Epineural Neurorrhaphy in Cats

Epineural neurorrhaphy is a technique whereby the connective tissue around a lacerated nerve is sutured so as to close the gap between the ends.

The word "neurorrhaphy" refers to suturing a divided nerve, whilst "epineural" refers to the connective tissue surrounding the nerves.

The idea of epineural neurorrhaphy is to hold the separated ends of the nerves in apposition in order to give them the best chance of healing. In some respects, this is analogous to putting a plaster cast around a broken limb to allow the end of the fractured bones to knit together. 

This technique may be used in general practice as a salvage procedure when lacerated nerves are identified as a complication of a road traffic accident. 

In the case of a traumatic injury, nerve damage can be difficult to identify in a cat that is in pain and not bearing weight on a limb because of fractures. A transected nerve may then be detected visually during open repair of the fracture. 

Under aseptic conditions and with the patient under general anesthetic, the surgeon identifies and localizes the two ends of the lacerated nerve. Using fine forceps, the ends are drawn together and then fine sutures placed through the connective tissue of the nerve sheath in order to pull the ends together. 

If the injury is not fresh, the surgeon needs to debride the exposed ends of the nerve, in order to remove scar tissue. The latter could prove a barrier to the progress of healing cells travelling along the nerve. 

There are no hard figures for the success of epineural neurorrhaphy, but it should be regarded as a salvage procedure and hopes of fully recovery kept low key. When successful healing of the nerve progress at around 1mm per day, so it can be several weeks before improvement in sensation to the affected area is noted. 

Recovery from the surgery is likely to be governed by the severity of the inciting trauma. Repair of fractured bones or internal injuries sustained during a traffic accident are likely to be the limiting factors and may take weeks to months. 

Since the aim of neurorrhaphy is to regain sensation, this implies there is a loss of feeling to the affected area. With this in mind, rest is advisable since the area may easily be further traumatized by the cat being unaware of hazards such as extreme heat or cold, caustic substances, or indeed hazards that could trap a denervated limb. 

Epineural neurorrhaphy is likely to be carried out as part of a larger surgery for fracture repair or to suture lacerations. As such, these surgeries range from $700 to $4,000 depending on the type of surgery or fracture repair and the methods necessary for reconstruction.

Investigation of different neurorrhaphy techniques is more advanced in human medicine than in veterinary science. In the human field, techniques such as nerve grafts and stem cell therapy are under investigation in order to improve the chances of nerve regeneration. 

Unfortunately, nerve healing is notoriously poor. This is because scar tissue formation can disrupt the transmission of nerve signals. Thus, although the nerve is physical joined together, it no longer efficiently conducts the nerve impulse. Other factors that inhibit nerve repair include a changed microclimate around the ends of the damaged nerve which discourage orderly reorganization of the cells. 

This is a case of prevention of trauma being preferable to the need for a salvage procedure such as epineural neurorrhaphy. This means taking practical steps to protect the cat from trauma, such as keeping the cat indoors or only allowing them outside under supervision.