{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,20]],"date-time":"2026-01-20T11:42:08Z","timestamp":1768909328491,"version":"3.49.0"},"reference-count":33,"publisher":"Journal of Neurosurgery Publishing Group (JNSPG)","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2024,9,1]]},"abstract":"<jats:sec>\n<jats:title>OBJECTIVE<\/jats:title>\n<jats:p>The lateral spread response (LSR) is an important electrophysiological sign that predicts successful decompression in patients undergoing microvascular decompression (MVD) for hemifacial spasm (HFS). However, LSRs do not consistently correlate with clinical outcomes, and there are cases in which LSRs are absent. In this study, the authors identified a unique pattern on facial nerve electromyography (EMG) when the root exit zone (REZ) is touched. This distinctive EMG pattern, which the authors coined the \"Sang-ku sign\" (SKS), could aid in identifying the offending vessel on the REZ, even in the absence of LSRs.<\/jats:p>\n<\/jats:sec>\n<jats:sec>\n<jats:title>METHODS<\/jats:title>\n<jats:p>Between November 2022 and August 2023, the authors analyzed EMG findings from 185 patients undergoing MVD for HFS. Bipolar stimulation electrodes were placed at the marginal mandibular branch, and recordings were obtained from the frontalis and orbicularis oris muscles. Additionally, stimulation electrodes were placed at the temporal branch, and recordings were obtained from the oris and mentalis muscles. The authors statistically analyzed the presence of SKS and its association with demographic, surgical, clinical outcomes, and anatomical factors.<\/jats:p>\n<\/jats:sec>\n<jats:sec>\n<jats:title>RESULTS<\/jats:title>\n<jats:p>The authors observed a brief, burst-like wave pattern arising from all recorded muscle branches when Teflon felt was placed between the REZ and the facial nerve. This EMG pattern, the SKS, was found in 164 patients (88.6%). Among the factors analyzed, only patient age showed a significant association with the presence of the SKS in univariate analysis (p = 0.007). The presence of the SKS was significantly associated with predicting the disappearance of LSRs (p = 0.045). Clinical outcomes were favorable (99% at the last follow-up) in all cases; thus, no positive correlation was observed in the existence of the SKS and LSRs.<\/jats:p>\n<\/jats:sec>\n<jats:sec>\n<jats:title>CONCLUSIONS<\/jats:title>\n<jats:p>The SKS could serve as an excellent guide for the facial nerve REZ during surgery. Given that HFS results from abnormal vascular contact on the REZ, this finding plays a crucial role in ensuring surgical success. Alongside LSRs, the SKS could provide valuable insights for neurosurgeons.<\/jats:p>\n<\/jats:sec>","DOI":"10.3171\/2024.5.jns24125","type":"journal-article","created":{"date-parts":[[2024,9,28]],"date-time":"2024-09-28T01:25:14Z","timestamp":1727486714000},"page":"1-9","source":"Crossref","is-referenced-by-count":3,"title":["Enhancing surgical precision: a novel electromyography finding for confident identification of the root exit zone during microvascular decompression surgery"],"prefix":"10.3171","author":[{"given":"Kyung Rae","family":"Cho","sequence":"first","affiliation":[{"name":"Department of Neurosurgery, Konkuk University Medical Center, Seoul; and"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Soung Wook","family":"Park","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Konkuk University Medical Center, Seoul; and"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hyun Seok","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Konkuk University Medical Center, Seoul; and"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sang-ku","family":"Park","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Konkuk University Medical Center, Seoul; and"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kwan","family":"Park","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Konkuk University Medical Center, Seoul; and"},{"name":"Department of Neurosurgery, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1754","reference":[{"issue":"9","key":"b1","series-title":"Life (Basel)","first-page":"1825","article-title":"Lateral spread response: unveiling the smoking gun for cured hemifacial spasm","volume":"13","author":"Cho KR","year":"2023","unstructured":"Cho KR, Park SK, Park K. Lateral spread response: unveiling the smoking gun for cured hemifacial spasm. Life (Basel). 