The overactive bladder syndrome presents an overall prevalence of between 12-19% among the general population, and is characterided by the feeling of urgency, with or without urge incontinence, usually with increased diurnal voiding frequency and nocturia, in the absence of infection or other condition evident.
This symptomatology often leads to a significant impairment of quality of life of those patients suffering from it.
Conventional treatment involving bladder training and first-line pharmacological treatment not always manages to control symptoms, in addition to dropouts due to side effects, lack of effectiveness or contraindication of the first-line pharmacological treatment.
Treatment of overactive bladder with botulinum toxin
The injection of botulinum toxin is increasingly being used as a treatment for refractory overactive bladder syndrome that affects around 17% of the population and that is caused by a decrease in the capacity of the bladder to store urine.
The administration of BOTOX® must be performed on the inside of the bladder. The product must be injected in the bladder wall to reduce the activity of nerves that generate the symptoms and under conditions of local, epidural or general anaesthesia, depending on the characteristics of the basic process and the conditions of each particular patient.
The treatment can be repeated when the effect has disappeared, if and when there are 12 weeks of separation between the two injections. This is a very effective technique, which involves minimum discomfort for the patient and whose effects can have a duration of up to one year.
A growing number of clinical trials support the use of Botox® in patients with neurogenic overactive bladder, both as idiopathic, associated with incontinence, showing marked improvement in the quality of life of patients that have led to the authorisation of the clinical use of onabotulinumtoxin-A by different regulatory agencies (Spanish Drug Agency) for treatment.
Results of the treatment
BOTOX® has proven to be a very effective treatment in the control of the symptoms of overactive bladders refractory to first-line treatment, with reduction of frequency, urgency and incontinence associated with urgency in up to 75% of patients treated.
The effect of the treatment is usually transient and generally loses effectiveness after 4-9 months of the injection, so that it may be necessary to repeat the injection after this time has elapsed.
Mechanism of action
The mechanism of action of onabotulinumtoxin-A is complex. On the one hand, it blocks the release of acetylcholine at the level of the synapse, thus preventing the transmission of nerve impulses to the muscle, but it also inhibits the sensory transmission, by blocking the release of neuropeptides and neurotransmitters involved in the afferent signaling.
This mechanism of action at different levels explains the driving effect shown through relaxation of the detrusor muscle and its effect at sensory level, like the improvement of the sense of urgency.
Goals of Treatment
This treatment may improve symptoms associated with overactive bladder:
- Increased frequency
- Urge incontinence
Some patients (less than 10% of cases), may experience difficulties with urination after injection of BOTOX ® and may require placement of a vesical catheter or an intermittent bladder catheterisation for a varying period after treatment.
The treatment can also increase the risk of urinary tract infection, hence antibiotics are used immediately after the procedure.