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DEPARTMENTS: EDITORIAL

Neurourologic and Structural Determinants of Incontinence

A Major Pressure Ulcer Risk Factor

Salcido, Richard "Sal" MD

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Advances in Skin & Wound Care: March 2011 - Volume 24 - Issue 3 - p 106
doi: 10.1097/01.ASW.0000395040.74139.cc
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In this issue, our continuing medical education activity addressed the topic of "Incontinence and Incontinence-Associated Dermatitis." To further expand on this important topic, I'd like to discuss some of the neurourologic and structural causes of incontinence and its potential to impede wound healing and cause pressure ulcers.

The urologic system is a fascinating and complex structure that serves to filter the vascular system by eliminating metabolic waste, maintaining homeostasis, and reclaiming fluid volume and electrolytes. The urinary bladder, vesicle, or detrusor (a muscle that pushes down) has a urine storage capacity of about 500 milliliters. During neurological development, control over micturition develops caudally as the spinal cord is fully myelinized at about age 3 years, thus facilitating local control over storage and micturition. Subsequent development of higher cortical control over bladder function and the maintenance of urinary continence (UC) are established. Rostrally, several neurourologic servo-regulators maintain UC. They are cortical (control); the pontine micturition center (PMC) (brain-stem coordination) is responsible for synergy (detrusor contractions and urogenital diaphragmatic and sphincter relaxation to expel urine). Caudally, there are spinal and sacral micturition controls and sensory-motor afferent and efferent neuromuscular influences over the detrusor sphincters and the urogenital diaphragm.

The influence of urinary incontinence on the development of pressure ulcers and the impediment to wound healing can be described by listing the impairments to this complex system-from caudal to rostral anatomical taxonomies. In the aging process and in diabetes, neurotransmission essential to the maintenance of balanced integrated system of continence and micturition is reduced. In parallel, there is a corresponding loss of neurochemical receptors at the level of the detrusor, further negatively affecting bladder function. At the cortical level, dementia, Alzheimer disease, strokes, and demyelinating diseases, such as multiple sclerosis, Binswanger disease (subcortical periventricular white matter stroke and disease), and normal pressure hydrocephalus, are all factors that can affect bladder function. The PMC can be disturbed by strokes, demyelinating disease, high-level tetraplegia, and any structural impingement on the spinal canal by trauma, tumor, or bacterial or viral infection, such as myelitis. Spinal cord impingement at the level of the spinosacral micturition center can be caused by spinal cord damage and metastasis from oncological disease related to urinary function, such as prostate cancer.

Bladder management programs are primarily aimed at classification and subsequent safe and effective pharmacophysical amelioration of the specific disease entities and their influences on pressure ulcers and other wounds. The key goal is to reduce incontinence and prevent the breakdown and maceration to the wound and the periwound adjacent tissues. Pharmacological management is a common strategy that addresses the specific neurochemical target. The detrusor and the internal and external sphincters are rich in various receptors, including cholinergic, nicotinic, β, and α. Each of the medications used has a specific target for relaxing, contracting, and assisting in maintaining continence or reversing retention by acting on various receptors. For example, detrusor hyperreflexia with impaired contractility (DHIC), a phrase coined by the Japanese, describes a bladder that is hyperactive,with low volumes and with numerous contractions and incontinence. DHIC can be treated by reducing the contractions, increasing the capacity, and decreasing the number of incontinent events. In patients with diabetes and other diseases of afferent and efferent control, the bladder will be large with potentially huge volumes because of the lack of detrusor strength and atonic contractions. In this case, bladder contractions may need to be strengthened to reduce overflow incontinence and maintain a dry environment for the patient.

Although the classification and treatment of these entities are complex, diagnostic urodynamics and bladder scans, coupled with an appropriate urologic and pharmacological consultation, have improved our ability to diagnose and treat the patients who need wound protection from the negative effects of incontinence.

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Richard "Sal" Salcido, MD

Selected Reference

Salcido R, Fisher S, Schleenbaker R, Holmes G. Diagnostic effectiveness of bladder ultrasound in a large population of stroke patients. Arch Phys Med Rehabil 1991;72:787.
© 2011 Lippincott Williams & Wilkins, Inc.