn of munroe * between the bodies of the lateral ventricles * Cavum velum interpositium * estension of the quadrigeminal plate cistern to forament of monro * seen above the 3rd entricle and below the fornices.

Answer 36

The brain stem and posterior limb of the internal capsule are normally myelinated at birth.

Answer 37

* Apple Cider Vinegar * A = AVM * parenchymal PIAL malformations * dural AVIM and fistular * misxed dial dural AVM * C = Capillary telengectasia * C = Cavernoous malformation * V = Venous Malformations * venous anomally * vein of galen malf * venous varix

Answer 38

* Anastomotic vein of Trolard * connects the suprficial middle cerebral vein and the superior sagital sinus * Anastomotic vein of Labbe * connects the superficial middle cerebral vein and the transverse sinus.

Answer 39

* Acute Hx (3days) * hyperdense (80-100HU) relative to brain (40-50HU) * High density caused by protien Hb component (clot retraction). * Acute hx is not hyperdense if the hc is low (Hb \<8g/dL) *

Answer 40

* Diffusion imaging highly sensitive to detect abscess and empyema. * Risk factors for haematogenous spread include: * right to left shunt * congenital heart disease * pulmonary AVM and AVFs as seen in hereditary haemorrhagic telangiectasia (HHT) * infective endocarditis * intravenous drug use (IVDU) * lung infection * lung abscess * bronchiectasis * empyema * pneumonia * sinonasal infections * dental abscess * systemic sepsis * location * hematogenous seeding * multiple lesions at G/W matter junction * penetrating trauma or sinusitis * lesions around the entry site * ring or wall enhancement 90% * Capsule in 7-14 days. * **Casule thinner on WM side bc of lower perfusion of wm than gm.** * **bc of this, daughter cysts tend to occur on the medial side** * ventriculitis * ependymal enhancement * DWI increased. * May cause ventricular septations. * The capsule is T2 hypointense. The inner margin is often smooth. capsule formation may be delayed by steroid administration. * ventriculitis bc of ventricular spread. * increased CSF density bc of increased protein. * Pathology * Cerebral abscesses result from pathogens growing within the brain parenchyma. Initial parenchymal infection is known as cerebritis, which may progress into a cerebral abscess. Historically direct extension from sinus or scalp infections was the most common source. More recently haematological spread has become most common. Direct introduction by trauma or surgery accounts for only a small minority of cases. * Cerebral infection is commonly divided into four stages with distinct imaging and histopathologic features: * early cerebritis( a focal infection without a capsule or pus formation,can resolve or develop into frank abcess) * late cerebritis * early abscess/encapsulation - may occur 10 days after infection * late abscess/encapsulation - may occur \>14 days after infection * Microbiology * Streptococcus sp: 35-50% * especially S. pneumoniae 4 * sterile: 25% * mixed: variable, 10-90% of cases depending on source * Staphylococcus aureus and epidermidis: * following neurosurgery * Gram-negative species more common in infants * Listeria in pregnant women and older patients * group B Streptococcus (GBS) and E. coli in neonates * The immunocompromised patient is susceptible to a host of other organisms including: * Toxoplasma gondii * Nocardia asteroides * Candida albicans * Listeria monocytogenes * Mycobacterium sp * Aspergillus fumigatus

Answer 41

* GBM * most common primary brain tumour * 55% of astrocytomas * \>50 years * Majority arise de novo from neural stem cells * Secondary GBM arise from lower grade astrocytomas and frequently carry IDH mutations with a more favourable prognosis * Hemispheres * Tumor spread * WM tracts * across midline via commisures (like the CC) * Subependymal spread/seeding of the ventricles * CSF seeding of S.A space. * Imaging features * CT - low density heterogenous mass * Strong contrast enhancement * Haemorrage and necrosis common * Calc uncommon * +++ vasogenic oedema and mass effect * Bihemispheric Spread = butterfly lesion * HIgh grad gliomas located peripherally can have a broad dural base and dural tail, mimicking extra axial lesion. * CSF seeding leptomeningeal drop metastasis.

Answer 42

* HIV is a neurotropic virus that directly infects the CNS and is the most common CNS pathogen in AIDS. * HIV related infections include * HIV encephalopathy (most common) * Toxoplasmosis (most common opportunistic infection. * Cryptococcosis * Progressive multifocal leukoencephalopathy (PML) from reactivation of JC virus * TB * Syphilis * Varicella * CMV

Answer 43

metachromatic leukodystrophy This sign is characterized by multiple dark spots or stripes (spared perivascular white matter) of normal white matter intensity scattered within the bright demyelinated periventricular white matter on T2W images (Figure 10). Tigroid appearance of the white mater has been found in some cases with Pelizaeus-Merzbacher disease and metachromatic leukodystrophy. However, it has been recently reported that it may be observed in cases with lissencephaly accompanied by cerebellar hypoplasia [11,12]. Metachromatic leukodystrophy (MLD) is the most common hereditary (autosomal recessive) leukodystrophy and is one of the lysosomal storage disorders. It has characteristic imaging features including peri-atrial and to a lesser extent frontal horns leukodystrophy as well as periventricular perivenular sparing results in "tigroid pattern" on fluid-sensitive MRI sequences. Epidemiology It has an estimated prevalence of ~1:100,000 and typically manifests between 12 to 18 months of age. The disease can sometimes be classified according to the time of onset: late infantile: most common ~65% (range 50-80%) juvenile (onset between 3-10 years) adult (after age 16)

