Hemifacial atrophy secondary to poliomyelitis.

A 25-year-old woman is presented with hemifacial atrophy due to unilateral bulbar poliomyelitis infection. Although bulbar poliomyelitis is not an uncommon disease, it is rarely a cause of hemifacial asymmetry.

The post-polio syndrome as an evolved clinical entity. Definition and clinical description.

Post-polio syndrome (PPS) refers to the new neuromuscular symptoms that occur at least 15 years after stability in patients with prior acute paralytic polio-myelitis. They include: (1) new muscle weakness and atrophy in the limbs, the bulbar or the respiratory muscles [post-poliomyelitis muscular atrophy (PPMA)] and (2) excessive muscle fatigue and diminished physical endurance. PPS is a clinical diagnosis that requires exclusion of all other medical, neurological, orthopedic or psychiatric diseases that could explain the cause of the new symptoms. Routine electromyography is useful to confirm chronic and ongoing denervation and exclude neuropathies. Muscle biopsy, single fiber electromyography (EMG), macro-EMG, serum antibody titers to polio virus, and spinal fluid studies are very useful research tools but they are rarely needed to establish the clinical diagnosis. PPS is a slowly progressive phenomenon with periods of stability that vary from 3 to 10 years. Current evidence indicates that PPS is the evolution of a subclinically ongoing motor neuron dysfunction that begins after the time of the acute polio. It is clinically manifested as PPS when the well-compensated reinnervating process crosses a critical threshold beyond which the remaining motor neurons cannot maintain the innervation to all the muscle fibers within their motor unit territory.

Pathogenesis of human poliovirus infection in mice. I. Clinical and pathological studies.

Human poliovirus infection in mice was studied to determine the similarities to human poliomyelitis, the selective vulnerability of neurons to infection, the role of the immune response in age-dependent susceptibility, and possible viral persistence. Mice inoculated intracerebrally (ic) with the Lansing type 2 poliovirus developed a disease with clinical, pathological, and age-dependent features resembling human poliomyelitis. Adult mice had a shorter incubation period (50% paralysis, Day 8 vs. Day 13) and a higher incidence of paralysis (97% vs. 79%) than newborns. Only paralyzed animals had pathologic changes in the spinal cord, and these corresponded to the degree of paralysis. Fluorescent antibody staining showed that selective infection of neurons was most intense in the anterior horn motor neurons of the spinal cord. There was no extraneural virus replication and no systemic neutralizing antibody response. Cyclophosphamide immunosuppression enhanced rather than diminished disease, indicating that maturation of immune responses did not explain the relative resistance of newborns to paralysis.

Pathogenesis of human poliovirus infection in mice. II. Age-dependency of paralysis.

The mechanism of resistance of newborn mice to poliovirus-induced paralysis was studied by comparing regional virus replication in the adult and in the newborn central nervous systems (CNS) after intracerebral (ic) and intraspinal inoculation. Initial virus replication in the brains was similar in both age groups. Paralysis correlated with replication of virus in the spinal cord to a constant threshold, and this replication in newborns was delayed. Intraspinal inoculation of newborns eliminated the delay, indicating that neonatal anterior horn motor neurons were fully susceptible to infection. Cordectomy prevented the spread of virus, despite patent cerebrospinal fluid (CSF) pathways. Thus, poliovirus appeared to spread within the CNS via an axonal transport system. Known maturational changes in the fast transport system may explain the relative resistance of immature mice to poliovirus-induced paralysis.