Epineural Neurorrhaphy in Dogs

Epineural neurorrhaphy is a surgical procedure involving the anastomosis of a severed nerve endings completed by placing fine sutures in the epineural connective tissue of the nerve. In veterinary medicine, epineural neurorrhaphy is performed infrequently due to the small diameter of nerves in the distal limbs of canines. A canine may require epineural neurorrhaphy to be performed if the dog has damaged a large diameter nerve such as in the tarsal or carpal area. 

Epineural neurorrhaphy is divided into two repair groups: primary and delayed repair. Both primary and delayed procedures repair a nerve laceration by bringing the nerve endings together, but delayed epineural neurorrhaphy is completed when the surrounding tissues require healing time. Crushed or contaminated nerve tissues will be required to heal prior to nerve repair, therefore, adequate healing must take place to ensure a positive result. Epineural neurorrhaphy is a very delicate and complex surgical procedure, conducted by a veterinary surgeon with at least six years of experience in peripheral nerve repair. 

An epineural neurorrhaphy procedure begins will an overall health assessment of the canine patient to ensure the dog is well enough to undergo surgery. On the day of the surgery, the canine will be anesthetized with controlled injectable drugs such as ketamine and xylazine. The area in which the veterinary surgeon has located the damaged nerve will be prepped and draped in preparation for aseptic surgical technique. 

1. Severed nerves will require minimal debridement, therefore, the vet will begin by carefully wrapping the nerve in soft material such as moistened paper, plastic surgical drape, wide umbilical tape, or a Penrose drain. Forceps or a surgical clamp will assist in holding the wrapping material to allow the surgeon to access the nerve segment with ease.  
2. The nerve end is placed on a tongue depressor and transverse cuts are made across the end of the nerve using a razor blade, or scalpel. Lint-free neurosurgical sponges will be used alongside the cutting action to remove excess blood from the nerve end. 
3. The vet will note any longitudinal tension in the nerve, as this tension must be accounted for prior to placing any sutures. If tension is present, the distal limb will be extended to flexed (depending on the specific case) to relieve the tension from the anastomotic site. 
4. The soft wrapping material is then removed and the nerve endings and placed on a light-colored material to enhance visualization for suturing purposes. 
5. The surgeon will position the nerve ends in anatomic contact so that each fascicle on either end of the nerves will align with one another. 
6. Neurorrhaphy is performed with 8-0 to 10-0 monofilament, nonabsorbable suture material using a swaged-on fine taper point microsurgical needle. 
7. With the nerve endings aligned perfectly, the needle is ran through the epineurium of one nerve end to the opposing nerve end, followed by a tie off. 
8. The second suture will be placed 180 degrees from the first, followed by two additional sutures approximately 90 degrees from the previously placed sutures. 
9. The suture line is evaluated for anatomic alignment and security. Any present blood clots will be removed from the area using a moistened lint-free neurosurgical sponge.