Puncture of Cerebellar Horizontal Fissure for Retrosigmoid Approach: A Prospective and Quantitative Analysis.

BACKGROUND: Cerebrospinal fluid (CSF) drainage is important in retrosigmoid approached surgery; however, in some cases, it is not feasible due to cerebellar swelling.

OBJECTIVE: To introduce a method, puncture of the horizontal fissure of the cerebellum, which can reduce the cerebellum to easily obtain a good operative corridor and slowly drain CSF.

METHODS: Between January and December 2014, we estimated the precise location of the horizontal fissure in 56 patients who underwent surgery via a retrosigmoid approach. Then, we collected and analyzed CSF drained by puncturing the horizontal fissure. We investigated whether a good operative corridor was obtained with this method.

RESULTS: The location of the precise horizontal fissure was a mean of 3.97 mm caudal to transverse sinus and the mean amount of CSF drained in 56 patients was 50.4 mL. A good corridor was obtained in 46 (82.1%) of 56 patients without additional cistern puncture.

CONCLUSION: The puncture of the horizontal fissure can be useful in retrosigmoid approach surgery. Moreover, inexperienced surgeons can use this method to effectively avoid injury of the cerebellum.