Artikel
Facial nerve motor evoked potential for cerebellopontine angle surgery: Technical note and results
Facialis-MEP bei der Chirurgie am Kleinhirnbrückenwinkel: Technische Aspekte und Ergebnisse
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Autoren
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M. A. Acioly
- Klinik für Neurochirurgie, Universitätsklinikum Tübingen
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M. Liebsch
- Klinik für Neurochirurgie, Universitätsklinikum Tübingen
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C. H. Carvalho
- Klinik für Neurochirurgie, Universitätsklinikum Tübingen
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A. Gharabaghi
- Klinik für Neurochirurgie, Universitätsklinikum Tübingen
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M. Tatagiba
- Klinik für Neurochirurgie, Universitätsklinikum Tübingen
| Veröffentlicht: | 30. Mai 2008 |
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Gliederung
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Objective: The facial nerve function has an important role for human communication. Despite all efforts, facial nerve paresis remains a frequent postoperative sequel of major concern following cerebellopontine angle surgeries. A variety of facial nerve monitoring techniques is currently available. Among them, the facial nerve motor evoked potential (FMEP) has increasingly been described in different protocols. We have sought to develop a new FMEP protocol to assess the orbicularis oculi and oris muscle functions routinely during surgery searching for changes that may predict postoperative facial paresis.
Methods: 50 consecutive cases of cerebellopontine angle lesions were studied prospectively. The electrical stimulation was transcraniallly applied contralateral to the affected side by using a pair of spiral electrodes placed at CZ and C3 or C4. The stimulation was accomplished with 1 to 5 pulses of 200 to 600 V, 2 miliseconds of interstimulus interval and 50 microseconds duration. The responses were detected in the same needles used for electromyography of the orbicularis oculi and oris muscles. The M.abductor pollicis brevis was used as a control. The surgical procedure was divided into five surgical steps, namely baseline, dura opening, tumor dissection, tumor resection and dural closure. FMEP was recorded in each of the five surgical steps and on the surgeons' demand.
Results: FMEP from the M.orbicularis oris and oculi were obtained. Stimulus artifacts were occasionally documented preventing a consistent record of the FMEP from the M.orbicularis oculi. Hand MEP was not recorded with 1 pulse stimulation. Decreased FMEP amplitude of more than 50% between baseline and any surgical step was consistent with postoperative facial paresis.
Conclusions: FMEP is a promising method for facial nerve monitoring during cerebellopontine angle surgeries. Several measures during critical surgical steps are required to provide prompt feedback between neurophysiologists and neurosurgeons in order to detect and avoid damaging processes.
