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Odontogenic pain may be due to periodontic or endodontic etiology. Myofacial and temporomandibular joint pain as well as sinusitis may cause referred pain to teeth. The following cases demonstrate yet another source of referred pain that could potentially cause a misdiagnosis.
This is a case report of a 33-year-old woman who presented with an eight year history of deep left knee pain. The pain was originally diagnosed as deriving from osteoarthrosis of the hip secondary to dysplasia, however, the same pain returned at seven months, and again at 10 months, after successful hip resurfacing arthroplasty. Six to eight weeks after the start of the second relapse of referred knee pain, the patient sought acupuncture treatment at the British Medical Acupuncture Society's London Teaching Clinic. A single myofascial trigger point was found in iliopsoas that reproduced the patient's pain. It was successfully treated with two sessions of electroacupuncture applied directly to the point. Pain referral to the knee from trigger points in the upper part of rectus femoris is well recognised, however, this pattern of referral from iliopsoas has not been described previously.
Dorsal root ganglion (DRG) neurons with dichotomizing axons have been reported in several species and are thought to be related to referred pain. However, these neurons, which have dichotomizing axons to the lumbar muscles and to the knee, have not been investigated. Clinically, pain from the lumbar muscles is sometimes referred to the lower extremities. Two kinds of neurotracers [1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine perchlorate (DiI) and fluoro-gold (FG)] were used in the present double-labelling study. DiI crystals were placed in the left lower back muscle, and FG was applied to the medial side of the knee. Bilateral DRGs from L1 through L6 were immunoreacted with calcitonin gene-related peptide (CGRP) antibodies and observed under a fluorescence microscope. DRG neurons double-labelled with DiI and FG were recognized only in the ipsilateral DRGs from levels L1 to L6. Approximately 1% of DRG neurons innervating the low back muscles had other axons to the medial side of the knee. In double-labelled neurons, the ratio of CGRP-immunoreactive DRG neurons was 60%. This finding provides a possible neuroanatomical explanation for referred knee pain from the lower back since CGRP is a marker of sensory neurons typically involved with pain perception. However, these neurons are rare, and mechanisms of referred pain may be explained by the convergence-projection hypothesis.
Human experimental visceral pain models using chemical stimulation are needed for the study of visceral hyperexcitability. Our aim was to stimulate the human gut with chemical activators (capsaicin, glycerol) and measure quantitatively the induced hyperexcitability to painful mechanical gut distension. Ten otherwise healthy subjects with an ileostoma participated. Increasing volumes of capsaicin 50 microg/ml (0.25, 0.5, 0.75, 1.0, 1.5, 2.0, and 3 ml), glycerol (2.5, 5, and 10 ml) or saline (2.5, 5, and 10 ml) intermingled with sham stimuli were randomly applied to the ileum via the stomal opening at three occasions separated by a week. After each application, pain intensity, qualities, and referred pain area were assessed together with the pain threshold to distension of the proximal gut. 'Boring' and 'hot' pain were evoked in all subjects by low doses (median 0.5 ml) of capsaicin. The median pain onset, peak pain, and pain duration were 55, 85, and 420 s, respectively. Referred somatic pain developed around the stomal opening with a correlation between the pain area and pain intensity. After application of capsaicin, significant hyperalgesia was found to distension of the gut (a 28% reduction pressure in pain threshold). No significant manifestations were found after application of glycerol and saline. Application of capsaicin to the human ileum induces pain and mechanical hyperalgesia. Specific activation of nociceptors in the gut mucosa provides new possibilities to study clinical relevant visceral pain mechanisms.
AIM: To investigate the clinical presentations of ruptured myocardial infarction, where the initial diagnosis of myocardial infarction was missed, to enhance the diagnostic rate of primary care physicians. METHODS: We studied 67 cases of myocardial infarction, terminating with left ventricular rupture, between January 1988 and December 1996. The study was restricted to sudden death where, at coroner-directed autopsy, a ruptured myocardial infarction was determined as the cause of death. It was also restricted to patients who consulted a doctor within the two weeks prior to death. The report made to the coroner by attending police and the autopsy report was studied, and the requisite data were abstracted. RESULTS: Half of our study group did not present with chest pain. Of the atypical presentations: 15/67 cases (22%) were from referred pain (neck, arm, abdomen or back), 12/ 67 patients presented with "flu-like illness" (18%), 4/67 cases had respiratory presentations (cough or shortness of breath) (6%) and 2/67 falls (3%). Of those with chest pain, 16/34 (47%) were diagnosed or referred and 2/15 infarcts with atypical or referred pain were diagnosed. None of those presenting with "flu like illness" or respiratory symptoms was diagnosed or referred. CONCLUSION: Fifty per cent of our patients had "silent" myocardial infarcts. A large proportion of this group complained of a flu-like illness, which is currently not considered a presentation of this disease. Patients at higher risk of a myocardial infarct, should be treated with a high index of suspicion when unwell, especially when complaining of a flu-like illness. Pathologically, posterior and lateral infarcts accounted for over half the cases.
