Rapidly Progressive and Relapsing Myelitis With Human T Lymphotropic Virus Type 1

A patient presented to our center in the northeastern United States with recurrent longitudinally extensive myelitis which was ultimately attributed to infection with human T lymphotropic virus type 1 (HTLV-1). The most common neurologic presentation of this infection is an insidiously progressive myelopathy, although reports of rapid progression with acute onset have been described, including some associated with inflammatory changes on spinal cord MRI. Here, we describe a case of this rare entity and provide a review of the clinical, diagnostic, and treatment data of similar published cases. Along with our case, 44 published cases of rapidly progressive or relapsing HTLV-1-associated myelopathy (HAM) were identified and included in this review. Patients were predominantly female and from Japan, the Caribbean, or South America with a median time from clinical onset to presentation of 5 months. There were radiographic features of myelitis in 98% of patients, with 93% showing longitudinally extensive lesions and only 1 patient with normal spinal MRI. Most patients received steroid therapy and 94% of patients experienced symptomatic or radiographic improvement after treatment, although longitudinal follow-up of these patients was limited. In summary, HAM may present as a rapidly progressive or relapsing myelitis. Patients with acute myelitis should be tested for HTLV-1 infection, especially in cases of longitudinally extensive myelitis with relevant exposure risk factors and negative testing for alternate diagnoses. Although these patients often experience clinical and radiographic improvement with steroid therapy, further work is needed to clarify whether this treatment influences chronic disease progression.