Minimally Invasive Surgical Management of Type III Cerebrospinal Fluid Leaks: A Retrospective Case Series and Outcome Evaluation

Introduction: Type III spinal CSF, or CSF-venous fistulas, can cause spontaneous intracranial hypotension (SIH). Diagnosis is challenging, even with advanced techniques, and often require lateral decubitus myelography or digital subtraction myelography for localization. Nontargeted and targeted patching can be effective, although transvenous embolization and surgical intervention are commonly required for durable treatment. This case series aims to evaluate the outcomes of minimally invasive surgical interventions for patients with Type III CSF leaks.

Methods: This retrospective case series included 31 patients with Type III CSF leaks who failed conservative measures and had surgical intervention between September 2022 and June 2024 in a single tertiary hospital by a single surgeon. A preoperative pan-CNS MRI and a CT myelogram (lateral decubitus) were completed for all patients and pre-op and post-op Bern scores were calculated by single neuroradiologist for each to determine SIH severity and response to treatment. Dural repair was accomplished through a minimally invasive, tubular surgical approach and involved obliteration of the peri-neural venous structures with papoose reconstruction of often-associated nerve root diverticulum. Post-operative outcomes, symptom resolution, and MRI-based Bern scores were conducted for all patients pre-operatively and at 4 weeks.

Results: In 31 patients with Type III CSF leaks, 96.8% had thoracic leaks, and all presented with headaches. Following surgical ligation of fistula, all patients had a reduction in pre-op Bern score with a mean Bern score improvement from 6.2 to 3.4 (p < 0.001). Clinical response was also robust with headache frequency dropping from 100% to 9.7% (p < 0.001). Only one patient experienced rebound hypertension and there were no reoperations or failures. At four weeks, 90.3% had complete pre-operative symptom resolution.

Conclusion : Surgical management of Type III CSF leaks via MIS approach is an effective option, offering a 100% Bern score improvement rate and 90%+ success in complete symptom relief.