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HeadWay, Issue #084 -- Trigeminal Neuralgia
October 21, 2010
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In this month's issue:
Botox, Motion Sickness, and More
Say what?! Myelin sheath
Trigeminal NeuralgiaTrigeminal Neuralgia (TN), formerly known as tic douloureux is a chronic pain condition in the head. It's estimated that about 1 in 15,000 people suffer from Trigeminal Neuralgia, though it may be more because it's often misdiagnosed.
As the name suggests, trigeminal neuralgia is related to the trigeminal nerve. This is one of the cranial nerves on each side of your head. A malfunction of the nerve causes the pain, but what causes the damage to the nerve?
Though we're not sure about the entire series of events that lead to TN, there are various things that may cause malfunction, including aging, abnormal contact with a blood vessel ("vascular compression"), a tumour or multiple sclerosis (MS). But just because we know some of the apparent causes, that doesn't mean we understand individual causes - in other words, if you have TN, your doctor may or may not be able to find a cause.
If vascular compression is the cause, we call it classical trigeminal neuralgia. If we find another structural lesion, we call it symptomatic trigeminal neuralgia.
Symptoms of Trigeminal NeuralgiaThe attacks of trigeminal neuralgia are brief but incredibly painful. The pain is in the face and may last for a fraction of a second up to two minutes. Sometimes there can be several attacks in succession. The pain has been described as electric shock-like, burning, extreme, sharp, stabbing, intense, crushing. Though for some people the pain can be mild, for many it is the worst pain imaginable and can totally incapacitate the patient.
Usually TN pain is one-sided, commonly on the cheek or chin, often the teeth, gums, lips and jaw, and occasionally the eye or forehead. It can also cause muscle spasm on the side with the pain.
The pain of TN is often the same every time for each patient, and it's often triggered by something. Typical triggers include talking, shaving, washing, brushing teeth, applying makeup, or being exposed to wind.
Though the pain may come in repeated attacks (over hours, days, weeks...), eventually (in some patients) there's a time when there is no pain - in fact, pain cannot even be triggered.
In other patients, the pain continues as a dull background pain.
TN can happen to anyone, even children. However, it seems more common in women, especially women over 50. One you have it, it can get worse and change over time (for example, it may start as various episodes and progress into constant pain).
It's important to get an expert diagnosis of TN, because it can frequently be misdiagnosed (for example, as MS, glossopharyngeal neuralgia, brainstem tumour, etc).
Another challenge is that TN can exist along with another disorder. For example, a cluster patient (cluster headache) may also have TN. Paroxysmal hemicrania is something else that has existed along with TN. In that case you need a proper diagnosis of both so you can have both treated. Once your doctor understands your symptoms, she may call for a full neurological exam and usually an MRI.
Treatment of Trigeminal NeuralgiaTreatment usually starts with drugs, and that is sufficient for many people. Anticonvulsants are most often prescribed first - for example carbamazepine (ie Tegretol, Carbama, Degranol), oxcarbazepine (Trileptal), lamotrigine (Lamictal) or gabapentin (Neurontin). Muscle relaxants are another option.
For temporary pain relief, you may be given a precise alcohol injection.
For patients that don't respond to medication, surgery may be an option. Unfortunately, even when surgery works it may only be temporary. However, many patients have found relief through surgery when they've tried various drug combinations without success.
One typical surgery is gamma-knife radiosurgery (GKR), which involves delivering a focused, high-dose of radiation to the base of the trigeminal nerve (sometimes this surgery is repeated). Microvascular decompression (MVD) actually removes blood vessels that are in contact with the nerve. It's quite invasive but also has a high level of permanent success. A glycerol injection is another very precise surgery in which nerve signals are blocked. Balloon compression is another method of blocking nerve signals. The electric current (radiofrequency thermal rhizotomy) method is a way to actually destroy the nerve fibers that seem to be causing the problem. Radiofrequency thermal lesioning is another way to block pain in the nerve. Sometimes the nerve is actually severed (rhizotomy). Posterior fossa exploration surgery finds blood vessels that may be causing problems (including this type of surgery, either alone or in combination with another, is often the patients best bet - especially if they've already had surgery).
It's important to note that a certain type of treatment will work for one person and not another. It's very important for your doctor to diagnose you properly, and then to clearly understand your symptoms.
Usually, TN is divided into two subgroups. Type 1 is more infrequent pain, whereas type 2 (sometimes called atypical trigeminal neuralgia) is constant pain (and less likely to respond to typical surgical methods). The type of pain may be different from patient to patient as well. Depending on your type of pain and diagnosis, your doctor can chose which treatments are most likely to succeed.
More on how trigeminal neuralgia works, and another Trigeminal Neuralgia Fact Sheet, and finally more specific information on trigeminal neuralgia.
Botox, Motion Sickness, and MoreDon't miss these recent posts at the blog:
Say what?! Myelin sheathA myelin sheath is a protective coating around certain nerves (the nerve axom). Damage to the myelin sheath in the trigeminal nerve can lead to the pain of trigeminal neuralgia.
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