2023;13(9):1825."},{"issue":"2","key":"b2","series-title":"J Neurosurg","first-page":"254","article-title":"Intraoperative monitoring of the facial nerve during decompressive surgery for hemifacial spasm","volume":"74","author":"Haines SJ","year":"1991","unstructured":"Haines SJ, Torres F. Intraoperative monitoring of the facial nerve during decompressive surgery for hemifacial spasm. J Neurosurg. 1991;74(2):254\u2013257."},{"issue":"8","key":"b3","series-title":"Life (Basel)","first-page":"1760","article-title":"Clinical application of botulinum toxin for hemifacial spasm","volume":"13","author":"Park CK","year":"2023","unstructured":"Park CK, Lim SH, Park K. Clinical application of botulinum toxin for hemifacial spasm. Life (Basel). 2023;13(8):1760."},{"issue":"2","key":"b4","series-title":"Heliyon","first-page":"e06115","article-title":"Predicting outcome of hemifacial spasm after microvascular decompression with intraoperative monitoring: a systematic review","volume":"7","author":"Nugroho SW","year":"2021","unstructured":"Nugroho SW, Perkasa SAH, Gunawan K, Manuhutu YN, Rahman MA, Rizky A. Predicting outcome of hemifacial spasm after microvascular decompression with intraoperative monitoring: a systematic review. Heliyon. 2021;7(2):e06115."},{"issue":"2","key":"b5","series-title":"Neurosurg Rev","first-page":"311","article-title":"Continuous intraoperative monitoring of abnormal muscle response in microvascular decompression for hemifacial spasm; a real-time navigator for complete relief","volume":"37","author":"Hirono S","year":"2014","unstructured":"Hirono S, Yamakami I, Sato M,  Continuous intraoperative monitoring of abnormal muscle response in microvascular decompression for hemifacial spasm; a real-time navigator for complete relief. Neurosurg Rev. 2014;37(2):311\u2013320."},{"issue":"11","key":"b6","series-title":"Acta Neurochir (Wien)","first-page":"2963","article-title":"Reoperation for residual or recurrent hemifacial spasm after microvascular decompression","volume":"164","author":"Jiang S","year":"2022","unstructured":"Jiang S, Lang L, Sun B,  Reoperation for residual or recurrent hemifacial spasm after microvascular decompression. Acta Neurochir (Wien). 2022;164(11):2963\u20132973."},{"issue":"3","key":"b7","series-title":"Operative techniques and results in 47 patients. J Neurosurg","first-page":"321","article-title":"Etiology and definitive microsurgical treatment of hemifacial spasm","volume":"47","author":"Jannetta PJ","year":"1977","unstructured":"Jannetta PJ, Abbasy M, Maroon JC, Ramos FM, Albin MS. Etiology and definitive microsurgical treatment of hemifacial spasm. Operative techniques and results in 47 patients. J Neurosurg. 1977;47(3):321\u2013328."},{"issue":"4","key":"b8","series-title":"J Neurosurg","first-page":"586","article-title":"Continuous electromyography monitoring of motor cranial nerves during cerebellopontine angle surgery","volume":"93","author":"Romst\u00f6ck J","year":"2000","unstructured":"Romst\u00f6ck J, Strauss C, Fahlbusch R. Continuous electromyography monitoring of motor cranial nerves during cerebellopontine angle surgery. J Neurosurg. 2000;93(4):586\u2013593."},{"issue":"9","key":"b9","series-title":"Intern Med","first-page":"1084","article-title":"Central motor conductivity in aged people","volume":"31","author":"Mano Y","year":"1992","unstructured":"Mano Y, Nakamuro T, Ikoma K,  Central motor conductivity in aged people. Intern Med. 1992;31(9):1084\u20131087."