What is masseter to facial nerve transfer surgery
The masseter to facial nerve transfer or trigeminal nerve transfer can significantly improve smile in select patients with facial paralysis. Your surgeon will be able to guide you through the process to see if you would benefit from this procedure. Masseteric nerve brings movement to a chewing muscle, called the masseter on the side of the face. Using masseteric nerve leaves nearly no deficit, because multiple muscles are responsible for that chewing and biting.
A major advantage of using masseteric nerve is that it results in quicker return of movement, usually within 3-4 months of surgery. In contrast, a cross-face nerve transplant takes 6-12 months to grow across the face. In certain time-sensitive situations, where patients have had long history of paralysis with significant wasting of facial muscles, your surgeon may recommend masseter to facial nerve transfer in order to keep your own smile muscles alive. Another advantage of connecting a smile branches to masseteric nerve is the expected decrease in synkinesis in patients who undergo additional nerve transplant surgeries.
The smile obtained from this technique is triggered by biting down. Initially, patients have to think to bite down to smile on the paralyzed smile, but through work with our facial physiotherapists, patients learn to smile more naturally. If a cross-face nerve transplant is performed at the same time as masseter to facial nerve transfer, smile becomes most natural and spontaneous in 6-12 months after surgery.
Patients with paralysis of more than 2 years may no longer have functional facial muscles, because the muscles waste away if they are not used. In rare cases, smile muscles may be removed during cancer surgery. In those circumstances, patients do need both a nerve transplant and a muscle transplant in order to achieve most natural movement on the paralyzed side. Your surgeon may recommend dual nerve transfer to bring most natural smile using both masseter nerve as well as cross facial nerve graft to power the transplanted smile muscle. The muscle from the inner thigh, called gracilis muscle can be used as a free flap to replace missing or wasted smile muscles. A free flap means that the muscle is brought up with its own artery, vein and nerve like a transplant. It is then connected to nerves in the face and the arteries and veins in the neck under a microscope. The muscle transplant then slowly learns movement from the nerve transplant over additional 8-12 months.
When do I need masseter to facial nerve transfer surgery?
Facial paralysis surgery is different in all patients, your surgeon will be able to create a custom plan for your unique situation in order to get the best results. Patients with flaccid facial paralysis of less than 2 years in duration may benefit from nerve to masseter transfer with or without a cross-face nerve graft. If paralysis has been present for over 2 years patients often need both a cross-face nerve graft and a muscle transplant from their inner thigh.
During cancer surgery of the parotid gland or tumor removal operations a segment of the facial nerve may have to be removed with the tumor or cancer. These patients will need substitute nerve transplants during their cancer removal operation in order to maintain facial movement. In order to reduce synkinesis, your surgeon may combine that surgery with masseter to facial nerve transfer surgery if it is safe from cancer treatment perspective. Sometimes cancer that involved the facial nerve may also affect the masseteric nerve as they are located close to each other. If a nerve transplant is performed for a missing piece of the facial nerve, it generally takes 6-12 months for the nerves to regrow. Time to being able to smile again can be reduced by the use of masseter to facial nerve transfer to 3 months.
How do I prepare for masseter to facial nerve transfer surgery?
Prior to masseter of facial nerve transfer surgery, your surgeon may get an electromyography (EMG) study of your facial muscles to determine if you are a candidate for the nerve transfers. Some patients will have a few sessions of facial physiotherapy before surgery to prepare.
What happens during masseter to facial nerve transfer surgery?
Patients are taken in to the operating room and surgery is performed under general anesthesia. Nerve monitoring system is used to help in identification of nerve to masseter muscle. Once identified masseteric nerve is isolated and connected to smile branch of the non-functioning facial nerve. The nerves are hand stitched together under a high-powered microscope using sutures smaller than the size of human hair. Special nerve sheaths are also placed on suture connections in order to facilitate nerve growth. The nerves do not function right away, but the surgery creates new pathways or conduits for nerves to grow and therefore create movement on the paralyzed side of the face.
What are the risks of masseter to facial nerve transfer surgery?
The risks of surgery will vary depending on what nerve transplant or transfer surgery is performed. The general risks of facial surgery include bleeding, bruising, infection, injury to the movement nerves on the donor sites, numbness, the need for additional surgery, chronic pain, numbness, temporary or permanent loss of facial movement on the functional side risks of general anesthesia. Preparing for surgery and following your surgeonโs instructions are useful to help minimize risks.