MOTOR-NEURON DISEASE AND HIV-1 INFECTION IN A 30-YEAR-OLD HIV-POSITIVE HEROIN ABUSER - A CAUSAL RELATIONSHIP

Although human retroviruses seem plausible agents of motor neuron dise ases, there are only few reports of patients infected by the human imm unodeficiency virus, with documented motor neuron disorder. That retro viral infections may cause motor neuron pathology by various mechanism s in animals and humans is known. Neurological symptoms potentially at tributed to damage of lower motor neurons are often described during t he course of HIV-I infection and AIDS, however, it is often difficult to establish whether the disorder is primarly affecting the perikarya of lower motor neurons, or whether it is due to a focal proximal axono pathy, or to a dying-back process. We report a 30-year-old heroin abus er, HIV-1 positive, who presented a rapidly progressive limb weakness, muscle wasting, and bulbar signs, in absence of sensory loss of cereb ellar and pyramidal signs. Imaging studies were negative. CSF showed i ncreased protein content, negative cytology, and no oligoclonal bands. Serum protein electrophoresis, urinary heavy metal, and viral researc hes were negative. CD4 cells were counted 340 mm(3) with a CD4-CD8 rat io equal to 0.3. Electrophysiology showed acute and chronic neurogenic changes, confirmed by muscle biopsy. Conduction studies along motor a nd sensory nerves fell within normal range. Biopsy of sural nerve reve aled mild myelinated and unmyelinated fiber loss, occasional degenerat ion and regeneration, unremarkable inflammation. Despite treatment wit h AZT, zalcitabine, and steroids, the patient died after 3-month illne ss. Neuropathology showed normal cortical cell Betz's, and hemispheric white matter. Brain stem motor nuclei (inferior olival, dorsal motor of the vagus, hypoglossal) showed atrophy and intracytoplasmatic lipof uscin accumulation. Vacuolization, central chromatolysis, and neuronop hagia were rarely seen. As associated pathology, in the fourth ventric le there were two small subependymal foci of demyelination, with react ive astrocytes and vascular proliferation. A possible crucial role of the HIV-1 infection in the development and progression of our patient' s illness is considerd in view of the known altered immunity proved in MND and ALS cases.