},{"key":"b10","series-title":"World Neurosurg","first-page":"8","article-title":"Prognostic value of abnormal muscle response during microvascular decompression for hemifacial spasm: a meta-analysis","volume":"137","author":"Zhang J","year":"2020","unstructured":"Zhang J, Li ZH, Wang JF, Chen YH, Wang N, Wang Y. Prognostic value of abnormal muscle response during microvascular decompression for hemifacial spasm: a meta-analysis. World Neurosurg. 2020;137:8\u201317."},{"issue":"5","key":"b11","series-title":"Clin Neurophysiol","first-page":"2240","article-title":"Ephaptic transmission is the origin of the abnormal muscle response seen in hemifacial spasm","volume":"127","author":"Kameyama S","year":"2016","unstructured":"Kameyama S, Masuda H, Shirozu H, Ito Y, Sonoda M, Kimura J. Ephaptic transmission is the origin of the abnormal muscle response seen in hemifacial spasm. Clin Neurophysiol. 2016;127(5):2240\u20132245."},{"issue":"7","key":"b12","series-title":"Neurology","first-page":"969","article-title":"Hemifacial spasm: results of electrophysiologic recording during microvascular decompression operations","volume":"35","author":"M\u00f8ller AR","year":"1985","unstructured":"M\u00f8ller AR, Jannetta PJ. Hemifacial spasm: results of electrophysiologic recording during microvascular decompression operations. Neurology. 1985;35(7):969\u2013974."},{"issue":"6","key":"b13","series-title":"Neurosurg Rev","first-page":"3259","article-title":"Is the pre-operative lateral spread response on facial electromyography a valid diagnostic tool for hemifacial spasm?","volume":"44","author":"Park CK","year":"2021","unstructured":"Park CK, Lim SH, Lee SH, Park BJ. Is the pre-operative lateral spread response on facial electromyography a valid diagnostic tool for hemifacial spasm?. Neurosurg Rev. 2021;44(6):3259\u20133266."},{"issue":"1","key":"b14","series-title":"Stereotact Funct Neurosurg","first-page":"16","article-title":"Using the new clinical grading scale for quantification of the severity of hemifacial spasm: correlations with a quality of life scale","volume":"90","author":"Lee JA","year":"2012","unstructured":"Lee JA, Jo KW, Kong DS, Park K. Using the new clinical grading scale for quantification of the severity of hemifacial spasm: correlations with a quality of life scale. Stereotact Funct Neurosurg. 2012;90(1):16\u201319."},{"key":"b15","article-title":"Hemifacial Spasm: A Comprehensive Guide","year":"2020","unstructured":"Park K, Park JS, eds.Hemifacial Spasm: A Comprehensive Guide. 1st ed. Springer;2020."},{"key":"b16","article-title":"Intraoperative Neurophysiological Monitoring in Hemifacial Spasm: A Practical Guide","author":"Park SK","year":"2021","unstructured":"Park SK, Joo BE, Park K. Intraoperative Neurophysiological Monitoring in Hemifacial Spasm: A Practical Guide. 1st ed. Springer;2021."},{"key":"b17","series-title":"J Clin Neurosci","first-page":"6","article-title":"Using strength-duration analysis to identify the afferent limb of the lateral spread response in hemifacial spasm patients during microvascular decompression surgery","volume":"74","author":"Wilkinson MF","year":"2020","unstructured":"Wilkinson MF, Chowdhury T, Kaufmann AM. Using strength-duration analysis to identify the afferent limb of the lateral spread response in hemifacial spasm patients during microvascular decompression surgery. J Clin Neurosci. 2020;74:6\u201310."},{"key":"b18","series-title":"Eur Arch Otorhinolaryngol","first-page":"S216","article-title":"Electrophysiological evidence for central hyperexcitability of facial motoneurons in hemifacial spasm","author":"Poignonec S","year":"1994","unstructured":"Poignonec S, Vidailhet M, Lamas G,  Electrophysiological evidence for central hyperexcitability of facial motoneurons in hemifacial spasm. Eur Arch Otorhinolaryngol. 1994:S216-S217."