Hereditary spastic paraplegia (HSP) or Strümpell-Lorrain disease is a highly heterogeneous group of diseases, both clinically, with variable symptoms and course, and genetically, with many genes known to be involved. The main symptom of the disease is stiffness (spasticity) and weakness of the lower limbs, leading to severe walking difficulties due to damage to the motor neurons.
These diseases affect around 3 out of every 100,000 people in Europe, usually starting in adulthood but can also appear in childhood. These diseases are said to be chronic, progressing more or less slowly depending on the patient, with some patients becoming totally unable to walk, while others show very few symptoms several years after diagnosis.
The causes and biological mechanisms of Spastic Paraplegia
Spastic paraplegia is mainly inherited in several ways (autosomal dominant, recessive or X-linked).
Many chromosomal regions are now known to carry mutations responsible for these diseases, and more than 70 genes have been identified.
The causes of spastic paraplegia are characterised by a degeneration of the corticospinal neurons that control voluntary motricity, i.e. the transmission of information from the brain to the muscles via the spinal cord, leading to the motor disorders observed in patients.
Cerebellar ataxia, which is sometimes observed, is a sign of degeneration of the neurons in the cerebellum.
Symptoms and diagnosis of spastic paraplegia
In the so-called 'pure' forms of the disease, which are the most common, the disease is characterised by stiffness, spasticity, and weakness of the lower limbs, leading to severe walking difficulties. In more complex forms, balance disorders, eye damage, deafness and intellectual impairment may be associated with spasticity.
The diagnosis of spastic paraplegia is based on a clinical examination, a study of the family history and a genetic analysis to find a causative mutation.
Treatments for spastic paraplegia
There is currently no cure for spastic paraplegia, but treating symptoms such as spasticity can bring relief to sufferers. Physiotherapy, occupational therapy, balneotherapy and treatments based on muscle relaxants or botulinum toxin can help improve motor skills.
