Thermographic assessment of neuropathic facial pain

Ongoing pain, intermittent sharp pain, or intermittent dull aching pain around the teeth can evoke the suspicion of tooth pathology. However, when no dental cause can be found clinically or radiographically, the differential diagnosis involving neuropathic pain and pulpal pathology is still a challenge. Neuropathic facial pains are still too often misdiagnosed as tooth pain of dental origin, resulting in unnecessary dental extraction or endodontic therapy. The purpose of this study was to determine if electronic thermography was able to differentiate neuropathic facial pains presenting as toothache from pulpal pathology. Electronic thermography was used to compare asymptomatic subjects and subjects with neuropathic facial pains. Asymptomatic subjects and subjects with trigeminal neuralgia, pre-trigeminal neuralgia, and pulpal pain without periapical pathology showed no thermographic difference in the territory of the pain complaint when compared to the opposite nonpainful side. Patients with sympathetically maintained traumatic trigeminal neuralgia (atypical odontalgia) and half of the group with sympathetically independent traumatic trigeminal neuralgia presented with "hot" thermograms. The other half of the patients with sympathetically independent traumatic trigeminal neuralgia displayed "cold" thermograms in the area of their pain complaints. Electronic thermography was the least selective test for the group showing "cold" thermogram patterns (80% agreement with the thermographic characterization criteria). These data suggest that electronic thermography may be helpful in differentiating neuropathic pains from pulpal pathology.