A comparison of prone versus sitting position for the surgical treatment of Chiari malformation type I in children

Abstract

Objective: Posterior fossa decompression and duroplasty (PFD-D) for Chiari type I malformation (CM-I) is usually performed in the prone position. Nevertheless, few centres routinely perform it in sitting position. This study aims to compare, for the first time in the literature, the peri-operative surgical and anaesthesiologic outcomes of two similar cohorts of paediatric patients with CM-I treated with PFD-D in prone and sitting position.

Methods: Patients younger than 17 years old, who had undergone PFD-D for CM-I performed by a single surgeon between November 2013 and June 2024, were included. Surgical time, intraoperative and perioperative events, and post-operative complications were recorded. All patients had at least a 10-month follow-up.

Results: Twenty-seven patients were operated in the prone position [mean age: 9.3 years, M/F: 0.59] and twenty-five in the sitting position [mean age: 11.3 years, M/F 0.47]. 15/27 (55 %) in the prone group and 13/25 (52 %) in the sitting group had pre-operative syringomyelia. The mean operative time in sitting was significantly shorter (143 min) compared to 175 min in the prone position (p < 0.001), particularly in high BMI > 30 patients. Complications in the prone cohort included 3 post-operative pseudomeningocele (11.1 %), 3 aseptic meningitis (1 %), 1 CSF leakage (3.7 %), and 1 post-infective hydrocephalus requiring VP shunt insertion (3.7 %). In the sitting position, 1 patient developed pseudomeningocele (4 %), and another patient had a post-operative hydrocephalus (4 %) successfully treated with an endoscopic third ventriculostomy. No patient in this series developed clinical air embolism or tension pneumocephalus.

Conclusions: The study did not show any significant difference in the surgical and anaesthetic complications between the two groups of patients. Sitting position for CM-I when performed by a trained neuro-anaesthesiologic team is a safe option with similar clinical outcomes compared to the prone position.

Keywords: Chiari malformation; Duroplasty; Foramen magnum decompression; Prone position; Sitting position.