Cerebrospinal Fluid Diversion in Patients with Idiopathic Intracranial Hypertension and Slit Ventricles: The Cisterna Magna and Lumbar Shunts

Introduction: Idiopathic intracranial hypertension (IIH) is a cerebrospinal fluid (CSF) disorder defect that is frequently treated with CSF shunts. Although the lumbar shunt is a suitable option for treating IIH patients with slit ventricles, it carries risk of complications and is associated with a high failure rate. Shunts utilizing the cisterna magna as a proximal reservoir have been described in prior literature, however, the long-term effectiveness, revision rates, and clinical outcomes of this shunt are unknown. The present study compares these parameters in IIH patients shunted with cisterna magna and lumbar shunts.

Methods: Patient charts were retrospectively reviewed over a 27-year period. A “revision” was noted to be any instance of reoperation to adjust, replace, or remove a shunt. The “revision rate” was calculated as the total number of revisions divided by years of shunt placement. Average follow-up time was 10.5 years.

Results: 11 patients (8 females, 3 males; mean age 17.3 years) with IIH underwent shunting from the cisterna magna and lumbar subarachnoid spaces at our institution. All patients had slit ventricles on radiological imaging and eight patients had a diagnosis of Chiari malformation 1. The mean revision rates were 0.35/year and 1.30/year for 11 cisterna magna and 17 lumbar shunts, respectively. Cisterna magna shunts had a longer mean time until first shunt failure compared to lumbar shunts (101.9 vs. 87.7 days). Both shunts improved clinical symptoms in all shunted patients.

Conclusion : The cisterna magna shunt had a lower rate of revision and longer survival until first failure compared to lumbar shunts at our institution. Cisterna magna shunts may be a suitable treatment option for patients with IIH and slit ventricles.