ABNORMALITIES OF MICTURITION ATONIC BLADDER

ABNORMALITIES OF MICTURITION ATONIC BLADDER – EFFECT OF

DESTRUCTION OF SENSORY NERVE FIBERS

Atonic bladder is the urinary bladder with loss of tone in detrusor muscle. It is also called flaccid neurogenic bladder or hypoactive neurogenic bladder. It is caused by destruction of sensory (pelvic) nerve fibers of urinary bladder. Due to the destruction of sensory nerve fibers, the bladder is filled without any stretch signals to spinal cord. Due to the absence of stretch signals, detrusor muscle loses the tone and becomes flaccid. So the bladder is completely filled with urine without any micturition. Now, urine overflows in drops as and when it enters the bladder. It is called overflow incontinence or

overflow dribbling.

Conditions of Destruction of Sensory Nerve Fibers

1. Spinal injury: During the first stage (stage of spinal shock) after injury to sacral segments of spinal cord

(Chapter 143) the bladder becomes atonic

2. Syphilis: Syphilis results in the degenerative nervous disorder called tabes dorsalis, which is characterized by the degeneration of dorsal (sensory) nerve roots. Degeneration of sensory nerve roots

of sacral region develops atonic bladder. The atonic bladder in tabes dorsalis is called tabetic bladder.

AUTOMATIC BLADDER

Automatic bladder is the urinary bladder characterized by hyperactive micturition reflex with loss of voluntary control. So, even a small amount of urine collected in the bladder elicits the micturition reflex resulting in emptying of bladder. This occurs during the second stage (stage of recovery) after complete transection of spinal cord above the sacral segments. During the first stage (stage of spinal shock) after

complete transection of spinal cord above sacral segments, the urinary bladder loses the tone and

becomes atonic resulting in overflow incontinence. During the second stage after shock period, the

micturition reflex returns. However, the voluntary control is lacking because of absence of inhibition or facilitation of micturition by higher centers. There is hypertrophy of detrusor muscles so that the capacity of bladder reduces. Some patients develop hyperactive micturition reflex.

UNINHIBITED NEUROGENIC BLADDER

Uninhibited neurogenic bladder is the urinary bladder with frequent and uncontrollable micturition caused  by lesion in midbrain. It is also called spastic neurogenic bladder or hyperactive neurogenic bladder.

The lesion in midbrain causes continuous excitation of spinal micturition centers resulting in frequent and

uncontrollable micturition. Even a small quantity of urine collected in bladder will elicit the micturition reflex.

NOCTURNAL MICTURITION

Nocturnal micturition is the involuntary voiding of urine during night. It is otherwise known as enuresis or bedwetting. It occurs due to the absence of voluntary control of micturition. It is a common and normal process in infants and children below 3 years. It is because of incomplete myelination of motor nerve fibers of the bladder. When myelination is complete, voluntary control of micturition develops and bedwetting stops. If nocturnal micturition occurs after 3 years of age it is considered abnormal. It occurs due to neurological disorders like lumbosacral vertebral defects. It can also occur due to psychological factors. Loss of voluntary control of micturition occurs even during the impairment of motor area of cerebral cortex.

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