Effect of sacral-root stimulation on the motor cortex in patients with idiopathic overactive bladder syndrome.

ABSTRACT

AIMS OF THE STUDY It is presumed that idiopathic overactive bladder syndrome (OBS) is due to visceral hypersensitivity. Sacral-root stimulation can restore the bladder function, but its mechanism remains uncertain. It is well-known that long-term peripheral stimulation can induce brain plasticity. Hence, we investigated whether brain reorganization occurred along with clinical improvement after sacral-root stimulation. MATERIAL AND METHODS: Because toe flexion is the index for monitoring wire placement, we used the flexor hallucis brevis (FHB) as the target muscle. Transcranial magnetic stimulation (TMS) was applied to study motor cortex excitability and the brain mapping of the muscle. RESULTS: Six patients with idiopathic OBS were included in the study. All demonstrated clinical improvement after sacral-root stimulation. Motor cortex excitability and the area of representation for the flexor hallucis brevis muscle increased for at least 30 min after sacral-root stimulation had terminated. CONCLUSION: Our results showed that cerebral activities changed after sacral-root stimulation. The improvement in urinary urgency and urgency perception was probably due in part to brain reorganization.