Egyptian Board Neurosurgery key terms

A 3-to-15 point score summing eye opening, verbal response and motor response, used to grade impaired consciousness after head injury and to detect deterioration over serial assessments.

CSF-filled spaces around the midbrain and pons seen on CT; effacement or blood within them signals raised intracranial pressure or subarachnoid haemorrhage.

Constriction of the pupil to light, carried by the afferent optic nerve and efferent oculomotor nerve; a fixed dilated pupil suggests ipsilateral uncal herniation.

Medial displacement of the temporal uncus over the tentorial edge, compressing the oculomotor nerve and midbrain, typically producing a blown pupil and contralateral hemiparesis.

The principle that the skull is a rigid container, so any increase in brain, blood or CSF volume must be offset by a decrease in another compartment or intracranial pressure rises.

Mean arterial pressure minus intracranial pressure; the driving pressure for cerebral blood flow, usually targeted above 60 mmHg in neurocritical care.

The pulsatile ICP trace with P1 (arterial), P2 (compliance) and P3 (venous) peaks; a rising P2 relative to P1 indicates poor intracranial compliance.

The intrinsic ability of cerebral arterioles to maintain near-constant blood flow across a range of mean arterial pressures, typically 50 to 150 mmHg in health.

A clinical scale from I to V grading severity of subarachnoid haemorrhage by headache, meningism, focal deficit and conscious level, used to guide timing of intervention.

A CT-based grading of subarachnoid and intraventricular blood thickness that predicts the risk of delayed cerebral ischaemia after aneurysmal haemorrhage.

Delayed narrowing of subarachnoid arteries, usually days 3 to 14 after aneurysmal haemorrhage, causing ischaemic deficits; distinguished from the earlier, reversible angiographic narrowing.

New focal deficit or infarction after subarachnoid haemorrhage not explained by other causes, the main treatable driver of poor outcome in survivors of the initial bleed.

An oral calcium channel blocker given after aneurysmal subarachnoid haemorrhage that improves outcome, though it acts more on microvascular and neuroprotective mechanisms than on large-vessel spasm.

Vascular fronds within the lateral, third and fourth ventricles that secrete most cerebrospinal fluid, the remainder coming from interstitial and ependymal sources.

Ventricular enlargement caused by impaired CSF absorption or flow outside the ventricular system, with free communication between ventricles and basal cisterns.

A syndrome of gait apraxia, urinary incontinence and cognitive decline with ventriculomegaly but normal measured CSF pressure; potentially reversible with shunt surgery.

The ratio of maximum frontal horn width to maximum inner skull diameter on imaging; a value above 0.3 supports a radiological diagnosis of ventriculomegaly.

The ciliated columnar epithelium lining the ventricular system, whose specialised regions include the choroid plexus and the circumventricular organs.

A tumour arising from ependymal cells, most often in the fourth ventricle in children or the spinal cord in adults; perivascular pseudorosettes are characteristic histology.

A malignant embryonal cerebellar tumour of childhood that frequently seeds the CSF pathways, requiring craniospinal irradiation and chemotherapy after maximal resection.

A low-grade glioma, most common in children, typically cystic with a mural nodule in the cerebellum; Rosenthal fibres and eosinophilic granular bodies are seen.

A mutation in isocitrate dehydrogenase genes found in most lower-grade adult gliomas and secondary glioblastomas, conferring a better prognosis than IDH-wildtype tumours.

The commonest malignant primary brain tumour in adults, an IDH-wildtype astrocytic glioma with necrosis or microvascular proliferation, treated by resection plus chemoradiotherapy.

New contrast enhancement and oedema on imaging shortly after chemoradiotherapy that mimics tumour growth but reflects treatment effect and often settles without change in therapy.

A usually benign extra-axial tumour arising from arachnoid cap cells, showing a dural tail and homogenous enhancement; Simpson grade describes extent of resection.

Thickening and enhancement of dura tapering away from an extra-axial mass on contrast MRI, classically seen with meningioma but not specific to it.

A five-point surgical grading of meningioma resection from complete excision of dura and bone to biopsy only, correlating with the risk of recurrence.

