Bladder dysfunction in people with MS is a sign of early damage, particularly to the spinal cord, and an early indication of a poor prognosis. Why do people with MS who develop bladder dysfunction do worse than those with no bladder symptoms? Here, I explain why I take bladder problems seriously and their implications for MS management.

Key points

• Urinary hesitancy, urgency, frequency and incontinence, including at night, are bladder problems that affect many people with MS and cause significant frustration and anxiety.
• A range of drug-based treatments, behavioural techniques and specialist physical interventions can help people with MS to manage bladder dysfunction and achieve adequate control.
• However, the bladder pathways will probably continue to be affected in the long term due to the development of new lesions or the expansion of old lesions.
• Frequent and severe urinary tract infections (UTIs) increase the likelihood that MS will progress.
• I recommend regular dipstick testing at home, as part of your MS self-management, to increase the chances of early detection and treatment of a UTI.
• Lifestyle approaches, such as avoiding smoking and reducing alcohol and caffeine consumption, should help to reduce bladder symptoms. Pelvic floor exercises are also important.
• Dehydration is not a good way to control your bladder symptoms. Chronic dehydration can have a significant impact on your overall health and well-being and can exacerbate many of your MS symptoms.

Causes and significance of bladder dysfunction

Bladder dysfunction is the most common symptomatic problem I encounter in an MS clinic, affecting more than 50% of people with MS. It is one of the signs of early damage, particularly spinal cord damage, and an early indication of a poor prognosis. It therefore has important implications for treatment: if you have early bladder symptoms, you may want to take a more effective therapy early on rather than starting on a less effective DMT and waiting to see how you respond. It is best to maximise your chances of responding to treatment by opting for a highly efficacious therapy first-line. I call this ‘flipping the pyramid’.

Infections, both viral and bacterial, are a known trigger of relapse in MS. Frequent and severe urinary tract infections (UTIs) increase the likelihood that your MS will progress. This is why it is important to improve the management of bladder problems in people with MS to prevent or reduce UTIs. You can read more about managing  UTIs here.

Why do people with MS who develop bladder dysfunction do worse than those with no bladder symptoms? The bladder is a complicated organ with several neurological components that need to be coordinated. The descending nerve fibres that travel from the brain to the lower segments of the spinal cord are very long and have the greatest chance of being damaged by MS lesions in their path down to the bladder centre in the sacral area of the lower spinal cord. Therefore, any progressive or worsening MS damage is likely to manifest with bladder dysfunction early on.

The detrusor (or balloon) muscles and the sphincter (or valve) need to coordinate their action to enable normal bladder function. When the bladder is filling, the detrusor muscle relaxes to allow the bladder to expand and the sphincter contracts to keep the urine in the bladder. The opposite occurs when you pass urine; the sphincter opens and the detrusor contracts to empty the bladder.

Common MS-related bladder problems

Hesitancy

Urinary hesitancy occurs when the function of the detrusor and sphincter muscles is not coordinated: you try to pass urine, but the bladder sphincter won’t open. Hesitancy may be intermittent; if you try again later, the bladder will open, allowing you to pass urine. Conversely, the sphincter may close as you pass urine, which breaks up the urine stream or prevents complete bladder emptying; this can cause dribbling. The medical term for incoordination of the bladder muscles is dyssynergia or, more correctly, detrusor-sphincter-dyssynergia (DSD). People with MS find urinary hesitancy and its unpredictability very frustrating.

The drug treatment for DSD includes alpha-blockers (prazosin, indoramin, tamsulosin, alfuzosin, doxazosin and terazosin). Other strategies include small bladder stimulators or vibrators that are placed over the pubic area and work by blocking signals that inhibit the sphincters. The vibrators work in some people with MS and may help relax the sphincter.

Trying to relax when passing urine can help to improve hesitancy. The sound of running water, for example from a tap, may trigger the relaxation of the sphincter. Simulating this in public toilets may not be possible. Some people with MS find pressing on the lower abdomen helps. If all else fails, intermittent self-catheterisation (ISC) may be the only option to manage urinary hesitancy (see below).

