Involuntary detrusor contractions

In patients with conditions characterized by involuntary bladder contractions, oxybutynin increases vesical capacity, diminishes frequency of uninhibited contractions of the detrusor muscle, and delays initial desire to void. Oxybutynin thus decreases urgency and the frequency of incontinent episodes and voluntary urination. 

By the age of 4-5 years many children have been toilet-trained successfully and have adopted an adult pattern of urinary control. This is also characterized by the absence of involuntary or uninhibited detrusor contractions during bladder fiUing. Even if the bladder is full and there is a strong desire to void, no bladder contractions will occur. With micturition, coordinated relaxation of the external urethral sphincter takes place. Therefore, bladder emptying is under low intravesical pressure in children and adults. 

This chapter discusses drug s used to treat urinary tract infections (UTIs) and certain miscellaneous drag > used to relieve the symptoms associated with an overactive bladder (involuntary contractions of the detrusor or bladder muscle). Structures of the urinary system that may be affected include the bladder (cystitis), prostate gland (prostatitis), the kidney, or the urethra (see Pig. 47-1). These drug s also help control the discomfort associated with irritation of the lower urinary tract mucosa caused by infection, trauma, surgery, and endoscopic procedures. 

The miscellaneous drugp are used to relieve the symptoms associated with an overactive bladder (involuntary contractions of the detrusor or bladder muscle)... 

Neurobiological components of colorectal and anal sphincter mechanisms and pathophysiology are similar to the above-mentioned vesical components. In both systems, central, peripheral, and autonomic nervous system reflexes, partly involuntary and partly voluntary, interweave critically for appropriate function. Function and control are mediated through the lower spinal cord, as well as via cortical centers requiring coordinated voluntary (and reflex) relaxation of external sphincters, (reflex) relaxation of internal sphincters, and simultaneous coordinated contraction of detrusor... 

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