Answer 44

* TB * Lymphoma * HCC in Liver * Nasopharuyngeal Ca (Bettle Nut)

Answer 45

Venous Trivia * Vein of Labbe: **large** draining vein connecting **Superficial middle vein** to the **transverse sinus** * Vein of Trolard: **small** vein connecting **Superficial middle vein** to the **superior sagitral sinus** * Basal vein of Rosenthal: Deep veins that passes lateral to the midbrain thru the **ambient** cistern and drains into the **VOG.** * their course is similar to the **PCA** artery * Vein of galen * **Big** vein form by. the union of the **Two internal cerebral veins.**

Answer 46

Persistant fetal connection between the cavernous ICA to the Bsilar. Has a characteristic 'tau sign' on Sag MRI It increased the risk of aneurysm

Answer 47

Cerebral cavernous venous malformation * Case Discussion * This MRI demonstrates widespread focal regions of susceptibility induced signal loss (best seen on susceptibility weighted imaging (SWI)) ranging in size from microscopic to a number of millimetres in diameter * Remember that all T2\* sensitive sequences result in a degree of blooming and thus grossly overestimate the actual size of the lesion). * One of the lesions in the right temporal lobe demonstrates high T1 and T2 signal centrally and perhaps a small amount of peripheral oedema, best seen on FLAIR. This suggests a recent bleed. * This patient is from a known pedigree of **autosomal dominant multiple cavernoma syndrome.** * DDx * neurocysticercosis and * cerebral amyloid angiopathy. * **Against the diagnosis of neurocysticercosis** is the variability in the size of the lesions, which by the time they calcify are typically more regular, measuring a few millimetres each. * Furthermore there is no calcification in this case, although on the sequences provided that cannot be proven. * Review of a CT (not shown) or phase images of the SWI (also not shown) would confirm this. * **Cerebral amyloid angiopathy** can have similar appearances however against this diagnosis is that A) the lesions, in this case, are distributed randomly throughout all parts of the brain, not having a predilection for the peripheral subcortical white matter which microhaemorrhage of cerebral amyloid angiopathy, and B) there is no evidence of prior larger lobar haemorrhage or superficial siderosis, both of which would be expected in this degree of change. * Cerebral cavernous venous malformation * Cerebral cavernous venous malformations, also commonly known as cavernous haemangiomas or cavernomas, are common cerebral vascular malformations, usually with characteristic appearances on MRI. It is the third most common cerebral vascular malformation after developmental venous anomaly and capillary telangeictasia. * Cavernous malformations are found throughout the body. This article focuses on cerebral cavernous venous malformations. For a general discussion and links to cavernomas in other locations, please refer to the general article on cavernous venous malformation. * Terminology * Many alternative terms have been used over the years including cavernous haemangioma, cerebral cavernous malformation or simply cavernoma. As these lesions are not neoplastic, it has been argued that the terms 'haemangioma' and 'cavernoma' should be avoided. Additionally, it is important to note that according to newer nomenclature (ISSVA classification of vascular anomalies) these lesions are now officially termed slow flow venous malformations. * Having said all that, it is probably helpful in reports to include the word 'cavernous' as this term is ubiquitous in the literature and most familiar to many clinicians. * For clarity and brevity, the term cavernous malformation is used for the remainder of this article. * Epidemiology * Most patients who present symptomatically do so at 40-60 years of age. Most patients have single lesions. Multiple lesions may be familial and screening of family members may be indicated (see familial multiple cavernous malformation syndrome). Additionally, cavernous malformations, along with capillary telangiectasias, are commonly seen following cerebral radiotherapy 3. * Clinical presentation * The majority of lesions remain asymptomatic throughout life and are found incidentally. Presentation due to haemorrhage may cause a headache, seizure or focal neurological deficit. The risk of haemorrhage is 1% per year for familial cases and somewhat less for sporadic lesions. * Pathology * Histologically cavernous malformations are composed of a "mulberry-like" cluster of hyalinized dilated thin-walled capillaries, with surrounding haemosiderin 3. These vessels are thrombosed to varying degrees. Unlike AVMs, there is no normal brain between the interstices of these lesions. * On occasion, they are intimately associated with a developmental venous anomaly (DVA), in which case they are known as a mixed vascular malformation. * Radiographic features * Cerebral cavernous malformations tend to be supratentorial (~80% cases) but can be found anywhere including the brainstem. They are usually solitary, although up to one-third of patients with sporadic lesions have more than one 2. * CT * Unless large, these lesions are difficult to see on CT. They do not enhance. If large they appear as a region of hyperdensity resembling blood products and speckles of calcification. If there has been a recent bleed then the lesion is more conspicuous and may be surrounded by a mantle of oedema. * MRI * MRI is the modality of choice, demonstrating a characteristic “popcorn” or "berry" appearance with a rim of signal loss due to haemosiderin. * T1: varied signal depending on the age of the blood products, small fluid-fluid levels may be evident * T2 * hypointense rim * varied signal internally depending on the age of blood products * if a recent bleed has occurred, surrounding oedema may be present * GRE T2\*/SWI * prominent blooming * useful for detecting smaller lesions otherwise missed by conventional spin echo sequences, especially in patients with familial or multiple cavernous malformations * T1 C+ (Gd): generally no enhancement, although possible 7 * Cavernous malformations can be grouped into four types based on MRI appearances using the Zabramski classification 11. * Angiography (DSA) * Cavernous malformations are angiographically occult and do not demonstrate arteriovenous shunting. * Treatment and prognosis * Many cavernous malformations are asymptomatic and can be treated conservatively. Symptoms can relate to mass effect, epileptic activity or repeated haemorrhage. Symptomatic lesions should, when possible, be resected and complete resection is curative 9. * Differential diagnosis * The differential, when cavernous malformations are numerous, is that of other causes of cerebral microhaemorrhages, including 2: * cerebral amyloid angiopathy: usually numerous small foci * chronic hypertensive encephalopathy: more common in the basal ganglia * diffuse axonal injury (DAI) * cerebral vasculitis * radiation-induced vasculopathy * haemorrhagic metastases * Parry-Romberg syndrome 2 * Larger lesions can mimic: * haemorrhagic cerebral metastases * haemorrhagic primary brain tumours (e.g. ependymoma, glioblastoma) * Calcified lesions, such as old neurocysticercosis, or other infections (e.g. tuberculoma) should also be considered.

