Neurological Dysfunction and Critical Care Concepts

Vocabulary flashcards covering key neurological concepts, ICP monitoring and regulation, stroke management, hemorrhages, cerebral edema, and brain injury.

Consciousness

The condition of a client being aware of self and the environment, along with the ability to respond appropriately to external stimuli; it depends on alertness and cognitive function.

Reticular Activating System (RAS)

The brain and brainstem network responsible for governing arousal and alertness.

Monroe Kelly Doctrine

The principle stating that the cranial cavity is a rigid structure with a finite capacity containing three noncompressible elements (brain, cerebrospinal fluid, and blood); if the volume of one element increases, the others must decrease to maintain normal pressure.

Normal Intracranial Pressure (ICP)

The baseline hydrostatic pressure within the cranial vault, normally measuring between $5\text{ to }10\text{ mmHg}$.

Cerebral Perfusion Pressure (CPP)

The pressure gradient necessary to maintain cerebral blood flow and cell metabolism, calculated as mean arterial pressure minus intracranial pressure ($\text{CPP} = \text{MAP} - \text{ICP}$), with a minimum optimal target of $60\text{ mmHg}$.

Cerebral Autoregulation

The compensatory physiological mechanism wherein cerebral arterioles constrict their physical diameter or displace cerebrospinal fluid into subarachnoid spaces in response to increased intracranial pressure to maintain optimal cerebral perfusion pressure.

Cushing's Triad

A late clinical indicator of increased intracranial pressure and impending brain stem herniation, characterized by widening pulse pressure, bradycardia, and shallow or apneic respirations.

Decorticate Posturing

An abnormal motor response to painful stimuli in which the client flexes the arms and limbs inward toward the core of the body.

Decerebrate Posturing

An abnormal motor response to stimuli characterized by rigid outward extension and rotation of the limbs, scoring a $2$ on the Glasgow Coma Scale motor assessment.

External Ventricular Drain (EVD) / Ventriculostomy

An invasive catheter placed into the lateral ventricle of the brain that allows clinicians to transduce (measure) intracranial pressure and drain cerebrospinal fluid or blood for cranial decompression.

Apnea Test

A diagnostic procedure used in brain death determination where mechanical ventilation is withdrawn; it is failed if spontaneous respirations are absent and arterial $\text{CO}_2$ rises above $60$ without triggering respiratory effort.

Mannitol

An osmotic diuretic administered to draw fluid from swollen cerebral tissue into the vascular space by osmotic gradient so it can be diuresed out of the body.

Subarachnoid Hemorrhage (SAH)

Intracranial bleeding into the space between the arachnoid and pia membranes, frequently caused by a ruptured cerebral aneurysm and characteristically presenting as a sudden 'thunderclap headache' or 'worst headache of life.'

Cerebral Vasospasm

Narrowing and constriction of cerebral blood vessels that typically begins approximately $3$ days after a subarachnoid hemorrhage and can persist for weeks, causing localized ischemia.

National Institutes of Health Stroke Scale (NIHSS)

A standardized $42$-item quantitative neurological assessment tool used to evaluate deficits and identify clinical deterioration in stroke clients.

Permissive Hypertension

A hemodynamic management strategy for non-thrombolytic ischemic stroke that allows systolic blood pressure up to $200\text{ mmHg}$ and diastolic pressure up to $105\text{ mmHg}$ to force collateral blood flow past a lesion and salvage the penumbra.

Penumbra

The rim of ischemic cerebral tissue surrounding the dead infarction core that remains marginally perfused and potentially salvageable.

Vasogenic Cerebral Edema

Extracellular brain swelling caused by increased permeability of cerebral capillary endothelial cells, allowing plasma filtrate to accumulate in brain tissue.

Cytotoxic Cerebral Edema

Intracellular brain swelling resulting from failure of the cellular sodium-potassium pump, leading to an accumulation of sodium and water inside neurons and endothelial cells.

Coup-Contrecoup Injury

A dual-mechanism traumatic brain injury consisting of a primary impact at the point of direct trauma (coup) followed by a secondary injury when the brain rebounds against the opposite cranial wall (contrecoup).

Subdural Hematoma

A collection of blood between the dura mater and the arachnoid/brain surface, classically caused by a slow venous tear that may delay symptom presentation over several days.