Abstract
Introduction. Laparoscopic ventral hernia repair has many advantages over open techniques: adequate visualization of the entire abdominal wall, ease of placement of preperitoneal mesh with adequate overlap, and cosmesis. Intense and activity limiting pain is often one inferior aspect of this repair. We report the case of a patient who was intolerant of narcotic pain medicine with activity limiting pain. A novel technique for postoperative pain control was instituted utilizing Botox A (Allergan Inc., Irvine, CA, USA).
Methods. Botox A was diluted to 2 units per mL and three injection sites were chosen on each side of the abdominal wall. All three muscle bellies (external oblique, internal oblique, and transversus) were identified by ultrasound and 8 mL was injected in each. This resulted in three muscle layers at six sites for a total of 18 injections. A total of 300 units of Botox A were utilized.
Results. Pain scores improved from 10/10 to 2/10 and were durable at 3-month follow up.
Conclusion. Botox A provided significant pain control for this patient after laparoscopic ventral hernia repair. Continued prospective study to define long-term outcomes, cost savings, and appropriate timing of injections is underway.
Introduction
Botulinum toxin type A (BTX; Botox, Allergan Inc., Irvine, CA, USA) has been used in clinical applications for a wide variety of disorders. More common uses include glabellar wrinkles, cervical dystonia, blepharospasms, axillary hyperhydrosis, strabismus, anal fissures and achalasia [1–8]. Acute and chronic pain symptoms are also an active area of clinical utilization with a yet unknown mechanism of action [9–11]. Injections for Temporomandibular joint spasticity pain, migraines, arthritis, stump pain after amputation, myofascial pain syndrome (MPS), and acute periorbital pain following glaucoma attacks are well described with promising results [12–15]. Current literature documents expanding use in the perioperative setting as well as recent publications in head and neck, orthopedics and oncoplastic surgery [16–18]. We report a case of postoperative pain following a laparoscopic ventral hernia repair that was treated with Botox A injection under ultrasound guidance to the lateral abdominal wall musculature.
Case Report
A 63-year-old woman was seen in outpatient clinic for complaints of discomfort with normal activities and enlarging bulges along a previous midline incision from open gastric bypass, hysterectomy, and appendectomy 30 years ago. Physical exam revealed a partially reducible mass along the left aspect of her incision. A computed tomography (CT) scan revealed multiple fascial defects and diastasis recti with incarcerated omentum. The patient underwent an uneventful laparoscopic hernia repair with placement of a 20 × 22 cm oval Gore-tex Dual Mesh (W.L Gore and Associates INC, Flagstaff, AZ, USA). Full thickness fixation was undertaken in six points with Gore-tex suture. Nonabsorbable tacks were then used to complete fixation to the anterior abdominal wall in a standard fashion.
The patient was discharged on postoperative day number two, with bowel function and adequate pain control with oral oxycodone and Tylenol. The patient returned to clinic on postoperative day 14 with continued pain control with Tylenol only, as narcotics caused significant gastrointestinal upset. On postoperative day 20, the patient returned to the clinic with worsening anterior abdominal wall pain described as two distinct entities. The first was a burning sensation in the right lower quadrant (RLQ). This was accompanied with diffuse, intermittent pain in other areas of the anterior abdomen described as “muscle spasms.” Physical exam remained unchanged from previous postoperative visits with no obvious return of her hernia. Ibuprofen scheduled doses were instituted. The patient had continued worsening of her pain with little to no relief from nonsteroidal medication or Tylenol, rating it a 10/10. A CT scan of the abdomen and pelvis confirmed good placement of the mesh with no return of her hernia defect and no signs of postoperative infection. She then underwent trigger point injection of 0.25% bupivacaine with resolution of her RLQ pain, but her diffuse “spasms” continued.
Several options were then presented to the patient including pain service evaluation to explore further pharmacologic alternatives, as well as BTX injections for pain control. The patient wished to proceed with injections. Thus we proceeded to ultrasound-guided injection of BTX of the anterior abdominal wall. BTX was diluted to 2 units per mL and three injection sites were chosen on each side of the abdominal wall (Figure 1). All three muscle bellies (external oblique, internal oblique, and transversus) were identified and 8 mL was injected in each. This resulted in three muscle bellies at six sites for a total of 18 injections utilizing 300 units of Botox.
Anatomic location of injection sites. X = injection site.
