Anterior Belly of Digastric Transfer

The paralysis of the lower lip affects the downward depression of the lower lip whilst speaking or laughing and sometimes because of that biting of the lower lip can be a problem in addition to asymmetry.

If you have permanent paralysis of the muscles that move your lower lip, you may be offered a procedure to recreate this movement. The anterior belly of digastric muscle is one of the operations that can achieve this.

This webpage explains more about the procedure and what to expect, including the benefits, risks, any alternatives and what you can expect when you go to hospital.

If you have any further questions, please speak to the doctor or nurse looking after you.

What is an anterior belly of digastric muscle transfer?

This is a procedure to try and improve the position and movement of the lower lip. In patients with permanent paralysis of the muscles that move the lower lip, they will have asymmetry between the two sides of the lower lip both at rest and when they smile.

The anterior belly of digastric muscle sits underneath the chin. It can be used by surgeons to improve the symmetry of the lower lip as there are several other muscles in the same area that can perform its function. As a result, you won’t notice any problems with movement after the muscle has been used in this operation.

The anterior belly of digastric muscle is supplied by a nerve that is separate to the facial nerve. Therefore, even if you have a complete loss of your facial nerve function, this muscle will still have a seperate nerve supply allowing it to be used for this operation.

However you can also have the procedure done in two stages, as you can transfer fibres from the contralateral facial nerve transferred with a cross face nerve graft, followed by the muscle transfer at six months or longer following the first stage. This technique will ensure more symmetry during spontaneous smile – as the nerve graft is connected to the nerve of the muscle.

Who is a suitable candidate?

This procedure is suitable for those who have a facial palsy that will not recover. Typically, surgeons will wait around two years to be sure that there are no signs of recovery before offering this procedure.

Another factor to consider is that this procedure is permanent. Often surgeons will recommend that the patient try some Botox injections into the muscles of the lower lip on the healthy side at first to see if the patient wants to proceed to an operation that will aim to permanently improve the symmetry of the lower lip. Other options are myotomies or neurotomies to the lower lip on the good side, to achieve symmetry by paralysing the whole lower lip.

What are the risks?

In general the risks of any operation relate both to the anaesthetic and to the operation itself. The operation is performed under general anaesthetic, which means that you are asleep throughout. Your anaesthetist will go through the risks relating to the general anaesthetic with you before the operation.

Before suggesting the operation, your surgeon will have considered that the benefits of the procedure outweigh any disadvantages. However, in order to make an informed decision and give your consent, you need to know and be aware of the possible side effects, risks and complications. These include:

Bleeding and haematoma: If bleeding occurs after the surgery, it creates a collection of blood underneath the skin called a haematoma. If this occurs, you will notice worsening swelling and bruising around the chin and lower lip and should seek urgent medical attention. This is a rare complication.

Infection: All operations are at risk of causing an infection. This can occur in around 2-5% of these operations. You should look out for increasing pain, redness and fluid discharge from the wound and fevers as a sign that you may have a wound infection. This will require antibiotics and possibly re-admission to hospital.

Scars: Wherever a cut is made, a scar will form. To begin with the scar will become red and raised, but over the coming two years it will continue to soften and flatten. On occasions, scars can remain thick and raised and in this situation the surgeon will offer you some treatments to try and reduce this. In all cases, it is important that you massage the scar a couple of times a day once the wound has healed to help soften the scar. This should be continued for two years.

Asymmetry: The side of the face that has been operated upon will never move in exactly the same way as the normal side. This is because the muscle being used has been moved from its normal position. In some patients you may only notice an improvement in the position of the lower lip at rest, but may still have asymmetry when you smile. Despite this, in many patients excellent results can be achieved.

Are there any alternatives?

This is not a life-saving procedure and, therefore, the main alternative is to have no surgery at all. If you have decided that you would like surgery to improve your appearance and the function of your lower lip, other alternatives do exist. Broadly speaking, these can be split into those that aim to create movement on the paralysed side of the face or to reduce movement of the lower lip on the healthy side. Often your surgeon will suggest first trying some Botox treatment to paralyse the muscles on the healthy side of the face. Botox requires further treatment to maintain the effect every 3-6 months. This will improve the symmetry of the lower lip.

If you are seeking a more permanent solution the main other options include cutting the muscle on the healthy side or bringing in a muscle from elsewhere to recreate movement on the paralysed side of the lower lip. The later options are more extensive and will require a longer hospital stay and recovery with an increase in the potential risks of surgery.

How can I prepare for an anterior belly of digastric transfer operation?

You will need to take time off work for the surgery. After the operation you will normally require around one week off work to recover. You should avoid heavy lifting and exertion for at least one month.

Any sports should be avoided for one month and you should try to stop or cut down any smoking in the lead up to the operation and for the six weeks following surgery. Smoking will increase the risk of the muscle not working and the wound not healing.

With this being an operation performed under general anaesthetic, you will need to avoid any food in the six hours before surgery. You may drink water up until two hours before surgery.

Prior to coming in for surgery you will most likely be seen in a pre-assessment clinic. In this clinic they will go through any other medical problems that you have and list any medications that you take. Advice will be given on which medications to stop before surgery.

What does the surgery involve?

This operation is done under general anaesthetic so you will be asleep throughout the procedure which is about three hours in duration. Although an overnight stay is recommended, on some occasions you will be able to go home on the same day as the operation.

The surgeon will make a cut on the underside of the chin on the paralysed side to find the anterior belly of digastric muscle. The nerve and blood vessels going into the muscle are carefully identified so that the surgeon can be sure that these are still present. The muscle is then detached from the cartilage near your voice box so that it is then only attached to the chin itself.

A separate cut is then either made on the outside or inside of your lower lip on the paralysed side and this depends on the surgeon’s preference. The muscle is then passed underneath the skin from the chin to the cut in the lip and then stitched into its new position at the bottom of the paralysed lower lip.

At the end of the operation the cuts will be stitched and a dressing will be placed on the underside of the chin and some ointment put on the cut made in the lip.

Will I feel any pain or discomfort?

After the surgery it is likely that you will feel some pain, although you will be given a number of different painkillers to reduce and ideally remove this pain. The pain is normally around the wounds themselves and should begin to subside in the first 72 hours after surgery. You will be discharged from hospital with some strong tablet painkillers that should control the pain. If you find that the pain is increasing whilst at home, please contact your surgical team or the ward you were discharged from.

What happens after the surgery?

You should expect the lower face and chin to be swollen after the surgery and this may take a couple of weeks to fully subside. Some bruising is expected.

Will I have a follow-up appointment?

Your surgeon will make arrangements to see you around one week after leaving hospital to check that all is well with the wounds. They will also arrange an appointment to see you in their outpatient clinic at which point you will be given guidance on the exercises you should begin to practice to help the muscle start to work in the correct way. This will be done with the help of a physiotherapist experienced in managing patients with your condition.

What should I do if I have any concerns?

If, following the surgery, you have any concerns you should contact your surgical team or the ward that you were admitted to during your stay. They will then be able to give you further advice on what to do and whether they need to see you back at the hospital or not.