CD8 AND CD4 T-CELL-MEDIATED POLYMYOSITIS COMPLICATING THE HTLV-1 ASSOCIATED MYELOPATHY - QUANTITATIVE-EVALUATION OF CORTICOSTEROID TREATMENT

Introduction - Inflammatory myopathy is a treatable cause of worsening in the spectrum of neurological conditions that may develop during th e course of HTLV-1 infection. Material and methods - To investigate th e cause of subacute worsening in the strength of a 46-y-old black male with HTLV-1 associated myelopathy we performed electrodiagnostic exam ination and a muscle biopsy which was studied with histochemistry, imm unocytochemistry and electron microscopy. Serial measurements of isome tric muscle strength were performed during the course of corticosteroi d treatment. Results - The muscle biopsy showed evidence of denervatio n atrophy and prominent inflammatory changes with autoaggressive featu res. Lymphocyte typing showed a predominance of CD8(+) T cells. The pa tient had sustained, marked improvement in strength, especially of the upper extremities, with oral, high single-dose, alternate-day prednis one therapy. Conclusion - A muscle biopsy should be considered in all patients with HTLV-1 associated weakness, especially when electromyogr aphy indicates possible coexisting primary muscle involvement and/or s erum creatine kinase levels are elevated. HTLV-1-associated polymyosit is can be successfully treated with corticosteroids.