Symptomatic and Radiographic Improvement Following Surgery for Posterior Fossa Arachnoid Cysts: Meta-Analysis and Literature Review.

Objective: Arachnoid cysts are benign, intradural collections of cerebrospinal fluid that are often asymptomatic but, in rare instances, will grow and may cause symptoms. When these are in the posterior fossa, the symptomatology greatly ranges, and the indications for surgery are not well defined. The objective of this study is to examine radiographic and symptomatic outcomes following surgery for posterior fossa arachnoid cysts (PFAC).

Methods: A literature review was performed utilizing PubMed for all studies involving ≥ 5 patients with PFACs who underwent surgery. A single-arm meta-analysis was performed to assess the postoperative radiographic improvement. Given the heterogeneous variety of presenting symptoms, these were not conducive to meta-analyses but the outcomes are reported in detail.

Results: Nine publications with 67 patients met inclusion criteria. Excision/fenestration was the most common operation (n=60). Less common included CP shunts (n=2), concurrent excision/fenestration and ETV (n=4), and one patient who underwent concurrent VP/CP shunts. This literature review revealed improvement of headache in 90% of patients; 88% with cerebellar symptoms; 92% with nausea/emesis; 78% with hearing loss; 60% with tinnitus; and 91% with vision deficits. Meta-analysis of seven studies reporting postoperative radiographic size demonstrated that 75% of people experienced decreased PFAC size (Effect Size: 0.75, 95% CI: 0.50-0.94).

Conclusions: Although there is a high rate of radiographic improvement for PFAC surgery, there is a wide variety of presenting symptoms with differing postoperative improvement rates. This study reinforces the importance of preoperative counseling regarding symptomatic outcomes for PFAC surgery, with supporting statistical analysis but limited by the sample sizes available.