Botulinum toxin is already well established as a second line therapy for the overactive detrusor, despite several drawbacks, which include an increased cost and the potential for more severe complications compared to antimuscarinics. On the other hand, many neurogenic bladder patients need this treatment due to a lack of efficacy of the first line therapy if used alone. Our study aims to investigate whether adding antimuscarinics after the toxin injection might increase the interval between intravesical treatments while keeping the patient safe and satisfied with his therapy.

A series of 30 consecutive adult patients were included in this prospective trial. All patients had neurogenic detrusor overactivity demonstrated in our own urodynamics department and were treated with intradetrusor injection of botulinum toxin type A. After one month in which the toxin proved effective, a daily dose of solifenacin 10 mg was added. The patients were evaluated every three months using the OABq (33 questions) and PVR measurement. Reinjection was decided based on the same criteria and values as the initial treatment. Patient request was a criterion for retreatment. Urodynamics was performed before every retreatment. Data was compared to a similar series of patients from our own database. The parameters we monitored include time between injections, PVR values, OABqscore, Pdet and sensations reported by the patient. A t-test statistical analysis was done by our statistics department. The study was approved by the local Ethics Committee.

The follow up period is at least 24 months in our series. Six patients (20%) did not require reinjection, compared with only two patients in the reference group. The time between treatments increased by 6 ± 2.44 months (p < 0.0001). The PVR did not show any statistically significant variation, and the same was observed for the Pdet values. Although frequently mentioned in the literature, none of our patients developed de novo acute urinary retention. Detrusor overactivity was observed in all patients requiring retreatment, with similar parameters on urodynamics. The OABq symptom score showed progressive degrading, with sensations worsening slower than other parameters.

The neurogenic bladder patient is a very special one and, despite many years of research and achievements, there is no universal treatment which can play the role of a gold standard. In some countries, things are worsened by the lack of support coming from the health system, which is not paying for these treatments. We are in constant search for the optimal treatment that our patients can actually afford and this study is only one piece in this work. The idea to associate botulinum toxin and antimuscarinics is in line with our effort to find a balance between cost and long lasting results. In our country, antimuscarinics are subsidized by the public health system, while botulinum toxin is not. Our results show that we can delay retreatment while keeping a good health related quality of life and a good safety profile. Sensations play a significant role in the patients’ decision to ask for a different treatment, and our study showed that in most cases, under this combined treatment, sensations are somehow behind other parameters in predicting an overall worsening of symptoms.

The association between these two drug classes led to a statistically significant increase in the time between retreatments. Botulinum toxin made solifenacin effective in those cases where it didn’t show enough efficacy when used alone. Antimuscarinics apparently decreased the sensation, and that might be the main reason behind longer efficacy. Even when combined with botulinum toxin, antimuscarinics did not cause acute urinary retention. The increased cost of treatment might be balanced by the longer period of efficacy. In some countries, this combination of agents actually decreases the overall cost of treatment paid by the patient.