Four layer onlay stacking repair of dura preventing cerebrospinal fluid leakage in microvascular decompression

Background: Cerebrospinal fluid (CSF) leakage is one of major complication following cranial surgery. Many studies have been introducing surgical methods to prevent CSF leakage. Technique applying dural substitutes are being studied for its efficacy for preventing CSF leakage. We introduce four layer onlay stacking repair (FLOSR), effective dural closing technique for preventing CSF leak-age, while avoiding application of foreign material intradural space. Materials and Methods: Retrospective analysis of patients undergone microvascular decompres-sion (MVD) surgery for hemifacial spasm (HFS) and trigeminal neuralgia (TN) by a single surgeon in single center between September 2020 and September 2022 was done. MVD was done by retro-mastoid suboccipital approach. Number of patients who had CSF leakage, symptoms occurred by CSF leakage and treatment done for the patients were collected. Results: In this study, 355 patients underwent MVD for HFS and TN and 4 were excluded. Three patients of selected 351 patients who underwent MVD for HFS were suspected for CSF leakage which counts for approximately 0.9% of patients. All patients suspected for CSF leakage underwent MVD for HFS (3 of 3, 100%). Continuous lumbar drainage of 180-240 cc per day for 5 days was done and every patient had symptom improvement. Conclusions: FLOSR provided an effective method intra-operatively in preventing and lowering risk of severe CSF leakage after craniotomy by RMSOC (retromastoid suboccipital craniotomy) ap-proach without the risk of placing foreign materials inside dura.