Neurocritical Care

• Critical care of the nervous system is based on support of cerebral and spinal cord physiology and the prevention of secondary insults. This goal, in turn, depends on the comprehensive maintenance and adequacy of cardiopulmonary, gastrointestinal, renal, and endocrine function. • Cerebral function is critically dependent on perfusion and oxygenation matching metabolism. Increased intracranial volume beyond the capacity of compensatory mechanism increases intracranial pressure (ICP) and may diminish perfusion adversely. The resulting cellular energy failure both initiates and propagates edema and inflammation. • The resolution of cerebral edema depends on hydrostatic and osmolar forces applied to the blood-brain barrier. Excesses of perfusion pressure or intravascular hypotonicity worsen edema and must be avoided. Blood-brain barrier disruption varies over time and by pathologic process, and it affects the ability of hypertonic agents to exert an osmotic effect. • Fever is frequently overlooked in the neurocritical care unit, but it significantly affects patient outcomes across a range of pathologic processes. • Neurologic monitoring comprises placement of appropriate monitoring devices, as well as prompt response and institution of therapy to changes detected. The goal is to optimize the physiologic environment, despite the current lack of level 1 evidence to support the majority of monitors in common use. Clinical examination of neurologic function remains a crucial part of monitoring and care. • The incidence of traumatic brain injury has declined, but this disorder remains a disease of the young, with enormous long-term socioeconomic impact. Prompt surgical appraisal is mandatory. Decompressive craniectomy after diffuse injury is not currently recommended. Hypothermia may still offer benefit in refractory intracranial hypertension. Corticosteroids are contraindicated. • After the initial hemorrhage, mortality and morbidity from subarachnoid hemorrhage (SAH) arise from cerebral ischemia. Medical therapy for this complication involves augmentation of perfusion pressure, maintenance of blood volume, and optimization of oxygen delivery. Endovascular therapy with angioplasty with or without chemical vasodilation plays an important role in treating vasospasm. SAH may be accompanied by significant pulmonary, cardiovascular, or endocrine effects. • Successful therapy for ischemic stroke is contingent on a time window of viability. Urgent appraisal and rapid treatment are crucial to a good outcome. Endovascular therapy and ultrasound are going to play an increasing role in conjunction with advances in magnetic resonance imaging. • Injury to the spinal cord necessitates careful observation of respiratory adequacy because conditions may deteriorate before any observed improvement occurs. Fatigue is frequently a factor. • Infectious disease of the central nervous system demands an aggressive approach to resuscitation, cerebrospinal fluid sampling, and early empiric antibiotic therapy, similar to that for sepsis.