Managing Orofacial Pain in Practice

By Eamonn Murphy

The concept of pain management has evolved over the last 50 years. It encompasses several medical disciplines and has now become a distinct dental entity. This book explores the diagnostic techniques and management philosophies for common orofacial pain complaints; the different causes of orofacial pain like bruxism are presented.

• Language: English
• Publisher: Quintessence Publishing Co. Ltd.
• Release date: Mar 19, 2019
• ISBN: 9781850973287

Book preview

immeasurable.

Preface

The purpose of this book is assist practitioners in the differential diagnosis and management of orofacial pain. Ultimately, it is hoped that this book will reduce unnecessary suffering of patients afflicted with this disorder.

I have tried to maintain a balance between clinical relevance and the underlying scientific data. The field of Orofacial pain is still in its infancy and consequently we await the definitive studies on many aspects of treatment. In the meantime it is imperative not to dilute the principles of evidence-based practice when selecting a treatment option. If confusion arises regarding a specific case, it is best to refer or to get a second opinion as opposed to performing an intervention in the hope that it will make a difference. Hence the mantra: No Diagnosis – No Treatment!

Dentists are experts in the management of acute pain disorders. Patients with chronic orofacial pain pose a significant diagnostic challenge to the dental profession. Historically, patients with chronic orofacial pain were often labelled as ‘crazy, attention seekers, or malingerers’. An explosion in the understanding of pain mechanisms, pharmacology and imaging techniques over the past 20 years legitimised the complaints of many of our patients with chronic pain.

Orofacial pain management adheres to the principles of chronic pain management. In many respects the management of chronic orofacial pain resembles the management of chronic low back pain. The multidisciplinary team approach comprising pain specialists, pain psychologists, physiotherapists and allied health care professionals is essential.

Having Read This Book:

It is hoped that having read this book the reader will be able to:

Appreciate the myriad of conditions that can present as pain in the orofacial region.

Carry out a comprehensive orofacial pain history and screening examination.

Diagnose the most common orofacial pain conditions.

Identify red flags that may suggest a psychological co-morbidity.

Select the most appropriate treatment that should be provided and implement this in a logical fashion.

Understand the iatrogenic effects that may arise from a course of treatment.

Discuss complex cases with pain specialists/medical practitioners and decide on the most appropriate route of referral.

Eamonn Murphy

Chapter 1

Orofacial Pain: An Introduction

Aim

The aim of this chapter is to discuss controversies associated with chronic orofacial pain (OFP).

Outcome

Having read this chapter the practitioner should:

appreciate the multiple sources of OFP and the frequency of presentation

understand the differences between acute and chronic OFP

appreciate the model used in the management of OFP.

What Constitutes an Orofacial Pain Complaint: Classification Issues

The OFP conditions comprise a group of acute and chronic pain states that affect the mouth and face. The majority of those affected will attend a dentist; however, only some OFPs are related to the teeth. The diagnosis of OFP may prove to be one of the most challenging and frustrating problems faced by the dental practitioner. In an ideal world, patients would present with complaints with their own signature characteristics. This is rarely the case. In many instances, there is a significant overlap in the presentation of OFP conditions.

An important distinction that should be made when dealing with OFP conditions is whether the pain is acute or chronic. In general, chronic OFP conditions have been present for three months or longer.

A variety of classifications have been developed to represent the multitude of pain states that may present as OFP. These have evolved through the American Academy of Orofacial Pain, the International Headache Society and the International Association for the Study of Pain. Although there has been tremendous progress in this area since the 1980s, further work is required to provide a universal classification system. A simple classification system of OFP conditions is set out in Table 1-1.

How Common is Orofacial Pain?

The commonest form of OFP that a dental practitioner encounters is toothache. A national study conducted in the USA showed that the overall prevalence of toothache in adults in the six months leading up to the study was 12.2%. In addition, this study estimated that 22% of the general population experienced OFP in any given six-month period. The commonest form of chronic OFP that a dentist will encounter is temporomandibular disorders (TMD). Population-based studies reveal that the rate of TMD is 8–15% in females and 3–9% in males. Incidence-based studies show that there are approximately two to four new cases of TMD per 100 people per annum. This contrasts to the incidence of trigeminal neuralgia, which has been estimated to be in the order of three to five new cases per 100,000 people per annum. The prevalence of chronic pain following successful endodontic treatment in a tertiary referral endodontic centre was 12%. The few epidemiological studies carried out on the general population estimated the prevalence of cluster headache to be 0.1%. In contrast, similar studies have estimated migraine prevalence to be approximately 18% for women and 6% for men. Therefore, when a patient presents complaining of OFP, it should be considered to be of dental origin until proven otherwise. When a dental component is not identified, non-dental sources must then be considered.

The Stigmatisation of the Patient with Orofacial Pain

When a patient presents complaining of pain and the source of the pain cannot be readily identified, or dental intervention does not eliminate the complaint, questions are often asked regarding the psychological state of the patient (Fig 1-1). This has given rise to situations where patients are unfairly labelled as psychogenic, or their pain is described as psychogenic pain. The vast majority of OFP conditions have a legitimate cause; however, dentists are sometimes not in a position to diagnose the problem accurately.

Fig 1-1 The stigmatisation of the patient with orofacial pain.

