Communicating hydrocephalus after radiosurgery for vestibular schwannomas: does technique matter? A systematic review and meta-analysis

Background Communicating hydrocephalus (cHCP) after radiosurgery (RS) for vestibular schwannomas (VS) has been reported. Many hypothetical mechanisms for this pathology have been proposed without consensus. The aim of this study is to determine if the platform used to treat the disease, Gamma Knife (GK) versus linear accelerator (LINAC)-based RS, makes a difference in outcome. Methods We conducted a meta-analysis of databases PubMed and Cochrane to identify all articles for the period January 2000-August 2018 with the following inclusion criteria: (1) VS treated with single fraction SRS (2) > 10 patients (3) original reports only (4) hydrocephalus reported as complication (5) human study. Results A total of 7039 and 988 VS patients reported in 35 and 10 papers were treated with GK or LINAC RS, respectively. Demographic baseline characteristics not reported in aggregate did not differ between the two groups. The incidence of cHCP was 3% [95% CI 2-4] and 2% [95% CI 1-3] for GK and LINAC RS patients, respectively. Surgical CSF diversion was performed in 88% and 68% of patients evaluated for cHPC in the GK and LINAC group, respectively. Follow-up range was 30-150 and 29-92 months for GK and LINAC, respectively. Conclusions The incidence of cHCP following RS for VS is very low in both GK and LINAC treated patients, albeit not identical. The higher reported surgical intervention rate for VS patients treated with GK RS might be multi-factorial, including longer follow-up in the GK group.