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Alert Timing and Corresponding Intervention With Intraoperative Spinal Cord Monitoring for High-Risk Spinal Surgery

Yoshida, Go, MD, PhD; Ando, Muneharu, MD, PhD; Imagama, Shiro, MD, PhD; Kawabata, Shigenori, MD, PhD§; Yamada, Kei, MD, PhD; Kanchiku, Tsukasa, MD, PhD||; Fujiwara, Yasushi, MD, PhD∗∗; Tadokoro, Nobuaki, MD, PhD††; Takahashi, Masahito, MD, PhD‡‡; Wada, Kanichiro, MD, PhD§§; Yamamoto, Naoya, MD, PhD¶¶; Kobayashi, Sho, MD, PhD; Ushirozako, Hiroki, MD; Kobayashi, Kazuyoshi, MD, PhD; Yasuda, Akimasa, MD, PhD||||; Tani, Toshikazu, MD, PhD∗∗∗; Matsuyama, Yukihiro, MD, PhD

doi: 10.1097/BRS.0000000000002900

Study Design. Prospective multicenter study.

Objective. To analyze the incidence of intraoperative spinal neuromonitoring (IONM) alerts and neurological complications, as well as to determine which interventions are most effective at preventing postoperative neurological complications following IONM alerts in high risk spinal surgeries.

Summary of Background Data. IONM may play a role in identifying and preventing neural damage; however, few studies have clarified the outcomes of intervention after IONM alerts.

Methods. We analyzed 2867 patients who underwent surgery for high risk spinal pathology using transcranial electrical motor-evoked potentials from 2010 to 2016. The high-risk spinal surgery cases consisted of 1009 spinal deformity cases, 622 cervical ossification of posterior longitudinal ligament (OPLL) cases, 249 thoracic-OPLL cases, 771 extramedullary spinal cord tumor cases, and 216 intramedullary spinal cord tumor (IMSCT) cases. We set a 70% amplitude reduction as the alarm threshold for transcranial electrical motor-evoked potentials and analyzed the outcomes of the interventions following monitoring alerts and postoperative neurological deficits.

Results. The true positive, false positive, true negative, false negative, and rescue cases of IONM comprised 126, 234, 2362, 9, and 136 cases, respectively. Most alerts and interventions occurred during correction and release in deformity cases, posterior decompression and dekyphosis in OPLL cases, and tumor resection and surgery suspension with steroid injection in spinal cord tumor cases; however, individual interventions varied. The rescue rates (number of patients rescued with intervention after IONM alert/number of true positive cases plus rescue cases) for deformity, cervical-OPLL, thoracic--OPLL, extramedullary spinal cord tumor, and IMSCT cases were 61.4% (35/57), 82.1% (32/39), 40% (20/50), 52.5% (31/59), and 31.6% (18/57), respectively.

Conclusion. Our prospective multicenter study identified potential neural damage in 9.5% of cases and 52% rescue cases using IONM. Although the rescue ratios for t-OPLL and IMSCT were relatively low, appropriate intervention immediately after an IONM alert may prevent neural damage even in high-risk spinal surgeries.

Level of Evidence: 3

We evaluate the incidence of transcranial motor-evoked potential (Tc-MEPs) alerts and assess the occurrence of neurological complications following interventions after the alerts. The timing of the Tc-MEP alerts varied according to the procedure and pathology; however, adequate intervention immediately after an intraoperative spinal neuromonitoring (IONM) alert can prevent neural damage even in high-risk spinal surgeries.

Hamamatsu University School of Medicine, Hamamatsu, Japan

Wakayama Rosai Hospital, Wakayama, Japan

Nagoya University, Nagoya, Japan

§Tokyo Medical and Dental University, Tokyo, Japan

Kurume University, Kurume, Japan

||Yamaguchi University, Yamaguchi, Japan

∗∗Asa Citizens Hospital, Hiroshima, Japan

††Kochi University, Kochi, Japan

‡‡Kyorin University, Tokyo, Japan

§§Hirosaki University, Hirosaki, Japan

¶¶Tokyo Women's Medical University, Tokyo, Japan

||||Murayama Medical Center, Tokyo, Japan

∗∗∗Kubokawa Hospital, Kochi, Japan.

Address correspondence and reprint requests to Go Yoshida, MD, PhD, Department of Orthopedic Surgery, Hamamatsu University School of Medicine, 1 Chome-20-1 Handayama, Hamamatsu, Shizuoka Prefecture 431-3192, Japan; E-mail:

Received 9 July, 2018

Revised 16 August, 2018

Accepted 10 September, 2018

The manuscript submitted does not contain information about medical device(s)/drug(s).

Federal funds from the Japanese Ministry of Health, Labor and Welfare were received in support of this work.

No relevant financial activities outside the submitted work.

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