What is it?
Trigeminal neuralgia, also known as “tic douloureux,” is a pain of particular pattern affecting one side of the face. Women are twice as likely to be affected and average age of onset is 63 years old with an incidence of 4/100,000.
The pain is described as recurrent, intermittent, sharp, lancinating pain lasting a few seconds. Usually, it afflicts the upper and/or the lower portion one side of the face (V2 or V3 distribution of the trigeminal nerve), rarely the eye and forehead. The pain is triggered by sensory stimulation of the affected region such as touch, brushing teeth, chewing, talking, or even wind blowing over the cheek. Often, patients will have teeth pulled, erroneously thinking that will solve the problem.
No numbness to pinprick is appreciated in the affected distribution of the trigeminal nerve. The area may seem hypersensitive due to triggering trigeminal neuralgia. If numbness is present, then it is not trigeminal neuralgia.
Magnetic resonance imaging (MRI) will be normal. Abnormalities in the scan may suggest an alternative diagnosis.
Why does this occur?
No one really understands the answer to this question. In most cases, the trigeminal nerve is under vascular compression from an artery next to the brainstem. The trigeminal nerve provides sensation to the face and takes its origin from the brainstem behind the ear. Herpes zoster, multiple sclerosis, tumors, dental disease, etc., can cause facial pain, but this is usually called “atypical facial pain” and not trigeminal neuralgia.
Carbamazepine (Tegretol) is the first line medical treatment of choice. Up to 69% of patients can get relief. Dosing of up to 800 mg/day is necessary for success. Complications at this dosing are common and include nausea, drowsiness, rash, Stevens-Johnson syndrome, and leukopenia. Dosing is increased during periods of increased frequency of attacks, and can be decreased or stopped during pain free periods. Other drugs such as baclofen, neurontin, capsaicin, clonazepam, and lamotrigine can be tried but with a much lower success rate.
Microvascular decompression (MVD) is the treatment of choice for those who do not respond to medication. A small craniectomy (opening in the skull) is made just behind the ear. With the aide of a microscope, a loop of artery is usually found compressing the trigeminal nerve. An Ivalon sponge is placed between the two to separate and protect the nerve. The procedure is fairly quick, well tolerated, and has a low rate of complications relative to other procedures in this region of the brain.
Other surgical approaches include percutaneous trigeminal rhizotomy. This involves burning (ablating) the nerve and results in severe numbness of the face. Recurrence rates are very high and directly proportional to the degree of numbness achieved. Too much numbness can result in “anesthesia dolorosa”, a severe constant pain refractory to all treatment. Glycerol injections, temporary nerve blocks, and peripheral neurectomies are options though not popular amongst most neurosurgeons. Stereotactic radiation is another option with delayed affect, post treatment numbness, and relatively low success rate compared to MVD.
Outcome of MVD
MVD is the best option for most patients offering the highest long term success rate (70% have relief at 10 years). Recurrence may respond to medical treatment or require repeat surgical treatment. Trigeminal neuralgia is treatable and patients should pursue the best treatment option suited for them.
Whatever the neurosurgical approach, we have the latest techniques available to us for your benefit. Minimizing surgery and maximizing outcome is our goal. We have the clinical experience for great outcomes with a personal touch.