Take, for example, a patient presenting with a cluster headache. A dentist may never come across such a problem. An accurate diagnosis is, therefore, unlikely. Furthermore, how many practitioners competently palpate the masticatory jaw muscles to rule out a muscular cause of OFP, even though muscle-related TMD is far commoner than joint-related TMD. What is essential is that the practitioner can rule out the common OFP possibilities in the primary dental setting. If this does not eliminate the pain, referral to the most appropriate centre for further investigation is necessary. Common reasons for referring an OFP patient for further investigation include:

a diagnosis cannot be made following a comprehensive examination

the patient has already attended multiple healthcare providers or undergone multiple interventions without an improvement

the pain is out of proportion for common OFP complaints

the patient has a complex medical history

poor compliance with treatment

prominent psychosocial factors contributing to the ongoing pain.

Who Should Treat the Patient with Orofacial Pain?

The majority of patients complaining of OFP will attend their dentist. Most acute OFP complaints will be successfully treated by a dental practitioner; however, chronic OFP poses special problems requiring specific treatment strategies. The gold standard approach for treating chronic OFP is identical to that used in the management of chronic low-back or neck pain. The chronic pain model is not as familiar to dentists as the acute pain model. When a patient presents complaining of an acute dental abscess, for example, the source of the pain is identified and eliminated by extraction or root canal therapy. This generally eliminates the pain and resolves the problem. The same approach cannot be adopted, however, with a variety of chronic OFP conditions, including musculoskeletal or neuropathic OFP. When faced with a chronic OFP disorder, pain management is of utmost importance (Fig 1-2).

Fig 1-2 The controversy surrounding who should treat chronic orofacial pain conditions.

Initially, it is critical for a successful outcome to educate the patient to shift the focus from curing the condition to managing the complaint. Successful management of a chronic temporomandibular joint (TMJ) disorder can result in a patient having minimal or no pain, but this does not necessarily mean that the TMJ disorder has been cured. Successful treatment requires careful identification and control of the perpetuating factors. As chronic conditions are likely to return at some stage, patient education and participation contribute to a successful outcome.

From the above, it will be appreciated that the dentist serves an important, but not an exclusive, role in the management of chronic OFP. If, for example, a patient presents with chronic myofacial pain that is perpetuated by an anxiety-related clenching behaviour, it is often necessary to involve a clinical psychologist to teach the patient management strategies, such as relaxation training, biofeedback or meditation. Similarly, if a patient with trigeminal neuralgia that is refractory to medical and surgical management presents for treatment, input from a clinical psychologist is vital. Physiotherapy can also play a critical role. If a patient presents with a regional muscle disorder involving the masticatory and cervical muscle groups, it is essential to enlist the expertise of a physiotherapist trained in this field. Hence, a multidisciplinary or team approach is often indicated to achieve the best possible clinical outcome. In complex cases of chronic OFP, ear, nose and throat (ENT) specialists, neurologists, neurosurgeons, maxillofacial surgeons, rheumatologists and pain anaesthetists may also play an important role in the management of the patient.

Acute and Chronic Orofacial Pain

Acute OFP is experienced following most dental interventions, such as the extraction of a tooth. Acute pain serves a protective role. Overwhelming evidence indicates that psychological factors exert important influences on acute pain. An anxious patient will often complain of greater pain following dental intervention. Psychological interventions such as relaxation, distraction and hypnosis are effective in reducing enhanced OFP.

Chronic OFP refers to pain lasting three months or greater. It is distinguished from acute pain by its temporal characteristics and the initiating event, psychological factors and purpose. The initiating event is typically obscure for chronic pain; psychological factors are more strongly associated with chronic pain and, unlike acute pain, chronic pain serves little, if any, purpose.

Common Models Used in the Treatment of Orofacial Pain

If a patient presents with an irreversible pulpitis and a root canal treatment is performed, it will usually eliminate the pain. This represents the disease model of pain. The disease model is characterised by a strong association between pain and pathology. Unfortunately, this model cannot be applied to many forms of chronic OFP, as specific pathology cannot be identified. Many factors influence pain perception, indicating that pain is not simply a neurophysiological phenomenon. The perception of pain involves physiological, cognitive and behavioural aspects. Cognitive–behavioural therapy (CBT) generally refers to a treatment approach that operates on the assumption that thoughts and environmental events influence the experience of pain and the patient’s responses to pain. It represents the most commonly used form of psychological treatment in the management of chronic OFP. CBT aims to change the way patients think, to challenge their beliefs about their pain and in this way to influence how they respond.

Predictors for Chronic Orofacial Pain

A number of studies have investigated factors that may predict chronic OFP and more specifically factors predictive of chronic TMD and persistent postendodontic pain. Studies that may predict which patients with acute OFP develop chronic OFP have important clinical, prevention and treatment implications.

Factors that may predict chronic OFP include a history of current or previous chronic bodily pain, a history of previous painful treatment in the orofacial region, gender (females being more susceptible than males), duration and intensity of preoperative pain, the need for pharmacological management and high levels of psychological distress.

The importance of identifying patients at risk of developing chronic OFP affords the dental practitioner the opportunity to refer the patient at an early stage for comprehensive treatment. This provides the treating clinician with the option to initiate alternative forms of treatment, such as CBT, and thereby reduce unnecessary patient suffering and improve the prospects of a favourable prognosis.

Atypical Facial Pain: A Diagnostic Dilemma

A recent epidemiological study conducted in the primary medical care setting in the UK investigated the incidence of a variety of neuropathic conditions. This study estimated the incidence of trigeminal neuralgia at 27 cases per 100,000. This contrasts dramatically a similar study conducted out of a tertiary neurological referral centre in the USA, which estimated the incidence to be 4.7 per 100,000. It is considered that the actual incidence of trigeminal neuralgia is reflected in the lower estimate, as verified in various epidemiology studies.

The most likely explanation for an overestimation of trigeminal neuralgia in the UK primary care setting is lack of differentiation of non-trigeminal neuralgia conditions and, as a consequence,