Overall and area-specific tactile recovery following different methods of surgical reinnervation in post-mastectomy breast reconstruction - a systematic review and meta-analysis.

Abstract

Background: Breast cancer is a term that encompasses malignancy of any tissue structurally forming the breast. Due to its high prevalence, breast cancer places a significant burden on both patients and the healthcare system. Treatments such as radiotherapy, chemotherapy, hormonal therapy, and mastectomy are developed. Mastectomy is a lifesaving procedure but can cause decreased aesthetic and functional factors. Recent advances in medical technology have thankfully allowed surgeons to use advanced modalities that enable microscopic reconstruction of tissues, vessels, and nerves, giving sensation to the newly reconstructed breast. Surgical reinnervation is a procedure that describes the restoration of neurological function - both sensory and recovery - towards a body part that is lost or damaged. Reinnervation can be achieved both spontaneously and via surgery, hence termed surgical reinnervation. In this study, we review three surgical reinnervation interventions. First, end-to-end reinnervation comes under the neurorrhaphy group. Neurorrhaphy involves anastomosis of residual nerves in the proximal (healthy) and distal (denervated) tissues. Second, nerve allografts come under nerve transplantation. Third, nerve conduits mimic auto-transplantation but with an artificial conductor instead of a nerve donor. This study aims to measure and compare the overall and area-specific tactile recovery following different methods of surgical reinnervation following post-mastectomy breast reconstruction. Evaluation of the topic: This study is a systematic review and meta-analysis written according to PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) guidelines. Twelve studies used in this review, nine measured the difference between breasts receiving end-to-end nerve coaptation and those receiving no surgical reinnervation. Two studies used allogeneic nerve grafts, while one used polyglycolic acid (PGA) nerve conduit. Coincidentally, these three studies employ Pressure Specified Sensory Device (PSSD) instead of Semmes-Weinstein Monofilament Test to measure tactile recovery. The other nine studies measured tactile recovery using the earlier-found Semmes-Weinstein Monofilament Test (SWMT). Outcome of this study focused on tactile recovery to three interventions. The first group report from end-to-end coaptation, three studies report better outcome compared to flaps without surgical reinnervation. Pooled overall SWMT rod size in breasts with end-to-end nerve coaptation was found to be 3.96 (95% CI 2.96-4.96) with high heterogeneity (I2 94%, P < 0.01). Pooled overall SWMT rod size in breasts without surgical reinnervation was found to be 5.27 (95% CI 4.93-5.60) with high heterogeneity (I2 80%, P < 0.01). The second group report from nerve allograft, two studies report that nerve allograft has a significant effect to tactile recovery. The third group report from nerve conduit, one study report about nerve conduit reinnervation. The result of this study was lower that end-to-end nerve coaptation. We then performed an area-specific analysis and found that the largest SWMT rod sizes were generally in the flap nipple area. Pooled mean (95% CI) of SWMT rod size following end-to-end coaptation in the flap nipple area was 4.39 (95% CI 3.70-5.09), while in those not receiving surgical reinnervation 5.45 (95% CI 4.93-5.97). Pooled mean rod sizes were generally much lower in the non-flap areas than in the reconstructed breast.

Conclusion: In conclusion, there is a significant difference in overall sensory recovery between breasts receiving and not receiving surgical reinnervation, particularly breasts receiving end-to-end coaptation. Area-specific analysis found this difference is specifically significant in the upper medial portion of the mastectomy skin. Further research is needed to investigate recovery by other surgical reinnervation methods, particularly end-to-side coaptation, side-to-side coaptation, neurotization, anastomosis using conduits, and nerve grafts.