The oval pupil: clinical significance and relationship to intracranial hypertension

Abstract

✓ The oval pupil, or what has also been termed the “oblong” or “football” pupil, has been observed in 15 neurosurgical patients over a 2-year period. In 14 of the 15 patients, the intracranial pressure (ICP) was elevated, ranging from 18 to 38 mm Hg. While the oval pupil was primarily seen in patients suffering closed head injuries (11 cases), it was also observed in two patients with elevated ICP following hemorrhage from an arteriovenous malformation. In nine of the 14 patients in whom the pupillary abnormality was associated with intracranial hypertension, the oval pupil disappeared when the ICP was reduced to below 20 mm Hg. In four cases, the ICP could not be controlled and the pupil became progressively larger, and finally fixed and unreactive. The oval pupil represents a transitional stage indicating transtentorial herniation with third nerve compression. Although it may be seen in the absence of intracranial hypertension (one case in this series), this appears to be relatively uncommon. The presence of such a pupil on examination in a patient suffering an intracranial catastrophe, be it head injury, subarachnoid hemorrhage, or intracerebral hemorrhage, suggests impending transtentorial herniation with brain-stem compression.