ABA Neurocritical Care key terms

The pressure inside the rigid skull, normally kept under about 20 mmHg by balanced production and absorption of cerebrospinal fluid. Sustained elevation impairs cerebral blood flow and can cause herniation.

The driving pressure for blood flow to the brain, calculated as mean arterial pressure minus intracranial pressure. Targets are usually set between 60 and 70 mmHg in neurocritical care.

The principle that the skull is a fixed container holding brain, blood, and cerebrospinal fluid, so any increase in one component must be offset by a decrease in another or intracranial pressure rises.

The brain's ability to keep blood flow relatively constant across a range of arterial pressures, roughly 50 to 150 mmHg. This mechanism is often impaired after severe brain injury.

Sustained elevation of pressure inside the skull, generally above 20 to 22 mmHg, that threatens cerebral perfusion and can progress to herniation. It is treated with positioning, sedation, osmotherapy, and sometimes surgery.

Downward displacement of brain tissue through the tentorial opening, compressing the brainstem. It classically produces a blown pupil, deteriorating consciousness, and abnormal posturing, and is a life-threatening emergency.

Use of hypertonic agents such as mannitol or hypertonic saline to draw water out of brain tissue and lower intracranial pressure. Serum sodium and osmolality must be monitored to avoid renal and electrolyte complications.

Concentrated sodium chloride solutions given intravenously to reduce brain edema and raise intravascular volume. They are an alternative to mannitol and require frequent sodium monitoring.

Surgical removal of a portion of skull to allow a swollen brain to expand and relieve refractory intracranial hypertension. It can be life-saving but may leave survivors with significant disability.

Intracranial pressure that remains elevated despite maximal medical therapy, including sedation, osmotherapy, and controlled ventilation. It often prompts consideration of barbiturate coma or decompressive surgery.

Deep sedation with agents such as pentobarbital to suppress cerebral metabolism and lower intracranial pressure when other measures fail. It causes hypotension and requires continuous EEG monitoring for burst suppression.

An EEG pattern of alternating high-amplitude bursts and flat periods, intentionally induced with anesthetic agents to reduce cerebral metabolic demand. It is used in refractory intracranial hypertension and status epilepticus.

Continuous seizure activity lasting five minutes or more, or repeated seizures without recovery between them. It is a medical emergency requiring immediate benzodiazepines followed by antiseizure drugs.

Prolonged seizure activity without obvious motor signs, detectable only on EEG. It should be suspected in any patient with unexplained persistent coma or fluctuating consciousness.

Prolonged recording of brain electrical activity at the bedside, used to detect seizures, assess sedation depth, and identify ischemia in unconscious or high-risk patients.

Neurologic deterioration after aneurysmal subarachnoid hemorrhage caused by narrowing of cerebral arteries and reduced blood flow. It typically occurs days after the bleed and is managed with hemodynamic support and endovascular therapy.

Narrowing of cerebral arteries, often after subarachnoid hemorrhage, that reduces blood flow and can cause stroke. It is detected by transcranial Doppler or angiography and treated with calcium channel blockers and endovascular dilation.

Bleeding into the space between the arachnoid and pia mater, most often from a ruptured aneurysm. It presents with sudden severe headache and carries risks of rebleeding, vasospasm, and hydrocephalus.

A catheter placed into the cerebral ventricles to drain cerebrospinal fluid and measure intracranial pressure. It is used for hydrocephalus and intraventricular hemorrhage and carries a risk of infection.

Abnormal accumulation of cerebrospinal fluid within the ventricles, increasing head pressure and enlarging the ventricles. It may be treated with an external drain or a permanent shunt.

Irreversible loss of all brain and brainstem function, including the capacity to breathe, confirmed by a standardized clinical examination and ancillary testing when needed. It is legally equivalent to death.

The final bedside step in brain death determination, in which ventilation is briefly withdrawn to confirm absence of respiratory drive. It is performed only after other brainstem reflexes are absent.

A 3-to-15-point score based on eye opening, verbal response, and motor response, used to grade level of consciousness after brain injury. Lower scores indicate more severe impairment.

A state of unresponsiveness in which the patient cannot be awakened and shows no awareness of self or environment. It reflects dysfunction of the brainstem or widespread cortical structures.

A level of consciousness indicating severe brain injury, generally used as the threshold for securing the airway with intubation. It signals need for close neurologic monitoring.

Sudden loss of brain function from blocked blood flow to part of the brain. Rapid reperfusion with thrombolysis or thrombectomy can limit permanent damage.

