Transcranial motor evoked potential waveform changes in corrective fusion for adolescent idiopathic scoliosis.
OBJECTIVE Corrective surgery for spinal deformities can lead to neurological complications. Several reports have described spinal cord monitoring in surgery for spinal deformity, but only a few have included patients younger than 20 years with adolescent idiopathic scoliosis (AIS). The goal of this study was to evaluate the characteristics of cases with intraoperative transcranial motor evoked potential (Tc-MEP) waveform deterioration during posterior corrective fusion for AIS. METHODS A prospective database was reviewed, comprising 68 patients with AIS who were treated with posterior corrective fusion in a prospective database. A total of 864 muscles in the lower extremities were chosen for monitoring, and acceptable baseline responses were obtained from 819 muscles (95%). Intraoperative Tc-MEP waveform deterioration was defined as a decrease in intraoperative amplitude of ≥ 70% of the control waveform. Age, Cobb angle, flexibility, operative time, estimated blood loss (EBL), intraoperative body temperature, blood pressure, number of levels fused, and correction rate were examined in patients with and without waveform deterioration. RESULTS The patients (3 males and 65 females) had an average age of 14.4 years (range 11-19 years). The mean Cobb angles before and after surgery were 52.9° and 11.9°, respectively, giving a correction rate of 77.4%. Fourteen patients (20%) exhibited an intraoperative waveform change, and these occurred during incision (14%), after screw fixation (7%), during the rotation maneuver (64%), during placement of the second rod after the rotation maneuver (7%), and after intervertebral compression (7%). Most waveform changes recovered after decreased correction or rest. No patient had a motor deficit postoperatively. In multivariate analysis, EBL (OR 1.001, p = 0.085) and number of levels fused (OR 1.535, p = 0.045) were associated with waveform deterioration. CONCLUSIONS Waveform deterioration commonly occurred during rotation maneuvers and more frequently in patients with a larger preoperative Cobb angle. The significant relationships of EBL and number of levels fused with waveform deterioration suggest that these surgical invasions may be involved in waveform deterioration.
Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Kazuyoshi
K
Kobayashi
Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Shiro
S
Imagama
Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Zenya
Z
Ito
Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Kei
K
Ando
Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Tetsuro
T
Hida
Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Kenyu
K
Ito
Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Mikito
M
Tsushima
Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Yoshimoto
Y
Ishikawa
Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Akiyuki
A
Matsumoto
Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Yoshihiro
Y
Nishida
Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Naoki
N
Ishiguro
D000293:Adolescent; D002648:Child; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D064795:Intraoperative Neurophysiological Monitoring / Q000379:methods / Q000639:trends*; D008297:Male; D011446:Prospective Studies; D012600:Scoliosis / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D013123:Spinal Fusion / Q000379:methods / Q000639:trends*; D050781:Transcranial Magnetic Stimulation / Q000379:methods / Q000639:trends*; D055815:Young Adult
AIS = adolescent idiopathic scoliosis; EBL = estimated blood loss; EMG = electromyography; SCEP = spinal cord evoked potential; SSEP = somatosensory evoked potential; Tc-MEP; Tc-MEP = transcranial motor evoked potential; adolescent idiopathic scoliosis; posterior corrective fusion; spine; transcranial motor evoked potential; waveform deterioration