Distal-type cervical spondylotic amyotrophy: incidence and outcome after central corpectomy

Object: Distal-type cervical spondylotic amyotrophy (CSA) is a rare form of cervical spondylotic myelopathy (CSM). The authors documented the incidence, clinical presentation, radiological features, and outcome following central corpectomy (CC) in patients with this entity. Methods: The authors performed a retrospective institutional database search of patients who underwent decompressive surgery for CSM between 1992 and 2006 to identify patients with distal-type CSA. Distal-type CSA was defined as weakness and wasting of hands and forearms without gait impairment (Nurick Grades 0 and 1) nor any sensory symptoms or signs in the lower limbs. Results: The authors identified 7 male patients (1.1%) with distal-type CSA from among 653 patients who underwent either cervical laminectomy (135 patients) or CC (518 patients). There were sensory symptoms or signs in the upper limbs in all but 1 of the patients. Increased signal intensity in the cord was demonstrated on T2-weighted MR images in all patients. The compression was mainly at the C-6 vertebral level. At a mean follow-up of 46.5 months (range 12-98 months), 6 patients had improved by a mean patient perceived outcome score of 66.7% (range 20-100%). Patients' modified Japanese Orthopedic Association scores improved from a preoperative mean (± SD) of 16.1 ± 0.7, to a follow-up mean of 17.4 ± 0.5 (p = 0.004, paired t-test). One patient whose condition worsened 7 months after CC received a diagnosis of a coexistent motor neuron disease. Conclusions: Distal-type CSA is a rare form of CSM that should be differentiated from motor neuron disease on the basis of subtle sensory symptoms or signs in the upper limbs, and the presence of significant cord compression on the MR imaging. Patient outcome after central corpectomy is good and long lasting