Surgical therapy of symptomatic arachnoid cysts -: an outcome analysis

Background. Arachnoid cysts may present with various symptoms and in different locations. Optimal treatment is still controversial, although cyst fenestration or shunt insertion are recognized as standard procedures. In this retrospective analysis the authors sought to determine which factors influence the outcome after surgery of symptomatic arachnoid cysts. Methods. 37 patients (24 male, 13 female, mean age 40.2 years) were treated within a ten year period in our institution. Mean follow-up was 39 months; follow-up was done on an ambulatory basis. For analysis patient charts were reviewed and cranial CT scans or MR investigations were examined to determine pre- and postoperative cyst volumes. Clinical outcome was graded into four subgroups using a scale based on the patients self-rating of success. Different factors were studied concerning their influence on outcome. Findings. Fenestration was performed in 28 cases, cysto-peritoneal or cysto-atrial shunting in 9 cases. A favourable outcome (subgroups 3 and 4) was achieved in 19 of 28 patients (fenestration) and in 6 of 9 patients (shunting), respectively. Mean reduction of the cyst volumes was 58% after fenestration and 74% after shunting revealing both methods to be effective. Degree of cyst volume reduction correlated significantly with clinical outcome. Patients with infratentorial cysts had more often a favourable outcome. Headache as the only symptom did not influence outcome. Conclusions. Surgery of symptomatic arachnoid cysts resulted in favourable outcome in two thirds of the patients. Both standard procedures, fenestration and shunting, are equally effective for treatment. Factors that influence outcome are the rate of volume reduction and cyst location.