Circumferential intrathecal ossification in oculoleptomeningeal amyloidosis

Oculoleptomeningeal amyloidosis (OLMA) is a variant of familial amyloidosis that results in amyloid deposition in the vitreous and leptomeninges. A 60-year-old woman with a history of OLMA presented to the emergency department for obtundation secondary to apparent shunt malfunction and lower extremity weakness. CT imaging of her spinal axis showed high attenuation material present intradurally from the mid cervical level extending through the thoracic and lumbar spine in the extramedullary space. MRI demonstrated circumferential signal enhancement surrounding the entire spinal cord. The patient underwent open biopsy at L3-L5. Upon opening the dura, a homogenous intradural ossification encasing the nerve roots was seen. Given the extent of the ossification, no further attempt at decompression was performed. Microscopic review of the biopsy sample revealed sclerotic bone with focal amorphous material consistent with amyloid. To our knowledge this is the first case report of a patient with OLMA presenting with extensive circumferential intrathecal ossification from amyloid deposition. Despite examples of leptomeningeal enhancement in patients with OLMA, extensive intradural ossification is a finding that has not been previously reported radiographically or post mortem.