Unilateral Approaches for Posterior Spinal Canal Decompression in Cervical Spondylotic Myelopathy—An Evaluation of Conceptual Feasibility

Abstract

Patients with cervical spondylotic myelopathy (CSM) can be treated with posterior approaches for spinal canal decompression. We compared the patients' outcome after 2 different unilateral and a bilateral posterior approach for decompression to elucidate feasibility and potential procedure-related differences. Medical records of 98 patients with CSM undergoing posterior decompression between 2012 and 2018 were assessed. Patients were divided into 3 groups: (1) unilateral interlaminar fenestration with over-the-top "undercutting" (laminotomy) for compression limited to a ligamentum flavum hypertrophy, (2) unilateral hemilaminectomy for lateralized compression with a combination of ligamentous hypertrophy and osseus stenosis, and (3) laminectomy/laminoplasty for circular osseous-ligamentous spinal canal narrowing. The mean age was 73 years (m:f = 1.4:1), and most frequent symptoms (mean duration: 15 months) were ataxia (69%) and sensory changes (57%). Main location of stenoses (median Naganawa Score = 3; mean anteroposterior spinal canal diameter = 7.7 ± 2.2 mm) was C3 to C6. Thirty-one percent of the patients were assigned for a laminotomy procedure, 20% for a hemilaminectomy, and 49% for a laminectomy/laminoplasty. There were no significant differences of patients' characteristics, blood loss, and operation time between the 3 groups. Independent from the mode of surgery, the spinal canal was significantly widened (median Naganawa Score = 0; mean anteroposterior diameter = 11.4 ± 3.6 mm) and myelopathy (mJOA Score) improved ( P < .001); a higher body mass index was significantly correlated with a worse mJOA improvement (r = 0.293/ P = .003). Quality of life (Short-Form 36v2 Health Survey/Neck Disability Index) and reduction of the neck pain level were similar in the 3 groups at last follow-up (mean: 28 months). To minimize patients' periprocedural burden in CSM with dorsal compression, individual tailoring of the posterior approach according to the underlying compressive pathology achieves sufficient decompression and comparable long-term results.