Penile shear-wave elastography predicts the outcome of botulinum neurotoxin (Botox) in the management of non-responders to phosphodiesterase-5-inhibitors: A pilot study.

Objective: Botulinum neurotoxin (BoNT) was introduced as a minimally invasive treatment option for erectile dysfunction (ED). However, there is no proven method that predicts improvement after BoNT injection. Shear wave elastography is an emerging imaging modality that evaluates tissue stiffness. This study aims to assess the reliability of SWE in predicting BoNT response in patients with ED and phosphodiesterase 5 inhibitors (PDE-5i) non-responders.

Methods: This study comprised 20 men presenting with ED and PDE-5i non-responders. Mean tissue stiffness values (TSVs) were measured by SWE, international index of erectile function (IIEF-5), erection hardness score (EHS), sexual encounter profile questions 2 and 3 (SEP-2 and SEP-3), and global assessment questionnaire (GAQ) were evaluated before and after 100 IU of BoNT injection by 6 and 12 weeks.

Results: In comparison with baseline, there was a significant improvement in IIEF-5 and EHS scores after BoNT injection at 6- and 12 weeks (p < 0.001). Similar improvements were observed in SEP-2&3 (p < 0001 & p = 0.001, respectively) and GAQ-1&2 (p = 0.008 & p = 0.006, respectively). We found that mean SWE in a penile flaccid state can predict failure of clinically significant improvement after BoNT injection using a cutoff point of 12.7 kPa (sensitivity = 100%, specificity = 54%, AUC = 0.86, p = 0.014).

Conclusion: This finding could be applied to avoid unnecessary BoNT injections in men with ED and PDE-5i non-responders.