ABSTRACT
Hypertrophied ligamentum flavum is not a common cause of myelopathy. Only a minority of cases in the previous reports of myelopathy or radiculopathy secondary to thickening of the ligamentum f lavum had calcification of the ligamentum. We report two cases of thoracic myelopathy caused by ossified ligamentum flavum. One case was a twenty-five year old female who complained of weakness of lower limbs. The other was a fifty-three year old male who complained of tingling sensation on both lower extremities and weakness of right leg. These two patients showed weakness of lower extremities associated with hypesthesia below the level of calcified ligamentum flavum, positive ankle clonus, extensor plantar response, and hyperreflexia. Magnetic resonance imaging (MRI) showed clearly the spinal cord compression at the second to fourth thoracic level by a low-intensity-signal lesion. Metrizamide myelography with computerized tomography showed precise preoperative diagnosis and anatomic localization of the lesion. About one month after laminectomy and removal of the ossified ligaments flava, there was improvement of weakness, hypesthesia and ankle clonus.