Also known as hypoglossal-facial anastomosis, the hypoglossal nerve transfer is performed less frequently these days as more awareness now exists about other options.
The procedure involves transferring all or part of the hypoglossal nerve to the stump of the facial nerve. The hypoglossal nerve supplies the muscles of the tongue and, as a result, the major drawback of this procedure is weakening of the tongue which can affect speech and eating and its overall size. It is for this reason that current efforts aim to only take part of the hypoglossal nerve so that there is still some innervation to the muscles of the tongue. The other disadvantage of this procedure is that extensive retraining is required for the patient to learn to use the hypoglossal nerve to move the facial muscles. For this reason, spontaneous facial movements in response to emotion are very unlikely to occur. Instead, a conscious effort to move the facial muscles will be required which usually requires the patient to push their tongue into the roof of their mouth.
The two most common scenarios to consider a hypoglossal nerve transfer are:
a) As a definitive procedure when a section of the facial nerve has been removed and the end nearest the brain isn’t available to attach a nerve graft to, but the other cut end nearest the nerve branches and facial muscles is available and healthy. In this situation part/all of the hypoglossal nerve would be connected to this available cut end of the facial nerve and the patient would be taught how to use the new nerve to stimulate facial movements.
b) As a temporary measure to maintain the health and function of the facial muscles (‘babysitter’ procedure). When the facial muscles no longer receive innervation from the facial nerve they begin to waste away. After approximately 12-18 months, there is little capacity for the facial muscles to ever work again, even if they start receiving innervation. For this reason, some have advocated using the hypoglossal nerve to ‘babysit’ the facial muscles whilst waiting for a cross facial nerve graft (CFNG) to grow across from the other side of the face. This ensures that the facial muscles remain innervated and, therefore, healthy and functional in preparation for innervation from the CFNG (which will provide better spontaneous facial movement than a hypoglossal nerve transfer in the long-term).
Last reviewed: 20-08-2019 || Next review due: 20-08-2022