},{"issue":"5","key":"b19","series-title":"Neurosurgery","first-page":"612","article-title":"Microvascular decompression in hemifacial spasm: intraoperative electrophysiological observations","volume":"16","author":"M\u00f8ller AR","year":"1985","unstructured":"M\u00f8ller AR, Jannetta PJ. Microvascular decompression in hemifacial spasm: intraoperative electrophysiological observations. Neurosurgery. 1985;16(5):612\u2013618."},{"issue":"7","key":"b20","series-title":"Neurology","first-page":"969","article-title":"Hemifacial spasm: results of electrophysiologic recording during microvascular decompression operations","volume":"35","author":"M\u00f8ller AR","year":"1985","unstructured":"M\u00f8ller AR, Jannetta PJ. Hemifacial spasm: results of electrophysiologic recording during microvascular decompression operations. Neurology. 1985;35(7):969\u2013974."},{"issue":"5","key":"b21","series-title":"J Clin Neurosci","first-page":"459","article-title":"Hyperactivity of the facial nucleus produced by chronic electrical stimulation in rats","volume":"14","author":"Yamakami I","year":"2007","unstructured":"Yamakami I, Oka N, Higuchi Y. Hyperactivity of the facial nucleus produced by chronic electrical stimulation in rats. J Clin Neurosci. 2007;14(5):459\u2013463."},{"key":"b22","series-title":"J Pain Res","first-page":"437","article-title":"Neuromuscular blockade in the elderly patient","volume":"9","author":"Lee LA","year":"2016","unstructured":"Lee LA, Athanassoglou V, Pandit JJ. Neuromuscular blockade in the elderly patient. J Pain Res. 2016;9:437\u2013444."},{"issue":"1","key":"b23","series-title":"Semin Anesth","first-page":"35","article-title":"Effects of patient age on muscle relaxant","volume":"14","author":"Matteo RS","year":"1995","unstructured":"Matteo RS, Ornstein E. Effects of patient age on muscle relaxant. Semin Anesth. 1995;14(1):35\u201345."},{"issue":"9","key":"b24","series-title":"Acta Neurochir (Wien)","first-page":"933","article-title":"Abnormal muscle response monitoring during microvascular decompression for hemifacial spasm","volume":"147","author":"Yamashita S","year":"2005","unstructured":"Yamashita S, Kawaguchi T, Fukuda M, Watanabe M, Tanaka R, Kameyama S. Abnormal muscle response monitoring during microvascular decompression for hemifacial spasm. Acta Neurochir (Wien). 2005;147(9):933\u2013938."},{"issue":"7","key":"b25","series-title":"Clin Neurophysiol","first-page":"1542","article-title":"Excitability of facial nucleus and related brain-stem reflexes in hemifacial spasm, post-facial palsy synkinesis and facial myokymia","volume":"116","author":"Oge AE","year":"2005","unstructured":"Oge AE, Yayla V, Demir GA, Eraksoy M. Excitability of facial nucleus and related brain-stem reflexes in hemifacial spasm, post-facial palsy synkinesis and facial myokymia. Clin Neurophysiol. 2005;116(7):1542\u20131554."},{"issue":"6","key":"b26","series-title":"J Neurosurg","first-page":"1777","article-title":"Transposition versus interposition method in microvascular decompression for trigeminal neuralgia: midterm analysis of both techniques in a single-center study","volume":"140","author":"Uhl C","year":"2024","unstructured":"Uhl C, Faraj L, Fekonja L, Vajkoczy P. Transposition versus interposition method in microvascular decompression for trigeminal neuralgia: midterm analysis of both techniques in a single-center study. J Neurosurg. 2024;140(6):1777\u20131784."},{"key":"b27","series-title":"World Neurosurg","first-page":"e526","article-title":"Microanatomy around the facial nerve pathway for microvascular decompression surgery investigated with correlative light microscopy and block-face imaging","volume":"118","author":"Iijima K","year":"2018","unstructured":"Iijima K, Tajika Y, Tanaka Y, Yorifuji H, Yoshimoto Y. Microanatomy around the facial nerve pathway for microvascular decompression surgery investigated with correlative light microscopy and block-face imaging. World Neurosurg. 