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This study puts light on how high-frequency rTMS on the
contralateral primary motor cortex of traumatic amputees induced a clinically
significant pain reduction up to 15 days after treatment without any major
secondary effect.
This study puts light on how high-frequency rTMS on the
contralateral primary motor cortex of traumatic amputees induced a clinically
significant pain reduction up to 15 days after treatment without any major
secondary effect.
Land mines, one of the world’s most disabling public health
hazards, results in approximately 15,000 to 25,000 victims each year. After
trauma-related limb amputation for land mine injury, one of the significant
causes of disability is the presence of phantom limb pain (PLP). PLP is a
neuropathic syndrome characterized by pain felt in the patients’ remaining
perception of the amputated limb after partial or complete deafferentation.
This pain is usually described as a stabbing, throbbing, burning, or cramping
sensation. PLP is present in up to 87% of all amputees and is considered a challenging
condition because of its negative effect on quality of life and lack of
treatment response, particularly in patients with traumatic-related
amputations.
The high prevalence of PLP after amputation and its lack of
treatment response have resulted in major efforts to develop interventions to
decrease the pain in affected patients. In light of PLP mechanisms, repetitive
transcranial magnetic stimulation (rTMS) has been tested in this condition as a
tool to block the maladaptive plasticity in the sensorimotor cortex. rTMS
applied daily over the primary motor cortex (M1) has shown pain relief effects
in other neuropathic pain syndromes such as post stroke pain and spinal cord
injury pain. Some previous reports have also suggested analgesic effects of rTMS
in subjects with PLP. There have been only 3 trials testing rTMS in PLP. Two
were small pilot studies and other was a randomized clinical trial with 27
subjects. A recent meta-analysis judged this trial as a high risk of bias study
due to deficient randomization method, which led to an unbalanced distribution
between the intervention groups. There was a need for larger, rigorously
designed studies, particularly of longer courses of stimulation. This study
hypothesized that 10 Hz rTMS for 2 weeks over M1 contralateral to the PLP could
significantly decrease the level of pain compared with sham stimulation.
Rationale behind
research:
Objective:
To assess the immediate and sustained effects of a larger dose
of real rTMS of M1—10 sessions—on PLP compared with sham rTMS in land mine
victims.
Study outcomes
Primary Outcomes:
Primary end point of the study was the score change in visual analogue scale (VAS) for pain. This self-evaluation scale ranges from 0 to 10 as visually described in centimeter units, 0 cm indicates no pain and 10 cm the worst pain possible. Response was defined as a reduction of ≥30% compared with baseline at 15 and 30 days after treatment.
Secondary Outcomes:
Time Points: Baseline and at 15 and 30 days after treatment
Outcomes:
Figure 1: Average scores of
pain at baseline and after 15 and 30 days of treatment
Figure 2: Average scores of
depression at baseline and after 15 and 30 days of treatment
Figure 3: Average scores of
anxiety at baseline and after 15 and 30 days of treatment
The present study showed that treatment with 10 Hz rTMS of contralateral M1 during 2 weeks in traumatic amputees with PLP induced a clinically significant pain reduction up to 15 days after treatment than with sham stimulation. No serious adverse effects were found indicating that rTMS was a safe and effective in patients with PLP caused by land mine explosions.
Previous studies had shown some beneficial effects of rTMS on PLP. These reports have evaluated either the effects of low frequency rTMS (1 Hz), which may induce an opposite effect. In an initial case report, Topper et al evaluated the effect of rTMS series on phantom pain like syndrome in 2 patients with long-lasting brachial plexus avulsion. They underwent 10 and 1 Hz rTMS during 15 days, separated by 4 and 6 weeks, respectively (at 110% of RMT, 12-minute duration) over the contralateral posterior parietal cortex to the injured limb. The authors reported a maximum pain reduction of approximately 60% and 23.6%, during the rTMS treatment compared with baseline; however, the pain decrease was not maintained in the long-term. Similarly, Di Rollo and Pallanti in 1 patient with PLP of traumatic origin, applied 15 sessions of low-frequency rTMS (thirty 20-second trains at 80% of RMT, 15 minutes) over the ipsilesional motor cortex, showing a pain reduction of 33.3% at the end of the third week of treatment and a slight decrease (16.6%) at the follow-up visit (3 weeks after the last session).
Also, a significant reduction in depressive and anxiety symptoms after 30 days after the intervention without any differences between treatment groups, indicating an effect not attributable to rTMS.
rTMS is a safe and effective therapy in patients with PLP
caused by land mine explosions
The Journal of Pain 2016;17 (8): 911-918
Repetitive Transcranial Magnetic Stimulation for Phantom Limb Pain in Land Mine Victims: A Double-Blinded, Randomized, Sham-Controlled Trial
Alejandra Malavera et al.
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