History

From 1969 onwards Brindley developed the sacral anterior root stimulator, with successful human trials from the early 1980's onwards. Although both spinchter and detrussor muscles are stimulator at the same time, the slower contraction kinetics of the bladder wall (smooth muscle) compared to the spinchter (striated muscle) means that voiding occurs between the stimulation pulses, rather than during them.

Description

This device is implanted over the sacral anterior root ganglia of the spinal cord; controlled by an external transmitter, it delivers intermittent stimulation which improves bladder emptying. It may also assists in defecation and may enable male patients to have a sustained full erection. The device is implanted in one of two regions, intra-thecally or extra-durally. It is often performed in conjunction with a dorsal rhizotomy, and many groups believe that the best results are only seen when this procedure is performed alongside the implantation. The rhizotomy will remove sensory reflexes, which in men may include sexual reflexes. For some patients this is a major handicap to the device. For others, the benefits outwiegh the downside.

The related procedure of sacral nerve stimulation is for the control of incontinence in otherwise able-bodied patients.