Surgical treatment and outcome of posterior fossa arachnoid cysts in infants.

The aim of this cohort study was to describe and analyze the surgical treatment and outcome of posterior fossa arachnoid cysts (PFACs) in infants. Patients presenting with a PFAC at infancy or prenatally, between the years 2000 and 2019, and who were surgically treated before the age of 2 years, were included in this study. Patient data were retrospectively collected including baseline characteristics and surgical variables. Factors related to revision surgery were analyzed through uni- and multivariate analysis. Thirty-five patients, of whom 54.3% were male, were included. The cyst was diagnosed prenatally in 23 patients (65.7%). Surgery was typically recommended after a mean cyst follow-up of 3.4 ± 3.9 months, with a mean age at surgery of 6.1 ± 5.1 months. In 54.3% of patients (n = 19), surgery was performed before the age of 6 months. The PFAC was treated purely neuroendoscopically in 57.1% of patients (n = 20), while 28.6% of patients underwent open cyst procedures (n = 10), 5.7% (n = 2) were treated with a shunt, and 8.6% (n = 3) underwent a combined procedure. Additional surgery was required in 31.4% of patients (n = 11; mean 2.36 ± 2.11 surgeries per patient). At the last follow-up (61.40 ± 55.33 months), no mortality or permanent morbidity was seen; radiological improvement was apparent in 83.9% of the patients. Those patients treated before the age of 6 months (p = 0.09) and who presented before surgery with a stable cyst size that was maintained throughout preoperative monitoring (p = 0.08) showed a trend toward higher revision rates after surgical treatment. PFACs in infancy may require surgical treatment before the age of 6 months. Navigated endoscopy was a valid surgical option. Overall mortality or permanent morbidity was rare. Additional surgery was required in up to 30% of the patients; younger age and a preoperatively stable cyst might be risk factors for revision surgery.