Frequency and urgency

In MS the commonest bladder problem is spasticity, or irritability, of the detrusor muscle. The detrusor can’t relax, which prevents the bladder from filling to its maximum capacity. Frequent spasms of the detrusor muscle tell the brain that the bladder is full and you need to pass urine. This causes frequency, i.e. the need to use the toilet many times during the day and night. Frequency often accompanies the symptom of urgency, the need to get to the toilet as quickly as possible to prevent incontinence. 

When urgency is a problem, distraction techniques such as breathing exercises and mental tricks (e.g. counting) may be helpful. If urinary frequency is your main problem, you might try to retrain your bladder by holding on for as long as you can each time before passing urine. The aim is to train the detrusor muscle to expand more to hold on for longer when you need the toilet. These behavioural techniques rarely work for long; MS is a relapsing and/or progressive disease, and the bladder pathways will likely continue to be affected due to the development of new lesions or the expansion of old lesions.

Incontinence

Incontinence occurs when you lose the ability to suppress or ignore the signals from the detrusor muscle with the result that the sphincter relaxes or opens as part of a spinal cord reflex. We typically treat this problem with anticholinergic drugs, e.g. oxybutynin, solifenacin or tolterodine. The older generation anticholinergics such as oxybutynin cross the blood ̶ brain barrier and enter the brain, where they can exacerbate cognitive problems in people with MS. The commonest side effect of anticholinergics is dryness of the mouth; they can also worsen constipation. People with MS must be warned about the risk that anticholinergics will relax the bladder too much and precipitate urinary retention; the solution to urinary retention is ISC. 

The good news is that we now have a relatively new muscle relaxant, mirabegron (Betmiga), which activates the β3 adrenergic receptor in the detrusor muscle. I am increasingly using mirabegron to avoid the side effects (particularly cognitive issues) associated with anticholinergics. The main side effect of mirabegron is that it tends to increase your blood pressure.

Nocturia

Nocturia means you need to get up frequently at night to pass urine. If nocturia is your main bladder problem, using agents to concentrate the urine at night might help. A hormone called DDAVP works on the kidneys to reduce urine production; it is available as a nasal spray or tablets (Desmotabs or Desmospray). DDAVP should only be taken once a day, to avoid continuous water retention by the kidneys; this presents as swelling of the feet and reduces the salt or sodium levels in your blood, which can be dangerous. You therefore need to have your sodium levels checked about 4 ̶ 6 weeks after starting DDAVP therapy. 

Second-line treatments for bladder problems

If you fail to respond to anticholinergics, mirabegron and/or behavioural techniques, you need a bladder scan to see if you have a raised residual volume (the amount of urine left after you have emptied your bladder). If the residual volume is greater than 80 ̶ 100mL you may need to consider intermittent self-catheterisation (ISC). Some continence advisors act at the 80 mL threshold, and others at the 100 mL threshold, when recommending ISC.

Intermittent self-catheterisation

ISC serves two purposes. It increases your functional residual bladder volume, allowing more storage space for urine, which reduces frequency and urgency. This can help if you need to travel some distance or to join in a social activity without having to pass urine. It also helps to reduce nocturia, which in turn improves sleep and possibly MS-related daytime fatigue.

ISC also removes urine from the bladder. The residual urine acts as a culture medium for bacteria; by clearing your bladder you can prevent bladder infections. Conversely, if you don’t do the ISC technique correctly you can introduce bacteria into the bladder that then cause infections.

Botox

Botox injection into the detrusor muscle is increasingly used as a treatment for bladder dysfunction, in conjunction with ISC. Botox paralyses the muscle, turning it into a flaccid bag for urine storage. The surgical techniques that were previously used to remove the nerve supply to the bladder (which had the same effect as Botox) are now rarely used.

Percutaneous tibial nerve stimulation 

Percutaneous (or posterior) tibial nerve stimulation is a form of neuromodulation that can help with impaired bladder function and may improve urinary urgency, urinary frequency and urge incontinence. It is offered as a treatment in specialist neuro-urology units.

Permanent catheterisation

If all else fails, some people with MS may need to be permanently catheterised. This can be done via the urethra or the lower abdominal wall; the latter is called a suprapubic catheter. Being permanently catheterised sounds drastic, but this significantly improves the quality of life in some people with MS. Allowing bladder dysfunction to control your life can result in social isolation and constant anxiety about being incontinent in public. With the above-mentioned strategies, adequate bladder control should be the norm in MS.

