Hereditary spastic paraplegia (HSP) is a group of inherited diseases whose main feature is a progressive gait disorder. The disease presents with progressive stiffness (spasticity)  and contraction in the lower limbs. HSP is also known as hereditary spastic paraparesis, familial spastic paraplegia, French settlement disease, Strumpell disease, or Strumpell-Lorrain disease. The symptoms are a result of dysfunction of  long axons in the spinal cord. The affected cells are the primary motor neurons; therefore, the disease is an upper motor neuron disease. HSP is not a form of cerebral palsy even though it physically may appear and behave much the same as spastic diplegia. The origin of HSP  is different from cerebral palsy. Despite this, some of the same anti-spasticity medications used in spastic cerebral palsy are sometimes used to  treat HSP symptoms. HSP is caused by defects in  transport of  proteins, structural proteins, cell-maintaining proteins, lipids, and other substances through the cell. Long nerve fibers (axons) are affected because  long distances make nerve cells particularly sensitive to defects in these mentioned mechanisms.The disease was first described in 1880 by the German neurologist Adolph Strümpell. It was described more extensively in 1888 by Maurice Lorrain, a French physician. Due to their contribution in describing the disease, it is still called Strümpell-Lorrain disease in French-speaking countries. The term hereditary spastic paraplegia was coined by Anita Harding in 1983. Signs and symptoms
Symptoms depend on the type of HSP inherited.
Age is related to the incidence of periodontal destruction: "...in a well-maintained population who practises oral home care and has regular check-ups, the incidence of incipient periodontal destruction increases with age, the highest rate occurs between 50 and 60 years, and gingival recession is the predominant lesion before 40 years, while periodontal pocketing is the principal mode of destruction between 50 and 60 years of age. "There are a variety of periodontal risk factors which can affect the prevalence, rate, extent and severity of the disease progression. Major risk factors include smoking, lack of oral hygiene with inadequate plaque biofilm control. There is a slow to moderate rate of disease progression but the patient may have periods of rapid progression ("bursts of destruction"). Chronic periodontitis can be associated with local predisposing factors (e.g. tooth-related or iatrogenic factors). The disease may be modified by and be associated with systemic diseases (e.g. diabetes mellitus, HIV infection) It can also be modified by factors other than systemic disease such as smoking and emotional stress, anxiety and depression. Care should be taken however, when diagnosing a patient who smokes as smoking can alter some of the results of an examination. In smokers, the gingiva are pale and fibrous and tend to bleed less while being probed due to the effect of nicotine on the vasculature by vasoconstricting them. Thus, a lowered response is produced and this explains why incorrect data can be gained. There is also an increase in supragingival calculus alongside visible nicotine staining.