Orofacial pain diagnosis: finding the target before shooting it
The underlying reason for someone’s orofacial pain is best described by the diagnosis, which is a name given to a certain disorder or disease process. Ideally, the diagnosis should give us information about what is going on, which would consequently derive a conclusion on how to address it.
It is important to keep in mind though, that many times there are multiple factors playing a role in a single condition. Elements that serve to bring on the problem, called initiating factors, may not stay and therefore may not be observable along the course of time. The illness, however, may persist due to other influences, called perpetuating factors, or even worsen due to aggravating factors. Note that these might as well have been present before the onset of the problem without major issues, making it hard for the person to identify them as potentially negative, but they could definitely be harmful in this new context of dysfunction.
A simple example is walking on a sprained ankle. The injury may have been caused by a different event, and walking may have never been a struggle, but under those circumstances, the affected joint may need to be guarded from the activity or otherwise the lesion could be made worse or be prolonged. This complex puzzle needs to be carefully studied so all of the pieces fit together and hopefully lead to a resolution or adequate management.
To make the investigation even more challenging, pain conditions in the trigeminal innervation territory often present referral patterns; meaning that the location where the pain is felt is not the actual origin of the painful symptoms. Thus, treating the site of the referral will not address the true source of the problem and will very likely be ineffective. A key part of the diagnostic process is to unveil these potentially misleading clues and identify proper targets for treatment. For example, trigeminal neuralgia (TN) pain may be perceived as a “toothache” (since the innervation of the teeth is part of the trigeminal distribution), but dental care will not be helpful and may even make things worse.
When there is a classic presentation of TN as well as a concomitant continuous “background” pain; it would be hasty to assume that the latter is part of a TN without first considering a range of differential diagnoses, especially after a good response to treatment by the classic component of the pain. As an analogy, when a person has a sprained ankle, they may develop a limp to avoid putting weight on the injured limb when walking. If this becomes a habit, the other structures being overloaded in that process, such as the back, hip, and knees, may become painful as a result of the imbalanced use.
The cause for these pains are separate and different, though related. Making a parallel back to TN, patients with intense pain in their face, frequently develop regional muscle guarding, tightening the muscles in the affected area as a natural response and making them sore as a result. Treatment directed to the TN, in the presence of an uncontrolled daily constant jaw muscle pain, unfortunately may not change the muscular component, if the behavior related to its development has not changed. Even though multiple symptoms are most likely explained by a single process, there is no rule that there has to be only one problem occurring at a time.
Furthermore, misapplied procedures increase the risk of the condition becoming chronic, because the pain remains unsatisfactorily managed longer and negative thoughts, such as worry, fear, and anger, set in becoming new contributing factors.
An orofacial pain evaluation should consist of the following steps, in order of importance; (i) history taking, (ii) physical examination, (iii) obtaining diagnostic testing, such as imaging or laboratory tests, as needed.
History: Getting to a differential diagnosis
The most important step in the diagnostic process is the history taking, which leads the clinician to develop an initial differential diagnosis. In other words, by talking to the patient and collecting the right information, the provider narrows down the list of all the possible orofacial pain conditions to a few more likely ones. For example, knowing the patient’s age and gender already provide a good pointer towards conditions that may be more or less frequent in that specific demographic group.
Signs and symptoms teach us about the underlying condition and its nature. When preparing for a medical appointment, be ready to answer many questions about the characteristics of the pain and the context in which it presents. Your answers probably hold the most valuable diagnostic information. An astute clinician is not only interested in what you are saying, but also how you are saying it. For patients seeking care for orofacial pain, the pain itself will be called the chief complaint and the details of its history are often referred to by providers as history of present illness, including:
- Location: Where is the pain felt? Is it always in the same place? Is it punctual or affects a broader region? Is there a spreading or movement component to it? Is it easily localized or is it more diffuse? Does it feel superficial, on the surface of the skin, or deep, “in the bone”?
