Trigeminal Neuralgia Turnberg Building Neurosurgery Department 0161 206 2303 All Rights Reserved 2015. Document for issue as handout.
What is Trigeminal Neuralgia (TN)? Trigeminal neuralgia is a very specific type of facial pain. Various descriptions are given to the character of this pain, which includes stabbing, electric shock-like or burning. It is referred to as being lancinating, which means that the pains come in very short-lived bursts, but these can be in rapid succession. The usual trigger for pain is touching the affected area, and this can include touching or washing the face, eating, talking or even a light wind blowing against the face. The pain can affect either side of the face but never travels from one side to the other. TN does not cause numbness or weakness of the face. TN affects more women than men. The majority of people affected are over 50 years old, although young adults may also develop the condition. The trigeminal nerve is the one of the cranial nerves which sends sensory information to the brain from the face. The trigeminal nerve has three branches (or divisions) on each side of the face: l The ophthalmic branch which supplies the area above the eye, the tip of the nose, the forehead and to the top of the head l The maxillary branch which supplies the cheek, upper jaw, upper teeth and gums and the side of the nose l The mandibular branch which supplies the lower jaw, teeth and gums TN pains can result from one or more branches but the middle and lower branches are most frequently affected. When the nerve malfunctions, pain messages are sent at inappropriate times and the pains can be of great severity. The underlying reason for a non-painful stimulus such as light touch being amplified into a severe pain is a breakdown of the insulating sheaths that envelop the individual nerve fibres. This effectively leads to shortcircuiting within the nerve, and the production of electric shock-like pains. In fact, TN is regarded as the most painful condition that is known in the medical world. What are the causes of TN? TN develops because of abnormal conduction or shortcircuiting within the trigeminal nerve. This is brought about by the loss of the insulating sheath that surrounds individual nerve fibres (the myelin sheath). This demyelination is most often a consequence of pressure on the nerve by an adjacent blood vessel. Such an offending blood vessel is likely to have been against the nerve throughout one s life, and it is not clear why it leads to the development of TN in later life. Very occasionally other causes can lead to TN. This includes benign tumours occurring at the base of the brain and causing compression of the trigeminal nerve. Multiple sclerosis can also cause loss of myelin within the nerve without there being compression of the nerve. 1 2
Diagnosis Treatment Non-drug treatment of TN There is no diagnostic test for TN. The diagnosis is based purely on the patient s description of their pain. Any facial pain which does not fit the strict pattern described above is called atypical facial pain. This is important, as atypical facial pain does not respond to the same surgical treatments as TN. Therefore the patient s description of the pattern and nature of the pains is vitally important when it comes to getting an accurate diagnosis. An MRI scan may show a compression of the trigeminal nerve by a blood vessel but even if no compression is visible, the cause of the pain may still be TN. Following a new diagnosis of TN being made, it is important to have an MRI scan carried out. This is mainly to look for a compressive blood vessel against the nerve, but also to exclude the other rarer causes of TN. There are 3 main treatment types for trigeminal neuralgia including medication, surgery and radiation. This booklet will discuss each treatment modality with a specific focus on surgical treatments. Medication Medical treatment of trigeminal neuralgia can be very effective. Many patients will be commenced on a medication that is commonly used to treat epilepsy as they are also very good at controlling such nerve / neuralgic pain. Carbamazepine is the firstline treatment, and is almost uniformly effective in controlling the pain, to the point that response to Carbamazepine is often considered a strong diagnostic indicator. Carbamazepine can result in some significant sideeffects in some people including unsteadiness and drowsiness. This means that other drugs need to be considered The second-line treatment that is usually recommended is a very similar drug to Carbamazepine called Oxcarbazepine. This is not quite as effective, but usually has fewer side-effects. Other drugs that can be used include Gabapentin, Pregabalin, Amitriptyline, Phenytoin, Topirimate, Duloxetine and Lamotrigine. It is important that you take medication as instructed as missing doses or stopping abruptly can cause side-effects or may not control your pain adequately. You may be referred to a pain specialist or neurologist for specific medication management. If this treatment fails or if you are unable to tolerate the medication, then a different modality of treatment may be discussed with you. There are a variety of nonmedical treatment options which are used to treat TN. These vary in terms of how they are performed and how effective they might be. They can be broadly divided into two categories: 1. Decompressive procedures - these involve removing whatever might be pressing against the trigeminal nerve to cause the TN. It is typically a blood vessel, and the operation is called a microvascular decompression (MVD). Rarely it can also be a benign tumour in a few patients. 2. Destructive (ablative) procedures - this means procedures which damage the trigeminal nerve, and relieve the pain in this way. 3 4
