Preoperative Botulinum Toxin-A Injections Prior to Abdominal Wall Reconstruction Can Lead to Cardiopulmonary Complications

Abstract

The majority of incisional hernias is located in the midline of the abdominal wall (linea alba). Repair aims for a complete approximation of the rectus muscles in the midline. Different (surgical) techniques have been described as an adjunct to avoid bridging the hernia defect with mesh, instead of complete closure with native tissues(1-3). These are so-called component separation techniques (CST). Chemical CST is most recently described and potentially the most promising development(4, 5). Chemical CST uses ultrasound-guided depositions of Botulinum toxin-A (BTA) in the lateral abdominal wall muscles with the aim to reduce or completely avoid the need for surgical CST(6). The injections are performed some three to six weeks prior to the abdominal wall reconstruction and cause a temporary flaccid paralysis of the lateral abdominal wall facilitating closure of the midline of the abdomen during reconstruction(5).The number of publications on chemical CST is increasing rapidly but (serious) adverse events seem to be largely absent in the literature(7). Therefore, one may assume that BTA injections do not have any adverse effects (on the short-term). We want to emphasize that, despite chemical CST has a low risk of complications, it is definitely not without any risks. We discuss two patients with serious pulmonary complications following preoperative work-up with BTA injections prior to abdominal wall reconstruction, and a third patient where we refrained from BTA pretreatment. In addition, we suggest some future considerations for chemical CST.Case reportA 83-year old male patient presented at the outpatient clinic with chronic postoperative inguinal pain and suspected chronic infection of previous implanted lower abdominal mesh. Medical history includes pacemaker implantation, myocardial infarction, laparoscopic right hemicolectomy complicated by multiple intra-abdominal abscesses, open preperitoneal left-sided inguinal hernia repair complicated by a wound infection and subsequent recurrent hernias and incisional hernia repair using mesh in the retrorectus plane. Physical examination revealed a giant inguinal hernia, a small fistula in the left groin, plus a 6 cm wide lateral incisional hernia. Additional cross-sectional imaging demonstrates multiple fluid collections surrounding the giant inguinal hernia, running from the Anterior Superior Iliac Spince (ASIS) into the scrotum, where the fistula was present. Estimated loss of domain was approximately 25%. The patient was counselled and planned for complete mesh removal and abdominal wall reconstruction including reconstruction of the left groin. Prior to surgery, chemical CST was performed, using two bilateral BTA injections (total of 600 units of Dysport®, diluted into 120 mL of saline 0.9%), into all three lateral abdominal wall muscles (8). Some two weeks after the injections the patient developed complaints of general fatigue and dyspnea on exertion. Under the working diagnosis of cardiac decompensation due to mild anaemia (Hemoglobin 109.9 mg/dL; 6.1 mmol/L), and the inability to compensate pulmonary following the botulinum injections, surgery was postponed.A second patient, a 72-year-old female, was referred to our tertiary academic centre with a complex incisional hernia. Medical history was extensive, including cystectomy, uterine extirpation hysterectomy and sacrocervicopexy with mesh implant, and some years thereafter mesh removal for erosion. No chronic obstructive pulmonary diseases were diagnosed, although she had 9.25 packyears (patient ceased smoking 16 years before). Cross-sectional imaging showed a large lateral incisional hernia with a loss of domain of approximately 20%. Pulmonary testing – performed 14 months earlier – showed a n absolute FVC of 2.26 litre (relative value 82.11%), FEV1 was measured 1.63 litre (76.08 %) and FEV1/VCmax of was measured 721% (i.e., slightly reduced for her age). She underwent preoperative chemical CST using the same dosage, volume and technique as the patient described above. Twelve days after chemical CST she presented at the emergency room with respiratory insufficiency and was diagnosed with and treated for pneumonia. In the following weeks, the infection parameters decreased, however, the respiratory weakness remained, and the elective reconstruction was postponed until further notice.DiscussionThe two cases presented concretize that chemical CST prior to abdominal wall reconstruction can result in (short-term) cardiopulmonary complications. Some days after BTA injections, patients may experience adverse effects including back pain (compensation for truncal stability) or weakened coughing. One case of dyspnoea has been described previously (7). These effects can be experienced from two days after BTA injection, as functional denervation occurs after this period (5). It is key to be aware of the potential side-effects of BTA injections and assess preoperative cardiopulmonary function tests