The acutely comatose patient: clinical approach and diagnosis

A patient's acute and persistent unresponsiveness in the emergency department often triggers a neurology consultation. Given the many potential causes of unresponsiveness, the initial objective of the neurologist should be a comprehensive history and physical examination, which should allow localization of the lesion, if possible, and an initial narrowing of the differential diagnosis. In addition, neuroimaging review and laboratory evaluation have come to play an increasingly important role in identification of the potential causes of unresponsiveness. However, in some instances, the computed tomography or the magnetic resonance imaging scans are normal and sorting out the cause and depth of unresponsiveness requires clinical skill. The neurologist is adept at correctly moving through a differential diagnosis and this has a profound effect on management. Once appropriate treatment has been initiated, the outcome can be assessed. Recovery from coma can be prolonged, but is less likely if early involvement of the brainstem is apparent.