Urinary apparatus including kidneys, ureters, bladder, and urethra is a complex organ system that requires a detailed description to understand its functioning. Following is an overview:

Blood is filtered in kidneys and waste products are excreted in urine, which travel down through two tubes called ureters to the bladder. The bladder acts as a storage tank until it gets emptied. When empty, the bladder is like a deflated sac. As urine collects in the bladder it gets larger. When it is full, it sends a signal to the brain so that the person may empty it. In healthy young adults this may happen once bladder has about 250-500 cc of urine, depending gender and size of the person. If for whatever reason the person does not want to empty the bladder, another signal from brain is sent to the bladder making it lax, and the urge to urinate disappears. After some more time and after the bladder has more urine, another cycle of signaling starts with a stronger urge to urinate. If the person still wants to delay urinating, brain may send another signal to the bladder, and it relaxes further. This continues until the person decides to urinate, or the bladder cannot relax any further and one has to urinate.

The process of urination is a sophisticated act or a reflex of which only a small part is in our control. Bladder is mostly made up of muscle tissue with its lower end shaped like a funnel. Around this funnel is another special muscle (internal sphincter) that keeps the funnel closed, like a clothe-pin, until urination. The bladder muscle and this particular muscle around the funnel are not in our voluntary control. Attached to this funnel is a tube called urethra that takes the urine out. There is another set of muscle around the urethra (external sphincter), which is in our control. Both the internal and the external sphincters have to relax before urine can come out. Usually the process of urination starts with a message from the brain when we decide to urinate and assume an appropriate posture. Abdominal muscles around the bladder contract to put pressure on the bladder, while muscles in the pelvis relax. The bladder muscle starts to contract and the internal sphincter relaxes. Urine comes down the funnel in the urethra and at that point we relax the external sphincter around the urethra. Other than making the conscious decision to start the process of urination, this act of relaxing the external sphincter is also in our control. Rest is a reflex; once urination starts it is not easy to stop it until bladder is almost emptied. A problem with any of these structures may result in problem with urination, and the type of problem depends upon the structure affected. Following are some common examples, and in this list problem with the kidneys and ureters are not discussed, as they are generally not involved in neurological diseases:

A: Problem with bladder: Once inflated, the bladder muscle has the tendency to contract, which usually is suppressed or inhibited by signals from the brain. If there is any disruption of these inhibitory signals from damage to certain areas of brain or the spinal cord, bladder starts to contract prematurely. A normal person may not have any urge to urinate until there is about 150-300cc of urine in the bladder. An out of control bladder may start creating an urge with much smaller volume. Patient may get frequent urges to urinate but the amount urinated is relatively small. This type of bladder is sometimes called spastic bladder or hyperactive bladder. Like any other muscle, and like a vicious cycle, staying hyperactive may lead to further build up of bladder muscle mass, which may result in decrease in its internal capacity to carry urine, and thus over time making the situation worse. Typical symptom of hyperactive bladder problem is frequency of urination with smaller than normal volume urinated. It is usually treated with a medicine to relax the bladder msucle.

The opposite of hyperactive bladder is a bladder that is too relaxed, or atonic bladder. In this condition the bladder is usually large and has lost its muscle tone. This may happen after years of staying in a hyperactive form. This bladder cannot empty itself and for urination, one has to put a catheter inside the bladder on regular basis.

1. Problem with Internal Sphincter: This is a clamp or a clothe-pin like muscular structure around the lower or the funnel part of the bladder ending in urethra. It keeps the bladder closed until it is ready to be emptied, and bladder cannot be emptied if it stays abnormally constricted or tight. In normal situations, bladder muscle and this muscle work together in a synchronized manner. First the bladder contracts pushing urine down in the funnel, and then this muscle relax. Both of these actions are part of a reflex not in our control. In abnormal situations, bladder may contract but this muscle may not relax or relax well and the patient may not be able to urinate, or urinate well enough. Patient may get an urge to urinate but may have difficulty urinating. This may happen due to loss of higher control on these structures from damage to the spinal cord or the brain. It is not an easy condition to treat but fortunately is relatively less common. It may also be important to know that this structure, the internal sphincter, and the external sphincter may be damaged in women during difficult vaginal labor, in which case it may not be able to hold itself tight and the patient may complain of frequent urination or stress incontinence or frequent urine leaks.

C: Problem with External Sphincter: External sphincter is a muscular structure around the urethra with the type of muscle that is in our voluntary control. By holding it tight, we can hold urine for a while even if the bladder is full and trying to empty itself. To urinate, we voluntarily relax this structure. If for some reason it is not relaxed, urination is restricted. Common reasons where there is difficulty relaxing this structure include infection, inflammation, interruption of signal from brain or the spinal cord, or sometimes from psychological reasons, such as extreme anxiety or fear. Treatment depends upon the cause.

