Anatomy and pattern recognition of the central nervous systemnormal radiographic appearances and pathology Flashcards

Question

Cerebral hemispheres

Answer 1

Hemispheric lateralisation There is a difference in function between the left and right hemispheres Left receives somatic sensory signals from and controls muscles of the right side of body Right receives somatic sensory signals from and controls muscles of the left side of body Normally the left hemisphere: Reasoning, Numerical and scientific skills Ability to use and understand sign language, Spoken and written language Normally right: Musical and artistic awareness, Space and patter perception Recognition of faces and emotional content of facial expression, Generating emotional content of language, Generating mental images to compare spatial relationship, Identifying and discriminating among odours.

Answer 2

Contains Tracts. Bundles of axons on the central nervous system Allows: Two hemispheres to connect and integrate ‘talk’ Association (arcuate) tracts: Commissural tracts: Projection tracts: Internal capsule Project activity to and from the CNS Contains the 3 Basal Nuclei/ganglia – Globus palilidus, Putamen and Caudate nucleus relays to/from the premoter and prefrontal cortex: influences movement, especially starting, stopping and ‘coordinated’ movement such as arm swinging. Produces the neurotransmitter dopamine.

Answer 3

Under the cerebrum 3 areas: Thalamus, Epithalamus and Hypothalamus Thalamus two groups of nuclei – fibres to and from the cerebrum. Receives all sensory input and relays virtually all fibres to the cerebrum. ‘Gateway’ to the cerebrum. Provides crude sensations of pleasant/unpleasant. Concerned with sleep and alertness

Answer 4

Forms the roof of the 3rd ventricle Connected to the pineal gland – secretes melatonin, regluates sleep/wake cycle with the hypothalamus. Provides connections with the limbic system ‘emotions and feelings’.

Answer 5

Below the … Main ‘visceral’ centre – vital to homeostasis Control centre for the autonomic nervous system and endocrine function Centre for emotional responses,thermoregulation, water balance and thirst, food intake, sleep/wake cycle.

Answer 6

Hypothalamus secretes hormones that stimulate the pituitary gland to secrete hormones that stimulate other endocrine glands to secrete hormones Position Sits in sella turcica Pea size and shape Attached to hypothalamus 2 major lobes Anterior pituitary (adenohypophysis) Posterior pituitary (neurohypophysis

Answer 7

Contains Midbrain, Pons varioli, and medulla oblongata Provides a pathway between the spinal cord and the cerebrum Contains 10 of 12 pairs of cranial nerves Essential for regulation of physiology essential for life Pathway between spinal cord+ brain.

Answer 8

Mid Brain: Relays auditory and visual information Pons: Relays sensory information between the cerebrum and cerebellum. Very important in regulating the rhythm of breathing

Answer 9

Medulla: blends into the spinal cord Contains essential motor nuclei such as: Cardiovascular centre, respiratory centres and Reflex centres of vomiting, coughing, sneezing and swallowing. Under influence of the hypothalamus Broadens out to form two pyramids ‘cones’ formed by the cortico-spinal tracts that descend from the motor cortex. These cross over just before reaching the medulla called ‘decussation of the pyramids’ before descending down the spinal cord.

Answer 10

Beneath and protruding under the cerebrum Processes input from the cerebral motor cortex, brain stem and peripheral sensory receptors. Provides spatial awareness, balance, precise timing and subconscious regulation of muscular movement (>600 named skeletal muscles).

Answer 11

Continuous with the medulla oblongata superiorly It is covered by meninges and bathed in CSF. Is larger in the cervical and lumbar regions. cervical enlargement (superiorly) supplies nerves to and from the upper limbs. lumbar enlargement (inferiorly) supplies nerves to and from the lower limbs. The cord typically extends down to the intervertebral disc between the 1st and 2nd lumbar vertebrae. Conus medullaris – narrowing below lumbar enlargement Cauda equina - below the conus medularis spinal nerves descent inferior to exit lower intervertebral foramina and have the appearance of a horses tail. The meninges extend down to 2nd sacral vertebra Filum terminale arises from the conus medularis.

