Intraoperative Neurophysiology Practice in the Surgical Treatment of Posterior Fossa Lesions: Cerrahpaşa Experience

Abstract

Introduction:Posterior fossa surgery involves a risk of injury on a variety of critical neurological structures. Intraoperative neuromonitoring (IONM) has become a routine scrutiny with newly developed tests for sparing these structures. This present study aims to evaluate the IONM experience in posterior fossa surgery of a tertiery neurosurgical centre.Methods:Forty-five patients (26 females, 19 males; age between 2 and 72 years) who underwent surgery for different posterior fossa pathologies from 2016 to 2019 were retrospectively evaluated.Results:Six and thirteen patients experienced extremity motor evoked potential (MEP) and somatosensory evoked potential changes respectively. Brainstem auditory evoked potential changes were seen in four patients. Corticobulber MEP (CoMEP) of facial nerve deteriorated in seven patients. All new onset neurological deficits of cranial nerves or long tracts were concordant with IONM findings except for one patient who developed 6th nerve palsy without CoMEP findings. Loss of neurological function immediately after surgery was observed in 13 patients while permanent evident neurological worsening occurred in five patients.Conclusion:IONM is an indispensable component of the skull base surgery. Comprehensive multimodality monitoring provides a real-time, complete assessment of critical neurological structures, facilitates safer and more aggressive management and thus improves quality of life.

Keywords

• blink reflex
• brainstem auditory evoked potential
• corticobulber motor evoked potential
• multimodality
• neuromonitoring
• posterior fossa lesions
• skull base surgery