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  • Abnormal Muscle Response Monitoring by a New Method in Patients with Hemifacial Spasm : A Prospective Study

    Final Number:

    Seunghoon Lee MD; Sang-Ku Park; Juyoung Hwang; Jeong-A Lee; Byung-Euk Joo; Doo-Sik Kong MD; Dae-Won Seo; Kwan Park MD

    Study Design:
    Clinical Trial

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2017 Annual Meeting - Late Breaking Science

    Introduction: Intraoperative abnormal muscle response (AMR) has been a reliable diagnostic tool and an indicator of complete decompression of facial nerve from offending vessels in hemifacial spasm (HFS) patients. To the best of our knowledge, there have been no attempt to apply different methods of AMR monitoring to increase the efficacy.

    Methods: The study included 486 consecutive HFS patients prospectively who were performed with AMR monitoring by a new method during MVD. A new method comprised of preoperative facial nerve mapping and intraoperative AMR monitoring with antegrade stimulation of facial nerve. With the last 62 patients, we performed a comparison study in which patients were monitored AMR with both antegrade and retrograde stimulations at the same time.

    Results: Preoperative facial nerve mapping showed “F” was the location where maximal AMR was detected most frequently (66.9%). Intraoperative AMR was observed in 419 (86.2%) of 486 patients by a new method and it was disappeared after MVD in 404 (96.4%) of 419 patients. Comparison of AMR monitoring by antegrade and retrograde method showed that disappeared AMR after MVD was observed in 98.2% and 61.8%, and no AMR in 0% and 9.1%, respectively. Persistent AMR despite the thorough exploration and decompression was observed in 1.8% and 29.1%.

    Conclusions: A new method of preoperative mapping with intraoperative antegrade stimulation of facial nerve showed better efficacy in AMR monitoring, and it confirms that the disappearance of AMR is still a good indicator of complete decompression during MVD surgery.

    Patient Care: With a new method, AMR monitoring became more sensitive and specific measure to confirm that MVD was successful Therefore unnecessary exploration could be avoided during surgery.

    Learning Objectives: A new method guaranteed better efficacy in AMR monitoring during MVD surgery.


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