Shirley McCartney, Ph.D.: Can you tell us what you are trying to accomplish with your system for classifying facial pain?

Kim J. Burchiel, M.D.: Trigeminal neuralgia has been known for over 300 years. Despite this long record, there has never been a study done that definitely shows how TN behaves over the life of the patient. The goals of my classification system are not pathophysiologic; they are pragmatic and patient-oriented. My idea is to glean what we can from the history of the patient, and make the best diagnosis possible.

McCartney: How is this system different from other methods of diagnosing facial pain?

Burchiel: Since we are, to a substantial degree, at the mercy of the patient's history and can usually make the diagnosis from the history, my goal is to codify the ways in which we establish the diagnosis by questioning the patient.

McCartney: How did you go about finding the right questions to ask the patients?

Burchiel: I had a feel for the most important questions, and early versions of our questionnaire tested these questions and others. We found that certain questions were confusing or irrelevant, and these were dropped. The 22 that are left all seem to make a difference in establishing the target diagnosis — that being the diagnosis that I would reach after talking to the patient.

McCartney: What role does the doctor have in the process?

Burchiel: The diagnostic scheme effectively takes the physician out of the process — for better or worse. The patient makes the diagnosis by the answers to the questions.

McCartney: Could you explain how it works?

Burchiel: The "rules" of the scheme define the target diagnosis. The rules are more significant than they appear at first. Trigeminal neuralgia is considered a continuum from 100 percent episodic pain to 100 percent constant pain. The only additional rule on TN is that there cannot be any history of trauma, trigeminal nerve injury (accidental or therapeutic), multiple sclerosis (MS) or facial shingles.