Investigation of segmental motor paralysis after cervical laminoplasty using intraoperative spinal cord monitoring with transcranial electric motor-evoked potentials.

Study Design: A retrospective study of segmental motor paralysis after cervical laminoplasty for cervical myelopathy.

Objective: The objective of this study was to use transcranial electric motor-evoked potentials during cervical laminoplasty, to monitor and investigate the intraoperative electrophysiologic change in patients with cervical myelopathy, who subsequently develop postoperative segmental motor paralysis potentials.

Summary Of Background Data: There have been several reports about segmental motor paralysis after cervical laminoplasty for patients with cervical myelopathy. However, the pathogenesis of segmental motor paralysis of C5 myotome, so-called C5 palsy, remains unclear.

Methods: The cases of 184 consecutive patients who underwent cervical laminoplasty were analyzed to clarify the incidence of postoperative segmental motor paralysis and to monitor intraoperative change. Postoperative C5 palsy was defined as development of postoperative motor palsy of the deltoid and biceps muscles in the upper extremity by at least 1 grade in the manual muscle test without sensory disturbance or impairment of the lower extremities. All patients underwent cervical laminoplasty under intraoperative spinal cord monitoring with transcranial electric motor-evoked potentials. The evoked potentials were recorded over the deltoid, biceps, and triceps muscles in the bilateral upper extremities.

Results: Postoperative C5 palsy developed in 6 patients (3.3%, 5 males and 1 female) but there were no abnormal changes monitored. The incidence of C5 palsy involved 4 of 124 (3.2%) cervical spondylotic myelopathy patients, 2 of 31 (6.5%) patients with cervical ossification of the posterior longitudinal ligament. No patients with cervical disc herniation or cervical spondylotic amyotrophy developed C5 palsy.

Conclusions: There were no abnormal findings on transcranial electric motor-evoked potential monitoring even in those patients who developed postoperative C5 palsy. These results indicate that the development of postoperative segmental motor paralysis after cervical laminoplasty occurs even if there are no abnormal findings during intraoperative monitoring.