HTLV-1 encephalomyelitis; a case report of a treatable manifestation of HTLV-1 infection

Abstract

IntroductionHuman T-cell lymphotropic virus type-1 (HTLV-1) infection remains asymptomatic in >90% of the 20-million people infected worldwide. However in 3%, chronic inflammation within the thoracic spinal cord leads to progressive spastic paraparesis; HTLV-1 associated myelopathy (HAM). This pathological process is not limited to the thoracic cord. We present a case of HTLV-1 encephalomyelitis.CaseA 53-year-old woman with HAM of 9 years duration presented with subacute cerebellar dysfunc- tion, being unable to feed herself, 3-months after cessation of methotrexate. Investigations demonstrated extensive T2-hyperintensity within the brainstem, cortical and subcortical white matter with punctate contrast enhancement; lymphocytic CSF; and high blood (36%) and CSF (72%) HTLV-1 proviral load (DNA copies per 100 lymphocytes). We diagnosed HTLV-1 encephalomyelitis and commenced high dose methylprednisolone with slow steroid taper following which functional independence in the upper limbs was regained.DiscussionRisk of HAM rises exponentially once HTLV-1 proviral load exceeds 1%, while CSF:blood proviral load ratio ≥2:1 indicates CNS infiltration of HTLV-1 infected lymphocytes. This patient’s high HTLV-1 proviral load and widespread MRI changes indicated HTLV-1 associated inflammation of the brain and spine. Prompt immunosuppression resulted in significant recovery and highlights the importance of early rec- ognition and management of extraspinal manifestations of HTLV-1 infection.j.king-robson@nhs.net