Iraqi Board Neurosurgery key terms

Principle stating that the skull is a rigid container holding brain, blood, and cerebrospinal fluid at constant total volume, so any increase in one compartment must be offset by a decrease in another or intracranial pressure rises.

The pressure gradient driving blood flow through the brain, calculated as mean arterial pressure minus intracranial pressure; it guides blood pressure targets in head injury and neurocritical care.

The change in intracranial volume produced per unit change in intracranial pressure; low compliance means small added volume causes steep pressure rises, as seen with mass lesions or brain swelling.

A 3-to-15 point score summing eye opening, verbal response, and motor response, used to grade level of consciousness after head injury and to define severity as mild, moderate, or severe.

Traumatic shearing of white matter tracts from rotational acceleration-deceleration, producing immediate coma with punctate haemorrhages at grey-white junctions, corpus callosum, and brainstem on MRI.

Blood collected between skull and dura, usually from a torn middle meningeal artery after temporal bone fracture, appearing biconvex on CT and requiring urgent evacuation before transtentorial herniation.

Blood between dura and arachnoid, typically from torn bridging cortical veins, appearing crescent-shaped on CT; acute forms cause mass effect while chronic forms present with progressive headache and confusion.

Displacement of midline brain structures measured on CT, indicating unilateral mass effect; significant shift with altered consciousness suggests herniation risk and need for surgical decompression.

Downward displacement of temporal lobe uncus through the tentorial opening, compressing the oculomotor nerve and brainstem to cause ipsilateral dilated pupil followed by contralateral weakness and coma.

Placement of an intraventricular catheter or parenchymal transducer to continuously measure intracranial pressure and guide treatment of raised pressure, typically after severe traumatic brain injury.

The intrinsic ability of cerebral arterioles to dilate and constrict so that blood flow stays relatively constant across a range of mean arterial pressures, a mechanism often impaired after trauma or ischaemia.

Abnormal accumulation of water in brain tissue, either cytotoxic from cellular swelling or vasogenic from blood-brain barrier breakdown, causing raised intracranial pressure and mass effect.

Enlargement of the ventricular system from disturbed cerebrospinal fluid production, flow, or absorption, classified as obstructive or communicating and often treated with shunt or endoscopic third ventriculostomy.

A treatable syndrome of ventricular enlargement with normal measured pressure, presenting with gait disturbance, urinary incontinence, and cognitive decline, often responding to cerebrospinal fluid diversion.

A minimally invasive operation creating a stoma in the floor of the third ventricle so cerebrospinal fluid bypasses an obstruction and reaches the basal cisterns, avoiding shunt implantation.

Congenital downward displacement of cerebellar tonsils through the foramen magnum, causing headache on straining and sometimes syringomyelia or brainstem compression; type II accompanies myelomeningocele.

A fluid-filled cavity within the spinal cord that expands and damages crossing spinothalamic fibres, producing cape-like loss of pain and temperature sensation, often associated with Chiari malformation.

Abnormal fixation of the spinal cord by a thickened filum terminale or other lesion, restricting normal ascent and causing progressive leg weakness, sensory loss, and bladder dysfunction.

A congenital neural tube defect in which the spinal cord and meninges protrude through an unfused vertebral arch, requiring early surgical closure and often associated with hydrocephalus and Chiari II malformation.

Premature fusion of one or more cranial sutures, producing an abnormal head shape and potentially raised intracranial pressure or restricted brain growth; surgical cranial remodelling is the treatment.

A focal outpouching of an intracranial artery wall, most often at branch points of the circle of Willis, which may rupture to cause subarachnoid haemorrhage or be treated by clipping or coiling.

Bleeding into the space between arachnoid and pia, classically from a ruptured aneurysm, presenting with sudden severe headache and complicated by vasospasm, rebleeding, and hydrocephalus.

Delayed narrowing of cerebral arteries after subarachnoid haemorrhage, typically days 3 to 14, causing ischaemic deficits and managed with nimodipine and haemodynamic support.

A tangle of abnormal arteries and veins lacking an intervening capillary bed, creating high-flow shunts that may bleed, seize, or steal flow; treated by resection, embolisation, or radiosurgery.

A low-flow cluster of thin-walled vascular channels without intervening brain tissue, appearing as a popcorn lesion with haemosiderin rim on MRI and causing seizures or recurrent small haemorrhages.

Progressive stenosis of distal internal carotid arteries with compensatory fragile collateral vessels, causing strokes in children and adults, treated by revascularisation such as encephaloduroarteriosynangiosis.

A tumour arising from glial cells, graded by aggressiveness; glioblastoma is the highest grade, infiltrates surrounding brain, and is treated with resection, radiotherapy, and temozolomide.

A usually benign extra-axial tumour arising from arachnoid cap cells, appearing dural-based with homogeneous enhancement and a dural tail on MRI, often cured by complete surgical excision.

A mutation in isocitrate dehydrogenase genes found in many lower-grade gliomas and secondary glioblastomas, associated with younger age and better prognosis, and used in tumour classification.

Epigenetic silencing of the DNA repair gene MGMT in glioblastoma, which predicts greater benefit from temozolomide chemotherapy and is a standard prognostic marker.

Delivery of precisely focused high-dose radiation to an intracranial target in a single session using image guidance, used for small tumours, arteriovenous malformations, and functional disorders.

A benign tumour of the anterior pituitary that may secrete prolactin, growth hormone, or ACTH, or cause mass effect with bitemporal hemianopia; transsphenoidal resection is the usual approach.

A surgical corridor to the sellar region through the nasal cavity and sphenoid sinus, preferred for pituitary tumours because it avoids brain retraction and has lower morbidity than craniotomy.

Hypercortisolism caused by an ACTH-secreting pituitary adenoma, producing weight gain, hypertension, striae, and diabetes, treated by selective adenomectomy.

Escape of cerebrospinal fluid through a dural and bony defect, often after skull base surgery or trauma, risking meningitis and sometimes requiring repair or lumbar drainage.

Assessment of cerebrovascular reserve, often by acetazolamide challenge with perfusion imaging, used to judge haemodynamic compromise in steno-occlusive disease such as moyamoya before revascularisation.

Intracarotid injection of a short-acting anaesthetic to determine hemispheric dominance for language and memory before epilepsy surgery, guiding the extent of safe resection.

Implantation of depth electrodes into the brain to record seizure activity from deep structures, used to localise an epileptogenic zone when scalp EEG and imaging are inconclusive.

Implanted device delivering intermittent electrical pulses to the left vagus nerve to reduce seizure frequency in drug-resistant epilepsy not suitable for resective surgery.

Implantation of electrodes into targets such as the subthalamic nucleus or globus pallidus interna, with programmable stimulation to relieve tremor and rigidity in movement disorders.