Inadequate Surgical Decompression in Patients with Cervical Myelopathy: A Retrospective Review

STUDY DESIGN Retrospective study. OBJECTIVE We reviewed cases of surgically treated cervical spondylotic myelopathy (CSM) or chronic, degenerative myelopathy of the subaxial cervical spine to study the incidence of inadequate surgical decompression. METHODS We included all persons treated at our institution after a first surgical decompression for CSM over a 3-year period. Inadequate original surgical decompression was defined as neurologic decline within 12 months postoperatively and ongoing impingement of the spinal cord with <1-mm change in anteroposterior canal dimension from pre- to postoperative magnetic resonance imaging (MRI) leading to revision decompressive surgery. Revisions for other reasons were not counted as inadequate. RESULTS Of 50 patients, 5 (10%) required revision decompression for neurologic decline and inadequate change in space available for the cord on postoperative imaging; 4 patients declined within the first 6 months and 1 patient at 8 months postoperatively. None of the 5 declined further after posterior revision, but none recovered from the interval loss. All 5 had undergone anterior approaches, for an anterior inadequacy rate of 23% (5 of 22). None of the 28 patients having posterior or combined approach declined at 2 years or had <1-mm change on postoperative MRI. The difference between anterior and posterior approaches was statistically significant (p = 0.018). CONCLUSIONS The rate of inadequate surgical decompression for CSM was greater than expected in this series and directly associated with an anterior approach. No cases of inadequacy occurred for posterior or combined approaches. Postoperative neuroradiographic imaging such as MRI should be entertained routinely for this entity or at least for anterior-only approaches.