Microvascular decompression Microvascular decompression (MVD) is a procedure that is carried out relatively frequently at Salford Royal. The aim is to move away the vessel that is compressing the trigeminal nerve and to hold it away from the nerve to prevent further compression. Although this is the most invasive procedure it is also the most successful with an initial cure rate of over 90%. The surgery usually lasts 2-3 hours and is carried out under general anaesthetic. The surgeon will make a small incision just behind your ear. A small window of bone is removed in order to gain access to the brain cavity. The membranes surrounding the brain are then opened. The trigeminal nerve is found running from the base of the brain (brainstem) to the underside of the skull. At this point, the offending vessel should be visible and the surgeon will gently move it away from the nerve. The blood vessel will then be held away from the nerve by a variety of techniques including using slings and cushions to ensure the nerve remains free of any ongoing compression. The surgeon will then close the wound though the bone defect may not always be replaced. Clips or stitches are used to close the outer layer of skin and a sterile dressing is placed over the wound. The risks of surgery are very low, and serious complications are very rare indeed. However, there are a few risks that go with any brain surgery, and these are a tiny risk of stroke, bleeding in the brain or serious infection in the brain (meningitis). There are also specific risks to the nerves in the region of then trigeminal nerve, and these include: l Partial or full facial numbness (5%) l Hearing reduction or hearing loss (less than 2%) l Facial weakness (less than 2%) l Double vision (usually temporary) (2-3%) The commonest complication is leakage of cerebrospinal fluid (CSF) which is the watery fluid that surrounds the brain. This can occasionally make its way out of the wound, or it can track thorough the bone at the back of the ear and down to the back of the throat. The main significance of such a leak is the risk of infection getting back into the head through the same route. This therefore requires active treatment to correct it, which can include some reinforcing stitches in the wound, a drain being placed in the back or occasionally re-repair of the wound. Recovery after MVD Patients undergoing MVD for this condition are usually monitored in a high-dependency ward bed for the first night. This involves several lines being attached to you that monitor your blood pressure, pulse, oxygen levels and heart rhythm. The nurse will be observing you at frequent intervals initially to observe for changes in your neurology (brain function) and other vital signs. You are likely to be very tired after this operation. This lasts many weeks though is most marked in the first few days. continued page 7 5 6
It is common to have a headache and some wound pain after the operation. The ward nurses will be able to give you medication to help. Most patients also feel dizzy and nauseous. This usually lasts for 2-3 days and, again, the ward nurses will be able to give you medication to ease these symptoms. It is important to start mobilising as soon as possible after this operation. This is usually started on the first day after your operation. You can eat and drink as soon as you feel like it but some patients are a little nauseous initially and a fluid drip can be administered if you are not taking enough oral fluid/ diet. Your monitoring lines will gradually be removed over the course of the first 24 hours after the surgery. It will take a few days to start feeling steadier and for your headaches to settle. Once we are happy with your mobility and assuming you have no other complications, the team will plan your discharge. Most patients will go home between 2 and 4 days following the operation. This is a general figure and some patients require slightly longer. The ward staff will be observing for any post-operative complications, though these are rare. You will be given specific discharge advice by the ward staff or the Specialist Nurse on avoiding complications and who to contact if you are concerned. At home Once you are home it is important that you remember that you are still recovering. Fatigue and tiredness is likely to be a lasting symptom for many weeks. You will need to rest plenty in the first few weeks and avoid all strenuous activity. You should avoid excessive bending, lifting heavy objects, straining on the toilet and any housework in the first 6 weeks. Activity should be kept to a minimum for the first 2 weeks. It is then acceptable to increase activity gradually by taking short walks, and spending more time out of the house. If you are concerned about a CSF leak then you can call the specialist nurse, the ward, your GP, your consultant s secretary or attend A+E. Any watery leak from your nose, ear or wound should be reviewed. You can also call as above if you are concerned about your wound if it is red, hot, raised, painful or leaking fluid. This may be a sign of infection and should be assessed. Headaches and nausea that are infrequent and not worsening are usually expected. If they come with increased frequency, drowsiness, visual disturbance, confusion, vomiting, limb weakness or you are simply concerned, you can call for advice as above. The contact details for the Specialist Nurse are page 13 of this booklet. 7 8
