Open-door laminoplasty for cervical stenotic myelopathy: surgical technique and neurophysiological monitoring

Object. A modified technique of open-door laminoplasty for cervical stenoti c myelopathy (CSM) is described, and the role of evoked potential monitorin g in selecting patients for surgery and evaluating results is discussed. Methods. Between October 1992 and October 1996, 33 patients with CSM underw ent open-door laminoplasty. After surgery, in 27 patients (81.8%) different levels of clinical improvement were demonstrated, and in five of them (15% ) full recovery was observed. The Japanese Orthopaedic Association score in creased from 5 to 12 (mean 9.8) preoperatively to 8 to 14 (mean 11.6) posto peratively. At 1-year follow up, the N13 cervical response was restored in nine (75%) of 12 patients with isolated presurgical abnormality and in 57.1 % of those with combined abnormalities of both N13 and P14 response. Althou gh significant clinical improvement was observed in 82% of the cases, in 24 of 33 patients motor evoked potential abnormalities persisted at least at one explored level. Conclusions. Of several laminoplasty techniques, the one described here off ers some advantages: preservation of biomechanical function of posterior mu scular-ligamentous complex, prevention of laminar collapse, smaller degrees in reduction of range of cervical motion, stabilization of the spine with no postoperative malalignment, and maintenance of decompressive effect that avoids recurrent stenosis. Neurophysiological studies sometimes clarified neurological disorders that were only suspected on the basis of history and /or clinical examination. leading to early diagnosis.