Referred pain is associated with greater odontogenic spontaneous pain and a heightened pain sensitivity in patients with symptomatic irreversible pulpitis.

BACKGROUND: Symptomatic irreversible pulpitis often results in heightened reactions to thermal stimuli such as pain evoked by a cold stimulus, and spontaneous odontogenic pain (unprovoked pain). OBJECTIVE: This study primarily compared the clinical manifestations of odontogenic spontaneous pain and pain provoked by cold stimulus specifically focusing on their sensory discriminative characteristics (intensity, duration and quality) between symptomatic irreversible pulpitis patients with and without referred pain. METHODS: Twenty-three patients with symptomatic irreversible pulpitis with referred pain and 12 patients without referred pain were included in this cross-sectional study. The following outcomes were assessed: odontogenic spontaneous pain and its descriptors; pain evoked by cold stimulus and qualitative sensory testing before and after local anaesthesia; referred pain location; use of analgesic medication; complementary anaesthesia efficacy. T-test, chi-squared and McNemar tests were applied to the data (p < .50). RESULTS: Patients with referred pain presented a greater odontogenic pain intensity (p < .05) when considered the average of the last 24 h. These patients also showed higher pain rating and pain descriptors (p < .05). Intensity and duration of the pain evoked by cold stimulus in the non-affected contralateral tooth at baseline were higher for patients with referred pain (p < .05). CONCLUSION: Symptomatic irreversible pulpitis patients with referred pain present greater odontogenic spontaneous pain and a heightened pain sensitivity. Therefore, patients with referred pain seem more complex from a pain severity perspective, supporting the clinical utility of discriminating symptomatic irreversible pulpitis with and without referred pain.

The receptive field for visceral pain referred orofacially by the vagus nerves.

BACKGROUND: The nociceptive receptive field of the vagus nerves in animals includes virtually the entire thoracic, abdominal and laryngopharyngeal regions. However, the role of the vagus nerves in the transmission of visceral pain in humans, with the exception of pain from coronary artery diseases, is believed to be insignificant. AIM: The purpose of this report is to map out the clinical visceral pain receptive field of the vagus nerves relative to its nociceptive counterpart in animals. MATERIALS AND METHODS: The PubMed database and PMC were searched for case reports of patients with orofacial pain believed by the author(s) of the article to be referred from underlying non-cardiac thoracic, laryngopharyngeal or abdominal diseases. Reports of diseases for which non-neural explanations for the orofacial spread of pain were suggested were excluded. RESULTS: A total of 52 case reports of jaw pain and/or otalgia referred from laryngopharyngeal and noncardiac thoracic sources were discovered. In addition, a multicenter prospective study found that 25.8% of more than 3,000 patients with thoracic aortic dissection experienced pain in the head and neck region. In stark contrast, no case reports of orofacially referred pain from abdominal diseases were found. DISCUSSION: The results indicate that the laryngopharyngeal and thoracic portions of the vagal receptive field are capable of referring pain orofacially while the abdominal portion is not. The roles of the somatotopic organization of the trigeminal sub nucleus caudalis and neuromodulation in this referral of pain were discussed. CONCLUSION: Referred orofacial pain can lead to delayed diagnosis and poorer outcome in visceral diseases.

Referred pain.

Comprehending orofacial referred pain requires an understanding of the neuroanatomy of the trigeminal nerve and associated cranial nerves. It also requires knowledge of the concept of neuronal convergence as well as the recognition that the caudalis is laminated and is therefore responsible for sensory receptive fields-that one interneuron may receive multiple sensory inputs and that structures within a lamina have sensory neurons which project into the caudalis and may share the same interneuron.

Myofascial trigger points in the masticatory muscles in patients with and without chronic mechanical neck pain.

OBJECTIVES: The purpose of this study is to describe differences in the presence of masseter and temporalis muscle trigger points (TrPs) and jaw opening between individuals with mechanical neck pain and healthy controls. METHODS: Twenty patients with mechanical neck pain (60% women) without symptoms in the orofacial region, aged 20 to 37 years old, and 20 matched controls participated. Temporalis and masseter muscles were examined for the presence of TrPs in a blinded design. Trigger points were considered active if the subject recognized the pain as a familiar symptom, whereas the TrPs was considered latent if the pain was not recognized as a symptom. Jaw opening was assessed with a ruler. RESULTS: A greater number (P < .001) of TrPs in the masticatory muscles were found in patients than in controls. None of the patients or healthy controls recognized the referred pain as familiar; thus, latent rather than active TrPs were found. The distribution of TrPs between groups was different for the masseter (left odds ratio [OR], 3.4; right OR, 8.1; P < .001) and temporalis (left OR, 2.8; right OR, 5.7; P < .001) muscles. Patients with neck pain had smaller jaw opening than controls (P < .001). A negative correlation between active jaw opening and the number of TrPs within the masticatory muscles (r(s) = -0.6; P < .001) was found: the greater the number of TrPs, the smaller the jaw opening. CONCLUSIONS: For the subjects in this study, those with mechanical chronic neck pain had more latent TrPs in the masticatory muscles and reduced jaw opening compared to healthy controls. These findings may suggest the spread of sensitization from the cervical segment to the trigeminal brain stem sensory nuclear complex.

