What is hypoglossal to facial nerve transfer surgery
The hypoglossal to facial nerve transfer can significantly improve facial tone and eye closure 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. Hypoglossal nerve moves your tongue. Historically, we used to use the whole nerve to bring tone back to the face, which led to the loss of movement on one side of the tongue. Loss of tongue movement on one side frequently led to eating and swallowing troubles after the surgery. A new approach uses one third of the hypoglossal nerve, instead of the whole nerve, in order to bring tone back to the paralyzed face. Using one third of the nerve preserves tongue function simultaneously allowing for improvement in the paralyzed side. Facial tone is important because it helps with resting symmetry of the face.
Overtime, we have also learned that when the facial nerve is connected to the hypoglossal nerve, patients see improvement in facial symmetry at rest and eye closure. However, this nerve transfer alone does not usually result in a good smile. Frequently, we have to combine this procedure with masseter to facial nerve transfer in order to get meaningful smile. Conversely, masseter to facial nerve transfer gives nearly no resting tone, but it is able to provide good smile.
Hypoglossal to facial nerve transfer surgery is usually performed when a direct connection between each end of the facial nerve cannot be established. Candidates include patients who had skull base surgery or cancer surgery where the end of the facial nerve closest to the brain is not available for either a direct repair or a repair with a nerve transplant. Another reason to consider hypoglossal to facial nerve transfer, if there has been no return of movement to the face following paralysis over 1-2 years.
When a hypoglossal to facial nerve transfer is performed, it usually takes 6-12 months to see improvement on the paralyzed side of the face. That is because it takes time for nerves to regrow along a newly created path. Patients usually notice improvement in the appearance of the face at rest and easier eye closure. Following 12 months, patients will continue to have improvement as they strengthen their facial muscles with specialized facial physiotherapy. Patients may still need an eyelid weight for comfortable eye closure. Most patients chose to have a concurrent nerve to masseter transfer and a cross face nerve graft in order to achieve the most natural smile.
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 hypoglossal 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 hypoglossal to facial nerve transfer. They will need to have a special test called electromyography (EMG), that measures muscle activity to ensure there has been no irreversible muscle wasting. If paralysis has been present for over 2 years or there are signs of muscle significant wasting on EMG, 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. Hypoglossal to facial nerve transfer surgery is usually performed when a direct connection between each end of the facial nerve cannot be established. Candidates include patients who had skull base surgery or cancer surgery where the end of the facial nerve closest to the brain is not available for either a direct repair or a repair with a nerve transplant. Another reason to consider hypoglossal to facial nerve transfer, if there has been no return of movement to the face following paralysis over 1-2 years.
How do I prepare for hypoglossal to facial nerve transfer surgery?
Prior to hypoglossal 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. For hypoglossal nerve transfer, patients may need a swallow study or clearance by a Speech Language Pathologist because of a small risk of weakness of the tongue.
What happens during hypoglossal 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 hypoglossal nerve. Once identified Hypoglossal nerve is isolated and a part of it is connected to 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 tone and symmetry on the paralyzed side of the face.
What are the risks of hypoglossal 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, swallowing problems if tongue movement decreases, 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 doctorโs instructions are useful to help minimize risks.