Patients were eligible for inclusion if they had received BTA injections to the lateral abdominal wall muscles (external oblique, internal oblique, and transversus abdominis) prior to scheduled elective hernia repair and had completed a minimum of 4 weeks of follow-up after injection. Only patients with completed abdominal wall repair were included to ensure they could report on the full perioperative experience. All participants received BTA in preparation for large midline or parastomal hernias with or without loss of domain. The survey was intentionally designed as fully anonymized; therefore, no identifying or demographic information such as age, gender, or detailed medical history was collected. Likewise, information regarding the psychological background or chronic pain status of the participants was not requested to ensure compliance with data protection regulations. This anonymity limited the possibility of subgroup analyses based on demographic or clinical characteristics but allowed for broad international participation.

A structured questionnaire was developed in five language versions (German, English, Polish, French, Spanish) to accommodate the international patient population. The initial version was created by the study authors based on expert consensus within the European Hernia Society Guidelines Group. Key domains—such as pain perception, functional limitations, and organ-specific effects—were identified through clinical experience and a review of previously published studies on BTA in abdominal wall surgery. The survey included 9 single-choice questions using numerical or descriptive scales and one open-ended question (Supplementary Material 1). Translations were carried out by native speakers with a clinical background. Although the questionnaire was not formally validated through pilot testing or interview-based psychometric assessment, it was pragmatically designed for quick and simple application and international use. Topics addressed included pain during and after injection, perceived changes in mobility, breathing, bowel and urinary function, and subjective abdominal wall morphology. Importantly, patients were actively involved in the development of the questionnaire, providing feedback on clarity, relevance, and comprehensibility of the items. Their participation ensured that the survey addressed issues most meaningful from the patient perspective and enhanced the overall validity and accessibility of the instrument. Respondents were invited to complete the questionnaire at least 4 weeks after BTA injection and within 2 weeks after surgery. However, exact timing was not uniformly recorded, which may have introduced recall bias.

Patients received Botulinum Toxin A (e.g., Botox®, Dysport® or Xeomin®), reconstituted in saline and administered under ultrasound guidance into 2, 3 or 5 injection points on each side along the anterior axillary line. Doses and volume distribution varied depending on the surgeon or radiologist performing the procedure. All injections targeted the lateral abdominal wall musculature, and patients were instructed to avoid strenuous activity for 48 h post-procedure. Information on injection technique, number of punctures, drug formulation, and use of anesthesia varied among centers and was not consistently recorded, precluding formal subgroup analysis by technique or operator. The heterogeneity of administration technique was noted and considered a limitation of the study.

Responses were compiled and analysed using Microsoft Excel®. Descriptive statistics were used to present the distribution of responses for each question. No inferential statistical testing was performed due to the observational nature and heterogeneity of the cohort. Results are presented as proportions and frequency tables. Due to missing demographic and procedural data (e.g., number of punctures, anesthesia type, or operator specialty), stratified comparisons could not be conducted, and results were therefore summarized as descriptive statistics.

Pain during injection was generally low: 27 patients (38.6%) rated it 0–2/10, 23 (32.9%) rated it 3–5, and only 3 patients (4.3%) reported severe pain [9, 10].

Pain on the day after injection was minimal for most participants, with 55 patients (78.6%) rating it 0–2/10 and only 1 patient (1.4%) reporting severe pain. At 1 week post-injection, 60 patients (85.7%) continued to report minimal or no pain.

Pain duration was short in the majority: 60 patients (85.7%) reported resolution within 1–3 days. Only 1 patient (1.4%) still experienced pain on the day of surgery.

Breathing difficulty was absent in 52 patients (74.3%), mild in 13 (18.6%), moderate in 4 (5.7%), and severe in 1 case (1.4%).

Changes in abdominal contour were reported by 40 patients (57.1%): 32 (45.7%) described a small change and 8 (11.4%) a large change.

Regarding bed or chair mobility, 56 patients (80%) reported no change, 11 (15.7%) noted slight worsening, and 3 (4.3%) reported improvement.