beforehand, to appropriately select patients for this neoadjuvant treatment to avoid these adverse events.A third patient with a history of multiple sclerosis (MS) and related muscle weakness presented with a large incisional hernia requiring CST for abdominal wall closure. Before surgery was scheduled, she underwent spirometry, demonstrating a moderate pulmonary function. Hence, BTA injections were deemed to be contra-indicated, in order to avoid the previously described complications. Caution is warranted when using chemical CST in patients with any disorders that potentially influence respiratory muscle functions. Asthma and chronic obstructive pulmonary disease (COPD) are common respiratory disorders that restrict respiratory function. Besides the careful consideration of the indication for chemical CST, hernia surgeons should always assess pulmonary function (spirometry or cardiopulmonary exercise test; CPET) in pulmonary impaired patients to determine the eligibility. In patients with neurological/neuromuscular disorders involving neurotransmitter release of acetylcholine, BTA injections are considered overall contraindicated.The preoperative workup in all patients with complex incisional hernias (with or without enterocutaneous fistulas) include a complete prehabilitation program before repair, as recommended by the international hernia societies (9). Pulmonary training is part of this prehabilitation and is performed in the Netherlands by physical therapists. Before definite planning of a complex incisional hernia repair is done, patients with a cardiopulmonary history should undergo spirometry and/or CPET. However, to date, no definite cut-off values for spirometry in relation to chemical CST are available. We assume that FEV1 <70% could result in cardiopulmonary problems when BTA injections in the lateral abdominal wall are performed. In our opinion, a FEV1 <60% is a relative contra-indication and <50% is an absolute contra-indication for BTA injections prior to complex incisional hernia repair. Caution is warranted as this expert opinion-based recommendation is subject to new insights when more evidence becomes available in the future.The transverse abdominal muscle contributes to respiratory functions in humans and is recruited preferentially to the superficial muscle layer of the abdominal wall during breathing (10). Although this muscle is relatively thin compared to the other two lateral abdominal wall muscles, it is known to play an integral role in truncal stability (7). As based on the two cases presented, the contribution of the transverse abdominal muscle to basic respiration should not be underestimated, particularly in patients with pulmonary diseases. A previous study demonstrated some preliminary evidence that chemical CST in two (external and internal oblique) instead of the conventional three muscles have similar effects on subsequent fascial closure during repair (7). It can be questioned whether deviations in chemical CST protocols should be made based on patient comorbidities. Future research should focus on this particular issue before firm conclusions can be drawn.The physiological changes following chemical CST in lateral and midline complex hernias may be different. Both cases with cardiopulmonary complications of BTA injections described above, involved an incisional hernia outside the midline. As these complications are largely missing in the literature to date, it could be possible that patients with lateral abdominal wall hernias are more likely to develop pulmonary difficulties following chemical CST. As the transversus abdominal muscles has a relative large contribution on the respiratory function (10), patients with large lateral hernias could have an a priori compromised respiratory function compared to the more common patient with a large midline incisional hernia. To date, this statement is solely based on theorical grounds. Future studies on respiratory functions before and after BTA injections could clarify these potential differences and perhaps adjust the preoperative workup.ConclusionIn conclusion, the use of BTA injections in the lateral abdominal wall is emerging as an excellent surrogate for (or adjuvant to) surgical CST. However, before planning this chemical CST, we advise to consider the cardiopulmonary history and neurological disorders that could result in decreased respiratory function, pulmonary functional capacity, and anaerobic threshold, to avoid serious adverse effects of BTA. Pulmonary function tests, like spirometry (in pulmonary comorbid patients) and CPET (in cardiopulmonary comorbid patients), could give a good indication whether complications following chemical BTA are plausible. The clinical challenge is to weigh the potential postoperative pulmonary advantages of BTA pre-treatment - due to increased abdominal wall laxity and associated reduced chance of elevated diaphragm - versus its potential hazards of reduced axillary respiratory aid from the lateral abdominal wall muscles in patients with pulmonary disorders.

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