Micturition Disorders and Neurogenic Bladder

Micturition:

The process of voiding urine is called micturition. The urine is formed in the kidneys and collected into the urinary bladder. The urinary bladder is connected to kidneys through a pair of ureters. When a pressure of accumulated urine develops in the urinary bladder, we have a desire to urinate. An accumulation of 150 ml to 200 ml of urine activates the nerve endings in the muscular wall of the urinary bladder. The micturition is a reflex act controlled and inhibited by the higher centers in our brain. The act leads to the contraction of the muscular coat of the urinary bladder and relaxation of sphincter muscles. The urinary bladder is controlled by the pelvic nerves and the synaptic fibers from the hypogastric plexus. It may be voluntarily assisted by the contraction of abdominal muscles by increasing pressure in the abdominal cavity. The voluntary contraction of abdominal muscles exerts pressure on the visceral organs and in turn on the urinary bladder and helps in emptying of the bladder.

Neurogenic Bladder:

As stated above, the urinary bladder activity is controlled by the pelvic nerves and the sympathetic nerve fibers from the hypogastric plexus. A condition may arise due to a variety of causes leading to an interruption of the nerve messages between the brain and the urinary bladder. Due to lack of dynamic control over the muscles of the urinary bladder, the bladder fails to store or release the urine properly. Spinal cord injury due to some fatal accident, brain tumor, stroke, diseases such as multiple sclerosis or diabetes mellitus and congenital disorders could be the cause of neurogenic bladder.

There may be varied symptoms of neurogenic bladder depending on the lesion and the site of the injury and severity of injury. The patient may express inability to store the urine, excessive frequency of micturition and incontinence. All this is caused by overactive urinary bladder or a weak sphincter (outlet controlling muscles). On the other hand a weak urinary bladder or an over tight sphincter may lead to retention of urine and difficulty in urinating. Though the problem is associated with the urinary system but the cause is neurological and only a neurologist could help the patient in the right perspective. Renal function tests and ultrasound examination is must to evaluate the status of kidneys. A thorough evaluation is needed to ascertain the cause of neurogenic bladder disorder. Urodynamic testing with video x-rays and uroflometry should be carried out to evaluate the extent of emptying of the urinary bladder.