A focal ballooning of an intracranial artery wall, most often at branch points of the circle of Willis, which may rupture to cause subarachnoid haemorrhage.

A tangle of abnormal vessels with direct arterial-to-venous shunting and no intervening capillary bed, fed by enlarged arteries and drained by arterialised veins.

A scale scoring size, eloquence of adjacent brain and presence of deep venous drainage to estimate surgical risk of arteriovenous malformation resection.

Hypoperfused but still viable brain tissue around an infarct core that may be rescued by reperfusion, the target of thrombectomy and thrombolysis.

Removal of a skull flap to allow a swollen brain to expand and lower intracranial pressure, used in selected severe trauma and large hemispheric infarction.

Abnormal bone formation along the posterior longitudinal ligament, narrowing the cervical canal and causing progressive myelopathy, common in East Asian populations.

Progressive spinal cord dysfunction from degenerative disc and osteophyte compression in the cervical spine, producing gait disturbance, hand clumsiness and long-tract signs.

Flexion of the thumb and index finger when the middle fingernail is flicked, indicating corticospinal tract hyperreflexia, typically from cervical cord compression.

Transient flaccid paralysis, areflexia and loss of sphincter tone after acute spinal cord injury, followed later by spasticity as reflex arcs recover.

Hypotension with bradycardia and warm peripheries from loss of sympathetic tone after high spinal cord injury, treated with fluids and vasopressors.

Far-field recordings of waves I to V generated along the auditory pathway, used to monitor the eighth nerve and brainstem during skull base and posterior fossa surgery.

Cortical and subcortical responses to peripheral nerve stimulation used intraoperatively to detect injury to sensory pathways during spinal and brainstem surgery.

Muscle responses elicited by transcranial electrical stimulation of the motor cortex, used to monitor corticospinal integrity during spine and intramedullary tumour surgery.

The space between the cerebellum and pons containing cranial nerves V to XI, the internal auditory meatus and vessels; a common site for vestibular schwannoma and meningioma.

A benign tumour of Schwann cells on the vestibular division of the eighth nerve, causing progressive unilateral sensorineural hearing loss and tinnitus, with brainstem compression when large.

The network formed by ventral rami of C5 to T1 that gives rise to the major nerves of the upper limb; its roots, trunks, divisions and cords are defined surgically.

A reversible conduction block across a nerve without axonal loss, recovering spontaneously over days to weeks once compression or traction is relieved.

Median nerve compression beneath the transverse carpal ligament causing nocturnal numbness, thenar wasting and weakness; diagnosed by nerve conduction studies.

Selective intracarotid amobarbital injection that temporarily anaesthetises one hemisphere to establish language and memory lateralisation before epilepsy surgery.

Neuronal loss and gliosis of the hippocampus, the commonest pathology in temporal lobe epilepsy and a frequent target of anterior temporal resection.

Implantation of an electrode on the cervical vagus nerve with a chest generator to reduce seizure frequency in drug-resistant epilepsy not suitable for resection.

Stereotactic implantation of electrodes into targets such as the subthalamic nucleus or globus pallidus interna, delivering adjustable high-frequency stimulation to relieve movement disorder symptoms.

A rigid head-fixed coordinate system used to localise intracranial targets precisely for biopsy, electrode placement or radiosurgery, based on imaging-defined coordinates.

A radiosurgery device focusing multiple cobalt-60 beams on an intracranial target to deliver a single high ablative dose while sparing surrounding tissue.

Paroxysmal lancinating facial pain in a trigeminal division, often from vascular compression at the root entry zone; treated medically or by microvascular decompression.

A study allocating participants randomly to interventions to compare outcomes, the design least vulnerable to selection bias and the main basis for high-level evidence.

A structured, protocol-driven synthesis of all relevant studies on a question, often with meta-analysis, forming the top of the evidence hierarchy when well conducted.

The reciprocal of the absolute risk reduction; the number of patients who must receive an intervention for one additional favourable outcome.

A patient's voluntary authorisation of a procedure after receiving and understanding information on its nature, risks, benefits and alternatives, documented before surgery.