Effectiveness of repetitive transcranial magnetic stimulation for phantom limb pain in land mine victims
Land mines are one of the most substantial causes of distressing injuries, nearly affecting 15,000 to 25,000 victims every year. The common injuries are traumatic limb amputations and various related psychological disorders. The occurrence of phantom limb pain after the traumatic limb amputation is the biggest reason for debility in patients.
It is a neuropathic disorder in which patient feel sharp and burning pain in the amputated limb after partial or complete deafferentation. Almost all amputees suffer from this disorder and it also significantly affects the quality of life of the patients. The treatment response is not very good in patients with traumatic-related amputations. Lot of research is being done in finding out the new treatment approaches for phantom limb pain.
The different mechanisms involved in phantom limb pain had been studied and it has been found that reforming of the primary sensorimotor cortex, comprising variations in motor cortex excitability and peripheral factors like nociceptive inputs from the residual limb have been associated with the formation of this disease. Considering these mechanisms, repetitive transcranial magnetic stimulation (rTMS) has been found to block the maladaptive plasticity in the sensorimotor cortex. Some studies have suggested the analgesic effects of rTMS in subjects with PLP but in small population size.
Recently, researchers have tried to address the great unmet need for larger, rigorously designed study mainly of longer courses of stimulation. They evaluated the immediate and sustained effects of a larger dose of real rTMS of M1 10 sessions on phantom limb pain compared with sham rTMS in land mine victims. This study had 54 patients with phantom limb pain and the treatment involved real or sham rTMS of M1 contralateral to the amputated leg.
A rTMS series of 20 trains of 6-second duration (54-second intertrain, intensity 90% of motor threshold) was arranged at a stimulation rate of 10 Hz (1,200 pulses), 20 minutes per day, during 10 days. Sham coil was used for the control group. After administration of active rTMS, there was a significant reduction in intensity of pain 15 days after the treatment than the group with sham stimulation (−53.38 ± 53.12% vs −22.93 ± 57.16%; mean between-group difference = 30.44%, 95% confidence interval, .30–60.58; P = .03). There was no significant change in the pain intensity 30 days after the treatment. After 15 days, a considerable improvement in pain reduction was noted in 19 patients (70.3%) in the active group compared to only 11 patients (40.7%) in sham group. The results from the present study recommended the use of rTMS for its significant analgesic effect in patients with phantom limb pain.