Arab Board Neurosurgery Final Written key terms

The intrinsic ability of cerebral arterioles to constrict or dilate to keep cerebral blood flow nearly constant across a range of mean arterial pressures, roughly 50 to 150 mmHg in healthy adults. It is impaired in severe head injury and ischemia.

The pressure gradient driving blood through the brain, calculated as mean arterial pressure minus intracranial pressure. It guides blood pressure targets in neurocritical care; low values risk ischemia and high values may worsen edema.

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

The pressure within the cranial vault, normally below about 15 to 20 mmHg in adults. Sustained elevation causes reduced perfusion and herniation, and it is monitored with ventricular catheters or parenchymal probes.

A catheter placed into a lateral ventricle to measure intracranial pressure, drain cerebrospinal fluid, and treat hydrocephalus. It also allows sampling of cerebrospinal fluid and administration of intrathecal drugs.

A 3-to-15 point score summing eye opening, verbal response, and motor response that grades level of consciousness after brain injury. A score of 8 or less conventionally defines severe injury and prompts airway protection.

Patterns of brain tissue displacement across dural or bony boundaries, including uncal, central transtentorial, subfalcine, and tonsillar types. They produce characteristic pupillary, motor, and respiratory signs and are neurosurgical emergencies.

Bruising of brain parenchyma from direct impact, typically involving the crests of gyri at frontal and temporal poles. It may expand into a hemorrhagic mass over hours to days and requires repeat imaging.

Blood accumulating between the skull and dura, usually from laceration of the middle meningeal artery after temporal bone fracture. It appears biconvex on CT and is a surgical emergency when symptomatic or large.

A collection of blood between the dura and arachnoid, commonly from torn bridging cortical veins after acceleration-deceleration injury. It appears crescentic on CT and often accompanies underlying brain injury.

Bleeding into the subarachnoid space after trauma, seen as hyperdensity in sulci and basal cisterns on CT. It is common in moderate to severe injury and contributes to vasospasm risk and hydrocephalus.

Sudden bleeding into the subarachnoid space from rupture of an intracranial aneurysm, producing thunderclap headache and meningismus. Complications include rebleeding, vasospasm, hydrocephalus, and hyponatremia.

Neurological deterioration from reduced cerebral blood flow, typically occurring days 3 to 14 after subarachnoid hemorrhage, often linked to large-vessel vasospasm. Management includes nimodipine and maintenance of euvolemia and blood pressure.

A saccular outpouching of an intracranial artery, most often at branch points of the circle of Willis. Rupture causes subarachnoid hemorrhage; treatment options include microsurgical clipping and endovascular coiling.

A congenital tangle of abnormal vessels in which arteries shunt directly into veins without an intervening capillary bed. It carries hemorrhage risk and is treated by observation, microsurgery, embolization, or radiosurgery.

A cluster of thin-walled vascular channels with no intervening normal brain tissue, producing a popcorn-like lesion on MRI with a hemosiderin rim. It causes seizures and small hemorrhages and is often managed conservatively.

Microsurgical placement of a metal clip across the neck of an aneurysm to exclude it from the circulation while preserving the parent artery. It remains a durable option, especially for middle cerebral artery aneurysms.

Catheter-based delivery of detachable platinum coils into an aneurysm sac to induce thrombosis and exclude it from circulation. It is less invasive than open surgery but carries risk of recurrence and requires follow-up imaging.

A progressive steno-occlusive disease of the distal internal carotid arteries with compensatory fragile collateral vessels, causing stroke in children and adults. Treatment is revascularization by direct or indirect bypass.

Delivery of a single high dose of focused radiation to a defined intracranial target using stereotactic localization, sparing surrounding tissue. It treats small tumors, arteriovenous malformations, and functional disorders.

A stereotactic radiosurgery system that directs many cobalt-60 photon beams to converge on an intracranial target. It is used for small tumors, metastases, and functional lesions without an incision.

The most common malignant primary brain tumor in adults, an infiltrative astrocytoma with necrosis and microvascular proliferation. Standard treatment is maximal safe resection followed by radiotherapy with temozolomide.

The proportion of a tumor removed at surgery, assessed by postoperative contrast-enhanced imaging. Greater resection improves survival in high-grade glioma and is a key surgical objective.

New or enlarging contrast enhancement on MRI shortly after chemoradiotherapy that reflects treatment effect rather than true tumor growth. It is distinguished from progression by stability or improvement on later imaging.

Secondary tumors spread to the brain from cancers elsewhere, most often lung, breast, and melanoma. Management options include surgery, whole-brain radiotherapy, and stereotactic radiosurgery depending on number and size.

A usually benign tumor arising from arachnoid cap cells of the meninges, often dural-based with a tail sign on contrast imaging. Treatment is observation or surgical resection, with radiotherapy for atypical or residual disease.

A five-tier classification of the extent of meningioma resection, from grade I complete removal of tumor and involved dura to grade V biopsy only. Higher grades correlate with increased recurrence risk.

A benign tumor of the anterior pituitary that may secrete hormones or cause mass effect on the optic chiasm. Transsphenoidal surgery is first-line for most symptomatic lesions.

A surgical corridor to the sella turcica through the nasal cavity and sphenoid sinus, often endoscopic. It avoids brain retraction and is the preferred route for most pituitary tumors.

