Welling-up of cerebrospinal fluid is a sign of remote supratentorial hemorrhage during microvascular decompression: a case report

Background Subdural hematoma (SDH) at a remote operative site is uncommon following neurosurgical procedures. However, supratentorial SDH is one of the rare complications following microvascular decompression (MVD). We report a case of supratentorial SDH following MVD. The welling of cerebrospinal fluid (CSF) in the cerebellomedullary fissure was observed unexpectedly during the dissection. It is a signal case that can improve our understanding of the occurrence of such rare complications and of possible mechanisms. Case presentation A 54-year-old woman was diagnosed with left hemifacial spasm (HFS) and had been receiving botulinum toxin injections since 10 years before surgery. CSF welling-up in the cerebellopontine cistern was noticed by the surgeon during the arachnoid dissection. MVD was performed completely. A thin supratentorial SDH was found on the right side (contralateral) on immediate postoperative computed tomography (CT). The SDH was asymptomatic, and the size of hematoma did not increase in follow-up CT scans after surgery. During the follow-up period, she was relieved of HFS. CSF welling-up can be considered the time of initiation of the hemorrhage. Conclusion Limited case reports of supratentorial SDH following MVD have been published, and none of them have reported time of initiation of the hemorrhage. The phenomenon of abnormal CSF welling-up in the cistern could be a sign of remote supratentorial hemorrhage.