Pediatrics CNS Flashcards

Question

70) A 15-year-old girl with a history of multiple febrile convulsions as an infant presents to the neurologist with complex partial seizures. The episodes start with special and somatosensory aura followed by a wide-eyed stare with behavioural arrest, before finally proceeding to a generalized tonic-clonic seizure. MR imaging is requested. Which sequence is best to evaluate the temporal lobes for signs of mesial temporal sclerosis? a. axial T1W b. axial T2W c. axial FLAIR d. coronal T1W e. coronal T2W

Answer 1

e. coronal T2W Mesial temporal sclerosis is a pattern of hippocampal neuronal loss that can occur with long-standing temporal lobe epilepsy as a result of excessive neuronal depolarization leading to cytotoxic oedema. Three patterns of loss are described, with relative sparing of the CA2 subfield often a feature. The typical findings are of asymmetrical atrophy of the hippocampus with abnormally high signal returned on T2W images. Ipsilateral findings in the limbic system include atrophy of the fornix and maxillary body. Cortical abnormalities may exist in the temporal cortex, and this is best evaluated on high-resolution T1 sequences.

Answer 2

d. intraparenchymal haemorrhage Subependymal haemorrhage (grade 1) usually has no long-term consequence. Mortality rates for intraventricular haemorrhage, intraventricular haemorrhage with ventricular dilatation and intraparenchymal haemorrhage are 10%, 20% and more than 50%, respectively. These represent grades 2, 3 and 4 haemorrhage. Normal choroid plexus pulsates while haematoma at the same location is not pulsatile.

Answer 3

b. high T2 signal is masked by a low degree of myelination Neonatal hypoxic ischaemic encephalopathy occurs in 1-2/1000 live births. Clinically, it manifests as disturbed neurological function such as difficulty with respiration, abnormal tone, depressed reflexes, altered level of consciousness, feeding difficulties or seizures. Initial MRI findings, particularly in the first week of life, can be T1 shortening (bright) rather than a high T2 signal. This is because the unmyelinated white matter is brighter on T2W images and can disguise pathological lesions. T1 shortening is thought to be due to lipid breakdown products of damaged myelin or to mineralization.

Answer 4

b. scaphocephaly Craniosynostosis means premature closure of a suture of the skull, and skull growth is arrested in the direction perpendicular to the affected suture. Craniosynostosis of the sagittal suture therefore results in a head shape that is abnormally long and narrow and has the appearance of an upturned boat. This is called scaphocephaly (or dolichocephaly) and accounts for 60% of all craniosynostoses. Closure of the coronal suture accounts for 20% and results in a short, wide head called brachycephaly. Trigonocephaly is caused by craniosynostosis of the metopic suture and results in a forward-pointing head. Oxycephaly is the most extreme form, and all sutures may be affected, resulting in a high head. Plagiocephaly is unilateral craniosynostosis. Early recognition of all types is important to prevent permanent deformity and allow for surgical correction. Causes may be primary or secondary to dysplasia, a number of genetic syndromes, microcephaly, and metabolic or haematological conditions.

Answer 5

d. renal artery aneurysm Renal artery stenosis and aneurysms plus abdominal coarctation are associated with neurofibromatosis type 1 (NF1). Renal cysts are found in von Hippel–Lindau syndrome (VHL) and tuberous sclerosis, while renal cell carcinoma is found in VHL. NF1 and VHL are associated with phaeochromocytoma. Angiomyolipomas, usually multiple and bilateral, are found in 50% of cases of tuberous sclerosis.

Answer 6

c. branchial cleft cyst The described features are typical of a branchial cleft cyst arising from the second branchial cleft. The mass displaces the sternocleidomastoid posteriorly, and the carotid and internal jugular vessels posteromedially. The pointing between the internal and external carotid arteries is pathognomonic. Cystic hygromas present in infancy as a cystic mass in the posterior cervical space. Abscesses present with associated symptoms and a painful red swelling, though imaging findings may be similar. Carotid body tumours are solid, highly vascular masses lying between the internal and external carotid artery origins.

Answer 7

(b) CNS haemangioblastomas VHL is associated with CNS haemangioblastomas in 50%, pancreatic/ hepatic/ renal cysts, RCC, and phaeochromocytoma (10%). Phaeochromocytomas are also associated with MEN types 2A and 2B (also medullary thyroid cancer, parathyroid adenomas), NF-1, & TS. Bilateral acoustic neuromas are associated with NF-2.

Answer 8

(d) Enhancing, calcified cortical tubers The CNS features of tuberous sclerosis include: subependymal nodules which increase in number and calcification with time; parenchymal tubers which are non-enhancing and rarely calcified; hydrocephalus; giant cell astrocytomas; retinal phakomas; arterial ectasia.

Answer 9

(d) Hyperplastic falx A complex of anomalies secondary to a small posterior fossa. The falx is hypoplastic/ fenestrated, with concomitant gyral interdigitation. A summary of the major features: the 4th ventricle and brainstem are caudally displaced, there is tonsillar herniation, a myelomenigiocoele, syringohydromelia, dygenesis of the corpus callosum, obstructive hydrocephalus, absence of the septum pellucidum, and stenogyria.

Answer 10

(d) Scaphocephaly - sagittal suture The most common single suture affected is the sagittal suture (scaphocephaly), others include uni-coronal (anterior plagiocephaly), bi-coronal (brachycephaly), metoptic (trigonocephaly) and unilateral lambdoidal (posterior plagiocephaly). Craniosynostosis may be part of a syndrome, with multiple sutures involved, or secondary to drugs, metabolic disease, or other causes of microcephaly.

Answer 11

(c) Sturge-Weber syndrome Sturge-Weber syndrome is associated with a 'port-wine stain'' naevus in the distribution of the trigeminal nerve, tram-track gyral calcification (usually parietal lobe), ipsilateral choroid plexus enlargement, leptomeningeal venous angiomas, hemiparesis, seizures, mental retardation, glaucoma (30%) and choidoidal haemangiomas of the orbit.

Answer 12

(b) Dandy Walker variant The above is a description of Dandy Walker variant. By contrast, in Dandy Walker complex the cerebellar hemispheres and vermis are both absent or hypoplastic and the brainstem is compressed by a cyst. In mega cisterna magna, the cerebellum is normal and there is a simple dilatation of the CSF space posterior to the cerebellum.

Answer 13

(e) Mammillo-pontine distance of less than 1 cm Indicators of hydrocephalus include: dilatation of the recesses of the third ventricle, convexity of the third ventricle, expansion of the temporal horns, effacement of sulci, narrowing of the mamillopontine distance, and enlargement of the ventricles out of proportion to the sulcal dilatation. Specific MR findings include: transependymal CSF exudation (seen as high signal on FLAIR imaging), and accentuation of the aqueductal flow void in normal pressure hydrocephalus

Answer 14

(b) Extending between ECA/ICA Branchial cleft cyst is usually in the anterior triangle. The 'beak sign', where tissue points between the ICA and ECA is described as pathognomonic. Cystic hygroma is a single or multiloculated lymphangioma and is associated with chromosomal anomalies, including Turner's syndrome (coarctation in 15%). Both are high signal on T2, cystic hygroma may be low or high signal on T1 (depending on levels of lipid/ protein/ blood products).

