Assessment of cervical myelopathy using transcranial magnetic stimulation and prediction of prognosis after laminoplasty.
METHODS
This study investigated the clinical usefulness of motor-evoked potentials (MEPs) produced by transcranial magnetic stimulation of the brain for cervical myelopathy patients.


OBJECTIVE
The purpose of this study was to determine the usefulness of MEPs for the assessment of the severity of myelopathy and prediction of the outcome of laminoplasty.


BACKGROUND
Magnetic stimulation has been widely used for examination of the descending excitatory motor pathways in the central nervous system, but little attention has been paid to cervical myelopathy.


METHODS
We measured the MEPs of 56 patients who underwent surgery for cervical myelopathy. The MEPs from the abductor pollicis brevis, abductor digiti minimi, tibialis anterior, and abductor hallucis muscle were evoked by transcranial magnetic brain stimulation. The latency from the anterior horn cell of the spinal cord to the hand or foot muscles was also measured, with the F-value [(F + M - 1)/2] calculated. This was followed by estimation of the central motor conduction time (CMCT). Severity of clinical disability was scored on the basis of symptoms according to a modified ADL scale for cervical myelopathy of the Japanese Orthopedic Association (JOA) score.


RESULTS
The average CMCT of the symptomatic side significantly correlated with the preoperative JOA score. The average CMCT of the symptomatic side significantly correlated with the 1-year postoperative JOA score. The average CMCT for patients with poor outcome was significantly longer than that for patients with good outcome. CMCT of 15 milliseconds or more in the upper extremities or that of 22 milliseconds or more in the lower extremities indicated poor prognosis.


CONCLUSIONS
In patients with cervical myelopathy, the CMCT significantly correlated with the results of clinical assessment. These findings regarding the duration of CMCT may be useful parameters in spinal pathology for prediction of the outcome of surgical treatment.
Takahashi
Jun
J
Department of Orthopaedic Surgery, Shinshu University, School of Medicine, Matsumoto-city, Nagano, Japan. jtaka@hsp.md.shinshu-u.ac.jp
Hirabayashi
Hiroki
H
Hashidate
Hiroyuki
H
Ogihara
Nobuhiro
N
Yamazaki
Ikuya
I
Kamimura
Mikio
M
Ebara
Sohei
S
Kato
Hiroyuki
H
D000368:Aged; D000369:Aged, 80 and over; D002574:Cervical Vertebrae / Q000601:surgery*; D019299:Decompression, Surgical / Q000379:methods*; D004185:Disability Evaluation; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology; D011379:Prognosis; D011930:Reaction Time / Q000502:physiology; D013116:Spinal Cord / Q000473:pathology* / Q000503:physiopathology; D013117:Spinal Cord Compression / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery*; D050781:Transcranial Magnetic Stimulation; D016896:Treatment Outcome