The Applicability of Intraoperative Neuromonitoring in Patients with Preoperative Motor Weakness during Spine Surgery.
OBJECTIVE
The purpose of our study is to evaluate the success rate and feasibility of intraoperative neuromonitoring (IONM) focusing on transcranial motor evoked potential (TcMEP) monitoring for patients with preoperative motor weakness in spine surgery.


METHODS
Between November 2011 and December 2013, TcMEP and somatosensory evoked potential (SSEP) monitoring were attempted in 130 consecutive patients undergoing spine surgeries for cervical or thoracic cord lesions. Patients ranged in age from 14 to 81 years (mean±standard deviation, 56.7±14.8 years), and 84 patients were male. The success rates of both SSEP and MEPs monitoring were assessed according to the preoperative Medical Research Council (MRC) and Nurick grades.


RESULTS
TcMEP was recorded successfully in 0%, 28.6%, 72.3%, and 100% of patients with MRC grades 1, 2, 3, 4, and 5, respectively. SSEP was obtained from 0%, 37.5%, 21.5%, 61.4%, and 85.4% of patients with MRC grades 1, 2, 3, 4, and 5, respectively. TcMEP was recorded successfully in 84% of patients with Nurick grades 1-3 and 26% of patients with Nurick grades 4-5. SSEPs were recorded successfully in 76.3% of patients with Nurick grades 1-3 and 24% of patients with grades 4-5.


CONCLUSIONS
IONM during spine surgery may be useless in patients with MRC grades 1-2, applicable MRC grade 3, and useful MRC grades 4-5. MRC grade 3 is a critical point of indication for application of MEPs. In unmonitorable cases with MRC grade 3, increasing stimulus intensity or facilitation techniques may be considered to improve the usefulness of TcMEP.
Department of Neurosurgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.
Jae Meen
JM
Lee
Medical Research Institute, Pusan National University Hospital, Pusan National University College of Medicine, Busan, Korea.
Dong Hwan
DH
Kim
Medical Research Institute, Pusan National University Hospital, Pusan National University College of Medicine, Busan, Korea.
Hwan Soo
HS
Kim
Medical Research Institute, Pusan National University Hospital, Pusan National University College of Medicine, Busan, Korea.
Byung Kwan
BK
Choi
Medical Research Institute, Pusan National University Hospital, Pusan National University College of Medicine, Busan, Korea.
In Ho
IH
Han
Intraoperative neuromonitoring; Motor weakness; Spine surgery