An older female patient reported to the Oral Surgery clinics with a complaint of electric-shock like pain on the facial region. She pointed to a region on the face where any contact would elicit the pain. It was on right cheek. The pain lasted for a few seconds. The patient had extracted the teeth in that site over a period of time. She had a stroke a couple of years ago and had paralysis on the left side of the face and weakness in the upper limb. She was using medication for hypertension and was using anticoagulants to prevent future strokes. She was severely disturbed by her symptoms.
The condition was rightly diagnosed as trigeminal neuralgia by her physician in a different city who gave her 400 mg of Carbamezapine (200 in the morning and 200 before bedtime). Although the medication helped relieve her symptoms, the side effect of dizziness became intolerable, so she had to stop using the medication.
When she came to me the surgeon was already contemplating temporarily anesthetizing the infraorbital nerve through a glycerol injection. Another doctor had suggested using 75 mg of Lyrica (Pregabalin) twice a day. She tolerated the medication well but called me two days later saying that the pain was still there. Another 75 mgs was added in the afternoon and the patient was asked to give the medication at least a week to start acting. She called the next day saying that her symptoms were under control. The patient is continuing this regimen. She follows up 2-monthly by a personal visit or through phone call.
Trigeminal Neuralgia:
Trigeminal neuralgia is a type of neuropathic pain, which means that the nerve is messed up somewhere along its path resulting in the pain sensation. The cause of the damage to the nerve is usually unidentifiable. The criteria for diagnosis is fairly simple, electric-shock like pain, along the course of the trigeminal nerve, elicited on contact with a "trigger zone". All three of these features were reported in the case we discuss above.
Although any three of the trigeminal branches can be affected, the maxillary branch is most commonly involved, like in our case. The affected population is usually comprised of individuals over the age of 50.
Because the initial symptoms may be more sporadic, the condition is usually misdiagnosed as an odontogenic problem. This results in most patients going through repeated endodontic therapy and extractions at the site of pain. Once the classic symptoms set in and the patient is seen by an oral pathologist, oral medicine expert or a neurologist, the teeth in the vicinity of the pain are all missing. We witnessed this in our patient.
Management of the disease can be complex. It is important to inform the patient that the drugs for this condition work differently than other analgesics. The pain will not stop in a few hours, it may take up to a week for the medication to begin working. It is also important to start from the minimal dose up, for Carbamezapine, the most popular drug used for management of this process, it is 200 mg (100 in the morning and 100 before bedtime). Other medications that can be used are Pregabalin, Gabapentin and Phenytoin. When the medications fail to work, we have to rely on surgical options.
Glycerol injections are sometimes used to temporarily anesthetize the nerve at the site where it exits the skull. It is a risky procedure because it can result in uncontrolled damage in the area. It may also cause only partial damage to the nerve causing dysaesthesia. The effects of the injection last about 3-6 months. So this is not something to favor over medical therapy.
Other surgical procedures include microvascular decompression of vessels impinging the nerve in the skull, application of heat to sever the nerve through gamma knife procedure and neurectomy. The success of these procedures varies between 70-80%.
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