Postoperative cerebellar cyst with pesudomeningocele following tumor removal at the craniovertebral junction: A case report

Abstract Background Cerebellar cyst formation following surgery is uncommon, and few cases of this condition have been previously reported. These cases had an intraparenchymal cyst in the cerebellar hemisphere that required surgical fenestration of the cyst. We herein present a rare case of a postoperative cerebellar cyst with pesudomeningocele and MR images indicating a fistula between the cyst and pesudomeningocele. Case description A patient presented with an intraparenchymal cyst and surrounding edema in the cerebellar hemisphere that developed following a C1 laminectomy and a small suboccipital craniectomy for the removal of an accessory nerve neurinoma at the craniovertebral junction. Fast imaging employing steady-state acquisition images identified the fistula connecting the cyst and extradural cerebrospinal fluid retention. Conservative management with administration of dexamethasone induced spontaneous regression of the cyst, and no recurrence had occurred by the one-year follow-up. Conclusions Water-tight dural closure is important for the prevention of this rare complication following posterior fossa surgery. However, an arachnoid tear on the cerebellar fissure and adjacent dural defect are necessary antecedents for this rare condition. High-resolution FIESTA images could provide additional information for the etiology of postoperative cerebellar cyst.