Answer 48

Ependymoma * Slow growing tumour of ependymal lining cells usually location in or adjacent to ventricles within the parenchyma. * fourth ventricle: 70% more common in children * Lateral ventricle or periventricular parenchyma 30%. * more common in adults * Spinal Ependymomas are associated with NF1. IMAGING FEATURES * Growth patten depends on location * supratentorial: * tumours grow in the cerebral hemispheres (resemples an astrocytoma) * remember to include ependymoma in the ddx of a supratentorial paranechyma mass lesion. Particularly a child. * Infratentorial * tumours grow inside fourth ventricle and extrude thoguht the foramen of LUSHCKA into the CPA and cisterna magana * this appearance is characteristic of a PLASTIC EPENDYMOMA and often helps to differentiate an ependymoma from a medulloblastoma * Hydrocephalus is virtually aways present when in the posterior fossa * fine calcifations * cystic areas * haemorrage. * DDX for sypratentorial Ependymoma * embryonal tumour: often periphal and has more edema * atypical teratoid/rhabdoid tumorL generally seen in infants and young children. * GBM: may be indistinguishable but less likely to be in proxiity of ventricular surface Case courtesy of Assoc Prof Frank Gaillard, Radiopaedia.org, rID: 5217

Answer 49

* The T1 changes preced the T2 changes * the adult T1 pattern is seen around age 1 * The adult T2 pattern is seen around age 2. * T1 is most useful for assessing meylination in the 1st year (esp 0-6months) * T2 is most useful for assessing muelinatipon in the second year (esp 6-18months)

Answer 50

* Primary parenchyma AVM drains into VOG which secondarily enlarges * Thalamic AVM with nidus is usually the primary avm * Uncommon in neonates * high risk of hx than GOV AVM Abstract A 28-year-old pregnant woman underwent an emergency caesarian section after 39 weeks of gestation because of decreased fetal movement and baseline fetal heart rate variability. The neonate was diagnosed with neonatal asphyxia and presented with right cardiac failure due to pulmonary hypertension. The neonate presented convulsion, and plane computed tomography (CT) showed dilation of the vein of Galen and sinuses on day 3. Magnetic resonance imaging and CT with contrast were performed after cardiac failure subsided, and there was no evidence of arteriovenous shunt and normalization of the vein of Galen. The patient was diagnosed with vein of Galen varix (VGV). In the previous literature, only 3 cases of VGV have been reported. VGV is considered to be caused by right cardiac failure without the presence of an arteriovenous shunt and requires treatment only for cardiac failure and its cause. Therefore, it is important to differentiate VGV from vein of Galen aneurysmal malformation. https://www.karger.com/Article/Abstract/500768

Answer 51

* Dilaed perivascular spaces * these are fluded filled spaces that accompany perforating vessels. They are a normal variant and very common. * They can be enlarged and assoicated with multiple pathologies, mucopolysaccaridoses (hurlers and hunters), gelatinous pseudocysts in cryptocooccal meningitis and atrophy with advancing age. * They dont contain CSF but instear have interstitial fluid * The common locations for these are * around the lenticulostriate arteries in the lower third of the BG * centrum semiovale * midbrain.

Answer 52

Fahr Disease

Answer 53

meningioma GBM lymphocystic hypophysitis

Answer 54

* INTRO * HSV1 * oral * kids and adults * usually activation of latent virus in TRIGEMINAL GANGLION * Change in mental status * fulminant course * LIMIBIC SYSTM * Frequently bilateral but assymetric * HSV2 * Genital * neonatal TORCH infection * acquired during parturition. * maniefsts several weeks after birth * diffuse/nonfocal encephalitis. * CT MRI usually normal in early disease * MRI -\> 1st abnormality apparent in 2-3 days after onset. * Distribution * limbic system * temporal lobe * cingulate gyrus * subfrontal region * ACUTE stage * emergency * high mortality * DWI restriction in affected areas * Gyral oedema T1 hypo, T2 hyper * no Enhancement * Subacute stage * increased oedema MARKED * Bitlateral assymetric involvement * gyral enhancement * hemorrhage.

