Untangling the Mysteries of Facial Pain

Last year, more than 2,000 new patients turned to the School of Dentistry’s TMD, Orofacial Pain, and Dental Sleep Medicine Clinic for answers to undiagnosed conditions and relief from life altering pain.

In 1980, the School of Dentistry established a first-of-its-kind clinic to diagnose and treat orofacial pain within a comprehensive, interdisciplinary patient care setting. In 2020, the clinic celebrates its 40th year.

Dentistry magazine talked about the TMD, Orofacial Pain and Dental Sleep Medicine Clinic with Don Nixdorf, DDS, MS, director of the dental school’s Division of TMD and Orofacial Pain. There was one obvious question to ask:

Dentistry Magazine: The clinic has been around for 40 years. What do we know now about orofacial pain that we didn’t know then?
Don Nixdorf: Historically, dentistry associated the symptom of pain with an infection or a mechanical issue. We now recognize that the pain experience is modulated by a number of biological mechanisms and psychosocial factors.

So, for example, we know that the pain experience, especially when chronic, involves changes of the sensory system and that these changes can heighten the patient’s ability to sense pain even in the absence of injury, disease or other changes in the tissues. We understand that the modulated pain involves multiple pathways, some that enhance and some that diminish the experience of pain. There also is an awareness of the potential for interactions between the immune system, as well as the microbiome, and the nervous system to produce pain.

What about the psychosocial variables? Psychological states––things like expectations and past experiences, emotions, fatigue, fear, etc.––affect how people experience pain. So much so that we now know pain to be a personal, private experience that is unique to each individual. That insight alone redefines treatment and influences outcomes because chronic pain can lead to maladaptive behaviors that perpetuate the pain. There also is a well-founded understanding that sleep disorders and pain are strongly associated.

What do sleep, TMD and painful knees have in common?  Pain can be accompanied by co-existing factors, including mood disorders (depression and anxiety), chronic pain, and disordered sleep. Diagnosis and treatment of chronic pain is a multidisciplinary endeavor because it can be a symptom of a disease or a disorder unto itself. The complaint of painful jaws and knees is an important clue, because it is a possible sign of a more general heightened sensitivity to pain.

How so? Pain in multiple locations suggests dysfunction of the sensory system and/or an underlying systemic disease, such as psoriatic arthritis, which can affect joints throughout the entire body. Disordered sleep and ongoing painful inflammation results in nervous system changes and hypersensitivity. Because we find that patients with serious facial pain have multiple overlapping pain disorders, we work with a wide range of professionals. For example, psoriatic arthritis is best treated by a rheumatologist.

Tell us more about your patients. Often, our patients have been in pain for months or years. Some might be suicidal…and we’re rarely the first provider they’ve seen. For pain in the face, it is not uncommon for patients to have consulted a primary care physician, ENT specialist, and their dentist. Most patients have pursued reasonable but unsuccessful discipline-based treatments with other providers. Our patients have dealt with ongoing pain, delays in appropriate treatment, medical complications, depression, anxiety and isolation.

Why isolation? Facial pain limits what people can do together and how they understand each other. We talk and take communication cues from facial expressions, feed ourselves and socialize over food, and we are intimate with our faces. But for some patients with chronic facial pain, a touch of the cheek can be torture. Chewing food can be a trigger for their pain. Many patients report fear that their pain might manifest at an inappropriate moment and result in embarrassment. So they avoid meals with friends and limit their social and  professional life. Fatigue, associated with the chronic pain itself, as well as the medications used as treatment, makes routine activities difficult and is yet another reason to limit social interactions.

What conditions do you treat? We treat patients with chronic orofacial pain, which is pain in and around the face, mouth and jaws that has lasted more than three months. That includes patients with musculoskeletal pains associated with the muscles of mastication, temporomandibular joints, and supporting structures.

We also treat neuropathic pain, the result of infection or injury, or dysfunction of the central nervous system, such as multiple sclerosis. Trigeminal neuralgia (TN) is one neuropathic pain disorder we see. Patients with TN will often turn first to their dentists, who have become adept at identifying the condition and refer patients to our clinic. We treat patients with neurovascular disorders, better known as headaches––such as tension-type, migraine, cluster, medication overuse, etc. We also are involved in managing patients with sleep disordered breathing problems––like obstructive sleep apnea––and movement disorders such as oromandibular dystonia.

What are the greatest challenges? There’s a need for greater awareness of orofacial pain disorders so that patients who have chronic pain are recognized earlier and referred for appropriate care. Too often, patients receive ineffective treatment or the “I don’t know” diagnosis. At our clinic, we are diagnosticians first and that’s the greatest challenge. It’s our job to figure out what’s going on and provide assurance, when we can…that it’s not cancer or that we’ve seen this before or that we can provide answers and help with the next steps. We triage, treat, refer, and/or collaborate with other providers to reduce pain, improve function, and prompt independence in patients with chronic orofacial pain and related symptoms.

How do you differentiate between disease and dysfunction? When it comes to pain as a symptom of disease, we are talking most often about inflammation. But when pain is the result of dysfunction of the sensory system, there are no objective measures by which to diagnose. Absent objective measures, we rely on self-reported symptoms and these are affected by the patient’s mood, personality, and ability to communicate. In that way, we’re like psychiatry and psychology.

What are your goals for that first appointment? To establish a relationship of trust, truly understand the patient’s chief complaint, discuss expectations, and complete a thorough evaluation. Information is the key to deciphering complexity and the ‘gold’ is in the history taking. We pay close attention to what’s said and not said, to how people perceive and report pain, and to findings of previously consulted care providers. We ask questions three and four different ways because patients might not think, at first, to mention something they do not associate with their primary complaint.

