Effectiveness of C5 or C6-Cz assembly in predicting immediate post operative facial nerve deficit

• Published in: Acta neurochirurgica Vol. 155; no. 10; pp. 1863 - 1869
• Main Authors: Verst, Silvia Mazzali, Sucena, Andrea Caivano, Maldaun, Marcos Vinicius Calfat, Aguiar, Paulo Henrique Pires
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.10.2013; Springer Nature B.V
• Subjects: Adult; Aged; Cerebellopontine Angle - surgery; Child, Preschool; Clinical Article - Brain Tumors; Cranial Nerves - surgery; Electric Stimulation - methods; Evoked Potentials, Motor - physiology; Facial Nerve Injuries - etiology; Facial Nerve Injuries - physiopathology; Facial Nerve Injuries - prevention & control; Female; Humans; Interventional Radiology; Male; Medicine; Medicine & Public Health; Middle Aged; Minimally Invasive Surgery; Monitoring, Intraoperative - methods; Neurology; Neuroma, Acoustic - physiopathology; Neuroma, Acoustic - surgery; Neuroradiology; Neurosurgery; Surgical Orthopedics; Treatment Outcome; Posterior fossa tumors; Intraoperative neurophysiologic monitoring; Facial nerve functional outcome; Motor evoked potentials; Cerebellopontine tumors
• ISSN: 0001-6268; 0942-0940
• DOI: 10.1007/s00701-013-1806-x

Background Intraoperative neurophysiology monitoring (IOM) is a valuable tool in cerebellopontine angle (CPA) surgeries posing risk to the cranial nerves. Transcranial electrical stimulation (TES) for cranial nerves has been performed in the last 7 years, for obtaining the facial nerve motor evoked potential (MEP), using either C3/C4-Cz or C3-C4 (or inverse) stimulating points, which have been correlated with facial nerve functional outcome. Method Intraoperative surgical and electrophysiological findings were documented prospectively. Patient files were reviewed for clinical data. We studied 23 patients undergoing CPA tumor resection using C5 or C6-Cz montage for TES, and were able to determine the correlation between facial nerve functional outcome and the amplitude drop of facial MEP above 50 %. Patients were evaluated for immediate facial nerve outcome and 6 months after the surgery. Follow-up was performed by structured telephone interviews with local physicians. Results The sensibility of the studied parameters was 92.8 % for amplitude drop of facial nerve MEP, with positive predictive value of 81.2 %. The absence of changes during IOM has shown a negative predictive value of 100 %. Conclusion In this series, the used montage was effective in predicting new facial deficit.