Migrating pseudomeningocele causing posterior fossa syndrome

Abstract

We present two cases of spontaneous intracerebellar migration of a pseudomeningocele. This is a rarely reported complication of posterior fossa surgery with possible life threatening cerebellar mass effect. The probable mechanism is a slow but progressive cerebrospinal fluid (CSF) movement (one-way valve mechanism) into the pseudomeningocele with secondary herniation or dissection through a weakened dura into the cerebellum causing progressive or acute cerebellar dysfunction. Evacuation and dural repair with or without CSF shunting or marsupialisation results in resolution of the symptoms.

Symptomatic Cerebellar Cyst Formation after Foramen Magnum Meningioma Removal: A Case Report

“…These reports, similarly to ours, concluded that dural defects and small tears in the arachnoid and parenchyma of the cerebellum affect the one-way valve mechanism, causing CSF to accumulate in the cyst. 3,4,8,9 This emphasizes the CSF connection between the pseudomeningocele and the cyst, similar to our case.…”

“…3 These lesions are primarily occipital, with few supratentorial lesions reported. Pseudomeningocele formation is mainly from inadequate closure of the dura mater 8 that allows extradural accumulation of CSF and cystic enlargement. 4 There are scarce studies on how pseudomeningocele accumulates CSF within the brain parenchyma.…”

Life-threatening posterior fossa cyst induced by pseudomeningocele after operation for acoustic neuroma

“…After lumbar drainage or other treatment efforts, CSF flow changes and moves rapidly to move CSF from the pseudomeningocele to the intracerebellar parenchyma via a weak area of the dura, resulting in formation of an enlarged cyst with a mass effect to vital brain structures. [ 2 ] The postoperative adjacent scarring, coagulation necrosis, brain tissue loss due to encephalomalacia following resection, and loss of the peritumoral arachnoidal plane are all possible leading factors of cyst formation in our case with the complication of pseudomeningocele. Since the best approach is prevention of cysts, we believe that we should have initially administered a more aggressive treatment such as surgical dural repair, rather than a conservative treatment, given the possibly fatal consequences of this condition.…”