Clinical neurological assessment of the critically ill patient

Neurological assessment of critically ill patients requires physical examination, although sensitivity and specificity of findings may be limited by co-existing cognitive impairment, sedative or paralytic medication, endotracheal intubation, mechanical ventilation, neuromuscular weakness, and injuries or surgery involving extracranial tissues. Neurological signs and syndromes are fundamental indicators of severity of illness and prognosis. Neurological syndromes commonly seen in intensive care unit (ICU) patients include disturbances in consciousness, delirium, seizures, generalized weakness, and focal neurological deficits. Neurological examination in responsive patients should include an assessment of mental status, attention, cranial nerves, motor, and sensory findings. If there is persisting diagnostic uncertainty, additional testing should be performed. Computed tomography of the head should be performed if there is a new onset of seizures, focal neurological deficits, and if there is an unexplained alteration of mental status or loss of consciousness. Brain magnetic resonance imaging has greater sensitivity for hyperacute ischemic stroke, microhemorrhagic lesions, anoxic-ischemic damage, and alterations of 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. Electromyography, nerve conduction velocities, and, in selected patients, cerebrospinal fluid (CSF) examination should be obtained when neuromuscular weakness is severe or cannot be assessed clinically. Physical examination is the cornerstone in the neurological assessment of critically ill patients, however, the validity and reliability of this examination is constrained by concurrent cognitive impairment and the effects of sedative or paralytic medication. Endotracheal intubation and mechanical ventilation pose significant obstacles to the assessment of cognitive (and in particular language) disturbances and to the interpretation of pathological breathing patterns. Neuromuscular weakness acquired in the ICU, and injuries or surgery may significantly limit the response to stimulation and the yield of neurological assessment [1]. Notwithstanding these constraints, neurological signs remain valuable indicators of severity of illness and prognosis [2–4].