The spinal cord extends from the brainstem down to the lumbosacral spine. It is located in the spinal canal and is protected by the cerebrospinal fluid, meninges, and a vertebral column. It is approximately 14 inches long in an adult. Along its course, the spinal cord sprouts off many nerve branches to different parts of the body.
The spinal cord functions as a long communication pathway between the brainstem and the sacral spinal cord. When the sacral cord receives the sensory information from the bladder, this signal travels up the spinal cord to the pons and then ultimately to the brain. The brain interprets this signal and sends a reply via the pons that travels down the spinal cord to the sacral cord and, subsequently, to the bladder. If spinal cord injury has occurred, the patient will demonstrate symptoms of urinary frequency, urgency, and urge incontinence but will be unable to empty his or her bladder completely.
The sacral spinal cord is the terminal portion of the spinal cord situated at the lower back in the lumbar area. This is a specialized area of the spinal cord known as the sacral reflex center. It is responsible for bladder contractions. The sacral reflex center is the primitive voiding center.
Peripheral nerves form an intricate network of pathways for sending and receiving information throughout the body. The nerves originate from the main trunk of the spinal cord and branch out in different directions to cover the entire body. Nerves convert the internal and external environmental stimuli to electrical signals so that the human body can understand stimuli as one of the ordinary senses (ie, hearing, sight, smell, touch, taste, equilibrium). The bladder and the urethral sphincters are under the influence of their corresponding nerves.
The ANS lies outside of the central nervous system. It regulates the actions of the internal organs (eg, intestines, heart, bladder) under involuntary control. The ANS is divided into the sympathetic and the parasympathetic nervous system.
Under normal conditions, the bladder and the internal urethral sphincter primarily are under sympathetic nervous system control. When the sympathetic nervous system is active, it causes the bladder to increase its capacity without increasing detrusor resting pressure (accommodation) and stimulates the internal urinary sphincter to remain tightly closed. The sympathetic activity also inhibits parasympathetic stimulation. When the sympathetic nervous system is active, urinary accommodation occurs and the micturition reflex is inhibited.
The parasympathetic nervous system functions in a manner opposite to that of the sympathetic nervous system. In terms of urinary function, the parasympathetic nerves stimulate the detrusor to contract. Immediately preceding parasympathetic stimulation, the sympathetic influence on the internal urethral sphincter becomes suppressed so that the internal sphincter relaxes and opens. In addition, the activity of the pudendal nerve is inhibited to cause the external sphincter to open. The result is facilitation of voluntary urination.
If a problem occurs within the nervous system, the entire voiding cycle is affected. Any part of the nervous system may be affected, including the brain, pons, spinal cord, sacral cord, and peripheral nerves. A dysfunctional voiding condition results in different symptoms, ranging from acute urinary retention to an overactive bladder or to a combination of both.
This is the really interesting part and what I need to try and remember to ask my neurosurgeon - ie is my neurogenic bladder issues worsened bc the nerves 'reset' themselves since whatever nerve signal injury occured and now these symptoms appear to be so much worse and testing verified these symptoms???? It also talks about children with myelomeningocele and one of my questions for tues for my neurosurgeon before tues and of which I asked the neurogenic bladder urologist was if my pseudomeningocele on my lumbar shunt/spine surgery incision could be affecting my bladder issues... ???Interesting???
Diseases or injuries of the spinal cord between the pons and the sacral spinal cord also result in spastic bladder or overactive bladder. People who are paraplegic or quadriplegic have lower extremity spasticity. Initially, after spinal cord trauma, the individual enters a spinal shock phase where the nervous system shuts down. After 6-12 weeks, the nervous system reactivates. When the nervous system becomes reactivated, it causes hyperstimulation of the affected organs. For example, the legs become spastic.
These people experience urge incontinence. The bladder empties too quickly and too frequently. The voiding disorder is similar to that of the brain lesion except that the external sphincter may have paradoxical contractions as well. If both the bladder and external sphincter become spastic at the same time, the affected individual will sense an overwhelming desire to urinate but only a small amount of urine may dribble out. The medical term for this is detrusor-sphincter dyssynergia because the bladder and the external sphincter are not in synergy. Even though the bladder is trying to force out urine, the external sphincter is tightening to prevent urine from leaving.
The causes of spinal cord injuries include motor vehicle and diving accidents. Multiple sclerosis (MS) is a common cause of spinal cord disease in young women. Those with MS also may exhibit visual disturbances, known as optic neuritis. Children born with myelomeningocele may have spastic bladders and/or an open urethra. Conversely, some children with myelomeningocele may have a hypocontractile bladder instead of a spastic bladder.
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