Neurologic Disorders and Neurocritical Care
Core concepts
Focus on the ABCs of neurocritical care: airway protection, oxygenation, and avoiding secondary injury through blood pressure and glucose control, normothermia, and seizure prophylaxis where indicated. Know the Glasgow Coma Scale and its trend value. Understand elevated intracranial pressure (ICP) physiology - the Monro-Kellie doctrine - and management: head elevation, sedation, osmotherapy (hypertonic saline or mannitol), and short-term hyperventilation only as a bridge. Recognize herniation syndromes, status epilepticus management, and the distinction between ischemic and hemorrhagic stroke pathways. Be familiar with targeted temperature management after cardiac arrest and brain death criteria.
Traps
Hyperventilation lowers PaCO2 and reduces cerebral blood flow - it is a temporary rescue, not maintenance. Mannitol is a diuretic that can cause hypovolemia and hypernatremia; hypertonic saline is often preferred in hypotension. Do not miss nonconvulsive status epilepticus in the unresponsive patient - get an EEG. In subarachnoid hemorrhage, avoid hypotension and watch for vasospasm and hyponatremia.
Worked example
A patient with a large hemispheric stroke becomes progressively drowsy with a fixed dilated pupil. This suggests uncal herniation. Immediate steps: elevate head, ensure sedation and normocapnia, give osmotic therapy (hypertonic saline or mannitol), and urgently involve neurosurgery. Rule of thumb: in suspected herniation, hyperventilate only to bridge to definitive therapy, targeting PaCO2 around 30–35 mm Hg, then return to normocapnia.