Introduction

Ventral incisional hernia is one of the most common log-term surgical complications after open midline surgeries and accounts for almost 20–30% of the cases [1, 2]. Repair of this incisional hernia is always challenging for general surgeons, especially for complex abdominal wall hernia (CAWH) which also have a major physical, social, and mental repercussions on patients [3]. Ramirez et al. devised a component separation technique (CST) which aims medicalization of rectus abdominis muscles by complete division of bilateral external oblique aponeurosis [4].

CAWH is the one with large hernia defects with size >10 cm; re-recurrence; loss-of-domain; large abdominal wall/soft tissue defect and or enterocutaneous fistula; hernias in anatomically peripheral locations; and close-to-bone or local recurrent infection [4].

Recently, Surgeon’s technological armamentarium has been widened for CAWH with introduction of preoperative injection of botulinum toxin A (BTA). It is a protein with neurotoxin activity and is produced by Clostridium botulinum and has an inhibitory effect on presynaptic cholinergic nerve endings [5]. This technique was first reported by Ibarra-Hurtado et al. in 2009, where he used BTA to facilitate fascial closure in 12 patients [6]. Lateral muscle paralysis was successfully achieved for tension-free hernia defect closure. BTA gives an additional advantage of narcotic analgesia with due action blocking the acetylcholine and also by preventing the release of substance P from presynaptic motor nerve endings [7]. Although BTA is a dangerous chemical, small well-calculated doses at specific points on abdominal wall, and also by avoiding vital muscles and viscera have good safety profile [7, 8].

Botulinum Toxin

Types, Mechanism, Effects, and Duration of Action

Commercially available brands of BTA are Botox® (Fig. 1) and Dysport®. This protein blocks the release of acetylcholine in nerve terminals and paralyzes the muscles.

Fig. 1
The text on the carton reads botulinum toxin type a, botox, purified neurotoxin complex, 50 units, and allergan. Some text is written on the top part of the carton as well.

One of the commercially available brand in author’s own practice

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BTA is injected into ventral abdominal wall muscles to achieve functional denervation with paralyzing effect that starts in 3–4 days and reaches maximum effect in 2 weeks [8]. This flaccid paralysis of muscles leads to an increase in abdominal cavity volume. This helps abdominal wall reconstruction without tension. Working in close collaboration with interventional radiologists provides very promising results.

Practical Applications

Selection of Patient

Initially, we have to make certain selection criteria on the basis of which we can provide benefits to the patients. There is no consensus but little evidence on certain criteria which are published in the literature, the most important of which is the complex abdominal wall hernia repair (CAWR) according to the size and site. The average length of frontal abdominal musculature from the linea alba to midaxillary line is about 15–20 cm; and the length gained by BTA administration is 3–4 cm on each side; and 6–8 cm in total. This suggests that a defect of 6–8 cm size would likely get benefit from the best results without component separation technique and the repair would be tension free as well [9]. The author has performed a limited number of cases and more randomized trials are needed to establish the facts.

Injections and Interventional Radiological Kit

Author recommends six injections of 50 IU Botox® (Botulinum Toxin A), Sterile water for dilution, and six sets of 25G spinal needles. Ultrasound kit should include minimum of linear transducer (4–12 MHz) in sterile housing; chlorhexidine can additionally be used as a coupling agent (Fig. 2).

Fig. 2
The image of 2 trays with syringes, 6 small botulinum toxin type used in the syringe, and a few pieces of cloth, on a table.

Equipment required in procedure room under ultrasound guidance

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Selection of Site

The site of BTA is crucial and needs to be defined very accurately. Elstner, Ibarra-Hurtado, Zielinski, and Zandejas have described four different techniques but with one end result. They concluded that BTA administration between midclavicular and midaxillary line pattern could be of a straight line or triangular from costal margin to superior iliac fossa [6, 10, 11]. According to Ibarra-Hurtado technique, patient is placed in left or right lateral position and five sites are identified. Two on midaxillary line at equal distance, three more on anterior axillary and midclavicular lines, and reciprocal is produced for other side as well. These techniques give advantage of increased length and decreased thickness of lateral ventral abdominal muscles (Fig. 3).

