8.2: Aetiology

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There are essentially only 3 reasons that an individual will experience difficulty with voiding:

Inefficient or absent detrusor contractility. Impaired detrusor contractility (IDC) and detrusor areflexia (DA).
Obstruction to urinary flow often called bladder outlet obstruction in males. (BOO)
Lack of co-ordination between detrusor contraction and relaxation of the urethral sphincter, known as detrusorsphincter dyssynergia (DSD).

It would seem quite simple to now present a trainee in gynaecology, urology or uro-gynaecology with a set of tables giving the causes of the three different types of dysfunction. The problem however is that neurological pathology can often be a cause of these dysfunctions and various neurological conditions can cause overactive bladder symptoms, impaired detrusor contractility and incontinence. A good starting point therefore is to list the various neurological factors which can affect the lower urinary tract (Table I).

Table \(\PageIndex{1}\): Neurological Disorders Affecting Voiding

Cerebrovascular accidents

Brain tumours

Cerebral Palsy

Parkinsons disease

Shy-Drager Syndrome

Multiple sclerosis

Spinal cord injuries – suprasacral and sacral

Infectious conditions (tabes dorsalis, poliomyelitis, transverse myelitis, herpes zoster)

Skeletal abnormalities of the spine (disc problems, ankylosing spondylitis)

Peripheral nerve damage (radical surgery, diabetes mellitus)

Neurological disorders often overwhelm the average clinician, who probably slept through neurology lectures at university. These are just a few important things to remember.

Most conditions of the central nervous system can produce the full range of bladder symptoms, varying sometimes from one stage of the disease to another.

Sacral spinal injuries, lumbar-sacral nerve route compression and peripheral nerve damage usually cause DA.

Important causes of DSD are spinal cord injuries and multiple sclerosis. These conditions can cause high pressures within the bladder of above 40cmH20 without the urethral sphincter opening. This causes severe back pressure and upper urinary tract damage. Fortunately most neurological conditions causing bladder pathology will be perfectly obvious. It is however important in the patient with atypical or mixed urinary symptoms to be on the lookout for more subtle neurological changes before instituting treatment, especially surgical treatment.

Table \(\PageIndex{2}\): Other Causes Of Voiding Dysfunction

Obstructive	Urethral stenosis Urethral sphincter hypertrophy Pelvic masses Uterine prolapse Anterior vaginal wall prolapse Foreign bodies Post surgical, especially surgery for urinary stress incontinence
Inflammatory	Severe vulvo vaginitis (genital herpes, severe vulvo-vaginal candidiasis) Urethritis and cystitis
Pharmacological	General anaesthesia Regional anaesthesia Analgesics (Morphine) Anti depressants Anti cholinergics
Detrusor Muscle Abnormalities	Detrusor myopathy Over distention
Psychogenic
Post Partum Voiding Difficulty
Idiopathic
Surgical	Will be discussed later in this chapter