Transcranial magnetic stimulation (TMS) has already been described in the previous section. Transcranial theta-burst stimulation differs from TMS in that the stimulation includes patterned (vs non-patterned in repetitive TMS) bursts of shorter duration pulses. Conceptually, intermittent transcranial theta-burst stimulation (iTBS), may produce a more robust strengthening of synaptic activity in residual neural pathways (Martin 2016; Huang et al. 2005).
iTBS is a new intervention being applied to people with incomplete cervical SCI to potentially improve upper limb spasticity, pain and sensorimotor function. Gharooni et al. (2018; RCT) administered a total of 600 pulses in 200 seconds 3 stimuli at 50Hz, repeated at 200 ms intervals for 2 seconds and interspersed by 8 seconds between pulse trains). Sham iTBS was the same except with the stimulation coil rotated 90° from the participants midline axis to ensure no brain stimulation. Sessions of iTBS (or sham iTBS) were delivered 10 times over 2 weeks with a 2-week washout period before crossover to the alternative intervention. Three spasticity outcome assessments (modified Ashworth Scale (MAS), Leeds Arm Spasticity Impact Scale (LASIS) and a Visual Analogue Scale for spasticity (VAS-S)) were applied to bilateral elbow and wrist extension and flexion. Results were reported to support a non-significant reduction in MAS compared to sham iTBS and that were not of a magnitude that could be perceived by participants as improved function (via VAS-S and LASIS).
Nardone et al. (2017), using SCAT (Spinal Cord Assessment Tool for Spasticity) and MAS and a stimulation protocol as described above (Gharooni et al. 2018) with the exception that the washout period was 2 months (vs 2 weeks), found a significant reduction of upper extremity spasticity (p<0.001 for both SCAT and MAS) that returned to baseline within one week.
There is level 1b evidence (from 1 RCT: Nardone et al. 2017) that iTBS reduces upper extremity spasticity for up to 1 week.