Overactive bladder (OAB) includes symptoms of urgency, frequency and urge incontinence.
Approximately 55% of individuals with OAB are women and 45% are men.
The prevalence of the condition increases with advancing age.
The prime effector of continence is the synergic relaxation of the bladder wall muscle (detrusor) and contraction of bladder neck and pelvic floor muscles.
The sympathetic nerve fibres originating from the T11 to L 2 segments of the spinal cord, which innervate smooth-muscle fibres around the bladder neck and proximal urethra, cause these fibres to contract, allowing the bladder to fill.
As the bladder fills, sensory stretch receptors in the bladder wall trigger a central nervous system (CNS) response.
The parasympathetic nervous system (PNS) causes contraction of the detrusor, while the muscles of the pelvic floor and external sphincter relax.
The PNS fibres, as well as those responsible for somatic (voluntary) control of micturition, originate from the sacral plexus from the S 2 to S 4 segment of the spinal cord.
The somatic fibers innervate the external sphincter and are responsible for the voluntary control of continence in the face of a pressing desire to void.
Causes & Risk Factors:
1. Idiopathic : The majority of cases are classified as without a demonstrable cause.
2.Neurological injuries, such as spinal cord injury or CVA.
3.Neurological diseases ,such as multiple sclerosis, dementia, Parkinson''s disease, medullary lesions.
4.Non-neurogenic causes :such as UTI, Ca bladder , bladder calculi, bladder inflammation, or bladder outlet obstruction(BOO).
5. Drug therapy : Diuretics can lead to symptoms of urge incontinence as result of increasing filling of the bladder, stimulating the detrusor.
Drugs used to treat urinary retention can also lead to increased contractions of detrusor leading to OAB.
. Sudden and urgent need to urinate
. Involuntary loss of urine
. Frequent urination, in the daytime and at night.
Types Of Urinary Incontinence:
Urge Incontinence involves a strong, sudden need to urinate, immediately followed by a bladder contraction, resulting in an involuntary loss of urine.
Stress incontinence is characterised by an involuntary loss of urine when the intra-abdominal pressure is suddenly increased, for example, during coughing, sneezing and laughing or during physical activity.
Overflow incontinence is the involuntary loss of urine associated with an overdistended bladder. It occurs when bladder filling exceeds the bladder functional capacity.
Functional incontinence occurs in patients who would otherwise be continent but for whom physical and/or cognitive impairments interfere with the ability to reach a toilet in time.
Mixed incontinence involves a combination of different type of incontinence, typically stress and urge incontinence occurring simultaneously.
There are three main approaches to treatment: pharmacotherapy, bladder retraining, and surgery.
Since acetylcholine is the neurotransmitter that mediates detrusor contractions, medication with anticholinergics is used to inhibit the premature detrusor muscle contraction.
Consequently, the most frequently used drugs to treat this condition aim to reduce the involuntary contraction of the detrusor muscles by blocking the muscarinic receptors.
This was among the first anticholinergic agents to be used to treat detrusor overactivity and its efficacy in treating OAB is well documented. However, the effects of oxybutynin are not tissue specific and studies have shown that oxybutynin has a greater inhibitory effect on salivation than bladder contraction.
Tolterodine is the first major drug to address the problems of tolerability of treatment. Unlike oxybutynin, tolterodine has a greater inhibitory effect on bladder contraction than salivation. Therefore it has fewer side effects such as dryness of mouth, but with comparable efficacy.
Tricyclic antidepressants like imipramine or doxepin have also been used to treat OAB.
It is an extract from mexican red peppers and has been investigated for intravesical administration in OAB .
Management of urge incontinence usually begins with a program of bladder retraining. Occasionally, electrical stimulation and biofeedback therapy may be used in conjunction with bladder retraining.
A program of bladder retraining involves becoming aware of patterns of incontinence episodes and relearning skills necessary for storage and proper emptying of the bladder. Bladder retraining alone is successful in 75% of people treated for urge incontinence
Pelvic Floor Exercises
Pelvic floor exercises, also known as pelvic muscle training exercises or Kegel exercises are primarily used to treat people with stress incontinence. However, these exercises may also be beneficial in relieving the symptoms of urge incontinence.
Surgery is rarely used to treat OAB . It is reserved for patients who are severely debilitated by their incontinence and who have an unstable bladder (severe inappropriate contraction) and poor ability to store urine.
The goal of any surgery to treat urge incontinence is aimed at increasing the storage ability of the bladder while decreasing the pressure within the bladder.
Augmentation cystoplasty is the most frequently performed surgical procedure for severe urge incontinence.
In this reconstructive surgery a segment of the bowel is removed and used to replace a portion of the bladder.
This technique is under development.
It requires the surgical implantation of a small device at the base of the spinal cord. It electrically or magnetically stimulates the sacral nerves that inhibit detrusor muscle contraction.
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