Answer 15

(e) Germinal matrix haemorrhage Obstructive (non-communicating) causes are more common and include spina bifida, aqueduct stenosis, Dandy-Walker syndrome, Arnold-Chiari syndrome, meningocoele, and encephalocoele. Nonobstructive causes result from reduced reabsorption within the arachnoid granulation tissue, e.g. infection or haemorrhage, or increased CSF production e.g. choroid plexus papilloma; these can also cause obstructive hydrocephalus also.

Answer 16

(c) Large posterior fossa Dandy-Walker malformation results from congenital atresia of the foramina of Magendie and Luschka, leading to an enlarged posterior fossa, a large posterior fossa cyst, hydrocephalus and varying degrees of cerebellar hemisphere and verminian hypoplasia. Both have syringohydromyelia and hydrocephalus; Chiari II has a small posterior fossa; Chiari I is associated with Klippel-Feil.

Answer 17

(b) A Lisch nodule and an optic nerve glioma **corrected** At least two of the following seven criteria must be fulfilled for a diagnosis: > 6 cafe-au-lait spots, > 2 neurofibromas of any type (or one plexiform neurofibroma), freckling of the axillary or inguinal region, optic glioma, > 2 Lisch nodules, a distinctive osseous lesion such as sphenoid dysplasia or thinning of long bone cortex, a 1st -degree relative with NF-1.

Answer 18

(c) Von Hippe! Lindau syndrome VHL disease is an autosomal dominant neurocutaneous syndrome characterised by renal cell carcinomas, often multiple and bilateral along with cystic renal and pancreatic disease, phaeochromocytomas and spinal, cerebellar and optic nerve haemangioblastomas. The cerebellar lesions can present as ataxia.

Answer 19

(d) Cutaneous angiofibromas VHL is associated with CNS, haemangioblastomas, retinal angiomas, pancreatic cysts and carcinomas and phaeochromocytoma. In the kidney it is associated with the presence of RCC and multiple cysts. The renal cell tumours are usually of the clear cell type, and have a variable appearance depending on the degree of soft tissue involvement. Cutaneous angiofibromas are seen in tuberous sclerosis.

Answer 20

(c) Plagiocephaly The common craniosynostoses include:

Answer 21

(b) Grade II Grade I: subependymal haemorrhage, Grade II: intraventricular haemorrhage, no ventricular dilation (10% mortality), Grade Ill: intraventricular hemorrhage with ventricular dilation (20% mortality), Grade ·IV: intraparenchymal haemorrhage (>50% mortality). There is no Grade V.

Answer 22

(e) Myelomenigocoele Chiari I is herniation of the cerebellar tonsils below a line connecting the basion and opisthion. Unlike Chiari II, Ill and IV, Chiari I is not associated with myelomeningocoeles. Indeed, the condition is frequently isolated without supratentorial anomalies. As well as the listed associations, Chiari I occurs with: basiliar impression, craniovertebral fusion, and Klippel-Feil anomaly.

Answer 23

(b) Hypothyroidism Craniosynostosis is the premature closure of the sutures, which may be primary (idiopathic) or secondary. Secondary causes include: metabolic (rickets, hypercalcaemia, hyperthyroidism, hypervitaminosis D), haematological (thalassaemia, SCD), and bone dysplasias (achondroplasia, metaphyseal dysplasia). It is also associated with syndromes (Crouzon, Apert, Treacher-Collins), and can occur following shunt surgery for hydrocephalus.

Answer 24

(a) Optic pathway gliomas The patient fulfils the diagnostic criteria for Neurofibromatosis type 2. Unlike NF-1, there is no association with Usch nodules, skeletal dysplasia, optic pathway gliomas or vascular dysplasia.

Answer 25

(d) Cystic hygroma The commonest 'soft' neck masses in infants and children are lipomas, haemangiomas and cystic hygromas. The latter have low-tointermediate signal intensity on T1 W and high signal on T2W.

Answer 26

(d) Symmetrical distribution PVL is more common in preterm children, is secondary to ischaemia and usually occurs in the watershed areas. Initially there will be hyperechoic changes which gradually become cystic (>2 wks); the cysts are never septated and usually resolve over time. Porencephaly can be developmental or due to a vascular or infectious process which destroys brain tissue; it is almost always asymmetrical, rarely disappears over time and is often seen as an extension of the ventricle or sub-arachnoid space. If secondary to ischaemia it can also be in a watershed distribution.

Answer 27

(a) Alobar This is the most profound form of holoprosencephaly, where there is almost no separation of the cerebral hemispheres or ventricles. There is a 'horseshoe' configuration of neural tissue with a single crescentshaped ventricle. There is no 'bilobar' form of holoprosencephaly. Septo-optic dysplasia can be considered part of the holoprosencephaly spectrum.

Answer 28

(c) Head and neck Rhabdomyosarcoma represents 4-8% of cancers in children and is the 4th commonest after CNS tumours, neuroblastoma and Willl)'s and is the commonest soft tissue sarcoma in children. The sites affected are: head and neck (28%), extremities (24%), genitourinary system, trunk (11%), orbits (7%), and retroperitoneum (6%); other sites in <3%.

Answer 29

(e) Lobar holoprosencephaly The US features described are those of agenesis of the corpus callosum. Other associations include: alobar and semi-lobar forms of holoprosencephaly, midline intracerebral lipoma, polymicrogyria, grey matter heterotopia and porencephaly.

Answer 30

(a) Bone cysts The underlying condition described is tuberous sclerosis. The associated bone cysts most commonly affect the small bones of the hand. Other skeletal features include sclerotic bone islands which most commonly affect the calvarium (in 45% of cases) and also the pelvis and long bones.

Answer 31

(b) Encephalocoele Chiari II malformation comprises a small posterior fossa, herniation of the tonsils and vermis through the foramen magnum, myelomeningocoele (90%), obstructive hydrocephalus (90%), agenesis of the corpus callosum, syringohydromyelia (50%) and abnormal cortical gyration. Chiari Ill is rare, has the features of Chiari II, but with an associated encephalocoele. Chiari I is associated with Klippel-Feil anomaly.

Answer 32

(a) Aqueduct stenosis is the commonest cause Aqueduct stenosis accounts for 43% of congenital hydrocephus. US assessment is difficult <20 wks because the ventricles normally occupy a large percentage of the cranial vault. The most sensitive modality for determining the cause (not presence) of hydrocephalus is MRI. Grade III germinal matrix haemorrhage has hydrocephalus, but in 2/3 this is stable and requires no treatment. Intracranial anomalies are associated in 37% (e.g. agenesis corpus callosum), extracranial anomalies in 63% (e.g. VSD, spina bifida).

Answer 33

(d) Tuberous sclerosis and pial enhancement Tuberosis sclerosis is associated with, amongst other features: cortical tubers, subependymal nodules, giant cell astrocytomas, white matter lesions, retinal phakomas and vascular abnormalities.

Answer 34

(a) Myelocoele In the case above, if the ventral subarachnoid space were dilated, this would be more appropriately termed a myelomeningocoele. If the dorsal placode were continuous with a lipoma, continuous with the subcutaneous tissues, this would represent a lipomyelocoele.