The prognosis of myofascial pain syndrome (MPS) during a fixed orthodontic treatment.

Among treatments in the literature for myofascial pain syndrome (MPS), the most reliable therapies in dentistry are spray and stretch, and, although less frequently used, anesthetic injection. Adult MPS subjects are often treated using fixed orthodontic therapy for resolution of malocclusion. There is no clarity in the literature on the prognosis of MPS during orthodontic therapy. The purpose of this study was to analyze the prognosis of MPS during orthodontic treatment of subjects with malocclusion, initially diagnosed as having MPS. The analysis covered the medical records of 91 young adult Caucasians scheduled for orthodontic treatment for various malocclusions. Thirty-seven of the patients were initially diagnosed as also having MPS (T0). Thirty patients began the orthodontic treatment and were recalled for a re-evaluation of MPS after dental alignment and dental class correction was achieved (T1). A wait-and-see strategy was applied in seven subjects who were included as the control subjects. They received no treatment for MPS. At T1, a statistically significant decrease was observed in the study group in the presence of any clicking or creaking noises from the jaw joint, a significant jaw joint and jaw muscle pain reduction, and a quality of life improvement. Among patients who were depressed at the beginning of treatment, the majority felt better at the follow-up evaluation. On muscular palpation, a statistically significant decrease was found on the visual analogic scale value of the middle fibers of the temporalis muscle, temporalis tendon, clavicular and sternal division of the sternocleidomastoid muscle, masseter muscles, and posterior cervical muscles. The temporalis and the masseter muscles showed a significant decrease in the number of subjects with trigger points (TrPs) in all areas in the study group, after treatment. The digastric and sternocleidomastoid muscles also showed a significant reduction in the number of subjects with TrPs. Subjects with MPS and malocclusion were treated using a fixed orthodontic treatment. They showed improvement, although no resolution, in the signs and symptoms of MPS, compared with the untreated control group.

Pain remapping in migraine: a novel characteristic following trigeminal nerve injury.

The location of pain during the headache phase of migraine varies between individuals as well as between attacks in some individuals. We have observed a "remapping" or a change in the location of migraine pain following injury to the trigeminal system that is a novel characteristic to migraine and has not been described in other trigeminal pain syndromes of the head, neck, and face. Recognition of this clinical feature implies that the pathophysiology of migraine is impressionable and may be why diagnosis and treatment are often delayed.

Toothache referred from heart disease and lung cancer via the vagus nerve.

New epidemiologic evidence suggests that referred craniofacial pain in coronary heart disease is more common than previously believed. Current medical reports suggest that in addition to coronary disease, thoracic disorders such as aortic dissection, pericarditis, and lung cancer can cause referred craniofacial pain. Recent physiologic evidence from animals and humans suggests that the vagus nerve mediates this referral of cardiac pain to the maxillofacial region. This article discusses the critical role of the dentist in patient education and recognition of referred head and neck pain in thoracic disease, in relation to the need for prompt medical treatment for these life-threatening conditions.

Elusive dental pain.

The dental profession is devoted to treating and preventing dental pain. Such pain can be referred from teeth in one jaw to teeth in the opposing jaw, and the origin of the pain a patient describes may not be the same as the source of that pain. As a result, dental procedures often produce no relief for the patient. This article discusses the neural mechanisms involved in referred pain from one tooth to another and from muscles to teeth.

Experimental jaw-muscle pain has a differential effect on different jaw movement tasks.

AIMS: To determine the effects of experimental jaw-muscle pain on jaw movements. METHODS: Mandibular mid-incisor point was tracked in 22 asymptomatic subjects during standardized (at 2.2 mm/s) protrusion, contralateral excursion, and open jaw movements, as well as free, right-sided chewing and chewing standardized for timing (900 ms/cycle). Tonic infusion of 4.5% hypertonic saline into the right masseter muscle maintained pain intensity between 30 and 60 mm on a 100-mm visual analog scale. Subjects performed tasks in 3 sessions on the same experimental day: control condition (baseline trials), test condition 1 (during hypertonic or 0.9% isotonic saline infusion), and test condition 2 (during isotonic or hypertonic saline infusion). RESULTS: In comparison with control, there were no significant effects of hypertonic saline infusion on amplitude or velocity for protrusion or contralateral jaw movements or on velocity for jaw opening. Jaw-opening amplitude was significantly smaller in comparison with control during hypertonic, but not isotonic, saline infusion. During free but not standardized chewing, subjects chewed faster and exhibited larger amplitude gapes during hypertonic and isotonic infusion in comparison with control. Therefore, it was unlikely that pain had an effect on the kinematic parameters of jaw movement during free chewing. Qualitatively, individual subject data revealed considerable variability in the effects of hypertonic saline on movement parameters, which suggests that the effect of pain on jaw movement may not be uniform between individuals. CONCLUSIONS: The data indicate that the effect of pain on jaw movement may vary with the task performed.

