Preventing C5 palsy after laminoplasty

Abstract

Study design: The incidences of postoperative C5 palsy between a group treated by a standardized diagnostic and surgical treatment and a control group treated by a different cervical laminoplastic technique were prospectively compared.

Objective: To investigate the cause, risk factors, and prevention of C5 palsy after laminoplasty for cervical myelopathy.

Summary of background data: No one factor could predict postoperative C5 palsy, although postoperative C5 palsy is a clinically significant complication of cervical laminoplasty.

Methods: One hundred eleven patients who underwent laminoplasty for cervical myelopathy were studied. Seventy-four patients who consulted two spinal surgeons (two of the authors) were placed into Group A. Thirty-seven patients who consulted the other two spinal surgeons (the other two authors) were placed into Group B. There were no statistical differences between the two groups for age at operation, gender, spinal disorders, preoperative neurologic severity, and length of the follow-up period. All patients in Group A underwent preoperative electromyographic testing. Patients with no electromyographic abnormalities underwent a standard midsagittal laminoplasty. Those with preoperative electromyographic abnormalities, reflecting a subclinical radiculopathy, underwent a modified en bloc laminoplasty with microcervical foraminotomy done at each level of the EMG abnormality. All Group B patients underwent midsagittal laminoplasty without preoperative electromyographic testing. Microcervical foraminotomy was performed for C5 root in 11 patients (14.9%) of Group A.

Results: No patients in Group A and three patients (8.1%) in Group B experienced postoperative C5 palsy. This difference was statistically significant (P = 0.035, Fisher's exact method).

Conclusions: Electromyography is a sensitive predictor of postoperative C5 palsy after laminoplasty. This complication may be avoided by performing selective foraminotomy in addition to posterior central canal decompression. Preexisting subclinical C5 root compression is a cause of C5 palsy after posterior cervical decompression for myelopathy.