Wrong side dilated pupil.

A 59-year-old man with alcoholic liver disease became comatose from a left acute subdural hematoma. He developed a fixed dilated right pupil but the left pupil was responsive to light. Oculovestibular responses were normal. He had right extensor posturing. At autopsy uncal herniation was not found, but there was a diagonally shifted and rotated brainstem likely tethering or compressing the contralateral third nerve against the tentorium ridge or clivus (figure). In the pre-CT era, a false localizing fixed pupil led to negative exploratory burr holes. Presently, this phenomenon is still a confusing, inadequately understood curiosity.