Chronic orofacial pain: a clinical challenge.

Most orofacial pain originates in the oral cavity and the surrounding structures. However, advances in the understanding of pain neurophysiology have shown that convergent afferent nociceptive transmissions from non-trigeminal, extraoral sources can enter the trigeminal system. This may confuse the diagnosis by presenting as (or contributing to) dental, sinus, temporomandibular and other head and neck pains. Incorrect diagnoses may lead to inappropriate and/or invasive procedures, creating further problems. Professor Richard Kroening (former Director of the UCLA Pain Management Center) repeatedly emphasised the maxim that "without correct diagnosis, there can be no prognosis". My own areas of special interest have included acute pain management (anaesthesia and conscious sedation) and chronic orofacial pain. I have seen many dental patients who have been referred to multidisciplinary pain management clinics, often after years of failed treatment attempts. More recent experience as a member of a hospital team evaluating long term ACC patients with many types of persistent pain problems again confirms the premise that accurate diagnosis is critical if management is to be successful.

The efficacy of acupuncture in the treatment of temporomandibular joint myofascial pain: a randomised controlled trial.

OBJECTIVES: To compare the effect of real acupuncture and sham acupuncture in the treatment of temporomandibulat joint myofascial pain, in order to establish the true efficacy of acupuncture. METHODS: A double blind randomised controlled trial conducted in the TMD Clinic, at the School of Dentistry, The University of Manchester. Twenty-seven patients were assigned to one of two treatment groups. Group 1 received real acupuncture treatment whilst Group 2 received a sham acupuncture intervention. Both the assessor and the patient were blinded regarding the group allocation. Baseline assessment of the outcome variables was made prior to the first treatment session, and was repeated following the last treatment. RESULTS: The results demonstrated that real acupuncture had a greater influence on clinical outcome measure of TMJ MP than those of sham acupuncture, and the majority of these reached a level of statistical significance. CONCLUSION: Acupuncture had a positive influence on the signs and symptoms of TMJ MP. In addition, this study provides evidence that the Park Sham Device was a credible acupuncture control method for trials involving facial acupoints.

Orofacial pain: a primer.

Orofacial pain refers to pain associated with the soft and hard tissues of the head, face, and neck. It is a common experience in the population that has profound sociologic effects and impact on quality of life. New scientific evidence is constantly providing insight into the cause and pathophysiology of orofacial pain including temporomandibular disorders, cranial neuralgias, persistent idiopathic facial pains, headache, and dental pain. An evidence-based approach to the management of orofacial pain is imperative for the general clinician. This article reviews the basics of pain epidemiology and neurophysiology and sets the stage for in-depth discussions of various painful conditions of the head and neck.

[Physiopathology and clinical data of referred pain at the level of the masticatory system]. / Physiopathologie et clinique de la douleur référée au niveau du système masticateur.

In the differential diagnosis of orofacial pain, the importance of referred pain from other anatomical regions should be taken into account. This contribution describes the neuroanatomical and -physiological background of referred pain and the role of peripheral and central sensitization in its genesis and maintenance. In addition to the effects of afferent neurons, also the resulting efferent effects like increased muscle tone are illustrated, as well as the role of the autonomic nervous system. Through practical examples out of the daily dental practice, it is elucidated how referred pain can interfere in the diagnosis, and how the source and the location of pain can be discriminated.

N-methyl-D-aspartate (NMDA) and non-NMDA receptor antagonists suppress the superior sagittal sinus-evoked activity of C1 spinal neurons responding to tooth pulp electrical stimulation in rats.

The aim of the present study was to determine whether there is a convergence of inputs from tooth pulp (TP) and the superior sagittal sinus (SSS) on rat C1 spinal neurons, and to examine the effects of iontophoretically applied N-methyl-D: -aspartate (NMDA) and non-NMDA receptor antagonists on the SSS-evoked activity of C1 neurons. Extracellular single unit-recordings were made from 20 C1 units responding to TP electrical stimulation with a constant temporal relationship to a digastric electromyogram signal, using a multibarrel electrode in pentobarbital-anesthetized rats. Ninety percent of C1 neurons (18/20) responding to TP stimulation also responded to the SSS stimulation. These neurons were considered to be SSS-afferent inputs from Adelta-fibers (5.8 +/- 0.6 m/s; n = 18), based on the calculation of nerve conduction velocity. After the iontophoretic application (30, 50, and 70 nA) of an NMDA receptor blocker (5R-10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d] cycloheptene-5,10-imine hydrogen maleate (MK801) or a non-NMDA receptor blocker (6-cyano-7-nitroquinoxaline-2,3-dione) (CNQX), the mean number of spikes responding to the SSS stimulation significantly decreased (30, 50, and 70 nA; P < 0.05). These results suggest that there is a convergence of inputs from SSS and TP afferents on C1 neurons; it is possible that both NMDA and non-NMDA receptors located on C1 neurons may be targets for the treatment of the trigeminal referred pain associated with migraine.