Trigeminal Neuralgia: ouch that hurts!

I recently saw a patient with trigeminal neuralgia. She was in severe pain when she walked in to see me. Trigeminal neuralgia is the condition we shall discuss in today’s post. In the tradition of this blog, I shall keep things simple and free of medical jargon.

So what is trigeminal neuralgia and how does the patient present? As the name suggests trigeminal neuralgia is basically pain in the distribution of the trigeminal nerve. The trigeminal nerve is a cranial nerve which supplies the skin of the face (so when I touch you on the forehead or on your cheek, you are able to appreciate that touch basically on account of the trigeminal nerve). Every nerve starts from somewhere and ends somewhere. In the case of the trigeminal nerve, the nerve originates in the brain (brainstem area) and then courses inside the brain/skull for a while before it exits out and supplies the skin of the face. The nerve also has a motor branch which innervates the muscles of mastication (which help in chweing function). Now if the nerve is compressed/pinched somewhere along its course (usually occurs near the origin of the nerve in the brainstem), it gives rise to a particularly painful and distressing condition which is called trigeminal neuralgia.

Patients with trigeminal neuralgia present with pain. The pain has been described as shooting, stabbing, brief electrical shock like sensations that radiate down into the face. Usually the history is typical. The pain is triggered by touching the face as what happens when the patient attempts to shave or brush his teeth. Sometimes even a gust of wind may trigger the paroxysm of pain. The pain does not respond to conventional pain killers such as ibuprofen (Advil or Motrin) and even stronger pain killers such as codeine and this results in a visit to a doctor.

Frequently the diagnosis may be delayed and the patient may initially consult a dentist since it is wrongly assumed that the pain is dental pain. Patients have undergone root canal and tooth extraction only to realise that the pain was not dental to begin with.

So what causes trigeminal neuralgia? Well the cause usually varies with age. Idiopathic trigeminal neuralgia usually occurs in the older age group. In these patients a MRI of the brain may reveal no gross abnormality (aka there is no obvious tumor found). The thinking behind idiopathic trigeminal neuralgia is that the nerve gets pinched by a tortuous blood vessel. As we grow old our blood vessels (including those inside the brain) become tortuous and thickened. A tortuous artery may press on the delicate trigeminal nerve in the brainstem giving rise to the pain of trigeminal neuralgia. When trigeminal neuralgia occurs in a young person other things need to be ruled out. Is there a tumor in the brainstem pressing on the nerve? Does the patient have multiple sclerosis (a young lady presenting with trigeminal neuralgia is the typical example. In such patients the multiple sclerosis lesion/ plaque is the culprit and presses on the nerve near its origin).

So now lets talk about management. There are two aspects to this. Firstly the cause of trigeminal neuralgia needs to be determined. Your doctor shall order a MRI scan of the brain with and without contrast with close attention at the trigeminal nerve. The idea is to find the culprit blood vessel which is pressing on the nerve and to rule out other lesions such as multiple sclerosis plaque or a small brainstem tumor. Simultaneously the pain has to be addressed. The pain does not respond to conventional pain killers but may respond to medications which are effective for neuropathic pain such as carbamazepine (Tegretol), oxcarbazepine (Trileptal), gabapentin (Neurontin). Other medications which may work include baclofen and amitriptyline (Elavil). My personal experience has been that the pain responds to carbamazepine but high doses are frequently needed. If pain relief is inadequate, I add low dose baclofen.

If the pain subsides well and good. At times I shall only keep the patient under observation and do nothing more (this of course applies to patients who have idiopathic trigeminal neuralgia).  If there is a tumor that is pressing on the nerve then that of course needs to be addressed. If the cause is multiple sclerosis then multiple sclerosis needs to be addressed. There are other options available. Namely:

 

Surgery–the surgery is called microvascular decompression. As the name suggests the idea is to decompress the nerve. The neurosurgeon shall expose the nerve and identify the blood vessel pressing on it. The vessel is then lifted off the nerve thus decompressing the nerve and providing long lasting pain relief. The surgery is not simple. It requires the expertise of a neurosurgeon trained in this procedure. As the trigeminal nerve is hidden deep in the brain, it takes sometime to expose the nerve. Another procedure which is becoming more popular nowdays is radiosurgery. Several reports have documented the efficacy of Gamma Knife‚ stereotactic radiosurgery for trigeminal neuralgia. This though is available only in some centers around the country. Percutaneous procedures are also available. They bascially involve injecting the trigeminal nerve ganglion with chemicals such as glycerol. The idea is to kill the nerve and hence abolish the pain.

I hope some of you find this post helpful.

 

 

Nitin Sethi, MD