Hereditary spastic paraparesis is a rare hereditary disorder that causes gradual weakness with muscle spasms (spastic weakness) in the legs.
Hereditary (familial) spastic paraparesis affects both sexes and may begin at any age. It affects about 3 of 100,000 people. Usually, the gene for this disorder is dominant (see Inheritance of Single-Gene Disorders). Therefore, children of a person with the disorder have a 50% chance of developing it. This disorder has several forms. All forms cause degeneration of the nerve pathways that carry signals from the brain down the spinal cord (to muscles). More than one area of the spinal cord may be affected.
Symptoms may begin at any age—from age 1 to old age—depending on the form.
Reflexes become exaggerated, and leg cramps, twitches, and spasms occur, making leg movements stiff and jerky (called a spastic gait). Walking gradually becomes more difficult. People may stumble or trip because they tend to walk on their tiptoes with the feet turned inward. Shoes are often worn down in the area over the big toe. Fatigue is common. In some people, muscles in the arms also become weak and stiff.
Usually, symptoms continue to slowly worsen, but sometimes they level off after adolescence. Life span is not affected.
About 10% of people with the disorder have other abnormalities due to damage of the brain, spinal cord, or nerves. For example, they may have eye problems, lack of muscle control, hearing loss, intellectual disability, dementia, and peripheral nerve disorders.
The disorder is diagnosed by excluding other disorders that cause similar symptoms (such as multiple sclerosis and spinal cord compression) and by determining whether other family members have hereditary spastic paraparesis. Blood tests (genetic testing) are sometimes done to check for the genes that cause the disorder.
Treatment focuses on relieving symptoms. Physical therapy and exercise can help maintain mobility and muscle strength, improve range of motion and endurance, reduce fatigue, and prevent cramps and spasms.
Baclofen is the drug of choice to reduce spasticity. Alternatively, botulinum toxin (a bacterial toxin used to paralyze muscles or to treat wrinkles), clonazepam, dantrolene, diazepam, or tizanidine may be used. Some people benefit from using splints, a cane, or crutches. A few people require a wheelchair.
Last full review/revision March 2013 by Michael Rubin, MDCM