We report the clinical and laboratory findings of six Canadian patients with progressive myelopathy associated with HTLV-1 infection. The diagnosis was suspected on clinical grounds and supported by serological studies and positive gene amplification. Only five had emigrated from an area endemic for HTLV-1 infection. Tropical spastic paraparesis should be considered in all patients with myelopathy, even those without standard serological markers of HTLV-1 infection. The pathogenesis of this condition and the serological and molecular biological means by which this diagnosis can be made are reviewed.

The epidemiology of multiple sclerosis (MS) and the planning and interpretation of clinical therapeutic trials were the subjects of a symposium on MS held on June 13, 1989. Several speakers addressed whether MS is a genetic or an environmental disease. An environmental trigger would resolve the relatively low penetrance of the disease in susceptible individuals, although the alternative hypothesis that MS is a multigenic disease would also account for this observation. Clinical trials have to date failed to confirm the efficacy of any immunosuppressive or other agent in the management of progressive MS. Magnetic resonance imaging (MRI) appears to be highly sensitive for monitoring the activity of MS. Preliminary evidence suggests that MRI activity correlates with longitudinal clinical assessments of disability. Immunologic tests, while valuable in determining pathophysiology of MS, have not been strongly correlated with clinical outcome.

We report the pathological and molecular biological findings of human T-cell lymphotropic virus type 1 (HTLV-1) infection of the spinal cord in a patient with a chronic progressive myelopathy. Light microscopy disclosed loss of myelin and axons, thickening of blood vessels and a lymphocytic cell infiltrate in the spinal cord especially at the cervical and thoracic levels. Electron microscopy confirmed the vascuolar appearance seen with light microscopy but virus particles were not observed. The HTLV-1 gag gene could be amplified (by polymerase chain reaction) from cervical spinal cord tissue while not from elsewhere in the neuroaxis. The presence of HTLV-1 geonomic material in spinal cord tissue has not been previously reported.