Trigeminal neuralgia is a condition in which only people who have experienced the pain understand the agony of the neuralgia. The trigeminal nerve is the largest of the 12 cranial nerves and it carries motor and sensory information between the face and the brain. It has 3 branches, each with different functions. Trigeminal Neuralgia occurs when pressure or damage to the nerve causes dysfunction. Symptoms can include sudden, intense facial pain that can feel like an electric shock, stabbing or burning pain. Episodes of pain can last between a few seconds and several minutes. Over time, episodes may become more frequent.
Trigeminal neuralgia is a complex condition with various treatment options including medication, and surgery when medication has failed or has unwanted side effects. Surgical treatment includes microvascular decompression, radiofrequency ablation, or glycerol rhizotomy of the trigeminal nerve. There is no guarantee that surgical treatment will be successful for all patients, and there remains a risk of recurrence of pain at a later date.
Microvascular decompression (MVD) is an open surgery approach that involves a small incision and drill hole behind the ear to expose the trigeminal nerve with a microscope. In many cases, a blood vessel is compressing the nerve. This needs to be carefully freed and moved away from the nerve. Teflon packing is placed between the nerve and vessel and held in place with tissue glue. The membrane linings of the brain are then closed and the bone returned in place followed by closure of the muscles and scalp.
For patients with typical trigeminal neuralgia this is the most effective, most durable treatment option. For patients with atypical symptoms the benefits of surgery tend to be less pronounced but in some cases are still significant. In elderly patients with trigeminal neuralgia the operation remains very effective though the risks of surgery are increased. There is risk of ongoing pain following surgery in 5-10% of patients and recurrence of pain in the longer term in ~30% of patients. The risk of recurrence is higher if no compression or venous compression is identified during surgery.
Radiofrequency ablation (RFA) involves a needle being inserted through the cheek into a small opening in the base of the skull under aneasthetic. When the needle is in place, heat is applied through its tip to carefully damage the trigeminal nerve, thereby stopping pain signals travelling to the brain. This damage treats the facial pain whilst preserving the normal function of the nerve. Patients will usually have slight numbness in the area where the pain used to be and sometimes have some weakness to the chewing muscles.
Pain is treated in 80-90% of patients with typical trigeminal neuralgia but in less patients with atypical pain. The treatment is durable in some patients, but pain recurs in more than 50% of patients at some point during a 10 year period (sometimes after shorter periods of time). The treatment takes about 15-30 minutes and can be repeated in the future if the trigeminal neuralgia returns. RFA can be a better option for high-risk surgical patients and for those whose trigeminal neuralgia is not caused by vascular compression.
Whilst RFA is less invasive than MVD, there is a small risk of experiencing anaesthesia dolorosa after this procedure. Anaesthesia dolorosa is a painful numbness and burning type sensation in the region of the face treated. Anaesthesia dolorosa can be very painful and difficult to treat, but thankfully occurs very rarely.
This procedure is very similar to radiofrequency ablation for trigeminal neuralgia. Once the needle is inserted next to the trigeminal nerve a special thick alcohol is injected which selectively damages the nerve.
The damage is intended to stop trigeminal neuralgia whilst keeping the normal functioning of the nerve, although the treatment does usually cause some mild numbness as well as stopping the pain.
As with radiofrequency ablation there is a small risk of serious complications including anaesthesia dolorosa.