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Page 6 of 9 Elhage et al. Plast Aesthet Res 2020;7:16 I http://dx.doi.org/10.20517/2347-9264.2020.03

This study included 18 patients who also received PPP, but because data on which patients developed
these complications was not reported, it is not certain these symptoms can be attributed solely to BTA
administration.

[22]
Elstner et al. did not report any complications related to BTA administration but do describe similar side
effects of weak cough and sneeze, and a sensation of bloating. Patients also described back pain, and one
experienced dyspnea. Similarly, abdominal binders were found to aid in symptom resolution. The authors
theorized that sparing the TA from BTA injection may allow for increased core stability and reduction of
these side effects. However, they no statistical analysis was performed to compare the three muscle layer
group and the EO and IO only group regarding these side effects.

DISCUSSION
Improving outcomes of AWR in large hernias starts with optimization of modifiable patient factors,
such as weight loss, smoking cessation and controlling diabetes. Furthermore, to reduce complication
and recurrence rates, the goal of AWR should be achievement of primary fascial closure with mesh
[26]
reinforcement, instead of bridging the hernia defect with mesh . Both increased intrabdominal pressure,
as well as morbid obesity which is associated with increased intrabdominal pressure, may play a role in the
[27]
development of hernias and hernia recurrences . Different component separation techniques can be used
to increase abdominal cavity volume and decrease intrabdominal pressure, but this necessitates destruction
of the anatomical tissue planes of the abdominal wall [28,29] . The use of BTA as a chemical rather than surgical
technique for components separation achieves abdominal wall compliance by elongation and thinning of
[16]
the musculature, although such application is currently off-label .
While there are relatively few studies evaluating the efficacy of BTA in AWR, and no randomized controlled
trials, the existing evidence remains promising. Studies evaluating abdominal wall muscle thickness and
length were able to show significant differences after administration of BTA [16,18-22,24] . As would be expected
with these effects on the musculature, many studies then showed a decrease in the mean transverse defect
size. In studies reporting fascial closure, all but one achieved very high success rates after pre-operative
[17]
BTA. Zendejas et al. reported a low fascial closure rate in their BTA patients (40.9%), but this was not
dissimilar from their propensity matched control group (36.4%). This raises the question of whether this
lower fascial closure rate reflects surgeon preference and surgical technique as opposed to BTA treatment
effect. Three studies, including the largest review to date by Bueno-Lledó et al. [20,21] , used PPP as an adjunct
[19]
to BTA in AWR, which makes extrapolation of results to patients receiving BTA only difficult . Further
limitations of this review include the significant amount of heterogeneity in regard to hernia characteristics,
surgical techniques, and the type of mesh used. While BTA appears to be an effective adjunct therapy in
AWR, none of the studies in this review detailed the selection criteria and hernia characteristics that may
define patients who would benefit most from BTA injection.

There is significant variation in technique, number of sites and timing of injection in the reviewed articles.
Functional denervation starts after 2 days and the effect peaks at approximately 2 weeks after BTA injection
and lasts beyond 30 days [12,30] . Injection at least 2 weeks prior to surgery seems most beneficial for AWR.
Ultrasound guidance appears sufficient for targeted BTA injection and was used in all but one study.
Guidance techniques should be based on the comfort of the provider however [16-24] . All studies injected at
least the EO and IO, with most injecting the TA as well. Theoretically, paralysis of all 3 layers of the lateral
abdominal wall could interfere with the stabilizing function of the core abdominal muscles, potentially
[22]
contributing to back pain and predisposing to injury, as hypothesized by Elstner et al. However, in large
ventral hernias, this stabilizing function is likely already impaired due to disruption of the midline. If this is
a concern in patients with pre-existing conditions, application of an abdominal binder or selective injection