Answer 55

* Leigh Disease

Answer 56

* intor * following a dissection an intramural haematoma may organise and result in a sac like outpouching * causes * trauma * vasculopathy (SLE FMD) * spont * Location * ICA \> VA * Imaging * elongated contrast collections extending beyond the vessel lumen * MRA - screening * CTA dx and F/u * Angio may be needed for imaging of vascular detail Extensive subarachnoid blood is demonstrated within the suprasellar, ambient, and quadrigeminal plate cisterns and the sylvian fissures bilaterally. Large volume of blood also fills prepontine cistern and extends through foramen magnum. Intraventricular blood demonstrated within the lateral, third and fourth ventricles. Periventricular hypodensity likely related to chronic microvascular ischaemia. A complex, multiple aneurysm arises from the right posterior inferior cerebellar artery (PICA) approximately 12mm beyond its origin, with both fusiform and saccular components. A high grade stenosis in the more proximal PICA supports a diagnosis of dissecting aneurysm. Conclusion: Large volume subarachnoid haemorrhage (largest volume posterior fossa) with intraventricular blood and hydrocephalus, with a large right PICA aneurysm. A complex abnormality of the right PICA is shown - shortly after its origin there is an eccentric high-grade stenosis with small false aneurysm, and some 10 mm beyond this is a smaller 3 mm mixed fusiform and saccular aneurysm, just beyond this a larger 4.5 millimetre aneurysm at the bifurcation of PICA, incorporating both branches in its base. The left vertebral is patent and fills the basilar but is of smaller calibre. No other intracranial aneurysm, and no arteriovenous or dural arteriovenous fistula or malformation is shown. Case Discussion PICA dissection without involvement of the vertebral artery is rare but reported, and usually requires management with sacrifice of the vessel. Endovascular sacrifice is preferred over microsurgical exploration. In appropriate clinical circumstances, balloon occlusion testing of adequacy of collaterals can be considered. https://radiopaedia.org/cases/posterior-inferior-cerebellar-artery-pica-dissecting-aneurysm-and-subarachnoid-haemorrhage?lang=gb

Answer 57

* Mnemonic to remember types of diffuse astrocytomas: "DAG" * Diffuse (DA) * Anaplastic (AA) * GBM * Diffuse Astrocytoma * young patients * low grade malig * Histo is low grade but it may upgrade to AA or GBM * Majority have IDH mutations (which is favourable re prognosis) * Not multifocal * +/- enhancement * Little or no oedema * 20% calcify * AA * Middle aged * High grade * malignant * possible to be multifocal * enhancing ++ * Edema +++ * Less calcification * GBM * 50 years old * High grade * Very aggressive * Most are IDH wild type. * Possible to be multifocal * Enhancing +++ * Calcification uncommon * necrosis ++ * Haemorrage ++