Answer 35

(e) Present in the posterior triangle of the neck Branchial cleft cysts are derived from the 1st or (more commonly) the 2nd cervical pouch. These are usually anterior triangle lesions and of water CT attenuation (< 20 HU). Rim enhancement is seen in infected cysts.

Answer 36

(b) Chiari II malformation The patient has lower motor neurone signs in the upper limbs and upper motor neurone signs in the lower limbs. The most likely diagnosis is a syrinx (syringohydromyelia) within the cervical-cord. A Chiari II malformation is usually accompanied by a myelomeningocele, abnormal development of the cerebellar vermis and hydrocephalus. The herniated cerebellum blocks CSF circulation and leads to the formation of a syrinx within the Spinal cord.

Answer 37

8.a. Dandy-Walker malformation Dandy-Walker malformation is characterised by an enlarged posterior fossa (not seen in Dandy-Walker variant) with high-rising tentorium cerebelli, dys/agenesis of the cerebellar vermis (intact in megacisterna magna) and cystic dilatation of the fourth ventricle (normal in arachnoid cyst). Ventriculomegaly is also common.

Answer 38

16. c. Fibromatosis colli This is a rare form of infantile fibromatosis that occurs solely within the sternocleidomastoid muscle. In the vast majority it is associated with birth trauma (e.g. forceps delivery). This is thought to lead to compartment syndrome, pressure necrosis and secondary fibrosis of the muscle. It usually locates to the lower third of the muscle, between the sternal and clavicular heads, and is usually unilateral. Ultrasound may reveal a well- or ill-defined mass or may just show homogeneous muscle enlargement. In approximately two-thirds of individuals, the abnormality spontaneously regresses by the age of two. Expected ultrasonographic appearances of a haematoma include a heterogeneous mass of mixed cystic and solid components.

Answer 39

18. e. Second branchial cleft cyst Failure of involution of branchial clefts can lead to branchial cleft cysts, fistulae and/or sinuses. Second branchial cleft cysts account for 95% of all branchial cleft anomalies. Male and female incidence is equal and the typical age of presentation is 10–40 years. Second branchial cleft cysts are classified into four types depending on their location. The most common is type II, which occurs along the anterior surface of the sternocleidomastoid muscle, lateral to the carotid space and posterior to the submandibular gland adhering to the great vessels. On CT/MR the ‘beak sign’ is pathognomonic. This is a curved rim of tissue pointing medially between the internal and external carotid arteries.

Answer 40

29. e. Diffusion-weighted MRI The history and MRI findings are suggestive of Canavan disease. This is an autosomal recessive disorder due to deficiency of the enzyme aspartoacylase. Accumulation of N-acetylaspartic acid (NAA) in the brain pursues and leads to leukodystrophy. Histology reveals soft and gelatinous white matter. Change is most prominent in the deeper cortex and subcortical white matter, with relative sparing of the deeper white matter and internal capsule. On T2-weighted MRI, the globus pallidus is always of high signal intensity, with frequent involvement of the thalamus but with relative sparing of the caudate and putamen. The main differential diagnosis on imaging is Alexander disease, a rare disorder which shows no pattern of inheritance. Both conditions are leukodystrophies with macrocrania. Brain biopsy can be used to differentiate. Diagnosis of Canavan disease is also possible with proton MR spectroscopy which shows a characteristic increase in the NAA peak. Levels of NAA are also abnormally high in urine and there will be a deficiency of aspartoacyclase in cultured skin fibroblasts. Aspartoacyclase is not present in plasma or blood cells. Diffusion-weighted MRI will add little to the information already obtained with T2-weighted imaging.

Answer 41

32. d. Enhancing heterotopic grey matter All of the other features may be found in either condition. Giant cell astrocytomas located in the region of the foramen of Monro in tuberous sclerosis may degenerate into high-grade astrocytomas. Cortical tubers show as multiple nodules which are hyperintense on T2/FLAIR imaging. CNS hamartomas (occurring in up to 75-90% of NF1) also display these characteristics - they are often termed ‘unidentified bright objects’.

Answer 42

43. d. Adrenoleukodystrophy (ALD) ALD is an inherited metabolic disorder characterised by progressive demyelination of cerebral white matter. It is commonly X-linked recessive and boys present between the ages of 3 and 12 years with ataxia, deteriorating vision, hearing loss, altered behaviour and mental deterioration. It is associated with adrenal insufficiency (Addison’s disease). Predominantly, there is posterior white matter involvement with the disease advancing toward the frontal lobes and cerebellum. Imaging shows CT hypodensity, MR T1 hypointensity and T2 hyperintensity. Administration of contrast shows enhancement of the lateral margins of the lesions, indicating areas of active demyelination. Acute disseminated encephalomyelitis is an autoimmune reaction against the patient’s white matter. It may present within days or weeks following an exanthematous viral reaction or vaccination. Imaging demonstrates multifocal hypodense (CT)/hyperintense (T2 MRI), usually asymmetrical, white matter abnormalities. Corticosteroids result in dramatic improvement and follow-up scans show no additional lesions.

Answer 43

48. a. Schizencephaly The combination of absent septum pellucidum and optic nerve hypoplasia is indicative of septooptic dysplasia (SOD). Most patients present in infancy with visual disturbance, seizures or endocrine abnormalities (pituitary dysfunction is seen in approximately 50% of cases). Additional abnormalities are often present with schizencephaly being the most common (50%).

Answer 44

51. e. Coronal plane demonstrating volume loss and increased signal intensity of the hippocampus on T2-weighted imaging Mesial temporal sclerosis (hippocampal sclerosis) is the most common lesion associated with temporal lobe epilepsy. Acquisition in the coronal plane is mandatory for its detection. MRI typically shows volume loss and increased signal on T2-weighted imaging.

Answer 45

54. b. Sturge-Weber syndrome Sturge-Weber syndrome is a congenital disease characterised by capillary venous angiomas involving the face (port-wine stain, usually ophthalmic division of trigeminal nerve), choroid of the eye and leptomeninges. Clinical manifestations include focal seizures (80% in the first year of life), developmental delay, hemiparesis and homonymous hemianopia. Seizures typically become refractory to medication. Leptomeningeal angiomas are confined to the pia mater and occur primarily within the parieto-occipital region. There is cortical hemiatrophy beneath the angioma due to local anoxia and usually after the age of two years there is cortical calcification manifesting as low signal intensity on T1 post-contrast images. Other findings include enlargement of the ipsilateral choroid plexus, dilatation of the transparenchymal veins that communicate between the superficial and deep cerebral venous systems, and orbital choroidal haemangiomas.

Answer 46

D Sphenoid wing hypoplasia

Answer 47

B Brachycephaly is associated with a higher incidence of neurological abnormalities compared with scaphocephaly. The sagittal suture is the most commonly affected in primary craniosynostosis. Involvement of the coronal suture (in brachycephaly) is often associated with clinical syndromes.

Answer 48

B Dandy-Walker malformation The Dandy-Walker malformation describes variable hypoplasia of the cerebellar vermis and a large cystic collection which is continuous with the fourth ventricle in the posterior fossa.

