Middle fossa arachnoid cyst fenestration for ruptured cysts associated with subdural collections: paediatric neurosurgery tertiary unit experience

Arachnoid cysts are commonly encountered benign cystic structures and often come to attention as incidental findings following cranial imaging. Surgical intervention rates vary in different studies; however, rupture of cyst and subdural collection with mass effect are some of the indications for surgical intervention. In this study, we aimed to evaluate our operated cohort of middle fossa arachnoid cysts to determine the rate of traumatic subdural collection in this cohort and further assess outcomes.

A retrospective review of all consecutive operated middle cranial fossa arachnoid cysts was carried out for the period 2010 to 2024. Demographics including age, sex, Galassi type, surgical technique for fenestration, preceding history of trauma, presence of papilloedema, and complications following surgery were extracted. Indication for surgery included papilloedema and headaches or increasing head circumference or rupture and subdural collections. Arachnoid cysts managed with CSF diversion as primary surgery were excluded.

Over the study period, 21 fenestrations of the arachnoid cysts were carried out in 19 patients with mean age of 7 years and M:F ratio of 2.2:1 (laterality: 9 right-sided and 10 left-sided). These included seven Galassi 2 and twelve Galassi 3 arachnoid cysts. At presentation, 10 had papilloedema, 5 with no papilloedema, and 4 with no available ophthalmological assessment. Fenestration of cyst included 12 microscopic, 6 endoscopic, and 3 combined approaches. Of the operated cohort, 8 were due to rupture of arachnoid cyst and subdural collections causing mass effect. Of 8 cases of ruptured arachnoid cyst with subdural collections, 75% had clear history of preceding head injury in the context of accidental or sports-related injuries. Two patients required redo-fenestration (10.5%), 1 patient required temporary lumbar drain (5.2%), and 2 patients required cysto-peritoneal shunts (10.5%).

Rupture of arachnoid cysts and subdural collections although rare can be associated with head injury in majority of cases. All operated cases belonged to grade 2 and 3 Galassi.