Answer 58

Cerebral amyloid angiopathy Dr Rohit Sharma◉ and Assoc Prof Frank Gaillard◉◈ et al. Cerebral amyloid angiopathy (CAA) is a cerebrovascular disorder caused by the accumulation of cerebral amyloid-β (Aβ) in the tunica media and adventitia of leptomeningeal and cortical vessels of the brain. The resultant vascular fragility tends to manifest in normotensive elderly patients as lobar intracerebral haemorrhage. It is, along with Alzheimer disease, a common cerebral amyloid deposition disease. Epidemiology Cerebral amyloid angiopathy can be divided into sporadic (spontaneous) and familial forms. Sporadic CAA Cerebral amyloid angiopathy is a frequent incidental finding, found on screening gradient-recalled echo imaging in up to 16% of asymptomatic elderly patients 4. Autopsy studies have found a prevalence of approximately 5-9% in patients between 60 and 69 years, and 43-58% in patients over the age of 90 4. Autopsies of patients who have evidence of Alzheimer disease have found cerebral amyloid angiopathy in the vast majority of cases (90%). This rate is still high (20-40%) in non-demented elderly individuals 14. Importantly it is usually not associated with systemic amyloidoses. Familial CAA Familial cerebral amyloid angiopathy describes a group of very rare disorders that are usually encountered as autosomal dominant conditions 14,21. Many of these disorders are only isolated to only a few families and they mainly differ from spontaneous CAA in an earlier age of onset, typically in middle to late middle age 14,21. Furthermore, they may also be part of multi-system or other central nervous system genetic disorders 14,21. Examples of familial CAA include 21: Aß peptide with precursor protein APP (chromosome 21): CAA related to familial Alzheimer disease CAA in Down syndrome hereditary cerebral haemorrhage with amyloidosis (Dutch, Italian, Flemish, Iowa, Piedmont, Arctic types) ACys peptide with precursor protein cystatin C (chromosome 20): hereditary cerebral haemorrhage with amyloidosis Icelandic type ATTR peptide with precursor protein transthyretin (chromosome 18): meningovascular amyloidosis (see cerebral transthyretin-associated amyloidoses) AGel peptide with precursor protein gelsolin (chromosome 9): familial amyloidosis - Finnish type PrPSc peptide with precursor prion protein (chromosome 20): Gerstmann-Straussler-Scheinker disease ABri peptide with precursor protein ABri precursor protein (chromosome 13): familial British dementia (see case 17) ADan peptide with precursor protein ADan precursor protein (chromosome 13): familial Danish dementia Clinical presentation Manifestations of cortical vessel involvement: lobar haemorrhages or cerebellar haemorrhages: present as stroke, often with headache, focal neurological symptoms, seizures, and decreased conscious state 19 cognitive impairment: occurs in three main patterns gradual decline: a vascular dementia thought to be secondary to lobar cerebral microhaemorrhages, ischaemic leukoencephalopathy, microinfarcts, and lobar lacunes 7,15, and occurs independently to cognitive impairment of Alzheimer disease 25 step-wise decline: due to recurrent lobar haemorrhages 25 rapidly-progressive decline: may be present in inflammatory cerebral amyloid angiopathy 25, which is discussed separately The primary manifestation of leptomeningeal vessel involvement is due to convexity subarachnoid haemorrhage, which can present with transient focal neurological symptoms (TFNS) or "amyloid spells" 25. These TFNS are classically described as recurrent, stereotyped, spreading paraesthesias lasting several minutes but there is a wide spectrum of presentations encompassing both positive (spreading paraesthesia or visual symptoms) and negative (paresis, aphasia or dysphagia) phenomenology 17,25. These symptoms are most prominent with the convexity subarachnoid haemorrhage is localised to the central sulcus 16, which is in close proximity to the primary motor and sensory cortices 25. Other manifestations of CAA, which are discussed separately, include: inflammatory cerebral amyloid angiopathy: an umbrella description for inflammatory reactions that present with rapidly-progressive cognitive decline, seizures, headache and stroke-like episodes (without haemorrhage) 1,11 cerebral amyloidoma: mass-like lesions that have a varied presentation depending on the location of the amyloidoma Pathology Cerebral amyloid angiopathy is characterised by the deposition of amyloid in the tunica media and/or tunica adventitia of small and medium-sized arteries of the cerebral cortex and leptomeninges 4,20. This is associated with fibrinoid degeneration with separation of the tunica media and tunica intima, and microaneurysm formation 1. There are a number of different proteins that can lead to intravascular amyloid deposition, however, the most common, as is the case in sporadic CAA, is Aß which is a short 42 amino acid peptide cleaved from amyloid precursor protein (APP) which is encoded on chromosome 21 20. Aß is an eosinophilic, insoluble protein, located in the extracellular space. It stains with Congo red yielding classic apple-green birefringence when viewed with polarised light 3,20. When staining with thioflavin T and illuminated with ultraviolet light, the Aß deposits emit bright green fluorescence 20. Associations Alzheimer disease pathological cerebral amyloid angiopathy changes are seen in ~80% of those with Alzheimer disease (Aß-42) 5-13 ~40% of those with cerebral amyloid angiopathy have Alzheimer dementia type symptoms Down syndrome 25 chronic traumatic encephalopathy spongiform encephalitis other familial syndromes (as discussed above) Radiographic features Findings reflect the various manifestations of the disease: haemorrhageintracerebral haemorrhageusually cortico-subcortical, in a so-called lobar location 22, but can also be seen in the cerebellum (especially in the cerebellar cortex or vermis) 24, may have finger-like projections 26 tend to spare the basal ganglia and pons (cf. hypertensive 'deep' intracerebral haemorrhage) CT: initially hyperdense with hypodense perihaematomal oedema, often exerts positive mass-effect 25 MRI: appearance will vary according to age of bleed (see blood on MRI) 25 cerebral microhaemorrhagedefined as 2-10 millimetre, round or ovoid areas of haemorrhage, and tend to be corticosubcortical (grey-white matter junction) in distribution, but can also be in the cerebellum tend to spare the basal ganglia and pons (cf. hypertensive microhaemorrhages) 4,14 CT: not appreciated 25 MRI: only seen on T2\* sequences (GRE, echo-planar, SWI) as regions of low-signal blooming artefact 12,25, not seen on conventional T1 and T2/FLAIR sequences 4 convexity subarachnoid haemorrhagehaemorrhage that is localised to one or more adjacent cortical sulci at the convexity of the brain tend to spare the basal cisterns, the Sylvian fissure, the interhemispheric fissure or the ventricles (cf. aneurysmal subarachnoid haemorrhage or perimesencephalic subarachnoid haemorrhage) 25 CT: hyperdensity localised to one or more adjacent sulci, can be subtle 25 MRI: appearance will vary according to the age of the bleed (see blood on MRI), but is best acutely seen on T2 FLAIR as a hyperintensity 18,25 cortical superficial siderosisa chronic sequela of convexity subarachnoid haemorrhage, including of haemorrhage that is asymptomatic 25 not present infratentorially (cf. superficial siderosis of the CNS) 25 CT: not appreciated 25 MRI: curvilinear regions of signal drop-out localised to one or more sulci best seen on T2\* sequences (GRE, echo-planar, SWI) 9,25 ischaemiaischaemic leukoencephalopathy chronic lesions, indistinguishable from leukoaraiosis due to other aetiologies, but tends to have a periventricular and posterior predominance 25 CT: diffuse hypodensity of the white matter 25 MR: T2 hyperintensity of the white matter without involvement of subcortical U-fibres (cf. cerebral amyloid angiopathy related inflammation) 7,25 microinfarcts and lobar lacunes acute cortico-subcortical lesions; lobar lacunes are 3-15 millimetres in size while microinfarcts are smaller 25 CT: not appreciated 25 MRI: same signal changes as in acute ischaemic stroke, most pronounced on DWI 25 othersdilated perivascular spaces of the centrum semiovaledilation of normal perivascular spaces in the centrum semiovale 25 tend to spare the basal ganglia and pons (cf. hypertensive dilated perivascular spaces) 25 CT: not appreciated 25 MRI: best appreciated on T2 images as CSF-signal structures with a varied appearance depending on the orientation of their draining vessel 25 cortical atrophy CT: not appreciated 25 MRI: not readily appreciated on conventional sequences, requires cortical surface reconstructions 25 Radiographic features of inflammatory cerebral amyloid angiopathy and cerebral amyloidoma are discussed separately. Diagnostic criteria The Boston criteria 7 and newer Modified Boston criteria 9 are a combination of clinical, radiographic and pathological criteria which are used to assess the probability of cerebral amyloid angiopathy. These criteria require patients to have either biopsy specimens and/or brain MRI data available 7,9. Additionally, the Edinburgh criteria for lobar intracerebral haemorrhage associated with cerebral amyloid angiopathy can be utilised, especially for patients with a lobar intracerebral haemorrhage without an MRI 26. Treatment and prognosis There is currently no disease-modifying treatment available 27. Additionally, there are no guidelines regarding use of antiplatelet, anticoagulant, or thrombolytic drugs in patients with CAA, all medications which have been shown to increase the risk of disabling haemorrhage in this patient group 27. Differential diagnosis Radiological differential diagnosis, particularly of cerebral microhaemorrhages, includes: hypertensive microangiopathy haemorrhages, including microhaemorrhages, are typically located in basal ganglia, pons and cerebellum not associated with subarachnoid haemorrhage or superficial siderosis multiple cavernoma syndrome lesions have a random distribution random size, although Zabramski classification type IV cavernous malformations are indistinguishable from cerebral microhaemorrhages related to CAA often characteristic cavernous malformations can be identified haemorrhagic metastases (e.g. melanoma) lesions have a variable size and can often be larger than microhaemorrhages enhancing diffuse axonal injury lesions are typically located at the grey-white matter junction, in the corpus callosum and in more severe cases, in the brainstem neurocysticercosis nodular calcified stage visible on CT or phase-filtered SWI random distribution fat embolism syndrome 'starfield' pattern of distribution lesions also show restricted diffusion on DWI and are likely visible on other sequences radiation-induced vasculopathy microhaemorrhages have a very similar appearance (similar pathophysiology) distribution related to the treatment field

