The ciliospinal reflex in pentobarbital coma

Object. This study was conducted to delineate the ciliospinal reflex (CSR), which is defined as pupillary dilation caused by a noxious stimulus to the face or head. The authors anecdotally observed that patients in a pentobar bital coma have a CSR that can mimic pathological conditions. A pentobarbit al coma obscures the results of the neurological examination in patients wi th potentially life-threatening cerebral edema: pupil size and reactivity a re the only readily monitored signs. Any condition that incorrectly suggest s evolving intracranial pathological processes can lead to unnecessary clin ical actions. Methods. The authors evaluated six consecutive patients in the neurointensi ve care unit in whom a pentobarbital coma had been induced, documenting the presence and duration of the CSR. The CSR was always bilateral and symmetr ical, manifesting as enlarged (6-8 mm), seemingly nonreactive pupils contin uing from 1 to 6 minutes and was usually seen after routine nursing maneuve rs. The pupils appeared nonreactive to short flashes of direct light but di d react if longer flashes were used. Conclusions. Recognition of the CSR can potentially lend to reduction of un necessary transportation and complicating medical interventions in critical ly neurologically ill patients in whom a pentobarbital coma has been induce d.