Pre-Trigeminal Neuralgia Similar to Atypical Odontalgia: A Case Report

A 68-year-old man underwent extraction of a left mandibular third molar and the mesial root of the left mandibular first molar by a dentist in November 2014 after suddenly developing toothache. In May 2015, he visited our clinic complaining of episodes of persistent pain in the left mandibular first molar, but could not give a clear description of the pain. Evoked pain was absent and there were no abnormal findings on a dental panoramic radiograph. The patient’s pain was diagnosed as atypical odontalgia of the left mandibular third molar and treated with Rikkosan (TJ-110) 2.5 g, followed by 3 times daily dosing. His pain resolved after 6 weeks and the treatment was stopped. In October 2015, the patient returned to the clinic with left mandibular pain suggestive of trigeminal neuralgia. Magnetic resonance imaging of the head confirmed neurovascular compression of the left trigeminal nerve root entry zone. Carbamazepine and baclofen treatment relieved the pain effectively, but were stopped because of side effects. Microvascular decompression surgery was performed in January 2016 and the pain resolved completely. The efficacy of carbamazepine and microvascular decompression surgery in this patient confirmed a diagnosis of trigeminal neuralgia and that this patient’s initial toothache was attributable to pre-trigeminal neuralgia. Pretrigeminal neuralgia should be borne in mind in patients presenting with atypical odontalgia, and their pain should be monitored for changes occurring over time.