Surgical outcome of thoracic myelopathy secondary to ossification of ligamentum flavum

Objectives: Thoracic myelopathy secondary to OLF is a rare disease described almost exclusively in Japanese patients. Few series of OLF in South Korean subjects has previously been published. This study is to describe the clinical and radiologic aspects, as well as surgical outcomes in a group of South Korean patients. Methods: A retrospective study of 8 consecutive patients, including 4 men and 4 women (mean age, 55.6 years), was conducted from 2002 to 2005. Diagnosis in each case was established using CT. Magnetic resonance imaging was also performed in every case. All patients treated surgically and pathologic studies were performed. A comparison between the preoperative neurological status and the status at follow-up was done using Japanese Orthopaedic Association (JOA) scoring system. Results: Walking difficulties were the most common presenting complaint. A picture of spastic paraparesis associated with sphincter dysfunction was the most common finding on initial examination. In each case, CT provided sufficient information to establish a diagnosis of OLF, while magnetic resonance imaging was helpful for showing spinal cord involvement. In most of the patients, OLF was located in the lower thoracic spine (T10-T11). Decompressive laminectomy with excision of the OLF resulted in significant improvement in motor weakness and gait in 5 (2 excellent, 3 good) patients who had short duration and no hyperintense intramedullary lesion of spinal cord on MRI. All patients improved in their gait and spasticity, but 2 patients had persistent sensory deficit. Conclusion: OLF is a rare cause of thoracic myelopathy. The frequency appears to have been rarely reported in South Korean subjects. CT with sagittal reconstructions and MRI are helpful for diagnosis and spinal cord involvement. When neurologic symptoms develop, decompressive laminectomy should be done immediately and the surgical outcome is generally good if hyperintense intramedullary signal changes of spinal cord have not yet developed.