What are the different causes of head trauma?
- Road traffic accidents
- Home and occupational accidents
- Bicycle or horse riding accidents
Why does head trauma cause facial palsy?
Skull fracture to the temporal bone (through which the facial nerve travels) is responsible for causing facial palsy. This is because the facial nerve travels through a small bony channel where the nerve can get crushed either by a blow to the head, or the swelling afterwards. This can result in temporary or permanent damage to one or both of the facial nerves.
What sort of fractures to the temporal bone cause facial palsy?
- The most common type of fracture to the temporal bone is a longitudinal fracture (a fracture that follows the long axis of the bone). A longitudinal fracture accounts for 80 per cent of all temporal bone fractures. These fractures are caused by a blow to the side of the head. The fracture tends to run along the base of the ear canal; this can result in a ruptured eardrum and bleeding from the ear can occur.
- Less common is a transverse fracture of the temporal bone (a fracture at right angles to the axis of the bone), seen in approximately 20 per cent of cases. These tend to be more serious, as the force needed to cause such damage is intense. There is a strong likelihood of ear damage as often the fracture will affect the inner ear area, resulting in hearing loss and balance problems.
What are the symptoms?
The complicating factor in head trauma is that commonly, other life-threatening issues are occurring, and require a great deal of time and attention before the temporal bone fracture is addressed. Moreover, a good assessment of facial function requires a cooperative patient, and many patients are in a coma following head trauma, making thorough examination of nerve function impossible.
In the first stages, there may not be any obvious symptoms that the facial nerve has been damaged. This is because medical staff may be busy preserving life, or the person may be in a coma, or under anaesthetic. In these circumstances there may be no facial movements to observe, and therefore any weakness in the facial muscles or facial movements will go undetected.
Symptoms of facial nerve damage or facial paralysis are usually one-sided, but damage to both sides of the skull can occur in rare circumstances. The symptoms will be as follows:
- Difficulty or inability to blink or close the affected eye.
- Difficulty or inability to carry out a range of facial movements and/or expressions, such as smiling, whistling and frowning.
- Difficulty chewing food, or losing food from the corner of the mouth.
- Difficulty drinking, with fluids leaking from the corner of the mouth.
- Difficulty speaking.
See symptoms of facial palsy for more information.
How can damage to the facial nerve be diagnosed?
- It can be difficult for medical or nursing staff at first. They may be concentrating on life support or other injuries in the early hours following injury.
- Commonly, it is not the fracture to the temporal bone itself that causes damage to the facial nerve, but swelling within the tight bony canal through which the nerve runs. Since there is no room for swelling to occur, the nerve gets ‘squeezed’ within the facial canal, leading to nerve malfunction. In this situation, usually the facial muscles are working normally right after the injury, but become weak over several hours or days, as the swelling develops.
- Computerised tomography (CT scan) of the brain or magnetic resonance imaging (MRI) of the brain may identify damage to the facial nerve.
- Regular observation by medical and nursing staff will allow them to notice whether facial movement is the same on both sides.
- Regular observation will alert staff to any problems the patient may have with eye closure or blinking.
What are the treatments in the early stage following injury?
- Medication may be given to reduce the swelling.
- An operation called ‘facial nerve decompression’ may be carried out to relieve the squeezing or pressure on the nerve. However, some clinicians feel that this is an unnecessary procedure because in many cases the pressure on the nerve will recover by itself.
- The main concern in the early stages of recovery is that the eye is protected if blink and eye closure have been affected. Administration of eye drops to keep the eye lubricated is essential. Taping the eye closed at night or when sleeping will also be essential in maintaining a healthy comfortable eye and to preserve vision. See the dry eye patient guide for more information.
What are the treatment options available in the later stages following injury?
- Facial rehabilitation involves a wide range of treatment options including physiotherapy and speech and language therapy.
- Each person is individual and treatment options will vary according to your symptoms and circumstances.
- Certain surgical procedures may be available to help with eye closure and smiling.
Last reviewed: 31-07-2019 || Next review due: 31-07-2022