Fig. 3
Four images display the various sites in the abdomen region to put injections for positioning of probe and needle.

Various sites of injections and positioning of probe and needle

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Consenting, Selection of Dose, and Procedure

Standard precautions for any interventional radiological procedure should be practiced as per national guidelines. Counseling and consenting regarding steps, and risks vs benefits should be explained in a surgical clinical visit by the surgeon first and later by interventional radiologists. Back ache once paralyzing effects of toxin on muscles should be addressed and abdominal binder therefore should be prescribed beforehand. Always explain to patient that respiration may be labored especially if undertaking heavy activity.

During the procedure, inform the patient that injections would be at various sites and not to cough or take any sudden deep breath during the procedure to avoid any injury to underlying structures. Identify three muscles [External Oblique Muscle (Ex Ob M.); Internal Oblique Muscle (In. Ob M.); and Transversus Abdominus (Tr. Ab M.) (Figs. 3 and 4)].

Fig. 4
The image of three muscles is shown with the black arrow. External Oblique Muscle, Internal Oblique Muscle and Transversus Abdominus are the three muscles shown in the figure.

Identify three muscles shown with black arrow [External Oblique Muscle (Ex Ob M.); Internal Oblique Muscle (In. Ob M.); and Transversus Abdominus (Tr. Ab M.)]

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There is a great personal bias in the selection of dose for BTA. Doses are varying in different studies but all are aiming to decide “good effective” amount with “best” dilution at “appropriate” time at “the best” site. Some believe a larger amount (400 IU) of BTA is safe but the author suggests 150 IU on each side with a total and maximum amount of 300 IU (six injections total as mentioned above).

Recently, we have proposed even a more conservative approach to reduce the dosing amount to 100 IU on each side to a total of 200 IU for up to 10 cm defect. Equal amount of six doses at six sites (three on each side) should be administered under ultrasound guidance by an expert hand to avoid complications [9, 10]. Although the surgeons are also expert in doing this procedure; radiologists are more helpful to perform this procedure [12].

Aftermath

The author’s routine is to request interventional radiologist, master in this technique and familiar with the results and outcome, of his hospital to perform the BTA injection to the bilateral anterior abdominal wall muscles (external oblique, internal oblique, and transversus abdominis) 3 weeks before the operation. Ideal time for surgery is in third or fourth week after injections. Either laparoscopic (preferably) or lap-assisted surgery is performed when BTA provides its peak effect at 4 weeks resulting in flaccid paralysis, and then declined gradually in the next 3–4 months. During this whole time, the patient is advised to wear an abdominal binder to avoid complications which might be a result of this flaccid muscle paralysis.

Complications

A study by Nielsen et al. reported one patient who had pain related to BTA injections which was managed by narcotic pain medications and resolved prior to surgery [13].

Three more studies [11, 14, 15] reported patients reporting with weak cough or sneeze after BTA injections but their condition improved after wearing an abdominal binder [14]. In addition to this weak coughing, few patients reported with a sense of bloating that resolved after hernia repair while some others reported with backache and dyspnea which improved with abdominal binder [15]. Based on these complications, the author devised a way to reduce the amount from 300 IU to 200 IU with a rationale of sparing the transverses abdominis muscle which may allow to increase core stability and ultimately will reduce the side effects.

Conclusion

Initial results have shown BTA as a very good alternative to CST for CAWH with minor side effects. Dual advantages of tension-free hernia repair and analgesic effect have raised the interest of researchers. Additionally, flaccid relaxation of abdominal muscles decreases the intra-abdominal pressure thus improving ventilation complications and ultimately reducing the need for and duration of invasive ventilation support. These advantages further facilitate the postoperative healing process as well. All these discussions are from initial results and large randomized control studies on the dosage, techniques, and timing of BTA would be needed to reach a consensus.