Answer 49

A Adrenoleukodystrophy This is the most common leukodystrophy of children. Demyelination begins in the posterior central white matter and progresses to the corticospinal tracts and visual and auditory pathways. The leading edge shows enhancement due to active inflammation.

Answer 50

E Thalami If an infant suffers hypoxic damage at term, the areas most affected are those that are most metabolicaliy active. These include the putamen, thalami and adjacent white matter

Answer 51

A Craniosynostosis Chiari I may be acquired under conditions with raised intracranial pressure, decreased intraspinal pressure or decreased posterior fossa volume. Hydrocephalus and elongation of the medulla may be features but these are also seen in Chiari II. Myelomeningocoele and tectal beaking are features of Chiari II.

Answer 52

A Bilateral adrenal masses that yield a high signal on T2w sequences Phaeochromocytomas are hyperintense on T2w sequences and iso- or hypointense to the liver on Tlw sequences.

Answer 53

B Hypoplastic cerebellar vermis The Dandy Walker malformation is a cystic dilatation of the fourth ventricle. The main differential is a posterior fossa arachnoid cyst; however, this does not communicate with the fourth ventricle.

Answer 54

A Neurofibromatosis type 1 with optic nerve gliomas and cerebral hamartomas

Answer 55

A Atrophy of the left cerebral hemisphere with enhancement overlying the left parietal cortex and enlargement of the right choroid plexus The clinical history describes Sturge-Weber syndrome. The imaging findings include leptomeningeal angiomas on the same side as the facial port wine.

Answer 56

E Von Hippel Lindau disease (VHL) The cystic pancreatic lesion is likely to be a serous cystadenoma and, in combination with simple pancreatic and renal cysts, is consistent with VHL.

Answer 57

C Haemangioblastoma

Answer 58

ANSWER: A Standard radiographs for craniosynostosis assessment includes Townes’, AP and lateral projections.

Answer 59

A Calcified subependymal nodules Subependymal nodules are the most common neurological abnormality, seen in 85—95% of patients.

Answer 60

C On Tlw images, myelination will have almost reached adult maturity by imaging criteria During the first 6 months of life, brain maturation is easiest to follow on Tlw images, where the appearance of myelin is bright. By 10 months the Tlw images will have an almost adult appearance, and further changes are easier to assess using the T2w images.

Answer 61

E Tuberous sclerosis This patient has subependymal hamartomas (which can calcify) and a giant cell astrocytoma. Other CNS features include cortical tubers.

Answer 62

2. A. Periventricular leucomalacia. This refers to white matter necrosis, typically involving the centrum semiovale, and is seen in premature infants. This results from hypoxic-ischaemic injury at the watershed areas, which in premature infants are present in a periventricular location. Porencephaly refers to an area of encephalomalacia, which may or may not communicate with the ventricular system and develops postnatally or in the third trimester. This is the end result of a destructive process, such as an intraparenchymal haemorrhage. Sylvian fissure cysts are the most common site for supratentorial arachnoid cysts. Vein of Galen malformations occur in the midline and exhibit Doppler flow. Subependymal cysts are detected in the caudothalamic groove.

Answer 63

7. B. Enlargement of the posterior fossa. Dandy-Walker variant is more common, accounting for a third of all posterior fossa malformations, but less severe than the malformation. Enlargement of the posterior fossa is not a feature. Cystic dilatation of the fourth ventricle with vermian dysgenesis is characteristic of both. Associated CNS anomalies, usually of the midline, are also seen, as is ventriculomegaly, although both are more common with Dandy-Walker malformation.

Answer 64

7. E. Von Hippel-Lindau syndrome. This syndrome is characterized by retinal lesions variously described as being retinal angiomas, retinal haemangiomas, or retinal hamartomas. These lesions (Lindau tumours) cause retinal calcification, although this is also seen in NF-1 and tuberous sclerosis (TS) from other causes. The findings describe the classical appearance of a cerebellar haemangioblastoma. These lesions can also be entirely cystic or solid in a minority of cases. A signal void and lack of dural enhancement help differentiate this from other infratentorial masses in adults. Twenty per cent of haemangioblastomas are associated with Von Hippel-Lindau syndrome and 80% of Von Hippel-Lindau syndrome patients have this tumour. The spinal finding also indicates a further haemangioblastoma in the cord. Unlike in the posterior fossa, these seldom have flow voids, but are associated with the development of a syrinx.

Answer 65

21. D. Caudal displacement of the cerebellar tonsils. Chiari II is seen in all patients with open spinal dysraphisms, such myelomeningocoele. Lacunar skull (luckenshadel) is also associated with Chiari II. Cervicomedullary kinking is common to both, although more so with Chiari II. Caudal displacement of the cerebellar tonsils is a feature of Chiari I, whereas in Chiari II the vermis herniates into the foramen magnum and the tonsils are lateral to the medulla.

Answer 66

26. A. Intracerebral cleft lined by gray matter connecting the lateral ventricle to the subarachnoid space. Schizencephaly can be defined as open or closed lip, depending on the presence of separation of the cleft walls. The remaining options describe lissencephaly, polymicrogyria, transmantle heterotopia, and subcortical band heterotopia, respectively. Transmantle heterotopia can potentially be confused with closed lip schizencephaly.

Answer 67

31. C. Sturge Weber syndrome. The gyriform low T2WI signal corresponds to cortical calcification, which in association with unilateral atrophy and leptomeningeal enhancement is characteristic of Sturge Weber syndrome, one of the neurocutaneous phakomatoses. Other findings include calvarial thickening and choroid plexus angiomas. Associated facial port wine stain in the distribution of the trigeminal nerve is classic.

Answer 68

36. C. Anechoic cystic mass anterior to sternocleidomastoid near the angle of the mandible. The other options are typical locations for cystic hygroma, infantile haemangioma, thyroglossal cyst, and first branchial cleft cyst, respectively. The majority (75%) of branchial cleft cysts are remnants of the second branchial cleft. Cystic hygromas are lymphatic malformations (lymphangiomas) that result from blockage of lymphatic channels. Most present before 2 years of age. Most are slow growing, but can suddenly enlarge following infection or haemorrhage into the lesion. Infantile haemangiomas usually grow rapidly until 9-10 months of age, followed by spontaneous resolution, which can take up to 10 years. Thyroglossal cysts are remnants of the thyroglossal duct, which extends from the foramen caecum at the base of the tongue to the pyramidal lobe of the thyroid. The majority (65%) are infrahyoid.

Answer 69

E. All of the above. All the findings are manifestations of von Hippel–Lindau (VHL) disease. VHL is a rare, inherited, multisystem disorder characterized by the development of multiple benign and malignant neoplasms. It is an autosomal dominant disorder caused by inactivation of a tumour suppressor gene located on chromosome 3p25.5. The clinical manifestations are broad and include central nervous system (CNS) and retinal haemangioblastomas, renal cysts and tumours, pancreatic cysts and tumours, phaechromocytomas, endolymphatic sac tumours, and epididymal cystadenomas. The diagnostic criteria for VHL include: (i) >1 CNS haemangioblastoma, (ii) one CNS haemangioblastoma + visceral manifestations of VHL (iii) any manifestation + known family history of VHL. The most common causes of death in VHL are renal cell carcinoma and neurologic complications of cerebellar haemangioblastomas. Genetic counselling & screening are important in early detection & Rx of VHL lesions

Answer 70

41. B. Metachromatic leucodystrophy. Leucodystrophies are dysmyelinating inherited white matter diseases, which are secondary to lysosomal, peroxisomal, or mitochondrial dysfunction. Metachromatic leucodystrophy is caused by deficiency of the lysosomal enzyme ayrlsulfatase A. The ‘tigroid’ pattern relates to sparing of perivascular white matter. Table 5.1 outlines characteristic radiological findings of the major leucodystrophies.

