Nerve grafting and Nerve transfer
The success in reversing facial paralysis depends on the status of the facial muscles. Paralyzed facial muscles can only be reverse when they have physiologically viable fibers with intact nerve motor units that will respond to ingrowing nerve axons. Innervating such muscles restores tone and movement to the face. On the contrary, atrophic and fibrotic facial muscles are irreversibly paralyzed and will not respond to reinnervation because of several mechanical and physiologic barriers to incoming axons. To restore tone and movement in irreversible facial paralysis, a functional muscle is needed to replace the damaged facial muscles. The length of time a facial muscle is denervated is a rough predictor of the reversibility of the facial paralysis. In our experience based on our peer reviewed scientific research and treatment of over 1000 facial paralysis patients, paralysis of 6 months without recovery is a good predictor of when to intervene.
Various nerves with can be selected to substitute for the function of defective facial nerves. The masseter nerve ( 5th cranial nerve ) is good in restoring facial movement but not always effective is restoring resting tone. On the contrary, the hypoglossal nerve ( 12th cranial nerve ) is effective in restoring tone but not as effective in reproducing facial movement. Facial nerve grafts borrowing nerve fibers from the non-paralyzed face is potentially good in restoring spontaneous facial movement but is not predictably reliable. The positive attributes of the various donor nerve options can be combined to achieve optimal results.
After a parotid surgery, the right facial nerve was completely cut. Nerve grafting with a combination of masseter nerve transfer and facial nerve grafting restored spontaneous movement and excellent tone.