The Effect of Low-Frequency Repetitive Transcranial Magnetic Stimulation (rTMS) in Stroke Patients

Post-stroke spasticity is a common complication that can severely impact daily living activities, causing pain and hygiene challenges for a significant number of patients. Spasticity is a clinical condition that arises as a result of abnormal or hyperexcitable spinal reflexes, and the excitability of the spinal stretch reflex is regulated through supraspinal descending pathways such as the Dorsal Reticulospinal tract, Medial Reticulospinal tract, and Vestibulospinal tract. The treatment of spasticity can be categorized into non-pharmacological, pharmacological, and surgical approaches. Pharmacological options include Baclofen, Tizanidine, Dantrolene, and Botulinum toxin injections. However, these treatments may cause side effects such as sedation, cognitive impairment, and muscle weakness. The application of Repetetive Transcranial Magnetic Stimulation (rTMS) is based on the hypothesis that neuromodulation, achieved by inhibiting the contralesional hemisphere with 1 Hz stimulation or facilitating the ipsilesional hemisphere with stimulation above 1 Hz, can normalize interhemispheric inhibition.The search for alternative effective treatments and the aim to minimize undesirable side effects have led to a significant rise in studies exploring the effects of rTMS on spasticity in recent years.

Our study is a randomized, double-blind, sham-controlled clinical trial. According to the statistical analysis 20 patients who were registered at Ankara Bilkent City Hospital Physical Therapy and Rehabilitation Hospital between July 2021 and May 2022 and met the study criteria were included. Patients were divided into two groups using a computer-based randomization program: a 1 Hz rTMS group (n=10) and a sham group (n=10). The researcher conducting the clinical assessments was blinded to the group assignments of the patients. Furthermore, the patients themselves were unaware of which group they had been assigned to. Active stimulation was applied to the M1 region of the non-lesional hemisphere using a 70-mm figure-eight coil, while the sham group received the same protocol with a sham coil that visually resembled the active coil. The coil was initially placed tangentially over the presumed motor cortex, and the motor hotspot was identified by applying single pulses at different positions until the lowest intensity produced a significant motor-evoked potential (MEP) in the first dorsal interosseous muscle. The resting motor threshold (rMT) was then determined as the lowest intensity to produce an MEP amplitude larger than 50 mV in more than 5 out of 10 trials. In the active treatment group, 1200 pulses at 90% of rMT were delivered to the hotspot of the first dorsal interosseous muscle in the contralesional hemisphere across 10 sessions over two weeks, while the sham group received sham stimulation. Safety protocols were followed, and both groups underwent physical therapy, including upper extremity exercises and occupational therapy, within 30 minutes after each TMS session.

Clinical evaluations were conducted three times for each patient: Baseline (before treatment), 2nd week (at the and of treatment), and 6th week.

Inclusion criteria

• Having a lesion in a single hemisphere confirmed by MRI,
• At least 6 months and at most 2 years having passed since the stroke,
• Spasticity in wrist flexors and finger flexors at levels 1+, 2, or 3 according to the modified Ashworth scale,
• Being between 18-75 years old,
• Having a Mini-Mental Test score of ≥ 24,
• If using antispastic medication, no change in medication dosage in the last month.

Exclusion criteria

• History of epilepsy, dementia, cognitive impairment, or neurodegenerative disease,
• Having a metallic materials in the area to be stimulated (such as a cochlear implant, brain pacemaker, or drug pump),
• Alcoholism,
• Pregnancy,
• Severe and newly decompensated heart failure,
• Using medications that lower the seizure threshold.