Answer 71

43. A. Fibromatosis colli. Fibromatosis colli or pseudotumour of the sternocleidomastoid muscle is a benign self-limiting condition that occurs in the first 2–4 weeks of life. It is often associated with breech or forceps delivery. It is thought to result from pressure necrosis and subsequent fibrocollagenous infiltration of the sternocleidomastoid muscle. Typical presentation is with a firm and non-tender mass in the lower two-thirds of the sternocleidomastoid muscle. It may be associated with torticollis in approximately 20% of cases. It usually resolves spontaneously in the first year of life. Typical findings on ultrasound include focal or diffuse enlargement of the sternocleidomastoid with variable echogenicity. The clinical history and ultrasound appearances are so typical that no further investigation is usually necessary.

Answer 72

47. B. Sagittal suture. Craniosynostosis refers to premature closing of sutures and is often present at birth. It may be primary or secondary to bone dysplasias or haemoglobinopathy, or as part of a generalized syndrome. Scaphocephaly is the most common craniosynostosis and results in a long skull. Brachycephaly arises from bilateral closure of the coronal suture, resulting in a short, tall skull. Unilateral fusion of the lambdoid suture is seen in plagiocephaly, giving a lopsided skull. Trigonocephaly is a forward-pointing skull from premature closure of the metopic suture. Intrauterine closure of coronal, sagittal and lambdoid sutures gives rise to the cloverleaf skull, which may be associated with thanatophoric dysplasia.

Answer 73

54. E. Second branchial cleft cyst. The majority of branchial cleft anomalies arise from the second branchial cleft. The described findings are typical of a second branchial cleft cyst. Similar ultrasound appearances may be seen in a first branchial cleft cyst or a dermoid cyst. The anatomical location is the key to the diagnosis. Dermoid cysts are typically midline in location in the neck and first branchial cleft cysts are located in the region of parotid gland, external auditory canal, and angle of mandible. Lymphangiomas are typically located in the posterior triangle. On ultrasound, they appear multiloculated with intervening thin septa. Abscesses appear as ill-defined, irregular collections with thick walls and internal debris. Surrounding soft-tissue oedema, hyperaemia, and enlarged adjacent lymph nodes are also noted.

Answer 74

67. D. Optic nerve glioma. NF-1 is an autosomal dominant neurocutaneous disorder. The gene locus is located on 17q11.2. Diagnosis of NF-1 requires two or more of the following: six or more cafe-au-lait spots, two or more neurofibromas (or one plexiform neurofibroma), axillary/inguinal freckling, optic nerve glioma, sphenoid wing dysplasia or a first-degree relative with NF-1. The classic imaging appearance is multiple focal areas of white matter and deep gray matter signal abnormality. Other potential findings include intracranial stenoses and moyamoya type proliferation. NF-2 characteristically presents with multiple intracranial schwannomas, meningiomas and ependymomas (MISME). Bilateral vestibular schwannomas is diagnostic of NF-2.

Answer 75

68. A. Porencephalic cyst. Porencephaly is a congenital/acquired cystic cavity within the brain parenchyma with adjacent enlargement of the lateral ventricle. They develop in utero or early infancy. Arachnoid cysts are also CSF isointense, but are extra-axial, displacing the brain away from the adjacent skull. Ependymal cysts are intraventricular and the surrounding brain is usually normal. Schizencephaly is characterized by an intraparenchymal cleft extending from the ventricular surface to the brain surface lined by gray matter. Hydranencephaly results from an early destructive process of the developing brain. The cranial vault is CSF filled with absence of the cortical mantle and ventricles (water-bag brain). Death in infancy is typical.

Answer 76

71. E. Delayed sulcation. Signs of ACC include absence of the cavum septum pellucidum, colpocephaly, high-riding third ventricle, and widening of the inter-hemispheric fissure. ACC is reported to be isolated in <10% on foetal MR imaging. Sulcation delay is present in most foetuses with ACC (particularly those imaged at <30 weeks gestation), including those with good neurodevelopmental outcome, implying a global white matter dysgenesis. Periventricular nodular heterotopia and parenchymal T2WI signal hypointensity are usually seen in association with abnormal sulcal morphology. Associated posterior fossa abnormalities are also common, with cerebellar hemispheric abnormalities seen more than abnormalities of the vermis. Brainstem abnormalities typicallyoccur in association with a cerebellar abnormality.

Answer 77

71. D. Funnel-shaped aqueduct. Aqueductal stenosis is a focal reduction in aqueduct size, which can be congenital or acquired. Stenosis occurs at the level of the superior colliculi or at the intercollicular sulcus. The best diagnostic clue is a funnel-shaped aqueduct. There is resultant ballooning of the lateral and third ventricles. The fourth ventricle is normal distal to the obstruction. The most specific finding is lack of CSF flow through the aqueduct on phase contrast MRI. Other findings include thinning of the corpus callosum and downward displacement of the internal cerebral veins and third ventricular floor. In older patients it can present similarly to NPH. Imaging findings in NPH include ventriculomegaly (with relative sparing of the fourth ventricle) out of proportion to sulcal enlargement, with normal hippocampi. The aqueductal ‘flow-void’ sign reflects increased CSF velocity through the aqueduct, although this can be observed in normal individuals.

Answer 78

26 Answer B: Neurofibromatosis type 1 Involvement of the optic tracts is typically seen in NF-1. Histologically, most lesions are low-grade astrocytomas although 20% of chiasmal gliomas may behave aggressively. Imaging is best on MRI where lesions are usually hypo to isointense on Ti and hyperintense on T2 with variable contrast enhancement.

Answer 79

27 Answer D: Spinal cord The underlying condition is von Hippel-Lindau syndrome (VHL). Differentials for intra-axial cystic lesions in the posterior fossa in adults include metastases, haemangioblastoma, lymphoma and lipoma. Most haemangioblastomas occur sporadically while 10-20% occur in VHL. In VHL 75% of haemangioblastomas occur in the cerebellum and 25% in the spinal cord. Appearances in the spinal cord are those of a syrinx-like cyst with an isointense nodule that enhances strongly after contrast.

Answer 80

29 Answer C: Chiari II malformation Chiari II is the most common and serious complex of anomalies resulting from a small posterior fossa. Chiari I is not associated with a myelomeningocele and is an isolated hindbrain anomaly without supratentorial abnormalities. Chiari III is rare and thought to be unrelated to Chiari I and II. It is associated with occipital/ cervical meningomyelocele. Dandy-Walker is characterised by a large posterior fossa, vermian anomalies and cystic dilatation of the fourth ventricle.

