Blood Supply to the Head, Brain Disorders, and Neurological Examinations

Comprehensive vocabulary flashcards covering the cranial arterial and venous circulation, stroke mechanisms, neurodegenerative conditions (Alzheimer's, ALS, Huntington's), neuroinflammatory and infectious disorders (meningitis, encephalitis, GBS, Bell's palsy), seizures, migraines, and standard diagnostic modalities.

Orthostatic reflex

A physiological reflex mediated by stretch receptors at the base of the common carotid arteries that increases heart rate to elevate and maintain blood pressure against gravity upon standing.

Circle of Willis

An arterial anastomosis at the base of the brain formed by the internal carotid arteries and branches of the basilar artery that provides collateral circulation to preserve cerebral blood flow if one artery is blocked or narrowed.

Ischemic stroke

A type of cerebrovascular accident accounting for $87\%$ of all strokes, caused by an obstruction in a cerebral artery that cuts off blood supply to brain tissue; subcategorized into thrombotic and embolic strokes.

Thrombotic stroke

The most common form of ischemic stroke, occurring when a thrombus forms inside an artery narrowed by atherosclerotic plaque; it characteristically develops at night or in the early morning and is commonly preceded by a transient ischemic attack (TIA).

Atherosclerosis

A vascular condition in which the arterial lining becomes thickened and narrowed by deposits of plaque composed of fat, cholesterol, fibrin, and calcium, predisposing the vessel to clot formation.

Embolic stroke

An ischemic stroke that occurs when an embolus originates elsewhere in the body—most frequently the heart due to atrial fibrillation—and travels to occlude a smaller cerebral artery.

Atrial fibrillation

A rapid, abnormal cardiac rhythm characterized by quivering of the atria rather than normal contractions, causing blood to pool and form thrombi that can migrate to cerebral vessels and cause a stroke.

Transient Ischemic Attack (TIA)

A temporary episode of focal neurologic dysfunction caused by reversible ischemia of the brain, spinal cord, or retina without acute tissue infarction, typically resolving in under $5\text{ minutes}$.

Intracerebral hemorrhage

A type of hemorrhagic stroke involving bleeding directly into brain tissue, typically caused by the rupture of a cerebral aneurysm.

Subarachnoid hemorrhage

A type of hemorrhagic stroke resulting from the rupture of a blood vessel on the surface of the brain, releasing blood into the subarachnoid space between the brain and skull without bleeding directly into the brain substance.

BE FAST

An acronym representing key signs of an acute stroke: Balance loss, Eyes/vision impairment, Facial drooping, Arm limpness or drift, Speech difficulty, and Time to seek emergency care (ideally under $90\text{ minutes}$).

Alzheimer's disease

The most prevalent form of dementia, pathologically marked by extracellular beta-amyloid plaques and intracellular neurofibrillary tangles, early loss of recent memory formation, progressive cognitive decline, and a survival time of approximately $3\text{--}9\text{ years}$ post-diagnosis.

Amyloidogenic pathway

The aberrant proteolytic cleavage of Amyloid Precursor Protein (APP) by $\beta\text{-secretase}$ (BACE) and $\gamma\text{-secretase}$, producing soluble $A\beta$ monomers that assemble into beta-sheet oligomers, fibrils, and senile plaques.

Amyotrophic Lateral Sclerosis (ALS)

Also called Lou Gehrig's disease, a progressive neurodegenerative disorder marked by the destruction of upper and lower motor neurons controlling voluntary muscle movement, resulting in muscle wasting, paralysis, and death usually within $2\text{--}5\text{ years}$.

Glutamate excitotoxicity in ALS

A hypothesized mechanism for ALS progression wherein the insufficient activity of cell membrane reuptake proteins leads to an accumulation of extracellular glutamate in the synaptic cleft, overstimulating and destroying motor neurons.

Rilutek (Riluzole)

A pharmaceutical treatment approved for ALS that slows the endogenous synthesis and release of glutamate, extending patient survival by an estimated $2\text{--}3\text{ months}$.

Bell's palsy

An acute peripheral facial palsy of unknown etiology characterized by unilateral swelling and inflammation of cranial nerve VII (facial nerve), causing weakness or paralysis of one side of the face with full recovery typically attained in approximately $6\text{ months}$.

Glasgow Coma Scale (GCS)

A standardized clinical assessment scoring eye opening ($1\text{--}4$), verbal response ($1\text{--}5$), and motor response ($1\text{--}6$) on a scale from $3$ to $15$, where a total score of $8$ or below designates a comatose state.

