Nerve Transplant

By Meg Marinis, Director of Medical Research Dec 13, 2012
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Are you worriedly holding your breath for our characters? 

'Cause I am. That's what happens when we do the thing where we leave you hanging. Will Adele be okay? Will Bailey make it to the altar? Will Derek's hand finally be fixed and lead him back to being the world-renowned neurosurgeon that we all know he is? I can't go on because I have the answers to these questions, and I'm not allowed to tell you them without getting into serious trouble. But what I can tell you is…

Derek's previous surgeries had not bridged the gap in his injured nerve.

Back in Episode 902, Callie operated on Derek's hand, grafting a piece of his anterior interosseous nerve to his median nerve, with the goal of restoring function and sensation to his hand. However, after surgery, Derek still struggled with prehension (the ability to grasp with his hand) and pronation (the ability to turn and rotate the hand and forearm). Both Callie and Derek knew that they needed to find another solution to help repair the nerve. And soon. Ideally, these deficits should be operated on within three to six months of the original injury to ensure the best chance that the nerves will regenerate through to the muscles. And Episode 909 marks the sixth month since the plane crash.

After carefully evaluating all of their options, Derek and Callie decided that a nerve transplant remained the best option to replace the damaged part of his median nerve. Replacement nerves can come from cadavers or living donors, but Derek's injury required more nerve length than most cadavers can give. Additionally, if a family member donated a nerve, it would be more suitable for Derek's body, and the surgery could be performed much sooner than if they had waited for an appropriate tissue match. Note: Usually, the only way a doctor would consider a nerve transplant is if all of the patient's own nerves have been destroyed, as in a severe trauma situation.

For the transplant, Lizzie donated a section of each sural nerve.

Located in the lower leg, the sural nerve remains an excellent source for nerve transplant material. Since it is almost entirely cutaneous (close to the skin), the sural nerve can be harvested from a patient's leg without losing any function. Barring rare complications, the harvest procedure is fairly simple and can produce approximately twenty-five centimeters of nerve graft that can be used for the patient's deficit.

After the donor graft has been sewn to the ends of the injured nerve, the recipient's own nerves should eventually regenerate through the transplant to reach their own muscles.

However, similar to patients who receive organ transplants, nerve recipients require immunosuppressants, which bring their own side effects. The effects vary according to the drug combination but generally may include any of the following symptoms: nausea and vomiting, diarrhea, headache, high blood pressure, high cholesterol, puffy face, anemia, arthritis, weakened bones, increased appetite, weight gain, trouble sleeping, mood swings, acne and other skin problems, and hair loss (don't worry, Derek's hair will be fine!). However, one specific anti-rejection medication, the agent FK506, has been shown to be an ideal choice for nerve transplant patients because it also has neuroregenerative properties.

And once the nerves have completely regenerated (which typically occurs within two years), these medications can be stopped.

Are nerve transplants common?

Due to the infection risk of immunosuppressant medications, surgeons prefer to only perform nerve transplants when all other options have been exhausted. More often surgeons advocate the use of nerve transfers to repair nerve defects. Nerve transfers can be described as rerouting a patient's own healthy nerves into areas left paralyzed by damaged ones. Experts have found that simply moving nerve branches to new locations allows the brain to eventually relearn which muscles to signal. For example, take the following situation: A nerve that should bend the elbow becomes injured near the shoulder; a surgeon can take a nearby nerve that runs all the way down to the hand and divide it; the surgeon takes the split branch and sews it to the elbow nerve. After time? That nerve not only still clenches the hand, but it also now bends the elbow.

Peripheral nerve (defined as the nerves in the extremities) reconstruction continues to be an exciting field for research. In addition to traditional nerve grafts, more surgeons have started to incorporate the use of nerve transfers, end-to-side repairs, nerve conduits, and neurotization. In the past, severe limb injuries typically resulted in amputation, but with the growing advances in nerve repair, these injuries now hopefully will be given a second look.

For more information on peripheral nerve injuries, please visit the following link: