Clinical neurological assessment of the critically ill patient

Neurological assessment of critically ill patients requires physical examination although coexisting cognitive impairment, sedative or paralytic medication, endotracheal intubation, mechanical ventilation, neuromuscular weakness, injuries or surgery involving extracranial tissues may limit sensitivity and specificity of findings. Notwithstanding these constraints, neurological signs and syndromes are valuable indicators of severity of illness and prognosis. Common neurologic syndromes in ICU patients include disturbances in the level of arousal and in cognition, delirium, seizures, generalized weakness, and focal neurological deficits. Whenever possible, neurological examination should include an assessment of mental status, attention, cranial nerves, motor and sensory findings. If there is persisting diagnostic uncertainty additional testing should be sought. Computed tomography of the head should be obtained whenever there is a new onset of seizures, focal neurologic deficits, alteration of mental status or loss of consciousness which are not immediately reversible or explainable. Magnetic resonance imaging has greater sensitivity for demyelinating and inflammatory diseases, hyperacute ischemic stroke, microhemorrhagic lesions, anoxic-ischemic damage, and disorders affecting the white matter and the brainstem. Electroencephalography is needed if seizures or status epilepticus are suspected as a cause or consequence of acute brain dysfunction. Somatosensory evoked potentials, best studied in patients with anoxic brain injury may help with prognostication following cardiac arrest. Electromyography and nerve conduction velocities should be obtained when neuromuscular weakness is severe or cannot be assessed clinically.