The use of a novel frequency pairing for transcranial magnetic stimulation (TMS) may effectively relieve upper and lower extremity pain associated with complex regional pain syndrome (CRPS), according to a study published in Neuromodulation.
The TMS protocol used in this study consisted of initial intermittent theta bursts (ie, burst of three 50-Hz pulses every 200 ms, 2 second-long trains repeated every 10 s, total of 600 pulses, delivered at 70% of the resting motor threshold [RMT]). This was followed by a 10-Hz stimulation (duration, 10 s; intertrain interval, 30 s; total pulses, 2000; delivered at 80% of RMT). Muscle activity was monitored throughout the stimulation.
Study participants had a CRPS diagnosis according to the Budapest Clinical Diagnostic Criteria, a pain score >3 on the 0 to 10 numeric rating scale (NRS), and demonstrated tolerability to TMS and magnetic resonance imaging. A deep coil allowing stimulation of lower extremity representation on the motor cortex was used.
Treatment response (ie, ≥30% reduction in pain scores) was assessed after a single TMS session(n=5) and 5 consecutive daily sessions (n=12). After a single TMS session, the response rate was 60% at week 1. After 5 consecutive daily TMS sessions, the response rate was 42% after the first day of treatment (P =.002), and increased to 58% at week 1 (P =.024) and 50% at week 2 (P=.009).
From each group, 2 patients reported a >50% reduction in pain beyond 6 to 8 weeks. Nausea and headache were the most frequently reported adverse events; no serious adverse events were reported.
The small sample size, lack of placebo group, and the predominantly female cohort were the main study limitations.
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