In line with previous studies [14, 15, 21, 22], we found in PD patients a significant improvement in urodynamic-, bladder diary parameters and consequently in the ICIQ score after 200 IU OnabotA injection with preserved micturition. The mean age of our patients was representative of the PD population.
The application of OnabotA injection in patients with NLUTD was pioneered by Schurch and colleagues . After OnabotA injection (200 of 300 IU, Botox®, Allergan) in patients with spinal cord injury urodynamic-as well as bladder diary parameters improved significantly . Since then, several studies, including randomized, placebo-controlled trials have approved the evidence of OnabotA injection in the treatment of neurogenic detrusor overactivity (NDO) using different study protocols [12, 24, 25].
Despite the fact that efficacy and safety of OnabotA injection has been studied in patients suffering from multiple sclerosis (MS) and spinal cord injury (SCI), there are only few data providing information on the impact of OnabotA injection on urodynamic-, bladder diary parameters, and ICIQ scores, including the specific dosage of 200 IU in PD patients. Currently, only 4 studies are available describing the effect of OnabotA injection in a PD population (Table 1).
Due to different study protocols used, the comparison of results from recent studies [14, 15, 21, 22] with our data is difficult. However, most parameters at the follow-up visits provided global improvement in urodynamic-and/or bladder diary parameters. With respect to decreased urinary frequency (day-and night time) results from the study by Anderson et al.  appear to be less pronounced than in the present study. Our data provide significant changes in the urinary frequency related to OnabotA-injection, which could be due to the elevated dosage of 200 IU. However, previous literature  also observed a significant improvement on urodynamic-and bladder diary parameters using 100 IU OnabotA-injection. Unfortunately, the latter findings mainly focused on female patients, and thus hamper a comparison with the present results.
Currently only two studies in PD patients [15, 21] are available describing the effects of an increased dosage exceeding 200 IU of intradetrusor OnabotA-injections. The first study, published by Giannantoni and colleagues  used OnabotA in a mixed population consisting of PD and multiple system atrophy. It demonstrated significant improvement in urodynamic-, bladder diary parameters as well as in the QoL. Our data confirm these effects in a considerably larger PD population. The second of these studies  used a different agent, Dysport ®, which may hamper an comparison due to particular pharmacodynamics.
Evidence concerning relevant PVR in patients treated with 200 IU OnabotA injection intravesically is controversial and sparse. Recently, published data showed an increased PVR and even urinary retention in patients with NLUTD, excluding PD [12, 26]. In contrast to these observations, White et al.  detected no PVR, when using 200 IU OnabotA-injections. Again, these controversial results might be attributed to the heterogeneity of patients’ cohorts with clinical symptoms of idiopathic or neurogenic detrusor overactivity. In our PD group PVR increased after the injection of 200 IU OnabotA. The increase was not significant and no form of catheterization was needed. Physiologically, this might be attributed to the fact, that only few PD patients demonstrate detrusor-sphincter dyssynergia  and thus voiding function remains unimpaired. On the other hand a dose dependent impact of OnabotA on detrusor contractility has to be taken into account. Although low dosage of OnabotA injection does not necessarily prevent the need for de novo ISC or even indwelling catheterization  the reduction of detrusor contractility in patients with NLUTD remains a relevant factor [12, 26]. Thus, independently of the dosage used, PD patients should be encouraged to learn ISC prior to OnabotA injection.
According to treatment technique, the injection into the bladder trigone is still under debate. The first reported injection techniques spared the trigone due to the potential complication of vesicourethral reflux (VUR) . However, a recent prospective study evaluated the impact of trigonal OnabotA injection (300 IU) and observed no de novo VUR . In addition, Lucioni et al.  observed no significant differences between the effects of sole trigonal and combined trigonal and intradetrusor OnabotA injection (300 IU). With regard to PD patients, the studies by Giannantoni , Anderson et al.  and the present study observed no treatment complication after trigonal OnabotA injection which might indicate a good eligibility of the technique in the selected patient group.
Impaired cognitive function is common in PD, affecting up to 30 % of patients, which might be aggravated by anaesthesia . But to date, it is unclear how far general anaesthesia impairs cognitive performance of PD patients. In line with the literature [15, 22], we mainly performed OnabotA-injections under general anaesthesia. Giannantoni et al.  excluded patients with cognitive impairment. However, in none of our patients an extended distinctive cognitive impairment was noted within a period of up to 4 months postoperatively. In all treated patients orientation, memory, and attention was present. Noteworthy, Anderson  and Kulaksizoglu  performed OnabotA treatment under local anaesthesia with respect to comorbidities and possible interactions with other parkinsonian medications this approach seems to be favourable in PD patients.
To avoid obstructive problems studies by Giannantoni et al. [15, 22] focused on female cases: overall 12 cases included only one male. The present study investigates both sexes. In fact, three of our patients received a PVP 3 months prior to OnabotA injection due to a mild obstructive micturition which didn’t change PVR and urinary urgency significantly (mean change in PVR 28.4 (±52.7), ml p = 0.82). This approach is in line with results of Kessler et al. that showed that TURP resolves urge symptoms in up to 70 % . But, according to the non-significant change in PVR between mean values of preoperative and postoperative data, it is unlikely that only PVP is the cause of the global improvement in urodynamic-and/or bladder diary parameters. Especially the persistent urinary urgency after PVP in those patients are caused by urogenic pathogenesis rather than subvesical obstruction.
In the follow-up, patients demonstrated significant improvement for QoL. To evaluate the QoL we chose the short from of ICIQ-LUT Sqol questionnaire, recommended by the International Continence Society (ICS), to make the evaluation of QoL more practical, particularly with regard to existing tremor in the upper limb.
Although we demonstrated a preserved micturition after intradetrusor OnabotA injection (200 IU) for treatment of NLUTD in Parkinson’s disease this study is limited by the small sample size, which is probably the cause of the high SD in some outcome parameters. Furthermore, it cannot be ruled out that comorbidities and their specific therapies do not affect in a limited extent the results of the bladder function. Nevertheless, our results, based on the largest published series are promising. All patients experienced significant benefit from OnabotA injection, which justify further prospective placebo-controlled investigations in this special patient group.