Decompressive laminoplasty in multisegmental cervical spondylotic myelopathy: bilateral cutting versus open-door technique

Purpose  The aim of the study was to evaluate patients with multisegmental cervical spondylotic myelopathy (MCM) surgically treated via a dorsal approach. Two different laminoplasty techniques were compared by assessment of enlargement of the spinal canal and the neurological outcome. Methods  Thirteen patients (mean age 49 years, 11 males) underwent decompressive laminoplasty over a 7-year period. The average duration of symptoms was 21 months. The pre- and postoperative degree of myelopathy was assessed by both the Nurick grading and the Japanese Orthopaedic Association myelopathy score (JOA score). Preoperatively, the mean Nurick grade was 3.1 and the mean JOA score was 11. Two different techniques of expansive laminoplasty were used. Six patients underwent a bilateral cutting (BL) technique with retropositioning of the laminae and bilateral mini-plating (BL group). Seven patients were operated on by simple open-door (OD) laminoplasty with unilateral mini-plating (OD group). Postoperatively, CT scans were obtained for all patients to measure the sagittal diameter of the spinal canal. The mean clinical and radiological follow-up was 33 months. Results  Four to five laminae were involved in all patients.The mean operation time was 180 min. Complications occurred in two patients of BL group, with immediate postoperative neurological deterioration due to ventral displacement of the laminae. Overall, the average sagittal diameter (SD) of the spinal canal increased from 9.2 ± 1.3 mm to 12.4 ± 1.3 mm after surgery. The average enlargement of SD was significantly higher for the OD group (p < 0.0075 ). In total, the improvement rate was 38% according to the Nurick grading and 69% according to the JOA score. For the OD group, improvement rates were 57% (Nurick) and 71% (JOA). Conclusions  Decompressive laminoplasty is comparable with anterior surgery in neurological outcome. The OD technique seems to be superior to our BL technique regarding both the enlargement of SD and complication rate.