Intracranial hypotension producing reversible coma: a systematic review, including three new cases.

Intracranial hypotension is a disorder of CSF hypovolemia due to iatrogenic or spontaneous spinal CSF leakage. Rarely, positional headaches may progress to coma, with frequent misdiagnosis. The authors review reported cases of verified intracranial hypotension-associated coma, including 3 previously unpublished cases, totaling 29. Most patients presented with headache prior to neurological deterioration, with positional symptoms elicited in almost half. Eight patients had recently undergone a spinal procedure such as lumbar drainage. Diagnostic workup almost always began with a head CT scan. Subdural collections were present in 86%; however, intracranial hypotension was frequently unrecognized as the underlying cause. Twelve patients underwent one or more procedures to evacuate the collections, sometimes with transiently improved mental status. However, no patient experienced lasting neurological improvement after subdural fluid evacuation alone, and some deteriorated further. Intracranial hypotension was diagnosed in most patients via MRI studies, which were often obtained due to failure to improve after subdural hematoma (SDH) evacuation. Once the diagnosis of intracranial hypotension was made, placement of epidural blood patches was curative in 85% of patients. Twenty-seven patients (93%) experienced favorable outcomes after diagnosis and treatment; 1 patient died, and 1 patient had a morbid outcome secondary to duret hemorrhages. The literature review revealed that numerous additional patients with clinical histories consistent with intracranial hypotension but no radiological confirmation developed SDH following a spinal procedure. Several such patients experienced poor outcomes, and there were multiple deaths. To facilitate recognition of this treatable but potentially life-threatening condition, the authors propose criteria that should prompt intracranial hypotension workup in the comatose patient and present a stepwise management algorithm to guide the appropriate diagnosis and treatment of these patients.