Classification of chronic orofacial pain using an intravenous diagnostic test

The aim of this study was to evaluate the ability of a preliminary intravenous diagnostic test to classify chronic orofacial pain patients into different subgroups. Patients with chronic orofacial pain conditions that could not be unambiguously diagnosed. A retrospective evaluation of series of conducted pharmacodiagnostic tests, consisting of the consecutive intravenous administration of drugs. Visual analogue scale scores were retrieved from all patients, based on which they were classified into different responder groups. In total, 46 pain profiles were analysed. Of these, 16 patients (35%) could be classified into one or more pain categories, while 30 patients (65%) could not be classified into any pain category. The pain duration or medication use did not influence the classification. Based on the results of this retrospective study, it seems that classification into subgroups is possible after intravenous testing in a minority of clinically unclassifiable patients. In patients where there is a substantial need for additional diagnostic information, these results may be of value. Recommendations are made for further research, which should include validation in patients with known pain mechanisms.