Answer 59

Case courtesy of Assoc Prof Frank Gaillard, Radiopaedia.org, rID: 4717

Answer 60

Developmental venous anomaly Dr Rohit Sharma◉ and Associate Professor Donna D'Souza◉ et al. Developmental venous anomaly (DVA), also known as cerebral venous angioma, is a congenital malformation of veins which drain normal brain. They were thought to be rare before cross-sectional imaging but are now recognised as being the most common cerebral vascular malformation, accounting for ~55% of all such lesions. A DVA is characterised by the caput medusae sign of veins draining into a single larger collecting vein, which in turn drains into either a dural sinus or into a deep ependymal vein. The appearance has also been likened to a palm tree. Epidemiology DVAs are very common as incidental finding, with an estimated prevalence of 2.5-9% on contrast-enhanced MRI scans 13. Clinical presentation Developmental venous anomalies are usually incidental findings. However, patients can present with intracranial haemorrhage (1-5%). An association has also been described with ischaemic stroke and epilepsy 8. Pathology The aetiology of developmental venous anomalies remains uncertain but may relate to arrested development of venous structures 2,3. Histologically they consist of a number of abnormally thickened veins with normal feeding arteries and capillaries 3. Location and classification The most common locations are: frontoparietal region (36-64%) 1, usually draining towards the frontal horn of the lateral ventricle cerebellar hemisphere (14-27%) draining towards the fourth ventricle However, DVAs can be seen anywhere, draining either superficially or deep. Associations lesions are usually solitary (75%) 2, except in blue rubber bleb naevus syndrome ~20% (range 8-33%) of cases 2 are associated with cavernous malformations and are referred to as mixed vascular malformations (MVM) venous malformations of the head and neck 2 cortical dysplasia (uncommon) 7 Radiographic features Developmental venous anomalies are seen on both CT and MRI as a leash of vessels draining towards a central vein. CT If large, the draining vein may be seen on non-contrast CT and is confirmed with contrast administration as a linear or curvilinear enhancing structure. Dystrophic calcifications may be seen associated in up to 9.6% of the cases 9. This can be particularly prominent in the basal ganglia and thalami resulting in unilateral calcification 10,11. Angiography (DSA) Angiographically the caput medusae appearance (collection of dilated medullary veins converge in an enlarged transcortical or subependymal collector vein) is pathognomonic and seen only in the venous phase. Arterial phase appears normal although late capillary blush may be present. No shunting is present. MRI Developmental venous anomalies are often visible on most sequences but can be subtle and are most easily seen on postcontrast T1 sequences and susceptibility weighted imaging (SWI). If there is an associated cavernous haemangioma, then susceptibility weighted sequences will be most sensitive to this component. Additionally, in ~10% of cases, high T2 signal will be seen in the surrounding white matter; this may be due to gliosis, oedema or leukoaraiosis 12. SWI is the preferred sequence in venous anomalies and proved to have better detectability of venous structures than conventional T2\*-weighted imaging. Signals on SWI are not compromised by low-velocity venous flow. Therefore, SWI has successfully demonstrated low-flow vascular formations such as DVA. The signal intensity of veins will be low on SWI images but will vary on phase imaging depending on the vendor. It will, however, be the same as other veins and the opposite of calcification. Treatment and prognosis If isolated developmental venous anomalies require no treatment. If part of a mixed vascular malformation then treatment will be predicated on the other component. Informing the surgeon of the presence of a DVA is, however, essential as cautery of the collecting vein can lead to venous infarction of the brain parenchyma it drains. When isolated, developmental venous anomalies have a very low complication rate (0.15% per annum) mainly from spontaneous thrombosis of the collecting vein leading to venous infarction and haemorrhage. A more recent study has demonstrated that in exceedingly rare cases, the DVA can become symptomatic by various vascular complications. The authors suggested identification of the underlying pathomechanism by MR and DSA for proper management. The importance of the preserved integrity of the DVA itself still holds true 6. Differential diagnosis Generally, the appearances will be typical and no differential should be offered. In some instances, imaging appearances may be atypical or be confounded by concurrent pathology (e.g. haemorrhage). In such cases it is worth considering: arteriovenous malformation dural sinus thrombosis or dural arteriovenous fistula with collateral transparenchymal drainage Sturge-Weber syndrome with leptomeningeal angiomatosis demyelination may also have enlarged medullary veins Practical points think of an associated cavernoma when a developmental venous anomaly is found in the context of an intraparenchymal haemorrhage investigation, as isolated DVAs rarely bleed developmental venous anomalies can be subtle on many MRI sequences; T1 C+ and SWI are most sensitive

