Supplementary Material for: Postoperative complications of microscopic fenestration for middle fossa arachnoid cysts: a retrospective study of 38 cases and literature review

Introduction: Middle fossa arachnoid cyst (MFAC) is one of the most common cranial cysts in children, and the various postoperative complications following cyst fenestration represent a major concern. We conducted a retrospective study in our department and performed a systematic review of the literature to identify the risk factors for complications. Methods: A retrospective survey was conducted on 38 patients with MFAC (< 14 years) who underwent microscopic fenestration from January 2019 to December 2020. Postoperative complications, including postoperative hemorrhage/hematoma, subdural hygroma (SH), cranial nerve palsy, central nervous system infection (PCNSI), and cerebrospinal fluid (CSF) leak, were collected. A systematic PubMed search for cohort studies on surgically treated MFAC published after 1980 was performed. The postoperative complications in the included studies were illustrated. Results: The overall complication rate in our series was 7.9%, among whom, nine patients (23.7%) developed postoperative SH, one of which required cyst-peritoneal shunting. Patients who developed SH were significantly younger (4.0 ± 1.8 vs 6.3 ± 3.4 years, p = 0.012). Binary logistic analysis showed that a lower age could be a risk factor for developing SH (odds ratio: 0.738, p = 0.067). One patient developed a subdural hematoma. No cranial nerve palsy or CSF leak was observed. Eighteen studies were included in the systematic review, comprising 649 cases of MFAC. The most common complication was SH (4.9%), and the postoperative complication rates were similar between the microscopic and endoscopic techniques. Conclusion: The complication rate of MFAC fenestration is considerable. SH is the most common postoperative complication, and it mostly occurs in young children. Strict surgical indications should be applied for young children.