Hereditary spastic paraplegias are a group of disorders that cause progressive muscle stiffness (spasticity) in the lower limbs that leads to paralysis (paraplegia). Complex hereditary spastic paraplegias, such as spastic paraplegia type 15 (SPG15), impact the lower limbs and also cause neurological impairment, which may include intellectual disability or dementia. Less commonly, some affected individuals also have vision and hearing problems.
Onset of symptoms in SPG15 typically occurs in childhood or adolescence and the first symptom is often either leg stiffness or intellectual disability. Neurological symptoms may include learning difficulties and intellectual disability, structural brain malformations (e.g., thinning of the tissue that connects the left and right halves of the brain, the corpus callosum), loss of nerve cells in different parts of the brain, involuntary movements, and dementia. These issues may be progressive. Additional symptoms may include numbness, tingling or pain in the arms and legs, problems with muscle movements and reflexes, and issues with bladder control. Some individuals with SPG15 also have problems with the retina in the eye, which can cause visual impairment. The severity of each of these symptoms is variable in affected individuals.
The worldwide frequency of SPG15 has not been established. It is estimated that autosomal recessive hereditary spastic paraplegias occur in approximately 1 in 50,000 births. SPG15 has been reported to account for 3 to 15% of all cases of autosomal recessive hereditary spastic paraplegias, depending on region. In areas where consanguinity (relatedness between parents of offspring) is common, the frequency of cases is likely higher.
There is no cure for the underlying cause of this condition. SPG15 is treated symptomatically and may include physical therapy, occupational therapy, and devices to assist with walking or use of a wheelchair. Various medications may be used to reduce muscle stiffness and pain. Patients with hearing impairment may use a hearing device.
Individuals with SPG15 typically have progressive spasticity that will often necessitate assistance with walking or a wheelchair approximately 15 years after the diagnosis. Remaining outcomes will vary based on the severity of symptoms. However, this condition is not expected to shorten lifespan.
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The Spastic Paraplegia Foundation is a non-profit organization dedicated to providing information about these conditions, creating opportunities for support and sharing, and funding research towards discovering the cures for hereditary spastic paraplegias and primary lateral sclerosis.
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