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HIV-Related Motor Neuron Disease

To investigate whether motor neuron disease (MND) can be a consequence of HIV infection, these researchers retrospectively analyzed data from approximately 1700 HIV-infected patients with neurologic complications who were referred to one researcher from 1987 through 2000. Six patients (0.35 percent; mean age, 34) with MND were identified: 5 men and 1 woman. All but one presented with CD4 T-lymphocyte counts below 200 cells/mm³. One met clinical and electrophysiologic El Escorial research diagnostic criteria for definite amyotrophic lateral sclerosis (ALS); the others were preliminarily diagnosed with either probable or possible ALS. MND typically manifested as monomelic amyotrophy with relatively rapid regional or symmetric progression (within weeks). All patients had both upper and lower motor neuron involvement; only 2 had brainstem involvement. Muscle biopsy was compatible with neurogenic muscular atrophy.

The disorder differed from typical ALS in several respects: earlier age of onset, rapid progression, and clinical improvement in response to antiretroviral therapy (including complete recovery in 2 patients). Thorough evaluations failed to reveal other potential infectious etiologies, and the authors posit that the MND was caused by the HIV infection. They propose several mechanisms by which HIV might affect motor neurons, including neuronal infection, response to toxic viral products, immune induction resulting in cytokine secretion, and autoimmune disease.

Comment: The most important finding from this study is that MND clinically indistinguishable from ALS may occur in association with HIV infection. This finding has been published previously, but generally in isolated case reports. This observation, and the patients' favorable clinical response to antiretroviral therapy, suggest that other instances of ALS may be due to treatable viral infections.

As the authors note, a selective vulnerability of motor neurons to certain viruses -- most notably polio virus -- had previously suggested that ALS was quite possibly a consequence of an as-yet undetected viral infection. Retroviruses have been considered likely candidates. A neurotropic retrovirus has produced MND in a murine model, and human T-cell lymphotropic virus type I has been reported to cause an ALS-like syndrome. It is probable that ALS results from a spectrum of disorders, ranging from genetically acquired defects of superoxide dismutase to acquired infections and toxins. The search for potentially treatable infectious etiologies of ALS should not be dismissed lightly.

— Joseph R. Berger, MD

Joseph R. Berger, MD, is Professor and Chairman, Department of Neurology, University of Kentucky College of Medicine, Lexington, KY.

Published in Journal Watch Neurology December 20, 2001

Citation(s):

Moulignier A et al. Reversible ALS-like disorder in HIV infection. Neurology 2001 Sep 25 57 995-1001.

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