- Onset: When did it first start and in which circumstances? Were there any initiating factors? Was it a sudden or gradual onset?
- Progression: Has it changed since the onset? Is it getting better, worse or staying the same? Is it always the same when it occurs, or does it change?
- Frequency: Is it constant or intermittent? How often does it occur?
- Duration: How long does it stay when it is there?
- Timing: Is there a time of the day when it is usually worse? Does it present “on the clock”? Are there periods of remission, times when you feel nothing?
- Quality: How does the pain feel like? Which words could be used to describe it? (i.e. sharp, dull, throbbing, shooting, electric shock-like, burning, etc.) Is there an emotional component?
- Intensity: Is it mild, moderate or severe? How would it be rated on a scale of 0 to 10, being 0 no pain and 10 the worst pain possible?
- Interference: Does it disrupt sleep? Does it affect the ability to perform daily activities?
- Aggravating/Alleviating factors: What makes it better and what makes it worse? Is it affected by physical activity, light, noises, jaw movements, body position, temperature, touch, sneezing/coughing, etc.? Does it respond to over-the-counter analgesics or other medications?
- Associated features: Are there other signs or symptoms present before, during or after the pain? Are there any appearance changes, for instance redness, swelling, tearing or sweating? Is it predictable? Can you feel or sense it coming on? Are there other changes in vision, movements, sensation?
- Prior Treatments/Tests: Were there other providers consulted? What therapies have been tried and what were the results? Are there any prior imaging, labs, etc. and what were their findings? What medications have you taken, at what dose, for how long, and what were the effects?
It is clear that the pain itself is where most of the attention of the patient will tend to focus; however, it is important to think of the whole person and the conditions in which the problem is presenting. The history can also uncover contributing factors that can help to understand the origin of the pain as well as to guide the therapy. Fundamental pieces of the puzzle are also frequently found “thinking outside of the box”:
- Medical history: Are there any other medical conditions? How are they being addressed? Are there any medications, vitamins or supplements being taken, at what doses and for how long have they been taken? Has there been any trauma? Are there any other pains throughout the body?
- Family history: Are there other cases of similar problems in the family? Are there any cases of auto-immune disorders, cancer, pain disorders?
- Habits: General exercise, diet, water, tobacco, caffeine? Oral parafunctional habits (i.e. teeth clenching and grinding, biting objects, fingernail, lips, cheeks, gum chewing, etc.)?
- Sleep: What is the typical sleeping routine? How long? Is it restorative? Is there difficulty falling or staying asleep? What is the sleeping position?
- Psychosocial history: What is the patient’s occupation, marital status, family dynamics? What is the level of psychosocial stress? Does the patient have a support system, coping strategies? Are there diagnoses of anxiety, depression or other mood disorders and how are they being addressed? Have there been traumatic life events? Is there ongoing litigation?
Physical exam: Refining the list of orofacial pains
After the history taking, the clinician should have generated a mental list of the possible conditions that could be going on. The physical examination will serve to confirm or refute such hypotheses and guide the process of diagnosis. The trained professional may be able to gather further information beyond what is volunteered by the patient, starting from general appearance, affect, posture, gait, speech and non-verbal communication.
One of the major goals of the physical exam is to duplicate the chief complaint, as to better understand its origin and response to stimuli. For instance, dental pain of pulpal origin is expected to be elicited or changed in a predictable manner by application of cold to the surface of the tooth, therefore dentists use a cold test and are trained to interpret the response as within normal limits or altered. To further illustrate this concept, in order to render the diagnosis of temporomandibular disorders (TMD), there should be a positive finding of familiar tenderness to palpation or range of motion of the involved muscles and/or temporomandibular joints (TMJ) on exam.
Since pain is a very personal and subjective experience, even during the exam, part of the findings will be subjective and dependent on patients’ reports. If at any point during the exam pain is provoked, it is of crucial importance to discuss how the provoked pain is the same or different than what is typically experienced. The exam maneuvers may provoke pain; however the pain which is familiar to them, fully or partially reproducing their usual symptoms is the one of interest.
