Surgical treatment and intraoperative spinal cord monitoring in scoliosis associated with chronic inflammatory demyelinating polyneuropathy: A case report
A 16-year-old boy consulted our scoliosis clinic from the department of pediatrics because of the progression of scoliosis. He had been diagnosed with retardation of locomotor development at the age of 1 year. He had no familial history of neuromuscular disorders. A nerve conduction study revealed reduced motor nerve conduction velocity and conduction block. A muscle biopsy revealed neurogenic change. At the age of 2 years, a nerve biopsy obtained from the sural nerve revealed demyelination, and he was diagnosed with CIDP. At the age of 14 years, he was diagnosed with scoliosis.\nA physical examination demonstrated muscle weakness in the extremities and the absence of deep tendon reflexes in all extremities. He was unable to stand on one leg, and he required two crutches for walking. Plain radiographs showed an 86° left convex coronal curve from T8 to T12 and a 67° thoracic kyphosis from T5 to T12 (). The correction rate of 31% on a lateral bending radiograph was considered a stiff curve. The spinal deformity was classified as type 1A+ according to the Lenke classification (). Three-dimensional computed tomography revealed a wedge deformity of the vertebral body, although rotational deformation was mild ().\nHe underwent posterior correction and fusion with pedicle screws from T4 to L2, and a sublaminar flexible ultra-high-molecular-weight polyethylene cable was used at levels at which screw insertion was considered to be dangerous. Intraoperative spinal cord monitoring with transcranial electric motor-evoked potentials (TCE-MEP) was performed under general anesthesia with propofol without neuromuscular blocking agents. Corkscrew stimulation electrodes were positioned at C3 and C4, and five serial anodal electrical stimuli of 450 V were applied at a pulse width of 50 μs at intervals of 2 ms. The TCE-MEP was recorded with surface electrodes that were placed on both abductor hallucis muscles and the right abductor pollicis muscle. Potential waves were not recorded during the initial recording period of 100 ms (), but leg potentials were recorded after the recording period was extended 4-fold to 400 ms. During this period, the latency period prolonged to 232 ms. Subsequently, during surgery, the potential remained stable (). Neurological complications did not occur. The coronal curve and kyphosis were corrected from 86° to 34° (correction rate was 60%) and from 67° to 50°, respectively, at the 2-year follow-up (). Written informed consent was obtained from the patient and his parents for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.