Why women have frequent urinary infection (UTI)?

Women are particularly at risk for frequent infection in urinary system, the so-called urinary tract infection or UTI. Reasons include a relatively small length of urethra, about 4cm compared to about 10cm in men, and its opening in a wet place. Other added issues may be obesity, damage to pelvic muscles or the urethra during childbirth, or the sexual activity. Depending upon these factors, all women are at higher risk for UTI. Proper genital hygiene may be the best approach for its prevention. Use water to clean instead of wipes, urinate and wash right after sexual activity, avoid tampons and use pads, avoid keeping a wet pad on for too long, thoroughly wash and/or shower after menstrual discharge is over, use probiotics or a serving of natural yogurt daily, avoid constipation, exercise regularly, and avoid obesity. Exercising pelvic muscles and the external sphincter helps, both men and women. This is done by the so-called Kegel exercises

What are the different neurological conditions affecting urination?

Variety of neurological conditions may affect urination. Following is an overview:

 

Conditions of the brain:

Basic fault: Loss of inhibition to control urination

Common conditions: Parkinson disease and many other Parkinsonian disorders, Multiple Sclerosis, Stroke, tumor, trauma, or any condition that may affect frontal part of brain.

Conditions of the Spinal Cord:

Basic fault: Loss of inhibitory control of brain due to damaged pathways, and loss of urinary reflex.

Common conditions: Multiple Sclerosis, trauma, tumor, spinal stenosis, or any condition that may damage the spinal cord.

Conditions of the Nerves:

Basic fault: loss of signal transmission due to nerve injury, the reason can be anywhere from the origin of the nerves in the spinal cord to until the nerves reach the bladder.

Common conditions: Diabetes mellitus and many other types of neuropathy, low back injury or disc disease, or any other pathology affecting nerve roots

Conditions of muscles:

            Basic fault: Loss of muscle tone and strength

Common conditions: Usually due to loss of nerve dysfunction, leading to either hyperactive muscle or a weak muscle. For example, spastic bladder is a common condition resulting from neurological causes, resulting in hyperactive bladder muscle. There are very few purely muscle disorder directly impacting bladder function. 

How do we diagnose the specific reason for a patient’s urinary problem?

It starts with a thorough history, examination, and sometimes testing. Many urinary conditions can be easily diagnosed by taking good history and examination. Following tests are available to figure out particular area involved (not everyone needs these tests): 

A: For UTI and some other urinary issues: Urine analysis

B: For brain conditions: An MRI or a CT scan of brain.

C: For spinal cord pathology: Mostly MRI, and rarely CT or CT with myelogram.

D: For nerve root pathology: EMG/Nerve conduction studies, and MRI.

E: For neuropathy: EMG/Nerve conduction studies, and rarely nerve biopsy.

F: For bladder and sphincter muscle dysfunction: Post-void residual, Ultrasound, Urodynamic study, and EMG/Nerve conduction studies.

 

What treatment options are available for urinary problems?

Treatment depends upon the cause. Following are common conditions and the available treatment options:

1. UTI: Usually an antibiotic. Patients with chronic UTI may need further evaluation to find its cause.
2. Spastic or an overactive bladder:
3. Anti-muscarinic agents. Many such medicines are available to help relax bladder muscle. The list of medicines include oxybutynin (Ditropan), tolterodine (Detrol), darifenacin (Enablex), fesoterodine (Toviaz), propiverine (not available in USA), solifenacin (Vesicare), and trospium chloride (Sanctura). Common side effects of these meds include dry mouth, dizziness, forgetfulness, constipation, blurred vision, and tachycardia. Some of them, darifenacin and trospium, have less negative effect on memory and mind.
4. B3-receptor agonist: Mirabegron (Myrbetriq) can also help with this condition. Side effects include tachycardia, high blood pressure, and rarely atrial fibrillation. It is a useful agent for patients with MS or spinal cord injury.
5. Desmopressin, by reducing urine production. It can be used to treat night- time frequent urination. Side effects include low sodium and fluid retention.
6. Botox: Small doses of Botox in the bladder muscle can also help relaxing the muscle, and with symptoms. Side effects include too much relaxation that may require catheterization.
7. Tibial Neuromodulation: If medical therapy fails, a procedure can be done to install an electrical signal generator that can help to manage overactive bladder. Technically, it can help avoid side effects of meds, or sometimes the need for self-catheterization.
8. Atonic or flaccid bladder: There is no medicine available to strengthen bladder muscle. Treatment of this condition is either manual catheterization, or a permanent catheter placement.

 

Where can I find more information about bladder issues?

American Academy of Neurology

American Urological Association