Answer 81

30 Answer C: Dandy-Walker malformation Dandy-Walker malformations are characterised by a large posterior fossa, vermin anomalies and cystic dilatation of the fourth ventricle filling the entire posterior fossa. Midline CNS anomalies are seen in >60%. Differentials include a posterior fossa extra-axial cyst, arachnoid cyst and a mega cisterna magna.

Answer 82

31 Answer C: Neurofibroma The condition described is NF-1. Abnormalities within the spine occur in about 60% of patients. Most of these are secondary to a neurofibroma which maybe dumbbell shaped along an exiting nerve root. Lateral thoracic meningoceles are also known to occur. Meningiomas and ependymomas are more common in NF-2.

Answer 83

32 Answer E: Sturge-Weber syndrome Sturge-Weber syndrome is a sporadically occurring phakomatosis in which facial port wine naevi, leptomeningeal venous angiomatosis and orbital manifestations are described. Presentation is usually with seizures contralateral to the site of facial naevus. The underlying aetiology is probably an abnormality in the development of cortical venous drainage. Cortical atrophy, tram track gyral Ca, enhancing pial angioma and prominent draining veins may be seen.

Answer 84

Answer E: Serous cystadenoma of the pancreas A serous cystadenoma of the pancreas is a benign lobulated neoplasm composed of innumerable small cysts 1-20 mm. The mass is usually lobulated with a mean size of 5 cm. Any part of the pancreas can be affected but it has slight predominance for the head and neck. The pancreatic duct can be displaced, encased or obstructed. A prominent central stellate scar is characteristic and there is a known association with Von Hippel-Lindau syndrome.

Answer 85

34 Answer A: Decreased grey and white matter density, decreased grey/white matter differentiation and increased density of the basal ganglia, thalami and cerebellum The `reversal' sign occurs in hypoxic ischaemic cerebral injury. It carries a poor prognosis. There is a high association with non-accidental injury, but it can also result from events such as significant accidental trauma, near drowning, cardiac arrest, status asthmaticus and status epilepticus.

Answer 86

46 Answer B: Subependymal giant cell astrocytoma Fifteen per cent of patients with tuberous sclerosis develop subependymalastrocytomas. They typically occur at the foramen of Monro and are usually a well-defined rounded mass with some calcification. They usually enhance uniformly with contrast and can degrade to a high-grade astrocytoma. Ninety-five per cent of tuberous sclerosis patients have subependymal hamartomas. These occur in the periventricular region, are isointense to white matter on Ti and calcified on CT. Fifty-five per cent of patients have cortical tubers, which are high signal on T2-weighted imaging.

Answer 87

50 Answer A: 2 months Myelination occurs through the infant's brain and peripheral nervous system from caudal to cranial and from posterior to anterior. Myelination milestones: * term birth - brainstem, cerebellum, posterior limb of the internal capsule * 2 months - anterior limb of the internal capsule * 3 month - splenium of corpus callosum * 6 months - gems of corpus callosum.

Answer 88

57 Answer B: Tuberous sclerosis The description is of multiple bilateral large angiomyolipomas, which occur in 80% of patients with tuberous sclerosis, usually presenting by the age of 10 years. AML are also associated with neurofibromatosis type 1 and VHL disease.

Answer 89

5 Answer C: III The diagnosis is a second branchial cleft cyst. The internal structure is from haemorrhage or infection. The Bailey classification is: I Along anterior surface of the sternocleidomastoid, just deep to the platysma II Along anterior surface of sternocleidomastoid, lateral to carotid space, posterior to submandibular gland and adherent to vessels III Extends medially between the internal and external carotid arteries to the lateral pharyngeal wall IV Within pharyngeal mucosal space. Type II is the most common.

Answer 90

9 Answer E: Bilateral choanal atresia Choanal atresia is failure of perforation of the oronasal membrane. Bilateral choanal atresia is a paediatric emergency because babies are obligate nasal breathers until two to six months. The septation is either bony (85%) or membranous (15 %). The bilateral form is slightly more common. It is associated with other congenital anomalies such as malrotation, DiGeorge syndrome and foetal alcohol syndrome. With bilateral disease babies are intubated and endoscopic perforation is performed.

Answer 91

20 Answer A: Sinus hypoplasia All the conditions can cause opacification of the maxillary sinus. Sinus hypoplasia is the most likely answer given the CT features. Maxillary dentigerous cyst contains a tooth or crown whereas primordial dentigerous cyst does not. In acute sinusitis one would expect an air/fluid level in radiological investigations representing the disease process. Classical CT findings of ameloblastoma are of multilocular lesion with scalloped borders on a background of diffuse groundglass changes within the bone.

Answer 92

25 Answer C: Corpus callosum agenesis Agenesis of the corpus callosum can be partial or complete. The rostrum and splenium are absent or hypoplastic in the partial variety. Widely separated lateral ventricles, with longitudinal white matter mater tracts (Probst bundles) indenting the medial margins of the lateral ventricles and dilated occipital horns (col- pocephaly) are seen. Associated abnormalities include Chiari II, Dandy-Walker malformation, migration disorders and lipomas.

Answer 93

26 Answer A: Schizencephaly Schizencephaly describes a full thickness CSF cleft lined by grey matter extending from the subarachnoid space to the subependyma of the lateral ventricle. This can be either open lipped (the walls of the cleft are separated) or closed lipped (the walls are opposed). The clefts may be unilateral or bilateral and asymmetric. The important differential is porencephalic cyst, which results from insult to a normally developed brain.

Answer 94

27 Answer C: Bilateral nodular subependymal grey matter Heterotopic grey matter occurs secondary to developmental arrest of migrating neuroblasts from the ventricular walls to the surface of the brain. Nodular and laminar forms are described. Signal is isointense to grey matter on all sequences.

Answer 95

29 Answer E: Scaphocephaly Craniostenosis is the premature closure of sutures. At birth all sutures are normally open. Typically, only one suture is fused but in a quarter of cases more than one fuses. Early fusion results in an abnormally shaped head. Boys are more commonly affected and it may be part of a syndrome. Scaphocephaly is the premature fusion of the sagittal suture, is the most common and leads to a long thin head. Brachycephaly is premature fusion of the lambdoid or coronal suture producing a short wide head. Plagiocephaly is unilateral fusion of the coronal and lambdoid suture producing a lopsided skull. Trigonocephaly is the fusion of the metopic suture producing a forward-pointing skull. A cloverleaf skull typically occurs in thanatophoric dysplasia and is due to premature closure of the sagittal, coronal and lambdoid suture.

Answer 96

30 Answer C: Transsphenoidal encephalocele This patient has a transsphenoidal or basal encephalocele. Basal encephaloceles account for 10% of all encephaloceles. They typically present with a soft-tissue mass within the nasal cavity, which can increase in size during the Valsalva manoeuvre. Affected patients may be obligate mouth breathers due to nasal obstruction. It is associated with agenesis of the corpus callosum, pituitary and hypothalamic dysfunction and hypoplasia of the optic nerves.