Changes in bowel movements were infrequent: 58 patients (82.9%) reported no change, 7 (10%) slight worsening, and 4 (5.7%) improvement.

Changes in urinary function were minimal: 65 patients (92.9%) reported no change, 4 (5.7%) reported improvement, and 1 (1.4%) slight worsening.

All responses with numerical distributions are presented in Table 1. The full questionnaire is provided as (Supplementary Material 1).

Pain is inherently subjective and influenced by multiple factors, including psychological state, prior experiences, cultural background, and individual pain thresholds. As shown in various studies, identical stimuli can be rated very differently by different individuals [18]. In our cohort, the majority of patients reported low pain scores during injection (71.5% rated 0–5/10), and discomfort typically resolved within 1–3 days in nearly 80% of cases. Nevertheless, a small minority reported high pain scores, including one patient rating the injection as 10/10. Such isolated responses should not automatically be interpreted as procedural complications, but rather as part of the expected variability in pain perception. These findings highlight the importance of pre-procedure counselling and cautious interpretation of patient-reported outcomes in studies of this nature.

The survey also reveals that while changes in abdominal wall shape were common, they were rarely distressing or functionally limiting. The frequency of reported changes in abdominal wall contour—typically described as minor and non-distressing—highlights the value of informing patients about expected, benign changes during preoperative counselling.

This study provides patient-centred data on the tolerability of BTA in hernia prehabilitation, highlighting its generally high tolerability among patients. As BTA becomes more integrated into surgical protocols, incorporating subjective experiences into routine evaluation will help tailor patient selection, improve shared decision-making, and balance perceived benefits with emerging safety concerns [19].

To further enhance patient-centred care, we propose that this questionnaire be routinely implemented in clinical practice as a standard tool for patients undergoing preoperative Botulinum Toxin A injection. Regular collection of such data at the local level would allow clinicians to monitor patient perspectives systematically, identify unexpected tolerability issues, and refine counselling strategies. Incorporating standardised patient-reported outcomes into routine care may also support benchmarking across institutions and contribute to the development of evidence-based guidelines.

This study has several important limitations that should be acknowledged.

First, the questionnaire used in this survey was not formally validated. It was designed pragmatically to ensure accessibility across languages and clinical contexts, but it lacks psychometric validation or pilot testing, which may influence reproducibility and generalizability of the findings.

Second, demographic and clinical background data—including patients’ age, gender, medical history, psychological status, history of chronic pain, and use of analgesics—were not collected in this anonymized survey. These factors are known to significantly influence pain perception and could have contributed to variability in the reported outcomes.

Third, there was notable heterogeneity in procedural details, including the number of puncture sites, doses and dilution of Botulinum Toxin A, as well as operator specialty (radiologist vs. surgeon) and use of anesthesia or sedation. Because these variables were not consistently recorded across participating centers, they could not be analyzed in relation to pain intensity or tolerance. It is possible that patients who underwent the procedure without anesthesia or sedation may have reported higher discomfort, although this could not be formally assessed. Future prospective studies should capture and compare these variables systematically.

Fourth, the international cohort was unevenly distributed, with variable patient numbers across countries (for example, 24 participants from Germany versus only 2 from Spain). Cultural and linguistic differences may have influenced subjective interpretation of pain or functional symptoms, potentially introducing reporting bias.

Finally, because participation was voluntary, patients who experienced serious complications may have been less likely to respond, introducing potential survivorship bias. Future prospective trials, such as the ongoing RCT NCT06499324 in France, are expected to provide structured data on BTA use under standardized protocols.

It is also important to acknowledge that patients who may have experienced severe complications following BTA administration—such as cardiopulmonary deterioration—are unlikely to have responded to the survey, introducing a potential survivorship bias. Given the relatively small sample size, this study is not powered to detect rare or serious adverse events. Future research efforts should include registry-based data collection to better define the true incidence of uncommon but potentially serious complications associated with BTA administration.