The Journal of Urology
Volume 162, Issue 3, Part 1, September 1999, Pages 936-942
Part 1 of 2
doi:10.1097/00005392-199909010-00094 | How to Cite or Link Using DOI
Copyright © 1999 American Urological Association, Inc. Published by Elsevier Inc.
Permissions & Reprints
Investigative Urology
“SKIN-CNS-BLADDER” REFLEX PATHWAY FOR MICTURITION AFTER SPINAL CORD INJURY AND ITS UNDERLYING MECHANISMS

Alert
This article is not included in your organization's subscription. However, you may be able to access this article under your organization's agreement with Elsevier.

CHUAN-GUO XIAOa, b, c, WILLIAM C. DE GROATa, b, c, CIRIL J. GODECa, b, c, CHENGPU DAIa, b, c and QIONG XIAOa, b, c

aFrom the Department of Urology, the Long Island College Hospital SUNY Health Science Center at Brooklyn, Brooklyn, New York, and the Department of Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania

b(C. G. Xiao) Requests for reprints: Department of Urology, Long Island College Hospital, Brooklyn NY 11203.

cSupported by grant R01 DK 44877-01 from the Department of Health and Human Services and a grant from the Spinal Cord Research Foundation, Paralyzed Veterans of America.
Accepted 12 April 1999.
Available online 4 November 2005.

Abstract
Purpose

A “skin-CNS-bladder” reflex pathway for inducing micturition after spinal cord injury has been established in cat. This reflex pathway which is basically a somatic reflex arc with a modified efferent limb that passes somatic motor impulses to the bladder, has been designed to allow spinal cord injured patients to initiate voiding by scratching the skin.
Materials and Methods

The skin-CNS-bladder reflex was established in the cat by intradural microanastomosis of the left L7 ventral root (VR) to the S1 VR while leaving the L7 dorsal root (DR) intact to conduct cutaneous afferent signals that can trigger the new micturition reflex arc. After allowing 11 weeks for axonal regeneration, urodynamic, pharmacological and electrophysiological studies were conducted in pentobarbital or chloralose anesthetized animals.
Results

A detrusor contraction was initiated at short latency by scratching the skin or by percutaneous electrical stimulation in the L7 dermatome. Maximal bladder pressures during this stimulation were similar to those activated by bladder distension in control animals. Electrophysiological recording revealed that single stimuli (0.3 to 3 mA, 0.02 to 0.2 msec duration) to the left L7 spinal nerve in which the efferent axons had degenerated evoked action potentials (0.5 to 1 mV) in the left S1 spinal nerve distal to the anastomosis. In addition, increases in bladder pressure were elicited by trains of the stimuli (5 to 20 Hz, 5 seconds) applied to the L7 spinal nerve. Urodynamic studies including external sphincter EMG recording demonstrated that the new reflex pathway could initiate voiding without detrusor-external urethral sphincter dyssynergia. Atropine (0.05 mg./kg., i.v.) or trimethaphan (5 mg./kg., i.v.), a ganglionic blocking agent, depressed the bladder contractions elicited by skin stimulation. The skin-CNS-bladder reflex could also be elicited after transecting the spinal cord at the L2-L3 or L7-S1 levels.
Conclusion

The cross-wired somato-autonomic bladder reflex is effective in initiating bladder contractions and coordinated voiding in cats with an intact neuraxis and can also induce bladder contractions after acute transection of the lumbar spinal cord. The new pathway is mediated by cholinergic transmission involving both nicotinic and muscarinic receptors. It is concluded that somatic motor axons can innervate bladder parasympathetic ganglion cells and thereby transfer somatic reflex activity to the bladder smooth muscle.
Article Outline

MATERIALS AND METHODS

RESULTS

DISCUSSION

References

Thumbnail image

Fig. 1. Illustration of skin-CNS-bladder reflex pathway in cat. Right side serves as control.