SMA comprises a group of neurodegenerative disorders characterized by the gradual loss of motor neurons — the nerve cells responsible for controlling voluntary muscles — leading to muscle weakness and wasting. It is typically caused by mutations in the SMN1 gene, which provides instructions for making the SMN protein essential for motor neuron survival.
SMA is divided into several subtypes from type 0 to type 4, depending on the age at disease onset and symptom severity. In patients with type 3, a late-onset and generally milder form of the disease, the symptoms become apparent during infancy, usually when a child is learning how to walk, and include poor balance and difficulty walking or standing unaided.
Electrotherapy is a form of physical therapy in which electrical impulses (delivered through the use of electrodes) are used to stimulate or relax muscle fibers and increase blood circulation in a specific part of the body.
It can be used treat muscle spasms, prevent muscle wasting, increase muscle mass and range of motion, improve motor function, and assist in physical activity in patients with certain neurological disorders, including stroke, spinal cord injury, and myotonic dystrophy.
“However, concerning SMA, limited evidence exists on the role of electrotherapy as an adjunct [therapy] for improving muscle strength and function,” the researchers wrote.
In this case report, investigators from the University of Brescia in Italy and their collaborators described the case of a boy with SMA type 3 who experienced significant improvements in motor function after completing a physiotherapy program consisting of electrotherapy and physical exercise.
The 13-year-old boy started showing signs of motor impairment at 14 months old, and was diagnosed with SMA after a genetic test was done when he was 32 months old. In an attempt to slow the progression of the disease, the boy frequently participated in physiotherapy sessions that included hydrokinesis — a combination of water exercises and physical therapy — and swimming.
“His medical history was characterized by a mild restrictive ventilatory defect, frequent falls, low physical endurance, and increased fatigability,” the researchers wrote.
After falling and breaking his left femur (the long bone in the upper leg) in May 2013, his motor impairments worsened, and he lost some of his independence and self-sufficiency, which also affected his overall quality of life.
In September 2014, the boy came to the center for the first time. A physical examination revealed he had extensive muscle wasting of his thigh muscles, lacked several tendon reflexes, and had mild scoliosis (curvature of the spine).
“During this initial assessment, [he] underwent also transcutaneous [through the skin] neuromuscular electrical stimulation (NMES) to assess the presence of elicitable contractions of the quadriceps muscles and ascertain patient’s tolerability to ES [electrical stimulation],” the researchers wrote. “Given the favorable response and good tolerance of the subject, we proposed him a personalized program for motor recovery centered on ES applications for lower limb strengthening.”
The 18-week muscle strengthening program was divided into two phases: in the first phase (weeks one through eight) the boy was instructed to follow a home-based quadriceps (thigh muscles) strengthening program using a personalized NMES protocol; in the second phase (weeks nine through 18), the home-based NMES program was combined with 10 sessions of cycling based on functional electrical stimulation, with the aim of further boosting the benefits of NMES.
After completing the program, the boy showed significant improvements in motor function (the size and strength of his thigh muscles increased) and regained the ability to climb stairs by himself.
“The findings of this case report, although with limited generalizability, reveal that a multimodal approach based on electrotherapy and cycling exercise may be well tolerated and may improve motor performance in SMA patients, thus contributing to designing more robust experimental studies aimed at investigating the effectiveness of ES as an add-on therapy to existing and emerging care,” the researchers concluded.