Spontaneous intracranial hypotension complicated by unilateral subdural hematoma, coma, and the rare Kernohan's notch phenomenon

Spontaneous intracranial hypotension (SIH) is a highly underdiagnosed condition with a wide range of manifestations. Although SIH has traditionally been viewed as having a benign disease course, recent evidence suggests otherwise. In this case report, we present a 71‐year‐old woman who was previously treated with a tapered dose of corticosteroids for an episode of SIH with behavioral manifestations. In this current report, we present her second episode which was complicated by a unilateral sub‐acute subdural hematoma leading to loss of consciousness and coma. While the patient regained full consciousness and recovered considerably, she still suffers from ipsilateral hemiparesis as a result of Kernohan's notch phenomenon 2 years post‐hospitalization. To the author's knowledge, this is the first case to involve persistent motor deficit after the resolution of SIH. We believe that surgical hematoma evacuation prior to addressing the cerebrospinal fluid leak may have contributed to aggregated downward displacement of the brain precipitating Kernohan's notch phenomenon.