Repetitive transcranial magnetic stimulation in central post-stroke pain: current status and future perspective

Abstract

Central post-stroke pain (CPSP) is an incapacitating disorder that impacts a substantial proportion of stroke survivors and can diminish their quality of life. Conventional therapies for CPSP, including tricyclic antidepressants, anticonvulsants, and opioids, are frequently ineffective, necessitating the investigation of alternative therapeutic strategies. Repetitive transcranial magnetic stimulation (rTMS) is now recognized as a promising noninvasive pain management method for CPSP. rTMS modulates neural activity through the administration of magnetic pulses to specific cortical regions. Trials analyzing the effects of rTMS on CPSP have generated various outcomes, but the evidence suggests possible analgesic benefits. In CPSP and other neuropathic pain conditions, high-frequency rTMS targeting the primary motor cortex (M1) with figure-eight coils has demonstrated significant pain alleviation. Due to its associaton with analgesic benefits, M1 is the most frequently targeted area. The duration and frequency of rTMS sessions, as well as the stimulation intensity, have been studied in an effort to optimize treatment outcomes. The short-term pain relief effects of rTMS have been observed, but the long-term effects (> 3 months) require further investigation. Aspects such as stimulation frequency, location, and treatment period can influence the efficacy of rTMS and ought to be considered while planning the procedure. Standardized guidelines for using rTMS in CPSP would optimize therapy protocols and improve patient outcomes. This review article provides an up-to-date overview of the incidence, clinical characteristics, outcome of rTMS in CPSP patients, and future perspective in the field.

Keywords: Analgesics; Central Post-Stroke Pain; Cerebral Cortex; Intractable; Neuralgia; Opioid; Pain; Quality of Life; Stroke; Therapeutics; Transcranial Magnetic Stimulation..

Fig. 1

Schematic illustration of the pathophysiology central post-stroke pain (CPSP). There are several structural and functional changes associated with the development of CPSP, including reduced M1 stimulation in the affected part of the brain, thalamic injuries, brain plasticity changes, and central sensitization.

Fig. 2

The repetitive transcranial magnetic stimulation (rTMS) treatment mechanism in central post-stroke pain (CPSP). Schematic illustration showing the mechanisms behind the use of rTMS to treat CPSP includes increasing CBF, normalizing connectivity between MD and amygdala, increasing neurotransmitter release, altering neuronal plasticity, and modulating cortical excitability. CBF: cerebral blood flow, MD: mediodorsal, BDNF: brain-derived neurotrophic factor, NGF: nerve growth factor, GABA: gamma-aminobutyric acid, NMDA: N-methyl-D-aspartate, LTP: long-term potentiation, LTD: long-term depression, ICI: intracortical inhibition, ICF: intracortical facilitation.