The anti-spasm agent is a protein substance (Onabotulinum Toxin A) that has a powerful muscle paralytic effect and has been used in medicine since the 1960s. It is commonly used for muscle spasm disorders and in plastic / cosmetic surgery (e.g., treating facial wrinkles).

What urological conditions does the anti-spasm agent treat?

Anti-spasm agents are commonly used to treat the overactive bladder (OAB). It is uncommonly used to treat a bladder with poor compliance (stiff-walled, inelastic bladder with high pressures). It is also rarely used to treat other conditions like detrusor sphincter dyssynergia (DSD), or a tight bladder neck.

Overactive Bladder

Patients with an overactive bladder often complain of the frequent need to urinate and sometimes urinary incontinence when they cannot get to the toilet fast enough. In those who have failed oral bladder-calming medications (refractory OAB), Anti-spasm bladder injection or sacral neuromodulation are the next lines of treatments. Both are considered minimally invasive procedures. A urodynamic test is usually done to confirm the correct diagnosis first before either of these treatments.

The anti-spasm agent is effective in treating OAB secondary to idiopathic (unknown) and neurogenic causes. Neurogenic causes include Parkinson’s, multiple sclerosis, stroke etc. When injected into the bladder, it paralyses the bladder muscle wall and results in relief or resolution of the bladder symptoms (success rate is about 80% - 90%). The patient will start noticing an improvement about 7 days after the injection. Typically, the effects peak at about 3 months and last for about 6 to 9 months. The patient will need more ‘top-up’ injections when the symptoms recur.

In Australia, this procedure has been approved for patients with neurogenic OAB (spinal cord injury, spina bifida, multiple sclerosis) and idiopathic OAB since Nov 2014. Therefore, the cost of the anti-spasm agent itself is now subsidised by PBS. Your doctor will usually apply for this on your behalf.

How is an anti-spasm bladder injection done?

  • The procedure takes about 15 minutes to do and is usually done as a day-case. It can be done under local or general anaesthesia or intravenous sedation (twilight anaesthetic). If you have it done under local anaesthesia, a solution will be infused into your bladder for about 15 minutes via a catheter to numb the bladder before the injections. You will be given antibiotics through a drip during the case. In some patients, you may also be given antibiotics to take when you go home.
  • A cystoscopy is first done to visualise the bladder, and a special needle is passed down the scope to deliver the injections. Typically, the anti-spasm agent is injected into 10 to 20 sites (1 ml each) in the bladder.

Insert image here ‘Anti-spasm bladder injection’

What are the side effects?

  • Anti-spasm bladder injection is a very safe procedure. To date, there have been no deaths reported.
  • Most patients will have minimal or no side effects.
  • The immediate symptoms you may notice are mild discomfort when you pass urine and minor bleeding in the urine. These should settle down within a day or two.
  • The small injections do not usually cause post-op pain in the bladder area.
  • A bladder infection is uncommon and may present as persistent burning during urination, smelly urine, cloudy urine, frequent need to pass urine and low-grade temperature. If this happens, you need to get your urine tested and be started on antibiotics.
  • In about 5% - 10% of patients, the anti-spasm agent may be too strong and ‘over-paralyse’ the bladder such that the bladder cannot contract fully to empty itself during urination (urinary retention). These patients will be taught how to drain their bladder by self-inserting a catheter a few times a day (intermittent self-catheterisation). Typically, the patient must do this for about 2 to 3 months until the anti-spasm agent starts to wear off and the bladder partially recovers.
  • Rarely, patients may experience flu-like symptoms and may need to be admitted to the hospital.

How do I prepare for it?

  • You may be asked to do a urine test to check for infection prior to the procedure. If you have an infection, this must be treated first before the procedure.
  • If you are on certain blood-thinning medications (Warfarin, Plavix, Eliquis, Iscover), you may be asked to withhold them 2 to 7 days before the procedure. Please check with your doctor regarding this.
  • Certain newer diabetic medications need to be withheld for 2- 3 days before your procedure. Please check with your doctor.
  • If you are already on a bladder-calming medication, you will be asked to stop it a few days before the injections. The combined effect of the medication and the anti-spasm agent may be too strong and result in the inability to pass urine.
  • You will usually need to fast for at least 6 hours before the procedure if you have it done under general anaesthesia or intravenous sedation. Your doctor will give you fasting instructions.
  • See preparing for surgery, for more details.

What happens after the procedure?

  • After the procedure, you should be able to go home. If you have general anaesthesia or intravenous sedation, do not drive home yourself. You can resume normal activities after the anaesthesia wears off. Drink plenty of fluids at home.
  • You are asked to watch for symptoms of a urinary tract infection in the few days after the procedure. The typical symptoms for this are burning when urinating, worse urinary frequency, smelly urine, cloudy urine, or bloody urine. In some patients, you will be given antibiotics in case these symptoms occur.
  • To screen for the 5% - 10% chance of you developing transient urinary retention (unable to empty the bladder fully), you may be asked to come into the rooms for a uroflow test and a post-void bladder scan. This is usually done at the 3 to 4 week mark. During this test, you are asked to pass urine in a specially calibrated funnel and your bladder will be scanned with an ultrasound machine after the void. If your bladder scan shows that you leave a significant volume of urine in the bladder after voiding, you may be taught to perform intermittent self-catheterisation (ISC). Patients who are unable to do ISC may need to have a short period of indwelling catheterisation.
  • Another appointment may be arranged at the 3-month mark, as that is when the effect of the injection peaks at its strongest. This is to assess if the dose you received is sufficient. Most patients need 1 vial (100 units) per injection, occasionally some may need higher doses of 200 units or even 300 units. The higher the dose, the higher the likelihood there is of developing transient urinary retention. Your doctor will advise you on the dose that you need.
  • Each cycle of injection usually lasts 6 to 9 months. When the effect starts to wear off, the overactive bladder symptoms will slowly recur. Patients can then call the rooms to arrange the next ‘top-up’ injection.

Related information

Read A/Prof Gani’s publication:
Download An analysis of rebooking methods and delay to reinjection of intravesical botulinum toxin a - PDF (174 Kb)

Read A/Prof Gani’s publication:
Download Modifications to botulinum toxin a delivery in the management of detrusor overactivity recalcitrant to initial injections - PDF (904 Kb)