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 diseases, there are only few reports of patients infected by the human immunodeficiency virus, with documented motor neuron disorder. That retroviral infections may cause motor neuron pathology by various mechanisms in animals and humans is known. Neurological symptoms potentially attributed to damage of lower motor neurons are often described during the course of HIV-1 infection and AIDS, however, it is often difficult to establish whether the disorder is primarily affecting the perikarya of lower motor neurons, or whether it is due to a focal proximal axonopathy, or to a dying-back process. We report a 30-year-old heroin abuser, HIV-1 positive, who presented a rapidly progressive limb weakness, muscle wasting, and bulbar signs, in absence of sensory loss of cerebellar and pyramidal signs. Imaging studies were negative. CSF showed increased protein content, negative cytology, and no oligoclonal bands. Serum protein electrophoresis, urinary heavy metal, and viral researches were negative. CD4 cells were counted 340 mm3 with a CD4-CD8 ratio equal to 0.4. Electrophysiology showed acute and chronic neurogenic changes, confirmed by muscle biopsy. Conduction studies along motor and sensory nerves fell within normal range. Biopsy of sural nerve revealed mild myelinated and unmyelinated fiber loss, occasional degeneration and regeneration, unremarkable inflammation. Despite treatment with AZT, zalcitabine, and steroids, the patient died after 3-month illness. 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 lipofuscin accumulation. Vacuolization, central chromatolysis, and neuronophagia were rarely seen. As associated pathology, in the fourth ventricle there were two small subependymal foci of demyelination, with reactive astrocytes and vascular proliferation. A possible crucial role of the HIV-1 infection in the development and progression of our patient's illness is considered in view of the known altered immunity proved in MND and ALS cases.