Orofacial Pain and Headache (eBook)

1

The Diagnostic Process

Yair Sharav, DMD, MS
Rafael Benoliel, BDS

Diagnosis and treatment of orofacial pain is a complex process compounded by the density of anatomical structures and the prominent psychologic significance attributed to this region. Management of orofacial pain thus demands the services of clinicians from various specialties, such as dentistry, otolaryngology, ophthalmology, neurology, neurosurgery, psychiatry, and psychology. Complex referral patterns to adjacent structures are common in orofacial pain and, indeed, one person’s headache is another person’s facial pain. In clinical practice, the two types of pain are often intimately related. Consequently, a patient with orofacial pain may wander from one specialist to another to try to find adequate help.

The second edition of this textbook continues to integrate the issue of orofacial pain with headache through contributions from practitioners in different disciplines, all of whom have extensive clinical experience and a thorough understanding of pain mechanisms specific to the trigeminal system. Accordingly, the authors address all regional craniofacial pains together and aim to present a wider picture of orofacial pain syndromes, including the overlap between primary headaches and primary orofacial pain entities. Many patients with chronic orofacial pain suffer primary headache variants in the orofacial region, and a lack of familiarity with these syndromes is likely a factor in misdiagnosis by dental practitioners and medical specialists. Other patients may suffer from primary orofacial pain entities that remain unclassified by the International Headache Society (IHS) and are unknown to neurologists, otolaryngologists, other medical practitioners, and even dentists.1–3 The integration of headache and orofacial pain classifications is of paramount importance. In the past, about half of the patients in tertiary-care craniofacial pain clinics were labeled as “idiopathic” or “undiagnosable” when the previous IHS classification was applied.2–5 The hope is that the current classification, which has witnessed a novel collaboration between orofacial pain and headache specialists, will improve the situation.

Moreover, there is considerable overlap in the clinical presentation of headaches, such as tension type with regional myofascial pains of the face, and generalized pain syndromes, such as fibromyalgia (see chapter 8). The relationship between isolated facial neurovascular pain (see chapter 10) and migraines or trigeminal autonomic cephalalgias remains unclear and is not accounted for by the recent IHS classification.6 Furthermore, a growing patient population has chronic craniofacial pain from trauma associated with traffic accidents or from invasive dental procedures, such as dental implants, which demands a multidisciplinary approach. This book bridges the gap between medically trained headache and dentally trained orofacial pain specialists. It will be useful to readers at different stages of their careers—undergraduate students, residents, practitioners, and dental and medical pain specialists.

Epidemiology: The Silent Crisis

Statistics from the United States indicate that 100 million adults suffer from chronic pain7 at an estimated annual cost of around $600 billion—higher than the cost for heart disease, cancer, or diabetes. However, chronic pain is a worldwide epidemic that has been termed “the silent crisis.”8 Examining relevant prevalence estimates gives important insight into the scope of the problem. Orofacial pain, of which about 10% is chronic, affects around a quarter of the general population.9–11 Painful temporomandibular disorders (TMDs) are quite prevalent; 4.6% of the population reports this type of pain (6.3% of women, 2.8% of men).12 This finding is in agreement with the 2009 National Health Interview Survey, which found that 5% of adults reported pain in the face or jaw over a 3-month period. Persistent facial pain, which has a reported incidence of 38.7 per 100,000 person-years, is more common in women and increases with age.13 Syndromes identified included trigeminal neuralgia and cluster headache, which are the most common forms. Paroxysmal hemicrania and glossopharyngeal neuralgia were among the rare syndromes. Clearly, orofacial pain is more prevalent than previously thought.

Therefore, diagnosis and management of orofacial pain and headache have become important subjects in medicine and dentistry. Both acute and chronic presentations may be benign or may signify serious underlying disease. The emphasis of this book is on the four major clinical families of orofacial pain: acute orofacial, neurovascular, musculoskeletal, and neuropathic (see chapters 6 and 8 to 12). In these chapters, the current etiology, diagnosis, and treatment are reviewed. The book includes many case presentations that are largely virtual, that is, created by integrating data from a number of cases seen in the clinic; thus, any resemblance to specific cases is purely coincidental. They are real, however, in that they reliably duplicate the type of cases seen in orofacial pain clinics. Typical textbook cases are rare, and each relevant section includes information related to the changes in presentation that may cause diagnostic confusion. Atypical cases may be difficult to manage; many have superimposed trauma and consequent neuropathic pain. Some of these cases present patients with a history of misdiagnosed acute pains in the orofacial region who have undergone repeated and unsuccessful interventions that slowly escalated and resulted in dental extractions and surgeries. Accurate diagnosis of acute dental and orofacial conditions is therefore essential (see chapter 6). The importance of acute and chronic otolaryngologic syndromes in the differential diagnosis of facial pain, particularly migraines and cluster headache, is paramount (see chapter 7). The growing number of older, often medically compromised, patients with orofacial pain deserves special attention (see chapter 14): Is orofacial pain in these patients related to their medical condition? Although this is essentially a clinical book, anatomy and neurophysiology are covered in a manner specifically relevant to the topic of orofacial pain (see chapter 2).

One of the mainstays of pain management is indisputably pharmacotherapy. Because many drugs are commonly used to treat many syndromes, two separate chapters on pharmacotherapy are included: acute and chronic (see chapters 15 and 16). The management of pain relies on accurate diagnosis and reliable follow-up that demonstrates objective improvement. Chapter 3 covers the important area of pain measurement as well as the assessment of pain modulatory systems and peripheral nerve function. Unfortunately, we are a long way from optimal patient care, and some of the best drugs offer notable relief for only a fraction of our patients, with some having disturbing side effects. Many patients inquire about complementary and alternative medicine and often actively search out these practitioners independently (see chapter 17). Neurosurgical approaches, including neuromodulation, remain relevant options for selected syndromes (see chapters 11 to 13). No diagnosis and treatment of orofacial pain would be complete without understanding its emotional undercurrents and having a thorough knowledge of its psychologic aspects and treatment possibilities, which are covered in chapter 4. A novel and welcome addition to this second edition is a description of the interactions between sleep and orofacial pain and headaches.

Chronic Pain Is a Disease

Pain is a multifaceted experience with physical, cognitive, and emotional aspects (Table 1-1). Three mechanistically distinct types of pain are distinguishable: nociceptive, inflammatory, and neuropathic. Nociceptive pain is the baseline defensive mechanism that protects us from potential harm. Inflammatory and neuropathic pains are characterized by altered and often aberrant function of the nervous system as a result of persistent pathology or plastic changes in the nervous system.

Table 1-1 Definition of pain terms