Answer 12

Thumb width, a little flattened front to back with two grooves Anterior median fissure and posterior median sulcus Essentially dividing the cord into two connected halves Grey matter on the inside (core) white matter on the outside Gray matter looks like a capital H surrounded by columns of white fibres cross bar of H know as the transverse commissure Gray matter forms 2 anterior, 2 lateral and 2 posterior horns following the entire length of the cord In the centre of the grey matter is a central canal which contains cerebrospinal fluid

Answer 13

C3 and above: loss of diaphragm function –requires artificial ventilation C4 significant loss of use of biceps and shoulders C5 also loss of use of wrists and hands C6 limited wrist control, loss of hand control C7 and T1 some use if arms but limited, tends to represent a threshold for independent living T1-T8 intercostal and abdominal muscles affected Lumbar region effects on hips and legs

Answer 14

Vascular Stroke Subarachnoid, subdural, extradural haemorrhage Infections Meningitis Encephalitis Structural disorders Brain or spinal cord injury Brain or spinal cord tumours Seizure disorders Epilepsy Degeneration Parkinson's Alzheimer’s Autoimmune / inflammatory Multiple sclerosis Bells palsy Mental health disorders Schizophrenia Depression

Answer 15

Description Intracranial haemorrhage with blood in the subarachnoid space. Causes Risk factors include family history, hypertension, heavy alcohol consumption, connective tissue disorders, trauma, due to an aneurysm or AVM Symptoms Worst headache ever. Photophobia Diagnosis CT – generally done first. MRI – more sensitive and can look for causes. Identify where blood is coming from. Classified by fissures scale to see whether angiography or screening may be needed. Angiography – gold standard for diagnosis of vascular abnormalities Complications Increased intracranial pressure – may require shunt / drain Patients can develop neurogenic pulmonary oedema Can result in PEA (pulseless electronic activity) Treatment Depends on cause Differential diagnosis Meningitis Pre imaging = other causes of bleeding e.g. subdural / extradural haemorrhage

Answer 16

Description Blood within the subdural space between the dura and the arachnoid Generally look crescent shaped. Causes Mainly trauma Symptoms Unconscious or decreased conscious level Abnormal pupil reaction to light. Diagnosis Unilateral in adults, often bilateral in children CT – homogenous, hyper dense collection MRI – most sensitive standard sequence if FLAIR Complications Can be chronic in older patients Treatment Depends on size and effect on surrounding brain May watch and wait If large will surgically evacuate Differential diagnosis Subarachnoid haemorrhage Motion artefact

Answer 17

Hyperacute Phase (First Hour): Rarely imaged in this phase. Appearance: Isodense to the cortex with a "swirled" pattern (clot, serum, unclotted blood). May show cerebral swelling (common in younger patients, exacerbating mass effect). Acute Phase (0-3 Days): Classic Appearance: Crescent-shaped, homogeneously hyperdense collection over the hemisphere (>50-60 HU). Variations: Mixed density (hyper-/hypodense) due to unclotted blood, CSF, or clot retraction. May appear isodense if: Coagulopathies, severe anaemia, or anticoagulation present. Haematocrit fluid-fluid levels in coagulopathy cases. Subacute Phase (3-21 Days, Typical: 10-14 Days): Appearance: Density decreases to ~35-40 HU, becoming isodense with cortex (harder to detect). Clues to Identification: CSF-filled sulci fade before reaching the skull. Mass effect: sulcal effacement or midline shift. Apparent cortical thickening. Consider contrast-enhanced CT or MRI for better detection. Chronic Phase (≥3 Weeks): Appearance: Hypodense relative to the cortex (~0 HU), resembling CSF (mimics subdural hygroma). Shape: Crescentic, but may become biconvex. Rarely: Calcification along the periphery (calcified chronic subdural haematoma).