Meningitis

An acute inflammatory infection of the cerebrospinal fluid and the meningeal membranes (dura mater, arachnoid, and pia mater) surrounding the central nervous system, characterized by headache, fever, and neck stiffness.

Glass tumbler test

A diagnostic assessment for suspected meningococcal disease in which a clear glass tumbler is pressed against skin lesions; if the petechial rash fails to blanch (fade) under the applied pressure, immediate medical evaluation is required.

Encephalitis

An acute inflammation of the brain parenchyma itself, most commonly resulting from viral infections such as Herpes simplex virus or as a complication of measles, mumps, or chickenpox, presenting with fever, headache, confusion, seizures, or sensory deficits.

Partial (focal) seizure

A seizure whose paroxysmal electrical activity initiates within a single localized region of one cerebral hemisphere, categorized as simple (awareness retained) or complex (awareness and behavior altered).

Generalized seizure

A seizure characterized by abnormal electrical discharges engaging bilateral cerebral hemispheres simultaneously with altered consciousness from onset; variants include tonic-clonic, absence, atonic, tonic, and myoclonic.

Febrile seizure

An age-dependent convulsion occurring in response to fever in children aged $6\text{ months}$ to $6\text{ years}$ (peak incidence at $18\text{ months}$), associated with autosomal dominant familial inheritance; persistence beyond $10\text{ minutes}$ requires emergency care.

Guillain-Barré Syndrome (GBS)

An acute post-infectious autoimmune polyneuropathy characterized by immune-mediated demyelination of peripheral nerves, manifesting as ascending bilateral limb weakness, tingling, and areflexia over a course of less than $4\text{ weeks}$.

Cytoalbuminologic dissociation

A classic diagnostic finding in the cerebrospinal fluid of Guillain-Barré syndrome patients consisting of significantly elevated protein levels in the presence of a normal white blood cell count.

Huntington's disease

An autosomal dominant, progressive neurodegenerative disorder caused by a defect on chromosome $4$ affecting the basal ganglia, clinically characterized by involuntary choreiform movements, psychiatric and behavioral disturbances, and death within $15\text{--}20\text{ years}$ of symptom onset.

CAG trinucleotide repeat expansion

The pathological mutation responsible for Huntington's disease involving $36\text{--}120$ repeats of the CAG codon on chromosome $4$, where higher repeat numbers correlate with earlier disease onset.

Lyme disease

A tick-borne zoonotic disease caused by the bacterium Borrelia burgdorferi, transmitted via the bite of an infected deer tick (Ixodes), producing clinical manifestations such as fatigue ($76\%$), headache ($70\%$), and erythema migrans rash.

Migraine

A recurrent primary headache disorder characterized by unilateral, throbbing pain linked to trigeminal nerve activation and neurovascular inflammation, frequently accompanied by nausea, vomiting, photophobia, and phonophobia.

Normal CSF reference values

Diagnostic baseline parameters for human cerebrospinal fluid: clear and colorless appearance, opening pressure of $50\text{--}180\,\text{mm}\,\text{H}_2\text{O}$, lumbar protein of $15\text{--}50\,\text{mg/dl}$, glucose of $50\text{--}80\,\text{mg/dl}$, $0\text{--}5\,\text{WBCs}$, and absent RBCs.

Electroencephalogram (EEG)

A neurodiagnostic study that continuously monitors and records the brain's spontaneous electrical rhythms via electrodes attached to specific areas of the scalp.

Positron Emission Tomography (PET)

A diagnostic functional neuroimaging modality that evaluates the regional cellular metabolic activity of brain tissue by tracking the distribution and decay of administered radioisotopes.

Single-Photon Emission Computed Tomography (SPECT)

A nuclear medicine radiology exam utilizing a gamma-emitting radioactive compound and rotating detectors to assess regional cerebral blood flow and tissue function.

Chorionic Villus Sampling (CVS)

An early prenatal genetic diagnostic procedure performed as early as the $10\text{th week}$ of gestation, involving the extraction and direct analysis of placental chorionic villi tissue.

Amniocentesis

A prenatal diagnostic procedure initiated at or after the $15\text{th week}$ of pregnancy in which amniotic fluid containing desquamated fetal cells is aspirated via transabdominal needle for karyotyping and biochemical testing.