Effects of vibration stimulation on truncal lateropulsion in patients with lateral medullary syndrome.

BACKGROUND

Prognosis of body lateropulsion observed in lateral medullary syndrome is generally favourable; however, lateropulsion persists in some patients and delays social rehabilitation. One proposed pathophysiological mechanism of lateropulsion is impaired afferent input to the cerebellum due to disruption of the posterior spinocerebellar tract. This study examined whether activation of the posterior spinocerebellar tract system through vibration stimulation improves lateropulsion.

METHODS

First, following a representative case presentation, seven additional consecutive patients with lateral medullary syndrome were studied to analyse the immediate effects of vibration stimulation evaluated by the Romberg test, tandem standing test and 3 m Timed-Up-and-Go test. Next, a prospective observational study of vibration stimulation on balance disorders was performed in three patients who participated in a combined training approach (hybrid training) incorporating vibration stimulation and conventional balance training.

RESULTS

Balance function before vibration stimulation was assessed in seven additional patients using three tests. Regarding the immediate effect of vibration stimulation, all patients showed improvement in at least one test when vibration was applied to the lower limb on the lesional side, whereas only three patients improved with vibration on the non-lesional side. This difference indicated significant effectiveness of lesional-side stimulation (p<0.05, Fisher's exact test). There were no tests with worse scores after vibration. Long-term effects of hybrid training were evaluated by monitoring balance tests. Due to the limitations of a single-case observational study, it was not possible to objectively establish superiority of the hybrid training over conventional balance training.

CONCLUSIONS

We showed that vibration stimulation on lesional side is potentially useful to improve spinocerebellar dysfunction and lateropulsion.