Answer 18

Description Acute haemorrhage between the dura mater and the skull. Very outer part of the brain. Increases intracranial pressure. Cause herniation, more cerebellum, react to skull fracture. Causes Skull trauma, most commonly with a fracture Symptoms History of head trauma with decreasing consciousness, nausea, pain Diagnosis CT head is the gold standard – ‘lemon shaped’ mass. May also see midline shift and brainstem herniation. MRI – not used acutely but may be useful for assessing contusions Complications Infection Cerebral ischaemia- tissue death Seizures Treatment Conservative Surgery – craniotomy Differential diagnosis Other intracranial haemorrhages. Simple skull fracture

Answer 19

Description Infection of the meninges Causes Bacterial or viral infection Symptoms Stiff neck, fever, headache, vomiting Diagnosis CSF analysis is required to confirm cause and plan treatment (spinal tap) CT is often performed pre spinal tap to assess for increased intracranial pressure or brain herniation / bleed MRI with contrast can demonstrate abnormal meningeal enhancement (seen in up to 50%). Can also exclude other causes Complications Seizures, long term disabilities, meningococcal meningitis can lead to loss of extremities Treatment Antibiotics Differential diagnosis Generally cause – bacterial, fungal or viral

Answer 20

Description Rare, many different types. Schwannoma – benign tumour of schwann cells – most common tumour of the peripheral nerves Causes Generally solitary and random May be linked to patients with neurofibromatosis type 2 Symptoms Local pain and nerve dysfunction Diagnosis MRI is the best imaging method. If in acute pain patients may have a CT Will see a well defined mass, may have a fatty appearance Rarely calcify Complications Slow growing Very rarely undergo malignant change Treatment Surgery Differential diagnosis Other causes of localised pain e.g. arthritis, degenerative changes.

Answer 21

Tumor Distribution: 1/3 Metastatic lesions. 1/3 Gliomas (from glial cells). 1/3 Non-glial tumors. Gliomas: Tumors originating from glial cells (e.g., astrocytes, oligodendrocytes, ependymal, choroid plexus cells). Astrocytomas are the most common glioma and are categorized into: Low-grade: Pilocytic type. Intermediate-grade: Anaplastic type. High-grade: Malignant glioblastoma multiforme (GBM). GBM is the most common glioma (50% of astrocytomas). Non-Glial Tumors: A diverse group, with meningioma being the most common. Update: Metastatic brain lesions now outnumber primary brain tumors due to improved cancer survival rates.

Answer 22

Description Neurodegenerative disease (60-80% of all dementias) Thought to be due to amyloid plaques which form in the brain and stop the neurons functioning correctly along with decreased production o acetylcholine Causes risk factors include age, female gender, hypertension Symptoms Memory deficits Diagnosis Generally done by clinical examination. CSF to exclude other causes CT can show cortical atrophy but not detailed MRI demonstrated atrophy better SPECT / PET – can help give a prognosis of decline Complications Progressive decline Treatment There are many drugs to slow or delay progress but no definitive cure. Differential diagnosis Other forms of dementia

Answer 23

Description Demyelinating disorder. There is destruction of normally myelinated structures Patients develop lesions in different areas of the brain and at different times Causes May be an infective link Symptoms depends on plaque location Diagnosis Generally clinical history, oligoclonal bands in the CSF and MRI findings CT – non specific and may look normal MRI – good for diagnosis and follow up to assess disease progression T1 – black holes (hypointense lesions) Complications Disease progression Treatment Prognosis varies widely from patient to patient Medicines aim to stop progression and provide symptomatic relief Differential diagnosis Other infections e.g. fungal, or spinal cord tumours

Anatomy and pattern recognition of the central nervous systemnormal radiographic appearances and pathology Flashcards

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