Epineural methylene blue nerve staining on cadaver hand

Abstract

Introduction: Limited fasciectomy is the gold-standard treatment in Dupuytren’s surgery. The anatomical position of digital nerves can be altered by Dupuytren’s tissue resulting in a difficult dissection and localization, with a relatively high risk of iatrogenic nerve injury. This risk could be decreased by using intraoperative neural marking to facilitate locating the potentially displaced nerves. We recently demonstrated in an animal model that in vivo nerve staining with methylene blue is a suitable method to mark nerves without damaging them. Objective: We aimed to test the efficacy of our methylene blue nerve staining technique developed in a rat sciatic nerve model on human cadaveric digital nerves. Method: First, we performed epineural staining using 40 μl 1 : 80 diluted methylene blue solution on four human cadaver digital nerves fixed with formalin. In the second experiment, we stained six cadaver digital nerves without previous fixation. To increase the length of the stained segments, we used 200 μl solution on two nerves. Results: The epineural nerve labeling was not successful on formalin-fixed tissues. However, nerves without fixation were successfully stained with methylene blue. Forty μl methylene blue solution marked a 13 mm long segment, while 200 μl stained a 18 mm long segment. Conclusion: The epineural methylene blue nerve staining is limited on formalin-fixed digital nerves due tissue shrink-age. Non-fixed nerves with preserved histological structure can be stained in an 18 mm long segment. Further studies are necessary to determine the technique’s value in hand surgery by testing digital nerves surrounded by Dupuytren’s and scar tissues.