What does that involve? An extensive history of the pain complaint(s), which includes pain characteristics; an in-depth understanding of familial, social, and psychological histories; and the patient’s medical and surgical histories. We follow this with an examination––touch, pressure, pin prick, perception, muscle movement, palpation sensitivity, symmetry, etc. If the report is of jaw pain and their chief complaint is replicated when we palpate the muscles, we know that muscle reproduces the patient’s pain. If there is percussion sensitivity in a tooth…then we might think of periapical inflammation, but also referred pain from the masticatory muscles. We also use quite a lot of diagnostic imaging, mainly to rule out known causes of pain. It’s like putting together the pieces of a puzzle.

Then what happens?  If it’s determined that the pain is a symptom of inflammation from a disease process and I don’t see dysfunction, I’ll refer the patient to the most appropriate provider. For sinusitis, I’ll talk to our ENT colleagues. If it’s tooth-related, we can refer to a general dentist or specialist.

If we see dysfunction then the approach is to understand the major contributing factors involved. Using an analogy…contributing factors are like gasoline for a fire. So, first, we stop fueling the fire. Once the contributing factors are identified and addressed, sometimes the dysfunction resolves but almost always is greatly improved. This is when targeted treatments to modulate the dysfunctional nerves are used, if they haven’t already.

Is it true you once diagnosed a condition by looking at a painting?  No (laughing). But seeing the painting was an ‘aha’ moment. An artist patient suffered for years from TN pain, which patients describe as stabbing or electric. But his painting depicted pressure-related pain, which was a visual confirmation that he suffered from a second condition, paroxysmal hemicrania.

Is orofacial pain associated with aging?  Some disorders are and some are not. We all know that things sag when we age. In some patients with TN, it’s believed that a blood vessel in the brain sags and damages the insulating membrane of the nerve, resulting in pain. If the history and physical examination points to TN and you’re wondering if there’s a blood vessel pressing, a brain MRI can confirm the diagnosis. We’re fortunate to have some of the world’s best imagers here at the University. If confirmed, neurosurgery to change that physical relationship between the blood vessel(s) and nerve(s) is a treatment option.

Do sleep patterns also change with age?  Yes. We spend less time in deep sleep during each sleep cycle, resulting in a reduction in sleep quality and a feeling of being ‘less restored’ following the same number of sleep hours. There also is an important relationship between stress, sleep deprivation, mood disorders, sleep and pain. In fact, you can induce pain sensitivity after just two days of missing out on deep sleep. Orofacial pain dentists are uniquely positioned to deal with sleep disorders. Sleep is a big part of our practice.

I’m assuming not every condition can be resolved. True. We often talk about ‘managing’ chronic pain, much as we manage chronic diseases like heart disease, diabetes and cancer. Patients live with limitations of these disorders…medication use, dietary restrictions, etc., and they learn coping strategies to live the best they can. Our goal is to control the disorder so well that we minimize symptoms, maximize function, and promote independence.

So, what do dentists need to know?  First, our profession can make a huge impact in managing patient suffering by improving our ability to recognize and refer patients with orofacial pain. Second, patients with chronic pain are likely to have more than one pain diagnosis and we need to diagnose all involved and understand how they interact with each other if we’re to determine the best course of action. And third, some patient treatment needs require multidisciplinary care.

What do you see happening in the way of pain research?  Things like the development of diagnostic biomarkers and identification of risk factors are the first things that come to mind. The School of Dentistry conducts pain research in these areas.

What’s the focus?  We have programs in basic neuroscience and clinical research, as well as a developing translational research program. For example, Dr. Don Simone investigates the neural encoding of pain to learn about the underlying mechanisms that cause hyperalgesia, as well as the pharmacological modulation of pain…including the use of cannabinoids…and sensory testing for early detection of neuropathy. Dr. David Bereiter investigates the central nervous system and the mechanisms of craniofacial pain, the role of stress in enhancing the pain response––with particular emphasis on ocular pain and pain referred to the temporomandibular joint––and the role of sex hormones and psychophysical stress on craniofacial pain. Dr. Julie Olson investigates the role of microglia––the CNS resident immune cells––during the immune response to neuropathic pain and inflammation.

On the clinical side, Dr. Eric Schiffman has developed and is refining validated diagnostic criteria for TMD, conducting clinical trials to improve the care of patients with TMD, and studying the relationships related to treatment prognosis. I am involved in observational research to study painrelated outcomes of root canal treatment, with the goal of understanding both the risk factors for developing severe post-operative pain as well as longterm outcomes (e.g. why pain persists, how it affects the patient’s chronic pain experience, etc.)

Finally, Dr. Estephan Moana-Filho conducts translational research that uses sensory testing and cutting-edge, multimodal MRI to investigate how the brain modulates pain perception for patients with chronic TMD pain.

What do you see on the horizon?  We will see more team-based patient care so that all relevant aspects of the patient are being addressed. As we learn more about the underlying mechanisms involved in chronic pain and how they interrelate, patient management will become, of necessity, even more interdisciplinary. This will require greater functionality from health informatics to facilitate better access to shared health records and communication between providers.

We’ll see the insurance industry assert more influence over what providers and services are covered, which in turn, demands provider/clinic-specific outcomes data about the quality of care, patient satisfaction, and cost as justification for coverage. And we will have new treatment options based on the availability of new biodevices and pharmachological agents, and new insights into behavior approaches. These advances will occur because of a better mechanistic understanding of the patient’s biology and psychology, so future treatments will be more tailored to the individual patient and their comorbid conditions. During the first 40 years, we witnessed dramatic changes to patient care that have made significant improvements in their well being. The next 40 promise to be more exciting as science advances and we incorporate this knowledge and tailor care.

Dr. Donald Nixdorf
Dr. Donald Nixdorf