Spectrum of subdural fluid collections in spontaneous intracranial hypotension

Object. Spontaneous intracranial hypotension is a noteworthy but commonly misdiagnosed cause of new daily persistent headaches. Subdural fluid collections are frequent radiographic findings, but they can be interpreted as primary rather than secondary pathological entities, and uncertainties exist regarding their optimal management. The authors therefore reviewed their experience with subdural fluid collections in 40 consecutive patients with spontaneous spinal cerebrospinal fluid (CSF) leaks and intracranial hypotension. Methods. The mean age of the 26 female and 14 male patients was 43 years (range 13-72 years). Subdural fluid collections were present in 20 patients (50%); 12 of these patients (60%) had subdural hygromas alone, and eight (40%) had subacute to chronic subdural hematomas (SDHs) associated with significant mass effect. The subdural hygromas resolved within several days to weeks following treatment of the underlying CSF leak. Three patients with SDHs underwent evacuation of the hematoma prior to the establishment of the diagnosis of spontaneous intracranial hypotension, but the SDHs did not resolve until the underlying spinal CSF leak was treated. In the remaining five patients, the CSF leak was treated primarily and the SDHs resolved over a 1- to 3-month period without the need for evacuation. Conclusions. Subdural fluid collections are common in spontaneous intracranial hypotension, varying in appearance from thin subdural hygromas to large SDHs associated with significant mass effect. These collections can be safely managed by directing treatment at the underlying CSF leak without the need for hematoma evacuation.