Clinical and radiological outcomes following surgical treatment for intra-cranial arachnoid cysts

•All methods have similar rates of clinical and radiological improvement.•There is no significant difference in complication and re-operation rates.•Neuroendoscopy is associated with a shorter length of hospital stay.•Percentage of cyst volume change is not related to degree of symptomatic improvement. Intra-cranial arachnoid cysts are benign lesions which are usually incidental, however can produce neurological symptoms due to mass effect as they enlarge. Controversy still exists regarding the optimal option for the surgical management of these cysts. These options are neuroendoscopic fenestrations, microsurgical fenestrations +/− marsupialisation and insertion of a cysto-peritoneal shunt. A retrospective case note review of all patients with intra-cranial arachnoid cysts treated surgically at a single UK neurosurgical centre over a 15 year period. Data on clinical presentations and outcomes was collected from the patient notes and the pre- and post-operative cyst volumes were calculated by creating 3-dimensional volumetric models. Eighty-two patients were identified of which 45 were treated endoscopically, 34 microscopically and 3 underwent cysto-peritoneal shunting. The most common cyst location was the middle fossa (n = 25). Amongst the symptomatic patients, improvement or resolution of symptoms was seen in 35 out of 40 cysts treated endoscopically (88%), 28 out of 32 treated microsurgically (88%) and 3 out of 3 treated by shunting (100%, p = 0.79). The reoperation rate was not significantly different between the endoscopic and microsurgical groups (24.4% vs 14.7%, p = 0.49). The endoscopic and shunted groups had a shorter length of stay than the microsurgical group (3.0 vs 3.0 vs 4.5 days, p = 0.04). All three treatment modalities had a similar percentage reduction in cyst volume after surgery (30.0 vs 41.7 vs 30.9%, p = 0.98). This cohort series shows that endoscopic and microsurgical approaches to treat intracranial arachnoid cysts produce comparable clinical and radiological outcomes. Endoscopic fenestration is associated with a shorter length of stay as would be expected from a minimally invasive procedure.