IPLab:Lab 8:Poliomyelitis

Clinical Summary

Six days before his death, this 31-year-old white male became acutely ill with fever followed by an ascending paralysis which began in his feet. Three days later he was hospitalized because of difficulty in breathing. A lumbar puncture was performed and the patient's spinal fluid contained increased protein and polymorphonuclear leukocytes (4.30 PMNs/cmm). He died on the third hospital day.

Autopsy Findings

At autopsy, the thoracic and lumbar portions of the spinal cord were softer than normal and focally hemorrhagic.

Images

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  This is a low-power photomicrograph of a section of spinal cord from this case. Note that the anterior horns (arrows) are almost completely devoid of neurons.
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  This is a higher-power photomicrograph of spinal cord from this case. Note the absence of motor neurons in the anterior horns and the gliosis (arrows).
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  This is a high-power photomicrograph of the anterior horn of the spinal cord from this case. Note the absence of motor neurons and the diffuse gliosis.
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  This is a higher-power photomicrograph taken at the junction of the white and gray matter. Note the inflammatory cellular infiltrate and tissue breakdown. There is significant loss of neurons and myelin in this area.
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  This is another high-power photomicrograph of the anterior horn with inflammatory cell infiltrate and total loss of neurons.

Study Questions

• How does poliovirus cause cell death?

Poliovirus replicates inside neurons and causes lysis of the cell.

• What is the mode of transmission of poliovirus?

Poliovirus is an enterovirus that is usually acquired from contaminated water. It has been effectively controlled by immunization; however, among the nonimmune it causes a nonspecific gastroenteritis. In a small fraction of the vulnerable population, it can invade the nervous system where it attacks lower motor neurons.

Additional Resources

Reference

• eMedicine Medical Library: Pediatric Poliomyelitis
• Merck Manual: Poliomyelitis
• The WHO: Global Polio Eradication Initiative

Related IPLab Cases

An infiltrate is an accumulation of cells in the lung parenchyma--this is a sign of pneumonia.