Neuromodulation of detrusor hyper-reflexia by functional magnetic stimulation of the sacral roots.

OBJECTIVE

To investigate the acute effects of functional magnetic stimulation (FMS) on detrusor hyper-reflexia using a multi-pulse magnetic stimulator.

PATIENTS AND METHODS

Seven male patients with established and intractable detrusor hyper-reflexia following spinal cord injury were studied. No patient was on medication and none had had previous surgery for detrusor hyper-reflexia. After optimization of magnetic stimulation of S2-S4 sacral anterior roots by recording toe flexor electromyograms, unstable detrusor activity was provoked during cystometry by rapid infusion of fluid into the bladder. The provocation test produced consistent and predictable detrusor hyper-reflexia. On some provocations, supramaximal FMS at 20 pulses/s for 5 s was applied at detrusor pressures which were > 15 cmH2O.

RESULTS

Following FMS there was an obvious acute suppression of detrusor hyper-reflexia. There was a profound reduction in detrusor contraction, as assessed by the area under the curves of detrusor pressure with time.

CONCLUSIONS

Functional magnetic stimulation applied over the sacrum can profoundly suppress detrusor hyper-reflexia in man. It may provide a non-invasive method of assessing patients for implantable electrical neuromodulation devices and as a therapeutic option in its own right.