Answer 97

31 Answer D: Atrophy of the amygdala This boy has mesial temporal sclerosis, which is characterised by atrophy of the hippocampus, and high signal on T2-weighted MRI. There is also loss of the normal interdigitation of the hippocampal head. It is associated with atrophy of the ipsilateral mammillary bodies and fornix

Answer 98

6 Answer A: Intraventricular haemorrhage with ventricular dilatation, 20% mortality The grading system is: 1 Subependymal haemorrhage, no long-term abnormality 2 Intraventricular haemorrhage without ventricular dilatation, 10% mortality 3 Intraventricular haemorrhage with ventricular dilatation, 20% mortality 4 Intraparenchymal haemorrhage, 50% mortality.

Answer 99

11 Answer A: Giant cell astrocytoma The diagnosis is tuberous sclerosis. It usually presents with a classic triad of facial angiofibroma, epileptic seizures (these are usually the first sign but decrease in frequency with age) and mental retardation. There are a number of associated CNS abnormalities: subependymal hamartomas, giant cell astrocytomas, cortical/ subcortical tubers and heterotopic grey matter islands in the white matter.

Answer 100

19 Answer E: Agenesis of the corpus callosum Dandy-Walker malformation is characterised by an enlarged posterior fossa with a high tentorium, agenesis or hypoplastic cerebellar vermis and cystic dilatation of the fourth ventricle. It is associated with other CNS abnormalities: 20-25% have dysgenesis or agenesis of the corpus callosum, 25% have holoprosencephaly and 25% have malformation of the cerebral gyri.

Answer 101

25 Answer B: Septum pellucidum This patient has holoprosencephaly, which is always associated with an absent septum pellucidum. Holoprosencephaly is a failure or incomplete cleavage of the cerebral hemispheres. There are three types: ➢ alobar - the most severe form, which typically results in death below one year of age. There is a large single ventricle with a peripheral layer of cerebral cortex. No third ventricle, falx cerebri, interhemispheric fissure, corpus callosum, septum pellucidum, olfactory or optic nerves are present. The thalami are fused ➢ semilobar - is a milder form and children may reach adulthood. There is a single ventricle with partially formed occipital horns and minimally developed temporal horns. There is partial fusion of the thalami, a small third ventricle and rudimentary falx cerebri ➢ lobar - mildest form where there is separation of the cerebral hemispheres. There are two cerebral hemispheres and 2 lateral ventricles. The frontal lobes are dysplastic and there is a single fused frontal horn. The thalami are separated.

Answer 102

26 Answer D: Ipsilateral enlargement of the choroid plexus This child has Sturge-Weber-Dimitri syndrome, which is associated with a facial port wine stain (telangiectasia of the trigeminal nerve) and a leptomeningeal venous angioma. The leptomeningeal venous angioma is most commonly in the parietal lobe. It is associated with atrophy of the underlying cortex, thickening of the overlying skull vault and enlargement of the choroid plexus. There is gyriform cortical calcification, which can sometimes be seen on plain film. Angiomas may be seen in most visceral organs of the body.

Answer 103

27 Answer A: Open-lipped schizencephaly Schizencephaly is a cleft extending from the lateral ventricle to the cortex that is lined with grey matter. There are two types of schizencephaly: open-lipped and closed-lip. Closed-lip describes the apposition of the two sides of the cleft while in open lip there is CSF separating the two sides. Schizencephaly is caused by abnormal neuronal migration due to an in utero ischaemic insult in the germinal matrix at between 30 and 60 days' gestation. Ninety per cent of schizencephaly is associated with an absent septum pellucidum. It can also be associated with abnormalities to the optic nerve in septo-optic dysplasia.

Answer 104

29 Answer A: Periventricular leukomalacia Risk factors for germinal matrix haemorrhage are prematurity (less than 3 2 weeks), low birth weight, males, multiple births, prolonged labour and cyanotic heart disease. It typically occurs within the first two days of birth. The germinal matrix lies in the caudothalamic groove and is very metabolically active which makes it sensitive to low levels of oxygen. There are four grades of intraventricular haemorrhage as shown in the table below. A common finding in premature babies is flare within the periventricular white matter. Periventricular leukomalacia is the sequelae of ischaemia in the watershed areas, eventually the cystic areas are reabsorbed and ventriculomegaly occurs.

Answer 105

29 Answer E: Spina bifida Spina bifida is associated with Arnold-Chiari malformation in 90% and the ultrasound findings of Arnold-Chiari malformation include hydrocephalus, abnormally pointed frontoparietal region (lemon sign) and abnormally shaped cerebellum (banana sign).

Answer 106

30 Answer D: Neural tube defect The banana and lemon sign are seen on ultrasound in patients with neural tube defects. The head appears lemon shaped at the level of the lateral ventricles due to bilateral indentation of the frontal lobe cortex, which is typically seen before 24 weeks. The banana sign is obliteration of the posterior fossa and herniation of the cerebellum.

Answer 107

32 Answer A: Dandy-Walker malformation Dandy-Walker malformation is characterised by an enlarged posterior fossa with a high tentorium, agenesis or abnormal cerebellar vermis and cystic dilatation of the fourth ventricle. An arachnoid cyst is an ultrasound differential for Dandy-Walker but the anatomy and source of the cystic structure should be evident on CT. This child is too young and displaying incorrect symptoms for a diagnosis of epidermoid cyst. The cyst fluid in an astrocytoma is denser than CSF and shows some degree of solid tumour thus allowing differentiation.

Answer 108

42 Answer D: Leptomeningeal cyst A leptomeningeal cyst or `growing fracture' occurs in 1 % of all paediatric skull fractures. It is seen in fractures associated with dural tears where arachnoid herniation and CSF pulsations produce fracture diastasis. Typical appearance is of a skull defect with indistinct scalloped bony margins usually evident two to three months after the injury. Gliosis of the adjacent brain parenchyma is common.

Answer 109

44 Answer C: Thickening of the vomer The diagnosis is choanal atresia, which is the commonest cause of neonatal nasal obstruction. This is a life-threatening condition, which is more commonly bilateral. It usually presents with respiratory distress, as babies are obligate nasal breathers. Bony septations are present in 85-90% of cases, the remainder being membranous septations. Further imaging findings include inward bowing of the posterior maxilla and narrowing of the posterior choanae to <3.4mm in a child less than two years.

Answer 110

47 Answer D: A single central nervous system haemangioblastoma Criteria for diagnosis of VHL disease include: (1) more than one central nervous system haemangioblastoma, (2) one central nervous system haemangioblastoma and any visceral manifestations of VHL disease, and (3) any manifestation and a family history of VHL disease.

Answer 111

51 Answer E. Repetitive subarachnoid microhaemorrhage The most common cause of communicating hydrocephalus is repetitive subarachnoid microhaemorrhage mainly due to repetitive trauma. The other causes are less frequent but can cause hydrocephalus.

Answer 112

54 Answer A: Optic nerve glioma Tuberous sclerosis, neurofibromatosis one and two, von Hippel-Lindau, SturgeWeber and hereditary haemorrhagic telangiectasia are all neurocutaneous disorders. The cutaneous lesions suggest this patient has neurofibromatosis type one (NF1). Other cutaneous manifestations of NF1 are neurofibromas and iris hamartomas. Optic nerve gliomas are seen in up to 30% of 1-M. In 1-F2 the main cutaneous finding is cafe an laic spots. In patients with tuberous sclerosis there is adenoma sebaceum, shagreen patches and subungual fibrosis. In hereditary haemorrhagic telangiectasia there are cutaneous telangiectasia on the face and freckles on the lips. A port wine stain is seen in the distribution of a branch of the trigeminal nerve in Sturge-Weber.

