Fourth ventricular stenting in foramen magnum decompression for type 1 Chiari malformations with syringomyelia

Chiari malformation type 1 (CM-1) with syringomyelia is a common craniocervical abnormality and in symptomatic patients, there is ongoing debate regarding the optimum surgical strategy for decompressing the foramen magnum. The placement of a fourth ventricular-subarachnoid stent is a novel approach intended to increase symptom response rates and decrease the need for revision surgery, particularly in complex cases. The aim of this study was to present a single-center experience on the safety and efficacy of this technique.

A retrospective review was conducted of all CM-1 patients who underwent Foramen Magnum Decompression (FMD) + fourth ventricular stent between January 01, 2012, and September 20, 2022, at a single UK neurosurgical center. Patients were identified using a keyword search of the hospital's electronic medical records. Primary outcomes included syrinx size and neurological symptoms. Secondary outcomes included operative duration, length of stay, and number of revision procedures. Syrinx size was measured on axial T2 magnetic resonance imaging sequences.

17 patients received a stent as part of their FMD. The use of a stent improved or resolved the radiological appearance of the syrinx in 16 (87.5%) patients with an average AP diameter reduction of 57% (-4.86 mm standard deviation: 3.32). Clinically, 8 (62%) patients reported complete or partial resolution of limb symptoms. Following stent-assisted FMD only, 2 patients (11.7%) required further decompressive surgery.

This case series evaluates the use of a fourth ventricular stent as part of FMD for CM-1. The study demonstrates the efficacy of a stent with satisfactory radiological and clinical outcomes. The results support the use of fourth ventricular stenting as a useful adjunct in patients with complex obstruction of fourth ventricle outflow.