Answer 61

* **Imaging findings of TB Meningitis** * Tb meningitis is the most xommon CNS manifestation of TB followed by intraparenchymal Tuberculoma. * Spread is usually hematogenous from pulmonary TB * Basilar meningeal involvement by chronic granulomatous process leads to CN palsies. * Basilar meningitis * indistinguishable from fungal, lymphoma, sarcoid * intense contrast enhancement of basilar meninges (CT/MRI) * pituitary and para sellar involvement or hypothalamus involvement * T2 hypointense meninges * Calcifications occur late. * Tuberculous meningitis is the most common presentation of intracranial tuberculosis, and usually refers to infection of the leptomeninges. Uncommonly tuberculosis can be limited to the pachymeninges (dura mater), it is called tuberculous pachymeningitis and is discussed separately. * The remainder of this article pertains to leptomeningeal tuberculosis, which involves the arachnoid mater and pia mater. * Epidemiology * Tuberculous meningitis, although seen in all age groups, has a peak incidence in childhood (particularly 0-4 years of age) in high prevalence areas. In low prevalence areas, it is more frequently encountered in adolescents and adults. * Important risk factors include: * HIV/AIDS * immunosuppression * diabetes mellitus * alcoholism

Answer 62

* caused by an abnormality in the copper transport protein, CERULOPLASMIN. * AR inherritance * MRI appearance of the cns may be normal * T2hyperintense putamen and thalami * CT: low density BG * Hepatic cirrhosis * Giant panda face sign.

Answer 63

Perimesencephalic subarachnoid haemorrhage Dr Mostafa El-Feky◉ and Dr Laughlin Dawes et al. Perimesencephalic subarachnoid haemorrhage (PMSAH) is a distinct pattern of subarachnoid haemorrhage (SAH), which is centred on the basal cisterns around the midbrain. Epidemiology Perimesencephalic subarachnoid haemorrhage is rare with an incidence of 0.5 in 100 000 in adults 4. PMSAH represents 5-10% of all subarachnoid haemorrhages and ~33% of all non-aneurysmal SAH 3,4. Clinical presentation As per subarachnoid haemorrhage. Pathology Aetiology 95% of cases of perimesencephalic subarachnoid haemorrhage have a normal cerebral angiogram and the source of bleeding is not identified; the cause is thought to be a venous bleed. This is referred to as non-aneurysmal perimesencephalic SAH. The other 5% of cases are due to a vertebrobasilar aneurysm and the prognosis is worse 1,2. Rare causes include arteriovenous malformation, dural arteriovenous fistula, trauma and vascular tumours 4. Radiographic features CT Perimesencephalic subarachnoid haemorrhage has been defined as subarachnoid haemorrhage, which on CT within three days of symptom onset 4: is centred anteriorly to the pons and midbrain may extend into the basal and suprasellar cisterns and into the proximal/basal Sylvian fissure and interhemispheric fissure may settle as sediment in the occipital horns of the lateral ventricles but there is no overt intraventricular haemorrhage Specifically, there are criteria for non-aneurysmal perimesencephalic SAH, which if fulfilled, in the presence of a negative CTA negates the need for DSA 5: SAH in perimesencephalic cisterns anterior to midbrain if SAH extension into the anterior interhemispheric fissure, not extending into all of the fissure if SAH extension into the medial Sylvian fissures, not extending into the lateral fissure if layering interventricular extension, no frank intraventricular haemorrhage no intraparenchymal haemorrhage Treatment and prognosis CTA is recommended for perimesencephalic subarachnoid haemorrhage to investigate for possible aneurysmal cause. Overall, PMSAH has an excellent prognosis with better outcomes compared to aneurysmal SAH 1,2,4.

