Repetitive Transcranial Magnetic Stimulation
Repetitive transcranial magnetic stimulation (rTMS) has been widely explored as a tool for treating a variety of disorders, including depression (Martin et al. 2003; Couturier et al. 2005), pain (Lima & Fregni 2008), and motor disorders following Parkinson’s disease (Elahi et al. 2009) and stroke (Corti et al. 2011). Experimental studies in humans have shown that low-frequency rTMS (<1 Hz) can reduce the excitability of the motor cortex whereas high-frequency rTMS (>1 Hz) causes an increase in motor cortical excitability (Kobayashi & Pascual-Leone 2003). Given the ability for rTMS to modulate cortical excitability, there has been much interest in exploring its potential to facilitate supraspinal connectivity or restore the balance of interhemispheric inhibition (in stroke) as a means to promote motor recovery and function.
The recovery of functional ambulation following motor-incomplete SCI has been shown to be associated with enhanced excitability of motor cortical areas (Winchester et al. 2005) and corticospinal connectivity to the lower limb (Thomas & Gorassini 2005). Recently, Kumru et al. (2013) explored the potential efficacy of combining rTMS with locomotor training on gait outcomes in people with sub-acute (<12 months) motor-incomplete SCI (ASIA D). Seventeen participants were randomized to either a control group with sham stimulation or the rTMS group. Stimulation (sham or rTMS) was delivered while participants lay supine, 5 times/week for 3 weeks. All participants also received daily overground gait training for 1 hour for 3 weeks. The gait training session was performed within 30 minutes of the stimulation session. There was an additional 2 weeks of overground gait training only as a follow-up.
|Author Year; Country
Kumru et al. 2013; Spain
Randomized sham-controlled trial
|Population: 17 participants with SCI (13M, 4F); 19-60 yrs old; all AIS D.
Treatment: Patients were randomized to 2 groups: an active repetitive transcranial magnetic stimulation (rTMS) group and a sham group. 3 participants who began in the sham group were crossed over to the active rTMS group after a washout period of more than 3 weeks.Outcome Measures: Lower Extremity Motor Score (LEMS); 10 Meter Walk Test (10MWT); Timed Up and Go (TUG); Walking Index for Spinal Cord Injury (WISCI); Modified Ashworth Scale (MAS); Spinal Cord Injury Spasticity Evaluation Tool (SCI-SET).
- A significant improvement was observed after the last rTMS session in the active group for LEMS, walking speed, and spasticity. Improvement in walking speed was maintained during the follow-up period.
- Sham stimulation did not induce any improvement in LEMS, gait assessment, and spasticity after the last session and neither during follow up.
|Effect Sizes: Forest plot of standardized mean differences (SMD ± 95%C.I.) as calculated from pre- to post-intervention data and pre-intervention to retention/follow-up data
Benito et al. 2012; USA
|Population: 17 individuals- 13 males and 4 females; incomplete SCi; all AIS D; level of injury: C4 – T12; age range= 18 – 60y
Treatment: Patients were randomized to active rTMS or sham stimulation. Three patients from the initial group of 10 randomized to sham stimulation entered the active rTMS group after a 3-week washout period. Therefore, a total of 10 patients completed each study condition. Both groups were homogeneous for age, gender, time since injury, etiology, and ASIA scale. Active rTMS consisted of 15 days of daily sessions of 20 trains of 40 pulses at 20 Hz and an intensity of 90% of resting motor threshold. rTMS was applied with a double cone coil to the leg motor area.
Outcome Measures: Lower extremities motor score (LEMS), Modified Ashworth Scale (MAS), Walking Index for SCI (WISCI II), 10 MWT, Step length and cadence (assessed during 10 MWT), Timed Up and Go (TUG)
- There was a significant improvement in LEMS in the active group but not in the sham group.
- The active group also showed significant improvements in the MAS, 10MWT, cadence, step length, and TUG, and these improvements were maintained 2 weeks later.
- Following sham stimulation, significant improvement was found only for step length and TUG.
Guzman-Lopez et al. 2014; UK
|Population: 12 healthy individuals- 6 males and 6 females; mean age= 34y;
Treatment: The experiment included four different conditions in two positions: We examined participants lying supine at rest, which was considered the control condition (rest), and while maintaining a steady ankle tonic plantar flexion (pf), dorsiflexion (df) or standing still (ss) of about 30 % of their maximum voluntary contraction (MVC).
Outcome Measures: H-Reflex, EMG
- During pf, there was an increase in the facilitation of the H reflex at ISIs 0–20 ms.
- During ss, there was inhibition at ISIs 40–60 ms.
Few studies have investigated the effects of rTMS on gait-related outcomes (Kumru et al. 2013; Benito et al. 2012). The authors report significant improvements in LEMS and 10MWT in the rTMS group, but not the sham stimulation group.
There is level 1b evidence from one RCT (Kumru et al. 2013) that rTMS combined with overground locomotor training may not afford further benefits over overground locomotor training alone (with sham stimulation).