The patient was contacted on postinjection day five and she reported significant relief of her pain, now reporting it at 2/10. She was able to resume her normal daily activities following injection. Effects have persisted at 1 and 3 months' follow up.
Discussion
BTX, available in the United States as Botox (Allergan Inc.), has been used for many years for spasticity-related disorders and cosmetic procedures, with both its safety and efficacy proven [2,4–8]. More recently, active research has been focused on Botox for use in pain syndromes such as stump pain, migraines, MPS, chronic low back pain, arthritis, and periorbital pain [9–15]. The exact mechanism of action is not understood, but several mechanisms independent of its paralytic properties have been proposed. Included in these are direct effects on muscle nociceptors, motor neuron and muscle spindle afferent changes, alteration of neurogenic inflammation, neuroplastic changes in processing afferent somatosensory activity, and direct effects on pain afferents [10]. The clinical efficacy is demonstrable.
Wittekindt et al. confirmed previous findings of efficacy as well as safety in neuropathic pain syndromes associated with head and neck surgery. They showed a significant improvement in pain as measured by the visual analog scale at day 28 postinjection in the low dose arm, with scores dropping from 4.3 to 3. There were no adverse events reported; however, the sample size was limited, with only 23 patients enrolled [16].
Zhibo and Miaobo have also shown the pain control attributes of BTX during perioperative use. In their study, 20 women undergoing silicon breast implant reconstruction in the subpectoral position had 90 units of BTX injected into the pectoral muscle on one side and no injection on the opposite side. They developed a 3-point scale for rating postoperative pain at 2 weeks; serious, common, and light. All 20 patients rated the BTX side as light pain whereas 19 of the 20 patients rated the noninjection side as serious pain [17].
Chronic low back MPS has also been studied in a randomized, double-blinded study by Foster et al. Lumbar injections were undertaken, with 40 units at five lumbar paravertebral levels for a total dose of 200 units. At 8 weeks, Oswestry Low Back Pain Questionnaire was statistically improved in the Botox group (P = 0.018), with persistent effect at 16-week follow up [19].
In our patient, the intolerance to narcotics and subsequent ineffectiveness of non-narcotic medications left limited options, with the patient unable to tolerate activities of daily living without significant pain. Reoperative surgery is one option. More commonly described in inguinal hernia surgery, recent literature suggests that neuropathic pain presenting with localized, intermittent symptoms is highly susceptible to reoperative surgery with mesh explantation, neurectomy or fixation removal, whereas nociceptive pain presenting as diffuse pain is much less successfully treated with surgery [20]. The diffuse component of our patient's pain suggested more nociceptive pain rather than neuropathic pain.
The safety and feasibility for our approach was taken from a recent study published in the World Journal of Surgery. Anterior abdominal wall Botox injection is described in elective ventral hernia repair after open abdomen by Ibarra-Hurtado et al. [21]. Patients were injected under electromyography guidance to the lateral anterior abdominal wall musculature with BTX and then followed weekly with CT scans. The effect measured was a decrease in hernia size before primary repair, with CT scan evidence of significant decrease in hernia size at an average of 4 weeks after injection (P < 0.001). A total of 12 patients underwent repair, with a 0% recurrence rate at mean follow up of 9.08 months. A complication rate of 16% was reported, all from the hernia repair and none from the Botox injection. Pain was not an endpoint of the study, but it does provide clinical evidence for muscle relaxation as well as safety when used in the anterior abdominal wall.
Safety remains a concern for this protocol. While many small studies have shown safety and clinical efficacy for postoperative pain syndromes, as well as safety of intraoperative use, large, randomized studies are needed to help address lingering issues. Although no studies to date discuss any adverse interactions between BTX and intraoperative use of paralytics, this remains a question. It appears that until some of these questions are answered, certain patient populations should be excluded. This includes pregnant women, patients with preexisting pareses such as amyotrophic lateral sclerosis, myopathies and motor polyneuropathies, as well as impaired muscle transmission syndrome patients, specifically myasthenias gravis and Lambert–Eaton patients.
This patient achieved significant improvement in her pain control and activity level with Botox injection without any demonstrable complications. Abdominal wall function remained intact such that the patient had no complaints of decreased functionality, but formal testing was not undertaken. Longer-term follow up will be needed to see if the effect persists or if the injections will need to be repeated. Further study in the use of Botox injections for postoperative pain syndromes in the anterior abdominal wall is warranted.
