Poliomyelitis

Lara A. Hardesty, MD; Blaise V. Jones, MD

View content online at: http://www.appliedradiology.com/Issues/1998/03/Cases/Poliomyelitis.aspx

Abstract: A 42-year-old male presented with weakness of the right leg and right arm. Three days later, the patient developed flaccid quadriplegia, with absent deep tendon reflexes. Sensation remained intact. Electromyography was consistent with a lower motor neuron syndrome. A WBC/ml count of 175 with 100% lymphocytes was found in the spinal fluid. CT of the head, MR of the brain, and duplex sonography of the carotids were normal. The patient denied fever, rash, diarrhea, upper respiratory infection, headache, foreign travel, and risk factors for HIV. Twenty-eight days previously, the patient's 13-week old infant had received live attenuated oral poliovirus vaccine. An MR of the cervical spine was performed.

Diagnosis

Poliomyelitis.

Discussion

Poliomyelitis is an acute inflammatory infection that affects the lower motor neurons of the spinal cord and causes flaccid paralysis, muscle atrophy, hypotonia, and areflexia. In the acute to subacute phase, there is inflammation, active gliosis, and neuronophagia of the ventral horn cells. Hyperintense signal on T2-weighted images and enhancement of the ventral aspect of the spinal cord correlate with these pathologic findings. The differential diagnosis for these MR findings includes multiple sclerosis, acute disseminated encephalomyelitis (ADEM), HIV myelitis, and acute transverse myelitis.

Infection with the poliovirus occurs only in humans and is spread by the fecal-oral route. There is no effective treatment. Infection by the wild poliovirus has not been reported in the United States since 1980. The predominant form of the disease is now vaccine-associated paralytic poliomyelitis (VAPP). VAPP occurs sporadically in infants who receive the oral polio vaccine and in their parents, who are susceptible due to fecal excretion of the live virus. Seven to ten cases of VAPP are reported annually in the United States, with an incidence of one case per 2.5 million doses of vaccine.

References

1. Malzberg MS, Rogg JM, Tate CA, et al: Poliomyelitis: Hyperintensity of the anterior horn cells on MR images of the spinal cord. AJR 161:863-865, 1993.

2. Querfurth H, Swanson PD: Vaccine-associated paralytic poliomyelitis. Arch Neurol 47:541-544, 1990.

3. Strebel PM, Sutter RW, Cochi SL, et al: Epidemiology of poliomyelitis in the United States one decade after the last reported case of indigenous wild virus-associated disease. Clin Infect Dis 14:568-579, 1992.

Prepared by Lara A. Hardesty, MD, University of Pittsburgh/Magee Women's

Hospital, Pittsburgh, PA, and Blaise V. Jones, MD, Department of Radiology, Penn State-Milton S. Hershey Medical Center, Hershey, PA.