tropical spastic paraparesis

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Tropical Spastic Paraparesis

Definition

Tropical spastic paraparesis (TSP) is an incurable viral infection of the spinal cord that causes weakness in the legs. It is caused by the human T-cell lymphotropic virus-1 (HTLV-1) retrovirus.

Description

As the name implies, tropical spastic paraparesis usually occurs in tropical locales. Although isolated cases have been diagnosed in the southeastern United States and other places in the United States, TSP is most frequently found in:

the Caribbean
Japan
the Seychelles Islands
regions of South America
western Africa

TSP usually affects adults between the ages of 30 and 40, and is far more common in women than in men.

The disease may remain undetected for years after infection is contracted. When the immune system's response to the virus causes nerve damage, the legs gradually lose strength and flexibility.

Causes and symptoms

TSP is caused by the HTLV-1 virus, which also causes leukemia. The virus can be spread through the placenta, and also through blood transfusions, breast-feeding, contaminated needles, and sexual contact.

Symptoms may begin years after infection. In response to the infection, the body's immune response may injure nerve tissue, causing symptoms that include bladder abnormalities, leg pain, loss of feeling in the feet, tingling sensations, and unpleasant sensations when the skin is touched.

As many as 20% of patients with TSP may also experience:

deafness
double vision
the tendency to incorrectly estimate the amount of motion necessary to accomplish a specific task (dysmetria)
exaggerated reflexes
facial paralysis
tremor.

Diagnosis

Infectious disease specialists use blood tests and magnetic resonance imaging (MRI) of the spinal cord to diagnose this condition.

Treatment

While the disease is incurable, significant improvement has been reported in the condition of TSP patients treated with corticosteroids. These drugs are believed to alleviate symptoms by suppressing the immune system's response to the virus that causes them.

Plasmapheresis, a dialysis-like procedure in which symptom-producing antibodies are removed from the blood, also provides temporary relief.

Prognosis

As noted, TSP cannot be cured.

Prevention

The United States Food and Drug Administration (FDA) has approved screening procedures developed to detect HTLV-1 in donated blood and blood products designated for transfusion. These procedures, which can also be used to diagnose patients with TSP, are designed to prevent the spread of the disease.

Resources

Other

"Current Trends Licensure of Screening Tests for Antibody to Human T-Lymphotropic Virus Type I." Centers for Disease Control. May 27, 1998. http://www.cdc.gov/epo/mmwr/preview/mmwrhtml/00001311.htm.

Key terms

Retrovirus — A family of RNA viruses containing a reverse transcriptase enzyme which allows the viruses' genetic information to become part of the genetic information of the host cell upon replication.

Virus — A microorganism, smaller than bacteria, which can only replicate within the a cell of a living plant or animal. The virus provides the genetic code and the host cell provides the energy and raw materials for replication.

tropical spastic paraparesis

A gradually progressive disease of the spinal cord caused by infection with human T-cell lymphotropic virus–I. Synonym: HTLV-1–associated myelopathy

Symptoms

Symptoms include back pain with gradual loss of motor function in one or both legs, ataxia, and urinary incontinence.