Answer 64

* AKA * borreliosis * WHAT * deer tick vector * Multisystemic inflam disease caused by a SPIROCHETE (Borrelia burgdorferi) * single or multiple parenchymal abnormalities a/w meningeal and cranial nerve enhancement. * MIMICs * MS * ADEM * Lesions may or may not enhance. * Lyme disease, also known as borreliosis, is a condition caused by the bacteria Borrelia burgdorferi, with infection being via the ixodid tick. Terminology * Controversy around Lyme disease centres on chronic infection with some authors doubting its existence 3. There are some terms that help differentiate these patients with non-specific symptoms of fatigue, myalgia, and arthralgia, from those with acute infection 3: * post-Lyme disease symptoms: symptoms for \<6 months * post-Lyme disease syndrome: disabling symptoms lasting for \>6 months * Epidemiology * Lyme disease is endemic in some areas of North America and Europe. * Clinical presentation * Three disease stages have been proposed manifesting after the tick bite 2: * stage 1: flu-like illness and enlarging skin lesion (erythema migrans) (2-30 days) * stage 2: cardiac and neurological symptoms (1-4 months) * stage 3: arthritis and neurological symptoms (many years) * Lyme disease has nonspecific symptoms with multisystemic involvement 1,2: * Pathology * Lyme disease caused by the bacteria Borrelia burgdorferi and is transmitted by the bite of the ticks Ixodes scapularis and Ixodes pacificus. * Disease manifestations can be multisystem and nonspecific includes 1,2,4,5: cutaneous: erythema migrans * CNS: peripheral neuropathy, radiculoneuropathy, myelopathy, encephalitis, meningitis, facial nerve palsy * cardiac: myopericarditis, cardiac arrhythmia * musculoskeletal: Lyme arthritis * Radiographic features * Intracranial MR imaging findings in patients with Lyme disease are rare 2. Where present, findings include: * foci of periventricular / subcortical T2 hyperintensity * nerve root enhancement * meningeal enhancement

Answer 65

* manifests as high out put CHD infants and hydrocephalus in older children * intro * the complex group of central AVM and resultant Varix of the vein of Galen * 1. VOG AVM * primary malf of VoG * Directr AV shunts involving embryologic venous precurse of the VOG/Median prosenceph vein of markowski * choroidal AVF with no nidus * Absence of normal VOG * median prosencephalic vein does no drain normal brain tissue

Answer 66

Radiotherapy induced microhaemorrhages A previously biopsied lesion at the posterior aspect of the left cingulate gyrus. Minor local mass effect only. Diffuse punctate foci of susceptibility are consistent with post treatment change. Case Discussion This patient has a left cingulate gyrus anaplastic astrocytoma diagnosed 12 years ago treated with radiotherapy. The tumour has been been gradually growing over that time. Prominent changes of radiotherapy are noted conforming to the radiation field with a sharp demarcation. Radiation induced microhaemorrhages are one of the most common complications of cranial radiotherapy and give you an insight into the part of the brain irradiated.

Answer 67

* Indistinguishable on radiology. Both may metastasize * INTRO * rare tumors that arise from the epithelium of choroid plexus * Age: \< 5 years * They commonly present as a solid vascular tumour with a vivid frond-like enhancement pattern. In a quarter of cases, speckled calcifications are present. * TYpes * Choroid plexus Papilloma * 90% * Choroid plexus carcinoma * 10% * Typical locations * Kids: trigone/atrium * Adults: 4th ventricle/CPA * METS * drop Mets to spinal cord * IMAGING Features * intraventricular mass * intense enhancement * ventricular dilatation secondary to CSF overproduction or obstruction * Calcifications 25% * Supratentorial tumors supplied by choroid arteries * Complications * hydrocephalus and * Drop mets * Choroid Plexus Papiloma . CLUES: - intraventricular Mass - Hydrocephalus - Young child - Fine speckled calcifications - Can have small flow voids . DON'T MISS - Drop mets . DDX - Atypical Choroid plexus papilloma - Choroid plexus Carcinoma - Choroid plexus met - if in the posterior fossa ddx include: - Medulloblastoma - ATRT - Ependymoma . DDx in Adults: - Central neurocytoma - intraventricular meningioma - Subependymoma - Ependymoma #radanatomy #radiology #RANZCRpart2exam #choroidplexuspapiloma

Answer 68

1. Subdural effusion (common in children and infants) 2. Empyema 3. Parenchymal extension. Abscess and cerebritis 4. Ventriculitis 5. Hydrocephalus (communicating \> non-communicating) 6. Venous infarctions secondary to venous thrombus

Answer 69

* INTRO * Mets are a common cause of dural mass But less common than brain mets and meningiomas * MIMICK * 'en Plaque' meningioma * Pathological processes * direct spread from Skull lesion * Haematogenous * Lymphatic * Retrograde seeding from vertebral venous Plexus * DDX (most common to less common) * breast * Prostate * Lung * H/N * Haem * Neuroblastoma * Gastric adenoca * Colon ca * GBM

Answer 70

* WHAT * yeast * cryptococosis neoformans * WHO * occurs in immunocomprisied hosts * HIV/AIDS * Contact with births * PRESENTATION * manifests as meningitis (more common) and intraparenchymal lesions * Three main presentations * 1: T2 hyperintense foci that suppress on FLAIR in Basal Ganglia and Midbrain * Gelatinous pseudocysts * "Soap Bubble appearance * 2. Focal masses with variable enhancement * crtocococcomas * 3. Meningitis