Atypical Oscillating Pupillary Reaction in a Brainstem-Dead Patient.

Dilated and fixed pupils are a hallmark of the diagnosis of brainstem death. We present a case of a brain-dead patient whose pupil displayed unilateral spontaneous repetitive pupillary dilatation and constriction (in an oscillating manner) independent of external stimuli, which didn't respond to light. Central causes of this phenomenon were excluded by confirmation of brainstem death via ancillary test, leaving the peripheral cause as the most likely explanation. This rare and atypical phenomenon is not a sign of brain activity and can be explained that the pupillary constrictor muscle can become hypersensitive after brain death, and it can be spontaneously constricted or dilated in response to circulating neurotransmitters in the blood. Also, the cilio-spinal reflex may be caused in brain-dead patients due to terminal neural discharges from dying cells, which lead to sympathetic stimulation of the ciliary ganglion. This case shows that oscillating pupillary activity in the absence of external stimuli should not interfere with or delay the diagnosis of brainstem death to facilitate earlier organ donation. An oscillating spontaneous pupillary activity in a brain-dead patient is a rare, atypical phenomenon caused by a peripheral reflex rather than a central reflex. This atypical phenomenon should not interfere with or delay the diagnosis of brainstem death, which allows for proper and timely medical care and organ donation.