Brain Disorders and Injuries

Vocabulary and key concepts regarding brain injuries, pressure dynamics, strokes, neurodegenerative diseases, and seizure disorders.

Focal effects

Signs relating to a specific area of the brain or spinal cord where a lesion is located.

Decorticate posturing

Abnormal body positioning resulting from lesions or damage to the cerebral hemispheres, characterized by flexion of arms, wrists, and fingers, along with internal rotation and plantar flexion.

Decerebrate posturing

Rigidity resulting from damage to the diencephalon, midbrain, and upper brainstem, where the palms are turned away from the body, legs are stiffly extended, and feet show plantar flexion.

Oculocephalic reflex

A test for brain stem integrity where moving or rotating the head causes the eyes to move to the opposite side.

Cheyne Stokes breathing pattern

A respiratory pattern characterized by rapid breathing with intermittent apnea, often seen with cerebral injury.

Consciousness

The state of awareness of self and the environment and the ability to respond to new stimuli.

Lethargy

A level of consciousness characterized by slow responses and speech, though the individual still responds appropriately.

Glasgow Coma Scale

A scale used to assess level of consciousness based on the degree of eye opening, motor responses, and verbal responses, with scores ranging from $3$ to $15$.

Brain death

The irreversible loss of functioning of the brain, including the brain stem.

Persistent vegetative state

A prolonged coma lasting longer than $30$ days with loss of cognitive function and awareness, while reflexes and vegetative functions remain intact.

Excitotoxic brain injury

Brain damage caused by excessive stimulation of tissues from excitatory neurotransmitters, most often glutamate.

Increased intracranial pressure (ICP)

Elevation of pressure within the brain cavity caused by etiologies such as fluid, blood, inflammation, or tumors.

Cushing triad

A red flag for increased ICP consisting of hypertension, slow heart rate, and widened pulse pressure.

Pulse pressure

The numeric difference between systolic and diastolic pressure readings.

Brain herniation

The shifting of brain tissue from a compartment of greater pressure to one of lesser pressure.

Vasogenic edema

Accumulation of fluid in the extracellular space around neurons due to a dysfunctional blood-brain barrier.

Cytotoxic edema

The accumulation of fluid inside of the brain cells themselves.

Hydrocephalus

A specific accumulation of cerebrospinal fluid inside the ventricles of the brain.

Primary brain injury

Brain damage caused by impact trauma, including contusions, lacerations, and diffuse injuries.

Contusion

A hemorrhagic necrosis of brain tissue resulting from the brain hitting the skull.

Coup

The site of external force where the skull and brain are hit.

Contrecoup

A rebound injury that occurs on the opposite side of the brain from the initial impact.

Epidural hematoma

A collection of blood that builds up between the skull and the dura mater.

Subdural hematoma

A collection of blood that accumulates between the dura and arachnoid mater.

Stroke (Cerebral Vascular Accident)

An infarction of brain tissue resulting from blood vessels being blocked or ruptured.

Ischemic penumbra

A zone of vulnerable cells outside the zone of infarction that are at risk of dying due to hypoxia.

Transient ischemic attack (TIA)

A temporary reduction of blood flow in the brain, similar to a myocardial ischemic episode.

Amaurosis fugax

Vision loss in one eye that may occur as a focalized manifestation of a stroke.

Alzheimer's disease

A neurodegenerative disease characterized by progressive loss of cortical function, neuritic plaques, and neurofibrillary tangles.

Meningitis

Inflammation of the meningeal membranes associated with the brain and the spinal cord.

Encephalitis

Inflammation of the parenchymal tissue of the brain and spinal cord.

Epilepsy

A recurrent seizure disorder caused by uncoordinated electrical discharges from brain cells.

Status epilepticus

Continuous seizure activity occurring in clusters, considered a medical emergency.

Tonic clonic seizure

A generalized seizure characterized by jerking movements, loss of consciousness, and a postictal phase of confusion or sleep.

Absence seizures

Generalized seizures characterized by a brief loss of consciousness and a staring spell.

Atonic seizures

Also known as drop seizures, these involve a sudden loss of muscle tone.