Use of intravenous clot-dissolving medication, such as alteplase or tenecteplase, to restore blood flow in acute ischemic stroke. It must be given within a narrow time window after excluding hemorrhage.

Endovascular removal of a clot from a large cerebral artery to restore blood flow in acute ischemic stroke. It benefits selected patients with large-vessel occlusion, often within 24 hours of onset.

Bleeding into brain tissue that has been damaged by ischemia, sometimes occurring after reperfusion therapy. It can cause abrupt neurologic worsening and requires urgent imaging.

Bleeding within the brain substance, often related to hypertension or anticoagulation. Management focuses on blood pressure control, reversing coagulopathy, and preventing secondary injury.

Bleeding into the fluid-filled spaces of the brain, which can obstruct cerebrospinal fluid flow and cause hydrocephalus. It is often managed with an external ventricular drain.

Rapid neutralization of blood-thinning drugs to stop or prevent bleeding, using agents such as vitamin K, prothrombin complex concentrate, or specific antidotes. It is urgent in intracranial hemorrhage.

A disorder of blood clotting that increases bleeding risk, whether from disease, medications, or dilution. In neurocritical care it worsens outcomes after hemorrhage and must be corrected promptly.

Damage to the brain from external mechanical force, ranging from concussion to severe injury with bleeding and swelling. Care aims to prevent secondary injury from hypoxia, hypotension, and raised intracranial pressure.

Damage to the spinal cord from trauma or disease, causing loss of motor, sensory, or autonomic function below the level of injury. High cervical lesions can impair breathing and blood pressure control.

Loss of sympathetic vascular tone after high spinal cord injury, producing hypotension with bradycardia or lack of tachycardia. Treatment includes fluids, vasopressors, and sometimes atropine.

A dangerous surge in blood pressure triggered by a noxious stimulus below a spinal cord injury level, often from a full bladder. It causes headache, sweating, and bradycardia and requires removing the trigger.

Use of paralytic drugs to prevent movement and reduce oxygen demand or intracranial pressure. Paralysis masks neurologic examination and seizures, so sedation and monitoring must be ensured.

Controlled cooling or maintenance of body temperature within a set range after cardiac arrest or brain injury. It reduces metabolic demand and secondary damage but requires shivering control and careful monitoring.

A core body temperature below normal, either environmental or induced therapeutically. It can slow metabolism and protect the brain but risks arrhythmia, coagulopathy, and infection.

Involuntary muscle contraction that generates heat and raises metabolic demand during therapeutic cooling. It is controlled with sedation, analgesia, and surface counterwarming.

Use of a machine to support breathing when a patient cannot maintain adequate gas exchange. In brain-injured patients, carbon dioxide levels are adjusted to influence cerebral blood flow.

Deliberately increasing minute ventilation to lower arterial carbon dioxide, which constricts cerebral vessels and briefly reduces intracranial pressure. It is used as a temporary bridge because prolonged use risks brain ischemia.

Sudden severe lung inflammation with low oxygen levels and fluid in the air sacs not fully explained by heart failure. It requires lung-protective ventilation and careful oxygen targets.

Abnormally low oxygen content in arterial blood, which can worsen brain injury by starving neurons of oxygen. It is detected by pulse oximetry or blood gas analysis and corrected promptly.

Life-threatening organ dysfunction caused by a dysregulated response to infection. It can impair brain function and worsen outcomes in neurocritical care patients.

Sepsis with persistent low blood pressure requiring vasopressors and elevated lactate despite adequate fluids. It causes widespread organ dysfunction and requires urgent antibiotics and hemodynamic support.

A medication such as norepinephrine that constricts blood vessels to raise blood pressure. In neurocritical care it is used to maintain cerebral perfusion pressure.

An acute, fluctuating disturbance of attention and awareness, often triggered by illness, medications, or metabolic derangement. It is common in intensive care and associated with worse outcomes.

Use of medications to reduce awareness and discomfort, commonly for mechanically ventilated patients. In brain-injured patients it also lowers metabolic demand and can help control intracranial pressure.

A serum sodium level below normal, which can cause brain swelling and seizures when it develops rapidly. Correction must be gradual to avoid osmotic demyelination.

A serum sodium level above normal, often from water loss or hypertonic therapy. Rapid correction can cause brain edema, so it is managed slowly.

A measure of the concentration of dissolved particles in body fluid, influencing water movement across cell membranes. It is monitored during osmotherapy to guide dosing and avoid toxicity.

A calculated measure of how cerebral blood pressure and intracranial pressure change together, used to assess autoregulation. It can guide individualized perfusion targets in severe brain injury.