Trigeminal neuralgia, also known as 'Tic Douloureux', is a painful facial disorder. Ordinary triggers such as eating, washing, shaving, cold, heat, and draught, can elicit the pain. Trigeminal neuralgia is subdivided according to the three divisions of the nerve. Trigeminal neuralgia has a huge impact on a patient's quality of life, and social and economic functioning. In persons aged over 50 years, this is the most common form of facial pain.
The exact cause and associated pathophysiology are unclear. Based on clinical observations, it is assumed that compression of the arteries by a tumour near the origin of the trigeminal nerve of the brainstem, known as the root entry zone, plays a causal role. Local pressure demyelinisation occurs, resulting in abnormal depolarisation and ectopic firing.
Signs and symptoms
Short, heavy, sharp shooting attacks, characterise trigeminal neuralgia in one or more divisions of the fifth cranial nerve.
The diagnosis of trigeminal neuralgia is made, based on the following characteristics of the pain: the description of the pain is very important, it must always be flashing and shooting in character and the phrase 'electrical current' must be mentioned by the patient.
When establishing the medical history, the following six questions are important:
- Does the pain come in attacks?
- Are most of the attacks short-lasting (seconds to minutes)?
- Do you have sometimes very short pain attacks?
- Are the pain attacks unilateral?
- Are the pain attacks located in the area of the trigeminal nerve?
- Are there unilateral autonomous symptoms?
In this way, differential diagnosis can be arrived at without delay, and an impression can be formed of whether or not this is classic trigeminal neuralgia.
Neurological examination rarely shows any abnormalities in patients with idiopathic trigeminal neuralgia, but all the cranial nerves should be tested. In patients with neurological disorders, often known as secondary trigeminal neuralgia, trigeminal neuralgia can be a symptom of other diseases, including, for example, cerebellar pontine angle tumours, multiple sclerosis and isolated neuralgias.
Additional Somatic Diagnostics
Once the clinical diagnosis of trigeminal neuralgia has been made, an MRI scan should be performed in order to exclude specific pathology, such as a tumour or multiple sclerosis, known as secondary trigeminal neuralgia. An MRI scan can also be used when decompression of the trigeminal nerve in the posterior fossa is considered. Sometimes MRI scans are sensitive enough to detect blood vessels that are in contact with the trigeminal nerve. The role of venous compression in the pathogenesis of trigeminal neuralgia is still controversial.
- In medication treatment, the first choice is carbamazepine and oxcarbamazepine. Carbamazepine has a pain reducing effect in 70% of patients.
- Other medication, as yet without clinical evidence of efficacy, can be tried, such as gabapentine, pregabaline or baclofen.
Interventional Pain Treatment
If drug therapy is unsuccessful or has too many side effects, invasive treatment can be considered.
There are four possibilities, as follows:
- Surgical micro-vascular decompression in the posterior fossa.
- Stereotactic radio-surgery, gamma knife.
- Percutaneous balloon micro-compression.
- Percutaneous glycerol rhizolysis.