Hereditary spastic paraplegias (HSPs) are of numerous types (over 30), comprising a heterogeneous group of diseases little known in clinical practice due to low prevalence, slow progression, and difficult diagnoses.Wikipedia
Other names for HSPs include hereditary spastic paraparesis, familial spastic paraplegias, French settlement disease, or Strumpell-Lorrain disease, is a group of inherited diseases whose main feature is progressive stiffness and contraction (spasticity) in the lower limbs, as a result of damage to or dysfunction of the nerves. Some forms are inherited recessively while others are inherited in a dominant manner.
HSP is not a form of cerebral palsy even though it physically may appear and behave much the same as, for example, spastic diplegia. The origins of HSP are entirely separate phenomena from cerebral palsy. Despite this, some of the same anti-spasticity medications used in spastic cerebral palsy are sometimes used to try to treat HSP symptomatology.
The condition sometimes also affects the optic nerve and retina of the eye, causes cataracts, ataxia (lack of muscle coordination), epilepsy, cognitive impairment, peripheral neuropathy, and deafness. HSP is caused by defects in the mechanisms that transport proteins and other substances through the cell. Long nerves are affected because they have to transport cellular material through long distances, and are particularly sensitive to defects of cellular transport.