A sacral anterior root stimulator is an implantable

medical device A medical device is any device intended to be used for medical purposes. Significant potential for hazards are inherent when using a device for medical purposes and thus medical devices must be proved safe and effective with reasonable assura ...

enabling patients with a spinal cord lesion to empty their

bladder The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine enters ...

History

From 1969 onwards Giles Brindley developed the sacral anterior root stimulator, with successful

human trials This page is a list of the episodes of '' The Outer Limits'', a 1995 science fiction/dark fantasy television series. The series was broadcast on Showtime from 1995 to 2000, and on the Sci Fi Channel in its final year (2001–2002). Series overvi ...

from the early 1980s onwards. Although both sphincter and detrusor muscles are stimulated at the same time, the slower contraction kinetics of the bladder wall ( smooth muscle tissue) compared to the sphincter (

striated muscle tissue Striations means a series of ridges, furrows or linear marks, and is used in several ways: * Glacial striation * Striation (fatigue), in material * Striation (geology), a ''striation'' as a result of a geological fault * Striation Valley, in Anta ...

) mean that voiding occurs between the stimulation pulses, rather than during them.

Description

This device is implanted over the sacral anterior root of the

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spi ...

; controlled by an external transmitter, it delivers intermittent stimulation which improves the ability to empty the bladder. It may also assist in

defecation Defecation (or defaecation) follows digestion, and is a necessary process by which organisms eliminate a solid, semisolid, or liquid waste material known as feces from the digestive tract via the anus. The act has a variety of names ranging f ...

and also may enable male patients to have a sustained full

erection An erection (clinically: penile erection or penile tumescence) is a physiological phenomenon in which the penis becomes firm, engorged, and enlarged. Penile erection is the result of a complex interaction of psychological, neural, vascular, ...

. The device is implanted in one of two regions, either through intrathecal administration or extradurally. 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 drawback to the device. For others, the benefits outweigh the downside. The related procedure of

sacral nerve stimulation Sacral nerve stimulation, also termed sacral neuromodulation, is a type of medical electrical stimulation therapy. It typically involves the implantation of a programmable stimulator subcutaneously, which delivers low amplitude electrical sti ...

is to control incontinence in otherwise able-bodied patients.Schmidt RA, Jonas A, Oleson KA, Janknegt RA, Hassouna MM, Siegel SW, van Kerrebroeck PE. Sacral nerve stimulation for treatment of refractory urinary urge incontinence. Sacral nerve study group. J Urol 1999 Aug;16(2):352-357.

References

Implants (medicine) Neuroprosthetics {{neuroscience-stub