Trigeminal Glycerol Injection
This is done in the operating theatre as a day patient. You will usually be admitted early in the morning and will need to fast after midnight but these times will be confirmed before admission. A CT scan will be done preoperatively. In the operating theatre the anaesthetist will give you some sedation so that the procedure will not be uncomfortable and you will probably not remember much about it. While you are sedated, a needle is placed through the cheek into the hole in the base of the skull where the trigeminal nerve comes out.
The position of this is monitored on a computer using the information from the CT scan. One drop of glycerol (just like glycerine that is used in baking) is then injected into the space around the nerve. The glycerol causes a mild irritation to the outside of the nerve and this is enough to relieve trigeminal neuralgia in approximately 90% of patients. Usually the relief occurs within 24 hours. You will be able to go home later that day and should need no more than one more off work. Your medication should not be stopped suddenly and it is usually best to slowly reduce this over a couple of weeks.
This operation is named after the neurosurgeon who has really pushed the theory that trigeminal neuralgia is due to an arterial loop pulsating against the nerve. He advocates an operation done with the aim of separating the artery from the nerve. The success rate is certainly very high (in excess of 90%) but some people believe that the reason it works is that dissection of the artery away from the nerve causes some minor trauma to the nerve, just like the glycerol injection, and it is this that does the trick rather than the actual moving of the artery.
I usually reserve this operation for those patients in whom a glycerol injection has failed. It is a much bigger procedure and requires a general anaesthetic and up to a week in hospital. An incision is made behind the ear and an opening made through the skull. Using an operating microscope the cerebellum (part of the brain) is retracted away from the skull and the trigeminal nerve is identified as it enters the brain stem. There is almost always a loop of an artery or a vein up against the nerve at this point. This is carefully dissected away from the nerve and either a small piece of muscle or Teflon is placed between the nerve and the artery to maintain the separation. The operation takes approximately two hours and the first post-operative night is spent in the High Dependency Ward. You will have an intravenous drip and a needle in an artery in the arm to monitor your blood pressure. There is usually not much headache but sometimes there may be significant nausea and vomiting for the first day or two. This is probably related to the muscle or Teflon. The day after surgery you will transferred to the general ward and the physiotherapist will get you up for a walk. You will usually be in hospital for five or six days. The neuralgic pain will usually disappear within 24 hours and the anti-convulsants are gradually withdrawn over two weeks.
Are there risks involved?
There are risks involved with anything in life and surgery is no different. Some of these risks are common to most or all operations and some are specific to the particular procedure.
The following are the most common or most serious complications. Other problems may occur rarely and it is impossible to list every one of them. Just try to list all of the possible things that could happen on your drive to work-a car crash is obvious; an aeroplane crashing onto the road in front of you is also possible but extremely unlikely and would not normally be considered common enough to affect your decision to drive. If there is anything in particular that you are concerned about, please ask me.
General risks of any operation
Anaesthetic complications such as heart attack, drug allergy or even death are possible but very rare.
Blood clots in the leg (DVT) or lung (pulmonary embolus) may occur unexpectedly but are very uncommon in otherwise healthy people.
Infections such as pneumonia, wound infection or urinary tract infection may occur after any operation.
Bleeding may occur especially in people taking aspirin. It is therefore recommended to cease aspirin (also called Cartia or Disprin) two weeks before elective surgery.
Specific Complications of Glycerol Injection
In approximately 10% of people the injection will not relieve the pain. The reasons for this are not known.
If the pain is relieved by the injection, there is approximately a 30% chance of it recurring at some time in the future. This may be in a few weeks or after many years and there is no way of predicting this. If the injection has relieved the pain for a reasonable length of time it is possible to repeat it.
Passage of the needle through the cheek may sometimes cause bruising which will gradually go away over a week. Bruising is much more common in people taking Aspirin and it is recommended that Aspirin (Disprin, Cartia) be stopped for two weeks before injection. There is a potential for the needle to introduce infection (meningitis) but this is rare.
It is possible to get an outbreak of shingles on the face. The virus that causes shingles is the same virus that causes chicken pox and anyone who has been exposed to chicken pox during their life will have the virus in their nerves. Anything that irritates a nerve has the potential to activate the virus and cause shingles. The risk of this is approximately 4%. Fortunately there is now an antiviral drug available that is very successful if treatment is started early enough. If you develop a different sort of severe pain in the face with or without a skin rash in the first couple of days after injection, you should see your GP as soon as possible to start appropriate treatment.
Unlike nerve freezing or radiofrequency treatment, the chances of developing facial numbness after a glycerol injection are very small. It is not uncommon, however, to notice a slight difference in sensation between the two sides of the face without developing complete numbness. This will usually improve over time.
Many people are worried about developing facial paralysis but the trigeminal nerve only supplies sensation to the face with the muscles being supplied by a different nerve, the facial nerve. Facial weakness is therefore not seen with trigeminal nerve problems. The trigeminal nerve does, however, supply the muscles that are used to move the jaw when chewing and this can be affected with some other types of surgical treatment for trigeminal neuralgia, but I have never seen it with glycerol injection.
Specific Complications of Janetta Procedure
In up to 10% of people the procedure will not relieve the pain.
Recurrence rates are significantly lower than for injection techniques but are still approximately 10%-15%.
Numbness in the face or weakness of the jaw muscles may occur but this is rare.
Immediately adjacent to the trigeminal nerve are the facial nerve and the auditory nerve. The facial nerve is quite resilient and it is very rare for this to be injured but the auditory nerve is highly sensitive and there is a 5%-10% risk of deafness in the ear on the same side as the pain. Nerve deafness is permanent and cannot be helped with a hearing aid. In view of this I would not recommend a Janetta procedure to someone who has a pre-existing deafness in the other ear as there would then be risk of total deafness.
Nausea and vomiting may occur in the first few days post-operatively but this can be treated with medications.
Coming into hospital for surgery
These days, most operations are done on the same day as admission. You will need to come to the hospital admissions area at the advised time. If you have not already sent in the hospital admission forms, bring them with you.
You will need to fast for 6 hours which means nothing to eat or drink after the time notified.
You will usually be able to take your normal tablets but medications that affect your bleeding will usually be stopped preoperatively. Aspirin, (also called Disprin or Cartia),and Plavix (also called clopidogrel) should be stopped for two weeks if possible before an elective operation. Fish oil should be stopped for a week. Anti-inflammatories should be stopped for 48 hours. Warfarin will need to be discussed with me and your GP.
Make sure you bring your Xrays as these will be essential for most operations. If you cannot find them please let me know early so that they can be repeated if necessary.
If you are staying overnight and would like to have a private room that should be indicated on the hospital admission forms. There are only a finite number of single rooms and sometimes it will not be possible to go straight into one, but if you indicate your preference every effort will be made to move you into a private room as soon as possible. (I do not have any say in this except in cases of medical need eg infections).
I will see you in hospital before you go to the operating room and the anaesthetist will also see you preoperatively and will want to know about your general health and any medications you are on. Please bring your usual tablets with you.