Regional head and neck exams should include visual inspection and palpation of masticatory and cervical muscles, TMJs, face, thyroid gland, lymph nodes, teeth, mouth, and oropharyngeal mucosa. Changes in symmetry, shape, size, consistency, color and texture should be noted. Range of motion of the head and neck should be evaluated for limitations and coordination, as well as associated pain or noises. Cranial nerve screening evaluation is also valuable to evaluate motor and sensory functions of the major nerves supplying the face and neck. The teeth and supporting tissues should also be inspected for signs of disease, attrition, fractures and occlusion.
Imaging and other diagnostic tools: Taking a closer look
No tests or exams to date have been able to depict or objectively confirm the source or even the presence of pain. In the greatest majority of the cases, comprehensive history and examination will reach a diagnosis; however there are clinical findings that require further investigation of the causes of specific signs or symptoms, especially to rule out disease or pathology underlying these features. For instance, neuralgia-type pains or neurologic deficits should trigger a request for brain imaging to rule out intracranial processes that could be causing the symptoms.
In a few conditions, diagnostic imaging can be used to confirm a clinical diagnosis, but in order to avoid unnecessary costs, exposure to procedure risks and delay of therapy, it should only be indicated if the results will determine treatment recommendations. For example, in a typical case of TMJ, osteoarthritis the prognosis with conservative treatment is usually very good, and the clinical evaluation can assess with a reasonable degree of confidence that the condition is present. By the means of a computer tomography (CT), the diagnosis could be confirmed and graded in severity. Nevertheless, the initial treatment strategy would be the same as if no imaging was done, but the patient would have been exposed to a dose of ionizing radiation and there would be associated costs to the healthcare system.
It is also important to keep in mind that all tests have their particular ability to accurately detect the target condition. No test is perfect and a certain degree of false positives (test indicates disease being present when it is not there) and/or false negatives (test indicates disease not present when it is there) is expected. The practical conclusion is that tests ordered without previous clinical contextualization and indication can generate misleading and meaningless results. Going back to the osteoarthritis example, is it known that radiographic findings of degenerative changes in joints are very common and increase with age, but only a small minority of cases will present symptoms. In addition, there is no evidence of treatments that can prevent progression. Thus, treatment based on the imaging findings alone is not adequate.
The response to treatment is also sometimes diagnostic. Based on the disease mechanism, there are specific drugs that seem to work so well that a significant response tells much about what is going on. It is the case of carbamazepine for Trigeminal Neuralgia or steroidal anti-inflammatories for autoimmune conditions. The rates of improvement in those cases are so high that it makes a diagnosis very unlikely if there is no significant response to the medication. Another type of test that would have diagnostic and potential therapeutic benefit is nerve blocks, which help to locate the source of the pain and may provide relief as well.
There are also other tests such as nerve conduction and quantitative sensory testing (QST), as well as many others that may come, which at this time have not yet been demonstrated valid and reliable for clinical use, but research is being developed to explore their value in the diagnosis of pain conditions. Based on the rationale presented, it is always important to put it in a clinical context, compare risks and benefits before running any tests.
Once the information is collected, your doctor develops a list of diagnoses that are the most likely the reasons for your pain. Oftentimes there is a single diagnosis, one that fits the information that you are presenting. Other times the information is not clear or the doctor is unsure, so a list of possible diagnoses or a general diagnostic category is given. This list or general category is reviewed, and revised accordingly, as your doctor obtains more information about you over time, such as how your symptoms change and how you respond to initial treatments.
While the goal is to obtain the correct diagnosis right away, it can be a reiterative process occurring over a couple visits for more rare conditions that are not frequently encountered or chameleons in their presentation. Whatever the process is to derive a diagnosis, getting there is a very important step because one would not expect a treatment being applied to address the wrong diagnosis to be helpful. Rather, it tends to be expensive, time consuming, and sometimes harmful.