Tattooing agents for nerve marking in experimental surgery

Experimental nerve surgery involves test procedures, including those for nerve lesions in continuity, that leave no visible traces of impairment after surgery. In such cases, non-resorbable sutures are usually used to mark the lesion sites on the nerves. However, this method has two drawbacks: it is not completely atraumatic, and may be frustrating due to displacement of the suture material. The authors demonstrate the use of carbon tattoo pigment to mark nerve lesions permanently, thus allowing their identification reliably at any later date. Following successful preliminary experiments, the tattooing procedure was used in 12 New Zealand White rabbits that had been operated on for a specific nerve regeneration problem. Altogether, 56 tattoo marks were set. The small pigment spots were well-preserved and clearly visible during a second and third operation 4 and 15 weeks later. Histologic examination identified the carbon granules in the outer epineurium; there were no signs of inflammation. This simple, atraumatic, inert, and permanent method for nerve markings in the experimental animal is recommended.