Effects of microsurgical nerve repair on sensory function after breast reconstruction (2017)

A beautiful, naturally-shaped and symmetrical breast mound will be created for a breast cancer patient after mastectomy using a free abdominal flap. The disadvantage with the breast reconstructed with this method is its lack of sensation, even some spontaneous reinnervation takes place from the surrounding tissues. \n\nThe objective of the present study was to find and develope a method of dissecting and reconnecting nerves of the abdominal flap and the chest area in order to reconstruct a breast with sensation for the breast cancer patient. The first aim was to find out, which nerves in the chest and the flap, when coapted, would provide the best sensation to the reconstructed breast. The second aim was to investigate whether the dissecting of the nerves causes additional complications in the abdominal flap donor site. The third aim was to develop a better neurorrhaphy technique, using two nerve pedicles. The fourth aim was to assess and qualify the methods of sensory assessment employed in the study. \n\nBreast reconstruction with a free muscle-sparing transverse rectus abdominis myocutaneous flap (ms-TRAM flap) was performed in this study for 96 breast cancer patients in Savonlinna Central Hospital between 2001 and 2013. The reinnervation of the flap was performed in 44 patients with the novel dual neurorrhaphy technique and in 32 with single neurorrhaphy, and 20 breast reconstruction patients without flap reinnervation functioned as a control group. The contralateral healthy breasts of 38 breast reconstruction patients were used as the reference site, and 20 healthy volunteer women participated sensory testing of healthy abdominal skin. Skin sensation of the reconstructed breast was assessed two years after the surgery. In addition, between 2006 and 2013, sensory testing of the skin of the mastectomized breast was performed prospectively before the reconstruction surgery, and the healthy breast, abdominal skin and the reconstructed breast skin were also tested one year after the surgery. Sensory tests included clinical sensory examinations, quantitative sensory tests (QST), skin samples, and neurophysiological somatosensory evoked potentials (SEP). Additionally, a patient questionnaire of patients subjective sensory changes was carried out. \n\nBoth neurorrhaphy techniques provided the reconstructed breast with better skin sensation than without neurorrhaphy, and dual neurorrhaphy resulted in better sensory recovery than innervation with single neurorrhaphy. All available tactile nerves in the chest area proved to be capable of restoring sensation to the ms-TRAM flap breast. No significant complications occurred in the abdominal wall in the flap donor site with either of the neurorrhaphy techniques. Nerve coaptations did not cause pain symptoms, and the increase in the operative time was insignificant. \n\nThe function of large myelinated sensory fibres (i.e. vibration and tactile detection) recovered best. The poorest recovery took place in small unmyelinated sensory fibres (i.e. thermal detection and sharp-blunt discrimination). As a result of breast cancer treatment, tactile and thermal sensitivity of the mastectomized skin was reduced already before breast reconstruction surgery. \n\nAll methods of sensory assessment employed in the study could detect the nerve damage caused by the surgery and measure nerve regeneration, with the exception of epithelial nerve fibre density (ENFD) testing, which could not identify nerve regeneration in the comparison of innervated and non-innervated breast reconstructions. Additionally objective SEP proved to be quite an insensitive method in diagnosing nerve damage, they might be suitable for follow-up of its recovery. QST and the clinical sharp-blunt discrimination test were the most sensitive tests both for the identification of sensory damage and nerve regeneration. \n\nBased on this study, we recommend dual neurorrhaphy of the ms-TRAM flap in breast reconstruction for use in clinical practice.