Anatomical diagram of Facial Muscles.
Facial Rehabilitation in Patients with NF2
Written by: Omar A. Ahmed, Consultant Plastic Reconstructive and Head & Neck Surgeon
Royal Victoria Infirmary, Newcastle upon Tyne, UK
The majority of people with Neurofibromatosis Type 2 (NF2) develop tumours on the Vestibulocochlear Nerve (the Hearing Nerve, or 8th Cranial Nerve), called Vestibular Schwannomas (VS) or Acoustic Neuromas (AN). These often occur on both sides. Tumours can also develop on other nerves and other parts of the brain.
Vestibular Schwannomas can cause paralysis of one or both sides of the face by direct pressure on the Facial Nerve (7th Cranial Nerve) or, more commonly, by surgery to remove the tumour. In many cases, the facial paralysis is incomplete, and recovers spontaneously to a greater or lesser degree. If there is complete facial paralysis, however, which does not start to recover within a year of onset, surgery is possible to try and restore facial movements.
If one side of the face is paralysed and it is less than 2 years since the onset of paralysis, there should still be potentially functional muscles in the paralysed side of the face. In this situation, a nerve graft can be sutured to a branch of the functioning Facial Nerve (on the non-paralysed side) and passed across to the paralysed side of the face, where it is sutured to the paralysed Facial Nerve. This is called a “cross-facial nerve graft” and the nerve used is usually the Sural Nerve, taken from one of the legs.
If enough nerve fibres sprout down this nerve graft from the healthy Facial Nerve, the function to the paralysed side of the face can potentially be restored to some degree.
Alternatively, the Hypoglossal Nerve (12th Cranial Nerve) can be used to reactivate the paralysed facial muscles, either by suturing one of its branches to the paralysed Facial Nerve, or by using a nerve graft (“jump” graft) between the Hypoglossal Nerve and the Facial Nerve.
Often, a combination of the cross-facial nerve graft and jump graft can be used.
If one side of the face is paralysed and it is 3 years or more since the onset of paralysis, it is unlikely that there will be any residual function in the muscles of the paralysed side of the face.
In this situation a nerve graft alone will not restore function. If the patient is young (less than 50-55) and fit, the best option would be a 2-stage procedure.
The first stage would involve a cross-facial nerve graft as above, followed by the transfer of a muscle in the second stage, at which time the transferred muscle’s own nerve is sutured to the nerve graft. There is usually a gap of at least 6 months between stages. It takes at least another 6 months for the transferred muscle to start to contract.
The choice of muscle largely depends on the surgeon’s experience, but the commonly used muscles are the Pectoralis Minor (small chest muscle) or the Gracilis (inside of the thigh). Should the muscle transfer work, it can potentially restore symmetry to the face and movement of the corner of the mouth. Because the nerve graft is deriving nerve fibres from the opposite Facial Nerve, this technique can potentially restore both a voluntary and an involuntary smile to the paralysed side.
If both sides of the face are paralysed and it is less than 2 years since the onset of paralysis, there is no functioning Facial Nerve on either side, so a cross-facial nerve graft is not possible. There should still be potential function in the facial muscles, however, and a ‘Hypoglossal jump graft’ or transfer can be performed. This can potentially restore a voluntary smile (by pushing the tongue against the teeth) but not an involuntary smile.
If both sides of the face are paralysed and it is 3 years or more since the onset of paralysis, muscles can be transferred to both sides of the face (in 2 separate operations) [‘free muscle transfers’] and their nerves can be sutured to the Masseteric Nerve (chewing nerve) or to a branch of the Hypoglossal Nerve. (Again, the choice of harvested which muscle largely depends on the surgeon’s experience, but the commonly used muscles are the Pectoralis Minor or the Gracilis.)
Alternatively, ‘regional muscle transfers’ can be carried out, transferring muscles used for chewing (Temporalis muscles) to the corners of the mouth.
In both these situations above, a voluntary smile can be produced (by clenching the teeth or pushing the tongue against the teeth), but an involuntary smile is not possible.
All of the above procedures are called “dynamic” procedures because they can potentially restore function to the paralysed face. However, if the patient is not fit for, or does not want, some of these staged procedures, the facial appearance can be improved by “static” techniques, which do not restore a voluntary smile but improve the facial symmetry at rest.
- Facial Reanimation of Patients with Neurofibromatosis Type 2., by: Hadlock T. et al.
- Management of Facial Paralysis after Intracranial Surgery, by: Chen M. et al.