Clinical and radiological analysis of ossification of the anterior longitudinal ligament causing dysphagia and hoarseness

OBJECTIVE: We retrospectively analyzed the clinical and radiological characteristics of ossification of the anterior longitudinal ligament (OALL). METHODS: Seventeen patients with OALL who underwent surgery between 1995 and 2003 were reviewed. Symptomatic OALL was found in four patients. In 13 asymptomatic OALL patients who experienced mild to severe myelopathy, no swallowing difficulty was noted. The OALL was classified into three types by sagittal computed tomographic (CT) scans as segmental, continuous, and mixed and three types on axial CT scans as flat, nodular, and globular type. The thickness, numbers of involved vertebral bodies, and type and shape for symptomatic OALL were analyzed and compared with those for asymptomatic OALL. RESULTS: The mean thickness of 13.5 mm for symptomatic OALL was significantly higher than that of 6.5 mm for asymptomatic OALL (P = 0.0009). A globular shape on axial CT was common for symptomatic OALL. There were no differences in the numbers of involved vertebral bodies and types of OALL on sagittal CT scans. Surgical excision of OALL was performed for all cases of symptomatic OALL. In 7 of 13 asymptomatic cases, OALL was simultaneously removed during anterior decompressive surgery for the associated pathology. CONCLUSION: The thickness on axial CT scans was an important contributing factor to dysphagia and hoarseness as was the shape of the OALL. The type of OALL on sagittal CT scans was similar to that of ossification of the posterior longitudinal ligament but did not influence the development of dysphagia. Good relief from symptoms was achieved for symptomatic OALL after removal of OALL.