Factors predictive of surgical outcome for ossification of the posterior longitudinal ligament of the cervical spine.

Ossification of the posterior longitudinal ligament (OPLL) is a pathological ossification of the ligament that causes slowly progressive myelo-radiculopathy in adults. Because of long-standing compression of the spinal cord by OPLL, functional prognosis may not always be favorable. Efforts have been made in recent surgical series to identify prognostic factors, i.e., factors that are predictive of the outcome. The results are often inconclusive or conflicting, however.A review of the pertinent literature published between 1966 and 2007 is conducted with the use of PUBMED. Potential prognostic factors are summarized and evaluated. These factors include: gender, age, history of head/neck trauma, type of OPLL, preoperative duration of symptoms, preoperative neurological score, occupying ratio, alignment of the cervical spine, presence of intramedullary high signal intensity (HSI) on magnetic resonance imaging, and morphometry of the spinal cord.A total of 15 studies, all of which are retrospective case series, are identified which statistically evaluate relationship between the potential prognostic factors and outcome.The history of head/neck trauma, preoperative duration of symptoms, and spinal cord morphometry seems to be the prognostic factors in patients with cervical OPLL. The results are inconclusive or divided among the studies regarding whether age, preoperative neurological score, or presence of intramedullary HSI is predictive of the outcome. The gender, type of OPLL, occupying ratio, and cervical spine alignment seem to be the factors that are unlikely to be predictive of the outcome.