There are two different surgical operations available at The University of British Columbia for TN. The first is a small operation called Percutaneous Trigeminal Rhizotomy (or Rhizotomy for short). The second is a larger operation called Microvascular Decompression of the Trigeminal Nerve (or MVD for short).
The rhizotomy operation is designed to trade the patient’s pain for numbness. We have performed over 1,000 rhizotomies over the last 20 years.
If a patient develops numbness in the same division(s) of the trigeminal nerve where they had their neurlgia (TN), then their pain will be blocked. Some patients already know this because TN can be temporarily blocked by a local anesthetic (e.g. by a dentist’s injection or topical Oragel). The pain will be blocked as long as there is sufficient numbness in the face. Over time, the patient will heal from the rhizotomy and the numbness will fade. Eventually the neuralgia may break through again and the rhizotomy may need to be repeated. How long the rhizotomy lasts is directly related to how strong the post-operative numbness is (and how fast they can heal).
The operation is performed as day surgery (i.e. the patient goes home the same day a few hours later). The procedure is performed in the sterile conditions of the operating room. A brief pulse of anesthetic is given through an intravenous line and the patient is unconscious for a minute. A needle is then introduced through the cheek and up into the trigeminal nerve. An electrode is then placed through the needle so that its tip is touching the trigeminal nerve. When the patient wakes up, we confirm that the tip of the electrode is touching the correct division of the nerve. Small pulses of electricity are sent down the electrode until the patient feels “tingling” in one division of the nerve. The electrode can be moved slightly until the “tingling” is felt in the same division of the nerve that is causing the pain. Once the correct location is confirmed, another pulse of anesthetic is given while the electrode is used to burn the offending branch(es) of the nerve. When the patient wakes up, we check that the nerve has been sufficiently lesioned. They will have numbness in the division of the nerve that was lesioned. Typically a patient will still feel a pin touching their face but it will be described as feel dull rather than sharp.
This type of rhizotomy is called a radio frequency rhizotomy because the nerve is heated with a radio frequency to damage it – i.e. make it numb. Rhizotomies can also be performed by crushing the nerve (Balloon Rhizotomy) or chemically damaging the nerve (Glycerol Rhizotomy) or by shooting radiation throughout the head and focusing it on the nerve to damage it (Gammaknife Rhizotomy). The strengths and weakness of each of these approaches is best described by your personal neurosurgeon.
Two important concepts to keep in mind when talking to your neurosurgeon are:
This operation is quick and effective. It does not have the anesthetic risks associated with the MVD operation and is therefore preferred by older patients or those with poor health. The patient goes home the same day and their TN pain is gone. Most people get used to the numbness and do not notice it after a few weeks. Similar to getting used to ‘a white noise’, their face is still numb but they do not notice it.
Patients are urged to speak directly with their surgeons about complication rates, which can vary among institutions. This operation does not fix the cause of TN – only the symptoms are blocked. Patients will have numbness in an area of the face. This numbness is rarely annoying but in 1% of patients their symptoms can worsen into a syndrome called anesthesia dolorosa. Infection is rare. There are potential problems when treating V1 (forehead) TN because the rhizotomy will leave the eye numb. This means a patient would not feel an eyelash or dirt in the eye and this could lead to a corneal ulcer. There is mild post-operative discomfort (where the needle was placed) and patients can complain of soreness or weakness when chewing. The area of numbness usually gets smaller with time because the nerve heals. If the nerve heals sufficiently, it will begin to pass the TN pain signals again. The operation may then need to be repeated.
You will leave the hospital the same day you arrived (i.e. day surgery). It is important someone come to get you because you will have had some sedation during the surgery and should not drive that day. You will have new numbness in your face – that is the goal of the operation. Most patients (but not all) report that their trigeminal neuralgia is gone immediately. If you are painfree (i.e. no trigeminal neuralgia) you can beginning to reduce your anti-neuralgia medications. There is no set rule for this but my practice is to advise patients that if they are painfree for a week, they can reduce their anti-neuralgia medications by one pill a day. That means if you are taking 6 pills a day for your neuralgia, and are painfree for a week, you can take 5 pills a day for the next week. Each week reducing by one pill will mean that it will take you 6 weeks to get completely off the medications. If you are on two different types of pills (e.g. Tegretol and Neurontin), reduced one pill completely before starting on the second one.
You might have some new soreness in your jaw after surgery. This is probably a discomfort from the rhizotomy needle and responds to typical painkillers like Tylenol. It does not respond to your anti-neuralgia medications.