Surgical results It is envisaged that the MVD will be a curative procedure for the majority of patients. Our results for MVDs are as follows: l Complete relief of neuralgia in 91% l Partial relief of neuralgia in 6% l Recurrence of pain only occurred in 3 patients whose trigeminal neuralgia was not related to multiple sclerosis (recurrence rate of 6%) The specialist nurse will follow you up with a telephone call approximately 2 weeks after your discharge. You will then be seen in clinic approximately 6-12 weeks after your discharge. The majority of patients are usually discharged from the service at this point. Destructive (ablative) procedures These are procedures which purposefully damage the trigeminal nerve, which can be a very effective way of relieving TN. These procedures are not as effective as an MVD, but generally are more minor procedures with fewer risks. Destructive procedures are carried out when a patient may not be fit enough for a microvascular decompression or when there is no vessel visible in contact with the trigeminal nerve on an MRI scan, or when a patient prefers this option. The following destructive procedures are available: l Glycerol injection l Stereotactic radiosurgery (SRS) l Partial nerve section Glycerol injection The glycerol injection is carried out under general anaesthetic as a day case procedure. The injection is introduced into the cheek and is guided by X-ray to the nerve as it exits the base of the skull. The glycerol needs to remain in contact with the nerve, and for this reason you need to remain sitting up straight for two hours after the injection. You will usually be able to go home within 4 hours after your return from theatre. The effects of the glycerol are usually evident within a few days of the injection. However, it is important you continue your usual medication until it is clear whether there has been some benefit, and then slowly reduce your dose. With the stated aim of causing damage to the nerve, it is possible that some facial numbness can result from a glycerol injection. This is usually minor and often temporary. Rarely it can be more marked, particularly with repeated glycerol injections. In a tiny number of people, this numbness can even become painful, something known as anaesthesia dolorosa. Other risks with this procedure are as follows: l Bruising to the face and neck l Infection including meningitis (less than 1% risk) Surgical Results Our success rates of a glycerol injection are: l Complete relief of neuralgia in 50% (able to stop all medication) l Partial relief of neuralgia in 38% (able to reduce medication) l A recurrence rate of neuralgia in 1/3 of patients It is very likely that your TN will recur at some point, but the time to recurrence is very variable from a few months to many years. Your consultant will discuss this with you in more detail. 9 10
Stereotactic Radiosurgey (SRS) This is another technique to damage the nerve in order to disrupt the transmission of pain signals to the brain. It involves a targeted beam of high dose radiotherapy which is aimed at the site where the trigeminal nerve exits the brainstem. The treatment involves the fitting of a head frame that stays in place throughout the treatment. The patient then has an MRI scan and based on this, the radiotherapy delivery is planned. Following this the head is secured on a treatment table and the treatment commences. This is usually completed within 30-60 minutes. This is the least invasive procedure for dealing with TN, and does not even require a general anesthetic. It can therefore be the treatment of choice for people with many medical problems which increase the risk from a general anaesthetic. Although radiosurgery is a minimally invasive procedure, there are still some small risks as follows: l Facial numbness and altered sensation (1-2%) l New or worsening of facial pain (1-2%) l Reduction in hearing on the side of treatment (<1%) There are other less likely complications such as loss of taste, altered sensation to the radiosurgery site and facial weakness. The long term pain control rates are very similar to a glycerol injection (see above), although the benefit can be delayed for a period of a few weeks to months. The recurrence rate is also very similar to a glycerol injection. Partial nerve section (partial rhizotomy) This is a relatively uncommon option, which is predominantly used if no compressive blood vessel was seen on the MRI scan. It is also occasionally used for people with recurrent trigeminal neuralgia following a previous MVD who do not have a compressive blood vessel on the nerve. The surgery is done through the same approach as an MVD, with identical risks and recovery. The surgery partially divides the nerve fibres to the lower part of the face, whilst preserving the nerve supply to the eye and the forehead. This is important to reduce the risk of a numb eye, which in turn can lead to scarring of the eye and loss of vision. This inevitably causes facial numbness in the lower face. Its success rate is relatively high, although it is difficult to generalise given how seldom this procedure is carried out, and the complexity of the TN in the patients who have this surgery. Your surgeon will give you a clearer idea of this during your consultation. Reducing medication It is important that you do not stop any medication that you are on for your facial pain without advice from the consultant, specialist nurse or your GP. The reduction should be in a staged manner and you should not just stop taking them. The team will discuss reducing your medication on your discharge. 11 12
Contact details Andrea Wadeson Skull Base Specialist Nurse 0161 206 2303 andrea.wadeson@srft. nhs.uk Alison Dapoto Secretary to Professor King 0161 206 5541 Jane Riley Secretary to Mr. Rutherford 0161 206 0119 Melanie Hellawell Secretary to Miss Ward 0161 206 8340 Useful website and support groups Trigeminal Neuralgia Association http:/www.tna.org.uk PO Box 234, Oxted, RH8 8BE, England 01883 370 214 http://www.patient. co.uk/health/trigeminal- Neuralgia.htm Notes 13 14
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