Evaluation of therapeutic benefits of botulinum toxin for foot dystonia associated with Parkinson's disease.

[BACKGROUND] Foot dystonia occurs in patients with Parkinson's disease (PD) and leads to pain, malformation, and difficulty with walking. Botulinum toxin injections may be effective for foot dystonia, but the extent of improvement and effects on motor function are unclear.

[METHODS] In this study, we performed botulinum toxin injections for foot dystonia in 25 patients with PD. At 3 weeks and 3 months post-infection, we assessed changes in plantar pressure distribution utilizing the Pressure Plate system; dystonia using the Modified Ashworth Spasm score; pain using the visual analog scale (VAS) score; and lower extremity function using the Calf-raise Senior (CRS) test, Timed Up and Go (TUG) test, and gait parameters (eg, stride length, step length).

[RESULTS] We found improved Modified Ashworth Spasm score (p < 0.01) and VAS score (p < 0.01) post-injection. CRS test score (3 weeks, p = 0.006; 3 months, p = 0.068), stride length (3 weeks, p = 0.012; 3 months, p = 0.715), and step length (3 weeks, p = 0.011; 3 months, p = 0.803) also improved. Plantar pressure distribution improved after botulinum toxin injection (metatarsal 1, 3 weeks, p = 0.031; 3 months, p = 0.144; metatarsal 2, 3 weeks, p = 0.049; 3 months, p = 0.065; metatarsal 3, 3 weeks, p = 0.002; 3 months, p = 0.017; metatarsal 4, 3 weeks, p = 0.017; 3 months, p = 0.144; medial heel, 3 weeks, p = 0.01; 3 months, p = 0.395; lateral heel, 3 weeks, p = 0.035; 3 months, p = 0.109).

[CONCLUSION] Botulinum toxin injection for foot dystonia in patients with PD can reduce spasms and pain and normalize plantar pressure distribution, which improves balance and lower extremity function.