Short-term and long-term outcomes of transcutaneous spinal cord stimulation in SMA: findings from consecutive courses

OBJECTIVE: SMA is a genetic disorder that causes the progressive degeneration of spinal motor neurons, which can result in premature death. Restoring motor function in people with SMA is a serious issue. These individuals require lifelong motor rehabilitation to maintain their quality of life. A recent study showed that a two-week course of transcutaneous electrical spinal cord stimulation (tSCS) combined with physical therapy led to clinically significant improvements in Revised Upper Limb Module (RULM) and Hammersmith Functional Motor Scale Expanded (HFMSE), improved Forced Vital Capacity (FVC), reduced joint contractures in people with SMA types 2 and 3 receiving gene therapy. It is unclear how long the benefits of a tSCS course last. This study aimed to determine the long-term effects of tSCS and to evaluate whether consecutive tSCS courses can improve motor activity in individuals with SMA types 2 and 3 receiving disease-modifying therapy. APPROACH: Case series involved nine individuals with SMA types 2 and 3 (aged 5-20 years). They underwent two consecutive courses of tSCS combined with motor task performance. Each course lasted two weeks, with a break of 3 to 15 months between courses. The RULM, HFMSE, FVC and a goniometric assessment of knee extension were recorded before and after each course. MAIN RESULTS: Significant improvements achieved during the first course did not deteriorate between the courses. The second course demonstrated significant improvements in HFMSE scores and FVC. SIGNIFICANCE: This case series confirms the effectiveness of tSCS in motor rehabilitation for individuals with SMA types 2 and 3. It can be concluded that the effects of spinal stimulation treatment last for 4 to 5 months. Consecutive tSCS courses with an interval of less than a year between them can likely improve motor activity in people with SMA types 2 and 3 who have received diseasemodifying therapy.