Walsh & Hoyt: Disturbances During Coma

According to Plum and Posner, consciousness is the state of awareness of the self and environment, whereas coma is a state of unarousable psychological unresponsiveness in which the patient lies with eyes closed. Patients in coma show no psychologically understandable response to external stimuli or inner needs. Causes of coma include supratentorial lesions, infratentorial lesions, and diffuse brain dysfunction from a variety of inflammatory, infectious, degenerative, and metabolic processes. The prevalence of pupillary abnormalities in comatose patients is high and may, in some instances, help in the initial understanding and localization of the process. Accordingly, one should carefully examine the pupil size, shape, and reactivity in any patient who appears to be in a comatose state.