Hypercortisolism caused by an adrenocorticotropic hormone-secreting pituitary adenoma. It produces weight gain, hypertension, and glucose intolerance and is treated by transsphenoidal resection.

A benign tumor of Schwann cells of the vestibular division of the eighth cranial nerve, causing hearing loss and tinnitus. Options include observation, stereotactic radiosurgery, and microsurgical resection.

The space between the cerebellum and pons where several cranial nerves exit, and a common site for vestibular schwannoma and meningioma. Lesions there cause hearing loss, facial weakness, and ataxia.

Downward displacement of the cerebellar tonsils through the foramen magnum, often causing headache, syringomyelia, or brainstem compression. Symptomatic cases may require posterior fossa decompression.

A fluid-filled cavity within the spinal cord that expands and damages crossing spinothalamic fibers, causing a cape-like loss of pain and temperature sensation. It often associates with Chiari malformation or spinal trauma.

Surgical enlargement of the posterior fossa outlet by suboccipital craniectomy and often dural opening, used for symptomatic Chiari malformation. It aims to restore cerebrospinal fluid flow at the craniovertebral junction.

Ventricular enlargement caused by impaired absorption of cerebrospinal fluid over the convexities, with free flow between ventricles and basal cisterns. Causes include post-hemorrhagic and post-meningitic scarring.

A catheter system diverting cerebrospinal fluid from the lateral ventricle to the peritoneal cavity through a valve. It treats hydrocephalus but carries risks of infection, obstruction, and overdrainage.

Creation of a stoma in the floor of the third ventricle to allow cerebrospinal fluid to bypass obstruction and reach the basal cisterns. It is preferred for obstructive hydrocephalus and avoids implanted hardware.

A syndrome of ventricular enlargement with normal measured cerebrospinal fluid pressure, presenting with gait disturbance, urinary incontinence, and cognitive decline. Improvement after large-volume lumbar drainage predicts shunt response.

Protrusion of nucleus pulposus through the annulus fibrosus, most often at L4-L5 or L5-S1, compressing the traversing nerve root. It causes radicular pain and may need discectomy after failed conservative care.

Compression of the lumbosacral nerve roots causing saddle anesthesia, bladder and bowel dysfunction, and bilateral leg weakness. It is a surgical emergency requiring urgent decompression.

Narrowing of the lumbar spinal canal or foramina, usually from degenerative changes, causing neurogenic claudication relieved by flexion. Decompression is offered when symptoms are disabling and conservative care fails.

Forward slippage of one vertebra relative to the one below, commonly from degenerative change or a pars defect. It may cause stenosis and instability, and fusion is added when instability is present.

A focal dilation of an intracranial artery wall that may rupture and cause subarachnoid hemorrhage. Unruptured lesions are managed by observation, clipping, or coiling based on size, location, and patient factors.

Resection of a portion of the temporal lobe, most often the anterior and mesial structures, to control drug-resistant focal epilepsy. It is the best-established epilepsy operation when the seizure focus is confirmed.

Preoperative evaluation combining video-electroencephalography, high-resolution MRI, and sometimes invasive recordings to localize the seizure onset zone. Accurate localization predicts seizure freedom after resection.

Implantation of electrodes into deep brain targets connected to a pulse generator to modulate abnormal neural activity. It treats Parkinson disease, essential tremor, and selected dystonias and is adjustable and reversible.

A rigid head-fixed device providing a three-dimensional coordinate reference for targeting intracranial structures. It is used for biopsy, functional procedures, and radiosurgery localization.

Compression of the median nerve within the carpal tunnel causing nocturnal numbness and thenar weakness. Diagnosis uses nerve conduction studies, and treatment ranges from splinting to surgical release.

An electrophysiologic test measuring how fast and how well electrical impulses travel along a peripheral nerve. It localizes compression or injury and helps grade severity before surgical decisions.

Recording of electrical activity from muscle using needle electrodes to assess denervation and reinnervation. Combined with nerve conduction studies, it distinguishes nerve, plexus, and muscle disorders.

A five-point clinical scale classifying the severity of subarachnoid hemorrhage by headache, meningismus, focal deficit, and consciousness. Higher grades predict worse outcome and guide timing of intervention.

The process of explaining a proposed procedure, its risks, benefits, and alternatives, and confirming the patient's voluntary agreement. It is a core ethical and legal requirement in neurosurgical practice.

A collaborative process in which clinician expertise and patient values are combined to choose among reasonable treatment options. It supports informed consent and is central to patient-centered neurosurgical care.

An MRI sequence that detects restricted water diffusion, appearing bright in acute ischemic stroke and in abscess pus. It is highly sensitive within minutes of infarction and helps distinguish stroke from mimics.

A non-contrast or contrast-enhanced MRI technique that images blood vessels to detect aneurysms, stenosis, and vascular malformations. It is often the first screening study before catheter angiography.

Catheter-based imaging of cerebral vessels with contrast and image subtraction, considered the reference standard for vascular anatomy. It can be combined with endovascular treatment in the same session.

Escape of cerebrospinal fluid through a dural and bony defect, presenting as clear rhinorrhea or otorrhea after trauma or surgery. It risks meningitis and may need repair or diversion.

Abnormal accumulation of water in brain tissue from cytotoxic, vasogenic, or interstitial mechanisms, increasing brain volume and intracranial pressure. Management includes head elevation, osmotherapy, and treating the cause.