2018;118:e526\u2013e533."},{"issue":"11","key":"b28","series-title":"J Neurosurg","first-page":"947","article-title":"Concerning the mechanism of trigeminal neuralgia and hemifacial spasm","volume":"19","author":"Gardner WJ","year":"1962","unstructured":"Gardner WJ. Concerning the mechanism of trigeminal neuralgia and hemifacial spasm. J Neurosurg. 1962;19(11):947\u2013958."},{"issue":"7","key":"b29","series-title":"Clin Anat","first-page":"882","article-title":"The central myelin-peripheral myelin transitional zone of the nervus intermedius and its implications for microsurgery in the cerebellopontine angle","volume":"25","author":"Alfieri A","year":"2012","unstructured":"Alfieri A, Fleischhammer J, Strauss C, Peschke E. The central myelin-peripheral myelin transitional zone of the nervus intermedius and its implications for microsurgery in the cerebellopontine angle. Clin Anat. 2012;25(7):882\u2013888."},{"key":"b30","series-title":"Ann Anat","first-page":"152128","article-title":"Central myelin-peripheral myelin junction in trigeminal, facial, and vestibulocochlear nerve: a histo-morphometric study","volume":"250","author":"Gupta T","year":"2023","unstructured":"Gupta T, Munawara R, Kaur M,  Central myelin-peripheral myelin junction in trigeminal, facial, and vestibulocochlear nerve: a histo-morphometric study. Ann Anat. 2023;250:152128."},{"issue":"1","key":"b31","series-title":"Exp Neurol","first-page":"110","article-title":"Hemifacial spasm: ephaptic transmission or hyperexcitability of the facial motor nucleus?","volume":"98","author":"M\u00f8ller AR","year":"1987","unstructured":"M\u00f8ller AR. Hemifacial spasm: ephaptic transmission or hyperexcitability of the facial motor nucleus?. Exp Neurol. 1987;98(1):110\u2013119."},{"issue":"2","key":"b32","series-title":"J Korean Soc Stereotact Funct Neurosurg","first-page":"97","article-title":"Sole vein offenders confirmed by disappearance of the lateral spread response during microvascular decompression for hemifacial spasm","volume":"18","author":"Seo DH","year":"2022","unstructured":"Seo DH, Cho KR, Park K. Sole vein offenders confirmed by disappearance of the lateral spread response during microvascular decompression for hemifacial spasm. J Korean Soc Stereotact Funct Neurosurg. 2022;18(2):97\u2013102."},{"issue":"5","key":"b33","series-title":"Neurosurgery","first-page":"612","article-title":"Microvascular decompression in hemifacial spasm: intraoperative electrophysiological observations","volume":"16","author":"M\u00f8ller AR","year":"1985","unstructured":"M\u00f8ller AR, Jannetta PJ. Microvascular decompression in hemifacial spasm: intraoperative electrophysiological observations. Neurosurgery. 1985;16(5):612\u2013618."}],"container-title":["Journal of Neurosurgery"],"original-title":[],"link":[{"URL":"https:\/\/thejns.org\/view\/journals\/j-neurosurg\/aop\/article-10.3171-2024.5.JNS24125\/article-10.3171-2024.5.JNS24125.xml","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/thejns.org\/downloadpdf\/journals\/j-neurosurg\/aop\/article-10.3171-2024.5.JNS24125\/article-10.3171-2024.5.JNS24125.xml","content-type":"text\/html","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/thejns.org\/downloadpdf\/journals\/j-neurosurg\/aop\/article-10.3171-2024.5.JNS24125\/article-10.3171-2024.5.JNS24125.xml","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,2,1]],"date-time":"2025-02-01T01:21:33Z","timestamp":1738372893000},"score":1,"resource":{"primary":{"URL":"https:\/\/thejns.org\/view\/journals\/j-neurosurg\/aop\/article-10.3171-2024.5.JNS24125\/article-10.3171-2024.5.JNS24125.xml"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,9,1]]},"references-count":33,"URL":"https:\/\/doi.org\/10.3171\/2024.5.jns24125","relation":{},"ISSN":["0022-3085","1933-0693"],"issn-type":[{"value":"0022-3085","type":"print"},{"value":"1933-0693","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,9,1]]}}}