In my experience, the biggest hurdle to achieving adequate bladder control is when people with MS assume their bladder symptoms are part of the disease and resign themselves to living with them. Such patients may start using continence pads as if this is normal or inevitable for someone living with MS. This is not normal; incontinence can lead to skin rashes and pressure sores. Please don’t accept this as the norm or something you must live with. If you have problems, tell your MS nurse or neurologist; they can help you.

Anatomy of the human urinary bladder; reproduced from Wikipedia, created by U.S. National Cancer Institute’s Surveillance, Epidemiology and End Results (SEER) Program.

Lifestyle factors that impact your bladder

Smoking, alcohol and caffeine

Nicotine irritates the bladder. If you are a smoker, then stopping smoking may significantly improve your bladder symptoms. Similarly, reducing alcohol and caffeine consumption may help; these agents are diuretics and cause the kidneys to make more urine.

Pelvic floor exercises

One of the treatments recommended to all patients with bladder problems is pelvic floor exercises. These are also important for managing bowel and/or sexual problems. For detailed guidance on incorporating these into your daily life, please see pelvic floor training post.

Avoiding dehydration

Try to anticipate times when urinary frequency and urgency will be most inconvenient; reducing the amount you drink beforehand may help. For example, don’t drink too much for 2 ̶ 3 hours before you go out. After you have finished passing urine, go back to the toilet again after a few minutes to try to pass some more urine. This is called the double micturition technique, which aims to ensure the bladder is emptied completely. However, do not reduce your total fluid intake to less than 1.5 litres each day.

Dehydration is not a good way to control your bladder symptoms. The issue of people with MS dehydrating themselves to manage their bladder problems was highlighted as early as the 1960s by Professor Bryan Matthews, a neurologist in Oxford, in his textbook on MS.

When researching the topic in the 1990s, it became clear to me that people with MS with severe disability were most likely to have bladder dysfunction and were chronically dehydrating themselves to manage urinary frequency, urgency and nocturia. Studies showed that a high urinary concentration of creatinine, a waste product that the kidneys filter out of the blood through the urine, correlated with increased disability levels. Urine containing myelin basic protein-like material (MBPLM), an indicator of myelin damage in MS, was also shown to correlate with disability. It is dehydration that causes higher levels of MBPLM and creatinine in the urine, indicating that dehydration is associated with disability.¹ 

A more recent paper from researchers in the Southampton group described the same findings, that urinary tract symptoms are very common in people with progressive MS and are associated with inadequate hydration.²

Despite highlighting the issue of chronic dehydration in MS over the years, it remains a persistent problem. My message is clear: don’t use dehydration to manage your bladder symptoms. Chronic dehydration can have a significant impact on your overall health and well-being and can exacerbate many of your MS symptoms. Some potential effects of chronic dehydration are listed in the box below.

In conclusion

I advise using a holistic approach to managing urinary symptoms, in addition to medication or other aids where recommended. Please review the questions below to check whether you are optimising your self-management.

• Have you deconditioned your bladder because you are not training yourself to resist emptying it whenever you get the urge to pass urine? The bladder is a muscle that needs to be trained.
• Have you tried peripherally acting anticholinergics or mirabegron?
• Have you had a post-micturition bladder scan to see if you are emptying your bladder?
• Do you need to use intermittent self-catheterisation to increase your functional bladder volume?
• Do you have a chronic low-grade urinary tract infection? Are you performing regular urine dipstick testing (see post on UTIs and dipstick testing)?
• Do you have bladder stones?
• Have you tried DDAVP (Desmotabs or Desmospray) to help concentrate your urine without dehydrating yourself?
• Are you avoiding bladder irritants or stimulants such as caffeine and nicotine?
• Are you doing your pelvic floor exercises? If you are a post-menopausal woman, have you tried HRT (hormone replacement therapy)? Pelvic floor tone and bladder function often improve on HRT. 

References

1. Giovannoni G, et al. Urinary myelin basic protein-like material as a correlate of the progression of multiple sclerosis. Ann Neurol 1996;40:128 ̶ 9.
2. Kaninia S, et al. Dehydration associates with lower urinary tract symptoms in progressive multiple sclerosis. Eur J Neurol 2024;31: e16175.