Abstract Details

Sarcoid myelitis is a rare presentation of neurosarcoidosis. MRI features in sarcoid myelitis are highly variable. NSG is a little-known form of sarcoidosis. To our knowledge, the “string of pearls” sign has not been previously reported in NSG myelitis.

A 62-year-old Caucasian female presented with subacute development of bilateral leg tingling and weakness with urinary retention and constipation. Neurological examination revealed a symmetric thoracic myelopathic syndrome with T-10 sensory level for light touch, vibration and position sense impairment in both lower extremities. MRI of the cervical and thoracic spine showed multifocal longitudinally extensive lesion from cervicomedullary junction to the conus with a striking “string of pearls” pattern of dorsal linear subpial and nodular contrast enhancement. Cerebrospinal fluid (CSF) studies revealed pleocytosis (27 nucleated cells/mm³ with lymphocytic predominance), elevated protein (90mg/dL), normal CSF/serum glucose quotient, cytology and angiotensin converting enzyme level. Anti-aquaporin-4 and anti-myelin oligodendrocyte glycoprotein antibodies were negative. Computed tomography of the chest, abdomen and pelvis showed bilateral irregular nodular opacities in the lungs and enlarged bilateral external iliac chain lymph nodes. Left external iliac lymph node biopsy showed reactive lymph nodes with focal necrotizing granulomas suggestive of NSG. Staining was negative for mycobacteria or fungi. There was no immunophenotypic evidence of a lymphoproliferative disorder. The patient responded to intravenous methylprednisolone (1000 mg/day for 5 days) followed by oral prednisone taper and infliximab.

“String of pearls” MRI pattern of dorsal linear subpial and nodular enhancement is strongly suggestive of sarcoid myelitis and can be seen in patients with NSG variant. Recognizing distinct MRI phenotypes of sarcoid/NSG myelitis may be critical for timely diagnosis and treatment.