Answer 113

57 Answer B: Syringomyelia The condition described is Chiari II. This is associated with syringomyelia in 20% and hydromyelia (50%). Hydromyelia is distension of the central canal, while syringomyelia is CSF dissection through the ependymal lining to form a paracentral cavity. Imaging appearances are indistinguishable and the entity is often grouped together as syringohydromyelia. Syrinxes also occur in Chiari I and can be associated with spinal trauma, intramedullary tumours and extramedullary compressive lesions.

Answer 114

(a) Tuberous sclerosis The classical triad is adenoma sebaceum, mental retardation and seizures. Patients also commonly have bilateral renal angiomyolipomas.

Answer 115

7. (b) Tuberous sclerosis This is one of the phacomatoses with the classical triad of seizures, adenoma sebaceum and mental retardation. Other findings include hamartoma of kidney (angiomyolipomas), heart (rhabdomyoma) and brain (tubers). These CNS findings are typical and tubers are seen in the subependymal region, subcortical white matter and cortex. These commonly calcify. Sturge-Weber syndrome is characterised by multiple angiomatosis in face, eyes and leptomeninges. Sarcoidosis often affects the meninges, peripheral nerves and patients may have multiple sclerosis like symptoms. Klippel-Trenaunay syndrome presents with port-wine naevus, gigantism and varicose veins in affected limb. Neurofibromatosis type 2 is characterised by bilateral schwannomas, meningiomas and ependymomas.

Answer 116

9. (d) Sturge-Weber syndrome This is characterised by angiomatosis in the meninges, face and eyes. Meningeal angiomas result in cortical atrophy underneath due to hypoxia. Calcifications are seen in the underlying gyri and ipsilateral choroid plexus thickening is also seen. Retinal angiomas can lead to retinal detachment.

Answer 117

16. (b) Chiari type II malformation There is displacement of the fourth ventricle, brainstem and cerebellum into the cervical spinal canal and it is almost always associated with myelomeningocele. Other findings may include beaked tectum, fenestration of falx, hydrocephalus, colpocephaly and dysgenesis of corpus callosum. Chiari type I may show benign cerebellar ectopia up to 5 mm below foramen magnum. There is no hydrocephalus or meningomyelocele. Alobar holoprosencephaly shows a large single ventricle without occipital or temporal horns. There is no hemispheric development of the brain. Hydranencephaly represents liquefaction of cerebral hemispheres, which are replaced with cerebrospinal fluid, leptomeninges sac and remnants of cortex. Dandy-Walker malformation is characterised by an enlarged posterior fossa, dysgenesis of cerebellar vermis and dilatation of 3rd ventricle.

Answer 118

16. (b) Agenesis of corpus callosum This is associated with parallel, widely spaced lateral ventricles that may appear crescent shaped. There is dilatation of trigones and the occipital horn of lateral ventricles, along with a high riding 3rd ventricle. Callosal agenesis is associated with Dandy-Walker syndrome, Chiari malformations and fetal alcohol syndrome.

Answer 119

22. (a) Chiari I malformation Chiari I malformation is characterised by cerebellar ectopia and is frequently an isolated hindbrain abnormality without supratentorial abnormalities. 20-30% of cases are associated with syringomyelia.

Answer 120

23. (a) Aqueduct stenosis There are various causes for aqueductal stenosis, however the imaging features of this condition are dilated lateral and third ventricles with a normal 4th ventricle. This is the most frequent cause of congenital hydrocephalus. Its aetiology may be classified as post-inflammatory (commonest), congenital or neoplastic (rare).

Answer 121

24. (b) Dandy-Walker malformation These are the typical features seen in Dandy-Walker malformation.

Answer 122

29. (a) Neurofibromatosis type 1 This is the most common type of neurocutaneous disorder. Common lesions encountered include café au lait spots, peripheral nerve neurofibromatosis, optic nerve glioma, iris hamartomas, axillary and inguinal freckling, bony abnormalities, pseudoarthrosis, scoliosis and duct ectasias. It is also associated with malignancies including astrocytoma, malignant nerve sheath tumours, Wilms’ tumour, Rhabdomyosarcoma, leukaemia, thyroid carcinoma and pheochromocytoma.

Answer 123

47. (b) Sturge–Weber–Dimitri syndrome This is characterised by multiple vascular malformations in the face (‘port-wine stain’) and central nervous system (leptomeningeal V.angiomas), orbital and visceral angiomatosis (intestine, kidneys, spleen, thyroid, pancreas, lungs).

Answer 124

49. (c) Subependymal haemorrhage with ventricular dilatation The DD is from a normal choroid plexus. However, if the blood fills the ventricle then the diagnosis is easy.

Answer 125

Answers: (a) Correct (b) Not correct (c) Not correct (d) Not correct (e) Correct Explanation: In tuberous sclerosis subependymal nodules are most common along ventricular surface of caudate nucleus, with cortical tubers which are most prominent on T2W and FLAIR. Giant cell astrocytoma is a complication.

Answer 126

Answers: (a) Correct (b) Not correct (c) Correct (d) Not correct (e) Correct Explanation: In Sturge-Weber syndrome, lepto-meningeal angiomas are seen on ipsilateral side and angiomas are more common over parieto-occipital region.

Answer 127

Answers: (a) Correct (b) Correct (c) Correct (d) Correct (e) Correct Explanation: Dysgenesis of the corpus callosum may be complete (agenesis) or partial and represents an in utero developmental anomaly. There appears to be a male predilection (M:F ~2:1). Maternal alcohol consumption during pregnancy has been recognized as another risk factor.

Answer 128

Answers: (a) Correct (b) Not correct (c) Not correct (d) Not correct e) Correct Explanation: Renal angiomas cannot be distinguished from renal cell carcinoma on imaging. In VHL renal impairment is uncommon and renal cell carcinomas are usually bilateral and multicenteric.

Answer 129

Answers: (a) Not correct (b) Correct (c) Not correct (d) Correct (e) Not correct Explanation: Dandy Walker malformation is the most common posterior fossa malformation and consists of a triad of hypoplasia of vermis with cephalad rotation of vermis remnant, cystic dilatation of fourth ventricle and enlarged posterior fossa. There is superior displacement of vein of Galen.

Answer 130

Answers: (a) Not correct (b) Correct (c) Not correct (d) Not correct (e) Correct Explanation: In normal physiology, cerebellar tonsils ascend with increasing age. In Chiari 1, there is downward displacement of tonsils below the foramen magnum by more than 5 mm. It is usually associated with spinal cord and skull base abnormalities rather than other brain anomalies.

Answer 131

Answers: (a) Not correct (b) Not correct (c) Correct (d) Not correct (e) Correct Explanation: In tuberous sclerosis, the cortical tubers are seen in 95% of patients although enhancement is seen in less than 5% of tubers. 30-80% of all subependymal nodules enhance after intravenous contrast but it does not indicate malignant transformation. Renal Angiomyolipomas are seen in 40-80% of cases of tuberous sclerosis.

Pediatrics CNS Flashcards

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