Trigeminal Neuralgia (TN), characterized by paroxysmal lancinating or electric shock-like pain in the distribution of one or more divisions of trigeminal nerve, is one of the most devastating neuropathic pain conditions. TN can be triggered by innocuous stimuli on the face or intraoral trigeminal territory. The incidence of TN is estimated to be 12.6-28.9 per 100,000 person-years¹, higher among women than among men, and tends to increase with age.
TN pain symptoms are most common in the V2 (maxillary) and V3 (mandibular) divisions. Etiologies of TN can be idiopathic or secondary to underlying vascular or tumor impingement, multiple sclerosis, post-herpetic neuralgia, trauma, or dental injury². Although paroxysmal facial pain is the hallmark of trigeminal neuralgia, 24 to 49% of patients report continuous or long-lasting pain between paroxysmal attacks with unclear etiology². Facial pain in the areas that are not innervated by the trigeminal nerve suggests an alternative pathology under the category of “atypical facial pain” or “painful trigeminal neuropathy.”
Challenges
TN can have a significant negative impact on patients’ quality of life. Suicide in severe cases has been reported. Importantly, there is often an initial response to pharmacological treatment, followed by a later refractory period to medication. Many eventually require invasive interventions including surgery.
Treatment Recommendations
The sodium channel blocker carbamazepine is considered the drug of choice with an initial efficacy of 80% in treating pain. Other commonly used medicines include baclofen, gabapentinoids, tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, and opioids, but maintain weak clinical evidence to support effectiveness of these agents in TN. Many eventually require microvascular decompression (MVD) for vascular compression³, stereotactic radiosurgery, balloon decompression, glycerol rhizotomy, or radiofrequency ablation (RFA) of the trigeminal root or ganglion². Peripheral nerve treatments such as nerve block and ablation with easy access and limited risks, can also be considered for relieving TN pain symptoms, although the long-term evidence remians unclear.
Special Considerations
The Food and Drug Administration now recommends screening for the HLA-B*1502 variant in patients of Asian descent prior to starting carbamazepine due to increased risk of Stevens-Johnson syndrome⁴.
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Chen P, Lin JJ, Lu CS, et al. Carbamazepine-induced toxic effects and HLA-B*1502 screening in Taiwan. N Engl J Med. 2011;364(12):1126-1133.
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