Cerebellar Intermittent Theta-Burst Stimulation and Motor Control Training in Individuals with Cervical Dystonia

Abstract

Background: There is emerging evidence that cervical dystonia is a neural network disorder with the cerebellum as a key node. The cerebellum may provide a target for neuromodulation as a therapeutic intervention in cervical dystonia. Objective: This study aimed to assess effects of intermittent theta-burst stimulation of the cerebellum on dystonia symptoms, quality of life, hand motor dexterity and cortical neurophysiology using transcranial magnetic stimulation. Methods: Sixteen participants with cervical dystonia were randomised into real or sham stimulation groups. Cerebellar neuromodulation was combined with motor training for the neck and an implicit learning task. The intervention was delivered over 10 working days. Outcome measures included dystonia severity and pain, quality of life, hand dexterity, and motor-evoked potentials and cortical silent periods recorded from upper trapezius muscles. Assessments were taken at baseline and after 5 and 10 days, with quality of life also measured 4 and 12 weeks later. Results: Intermittent theta-burst stimulation improved dystonia severity (Day 5, −5.44 points; p = 0.012; Day 10, −4.6 points; p = 0.025), however, effect sizes were small. Quality of life also improved (Day 5, −10.6 points, p = 0.012; Day 10, −8.6 points, p = 0.036; Week 4, −12.5 points, p = 0.036; Week 12, −12.4 points, p = 0.025), with medium or large effect sizes. There was a reduction in time to complete the pegboard task pre to post intervention (both p < 0.008). Cortical neurophysiology was unchanged by cerebellar neuromodulation. Conclusion: Intermittent theta-burst stimulation of the cerebellum may improve cervical dystonia symptoms, upper limb motor control and quality of life. The mechanism likely involves promoting neuroplasticity in the cerebellum although the neurophysiology remains to be elucidated. Cerebellar neuromodulation may have potential as a novel treatment intervention for cervical dystonia, although larger confirmatory studies are required.

Cerebellar Deep Brain Stimulation for Acquired Hemidystonia

“…Noninvasive stimulation with transcranial direct current stimulation and transcranial magnetic stimulation led to slight short-term benefit in some studies. [26][27][28] Long-term improvement in dystonia has been reported after lesioning of the dentate nucleus. 23,24 Stimulation of the anterior cerebellar cortex has sometimes improved dystonic or athetoid movements in cerebral palsy, although typically a greater benefit reported in spasticity.…”

The Anatomical Basis for Dystonia: The Motor Network Model

“… 139 Another sham-controlled study involving a similar cerebellar TMS paradigm for 10 weeks combined with physical therapy also produced small but significant decreases (–10%) in TWSTRS motor scores and improvements in quality of life measures in 16 patients with cervical dystonia. 140 These studies are provocative because they imply that interventions involving the cerebellum may influence dystonic movements. On the other hand, a randomized sham-controlled study revealed no benefits after a single session of 1 Hz repetitive TMS over the cerebellum in 10 patients with writer’s cramp.…”

Systematic Review of Rehabilitation in Focal Dystonias: Classification and Recommendations

“…No differences were observed between rTMS followed by sensorimotor training in comparison to rTMS followed by massage and stretching in focal hand dystonia . In the only study of cervical dystonia in this category, neck motor training after real iTBS induced significant improvements in pain, quality of life, and hand dexterity in comparison to sham . The GRADE level for this category was rated as low.…”

“…Studies in this category tested some modality of motor training paired with neuromodulation methods ( n = 5), such as transcranial direct current stimulation (tDCS), repetitive transcranial magnetic stimulation (rTMS), or intermittent theta burst stimulation (iTBS) . Stimulation sites tested included the premotor cortex, primary motor cortex, and the cerebellum …”