遺伝性痙縮性対麻痺4型（SPAST遺伝子c.683-2A>Cバリアント）におけるファムプリジン：症例報告

BACKGROUND The most frequently mutated gene in hereditary spastic paraplegia (HSP) is SPAST. Only symptomatic treatment is available for this disease. Fampridine has been successfully used to treat gait disturbances in some patients with HSP. A positive effect of fampridine has not been previously reported in HSP4 caused by the c.683-2A>C variant in the SPAST gene. CASE REPORT We report the case of a 63-year-old woman with hypogeusia and hyposmia for several years, pollakiuria, gait disturbances, reduced walking speed, occasional dysphagia, constipation and delayed defecation, occasional memory problems, right-sided hearing loss, and exercise-induced myalgia and muscle cramps. Genetic testing revealed the c.683-2A>C variant in SPAST. Her 69-year-old sister also had pollakiuria since her youth, and since the age of 50 had frequent stumbling, unsteadiness, spasticity, and positional vertigo. At age 62, our patient began taking fampridine (4-aminopyridine) and has since experienced significant relief. Fampridine led to an improvement in spasticity, gait disorders, and walking speed, as documented by the 6-meter walk test, spastic paraplegia rating scale, and multidimensional self-esteem scale. CONCLUSIONS This case shows that HSP4 can progress slowly over a period of 7 years and can present with typical phenotypic characteristics of the disease as it progresses. The rate of progression can vary among affected family members, and people with HSP4 can still work even in old age and do not necessarily need antispastic drugs. This case also provides preliminary evidence that fampridine may be a viable symptomatic treatment option for patients with HSP4, including those with the mutation c.683-2A>C. It justifies further prospective, controlled studies in a larger SPAST-HSP population.