Little is known about sex differences in the temporal pattern of descending inhibitory mechanisms, such as descending noxious inhibitory control (DNIC). Sex differences in temporal characteristics of DNIC were investigated by measuring pressure pain thresholds (PPTs) over time in the trapezius muscles (local pain areas) and the posterolateral neck muscles (referred pain areas) following repeated bilateral injection of hypertonic versus isotonic saline into both trapezius muscles. Ten females and 11 males received two consecutive bilateral injections, with 15 min interval, of either 5.8% hypertonic saline (0.5 ml in each side for each bilateral injection) or isotonic saline as a control in a randomized manner. Following hypertonic saline injection, the maximal pain intensities of the first and second bilateral injections were significantly higher in females than in males. The PPTs in the trapezius muscles were significantly lower in females than in males. Significantly higher PPTs (hypoalgesia) in men than in women were shown 15 min after the first bilateral injection, and 7.5 and 15 min after the second bilateral injection in the referred pain areas. Importantly, the second bilateral injection failed to further increase the PPTs for both sexes. These results showed that there were sex differences in temporal characteristics of descending inhibition with long-lasting hypoalgesia in men than in women. Repeated noxious muscular stimuli may inhibit further build-up of DNIC, which may reflect a mechanism of plasticity of the descending inhibitory systems following recurrent nociceptive barrage for both sexes.
Two fluorescent dyes, 'True Blue' and 'Diamidino Yellow' were injected, respectively, into the pericardial sac and into the medial brachial cutaneous nerve or subcutaneously into the medial side of the brachium. Double-labelling was observed in ipsilateral dorsal root ganglia neurons of spinal cord segments C8, T1 and T2, indicating that dichotomizing afferent fibers supply both the pericardium and the brachium. This finding provides a possible morphological explanation for referred cardiac pain.
OBJECTIVES: The aims of the study were to: (i) determine the prevalence of panic disorder (PD) in patients referred to cardiological outpatient clinics for evaluation of chest pain; (ii) compare psychiatric comorbidity, psychological distress, pain characteristics and suicidal ideation in PD and non-PD patients: (iii) compare the prevalence of coronary risk factors and medical comorbidity in PD and non-PD patients; and (iv) describe current PD treatment and need for PD treatment as expressed by PD patients. DESIGN: A cross-sectional study based on psychiatric and cardiological investigation. SETTING: Four cardiological outpatient clinics in Oslo, Norway. SUBJECTS: One-hundred and ninety-nine consecutive patients without known heart disease referred to out-patient clinics for investigation of chest pain. MAIN OUTCOME MEASURES: Psychiatric state diagnosis (axis I); scores on self-assessment rating scales of psychological factors and pain modalities; cardiological diagnosis. RESULTS: Thirty-eight per cent of the patients met criteria for current panic disorder (PD). Panic disorder was associated with psychological distress, comorbid psychiatric disorders, medical disorders and significantly higher prevalence of coronary risk factors (P<0.05). Furthermore. the results suggest that these patients were not identified and appropriately treated for panic disorder prior to cardiological investigation. The results indicate that the patients are positive to screening for psychiatric disorder and communicate a need for treatment early in the investigation process. CONCLUSION: PD commonly occurs in this chest pain population. Thus, there is a need to educate physicians caring for these patients about PD identification and treatment.
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Myofascial trigger point is a sensitive spot in a palpable taut band of skeletal muscle fibers. Two important clinical characteristics of trigger points, referred pain and local twitch response, can be elicited by mechanical stimulation (palpation or needling). The trigger point is usually activated by acute or chronic injury to a muscle, tendon, ligament, joint, disc or nerve. Recent human and animal studies have suggested that the pathogenesis of either referred pain or local twitch response is related to integration in the spinal cord. It has been proposed that there are multiple sensitive loci in a trigger point region. A sensitive locus may contain one or more sensitized nociceptive nerve endings. Mechanical stimulation of a sensitive locus can elicit a local twitch response which is frequently associated with characteristic referred pain. Theoretically, sensitive loci can be found in any site of a skeletal muscle, but is usually distributed with highest concentration near the endplate region where a trigger point is frequently found. The trigger point is a common pathogenic pathway of muscle pain from different causes.
INTRODUCTION: Lower back pain (LBP) is one of the most frequent reasons for visits to basic and specialised health care centres and one of the commonest causes of referral for electromyographic (EMG) explorations. AIMS. The aim of this study is to determine the sensitivity and specificity of the clinical examination in patients with LBP and abnormal EMG findings. PATIENTS AND METHODS: A cross sectional study was carried out on 364 patients with LBP who had been referred to both basic and specialised clinics, and who were attended in the Electromyography Service of a hospital belonging to the Instituto de Seguros Sociales, throughout the years 2001 and 2002. The same clinical evaluation protocol (interview and physical examination) was applied to all the patients. They were also evaluated using the same electrophysiological protocol, which in all cases included a study of the H waves and the adductor longus, tensor fasciae latae, medial vastus, anterior tibial, extensor digitorum longus, the medial and lateral heads of gastrocnemius, gluteus maximus and paraspinal muscles. The abnormal EMG examination was taken as the reference criterion and we determined the sensitivity, specificity, probability ratio, pre test probability and post test probability of the following clinical categories: referred pain (RP), pain less than three months, muscular strength of dorsiflexors, plantarflexors and knee extensor mechanisms, hypaesthesia in the L4, L5, S1 dermatomes, patellar areflexia and Achilles areflexia. RESULTS: From the clinical history and physical examination, the pain referred to the extremity showed the highest sensitivity (80.89%), but its specificity was the lowest. This contrasted with the other clinical findings which, in general, showed high specificity (between 82.6% for hypaesthesia in the L5 dermatome and 97.5% for the weakness of the plantarflexors), but low sensitivity (from 6.37% for the weakness of the quadriceps to 35.67% for hypaesthesia in the L5 dermatome). Achilles areflexia showed the highest positive predictive value (85%) and the highest probability ratio (7.47), while the highest negative predictive value was found in pain referred to the extremity (68.75%). CONCLUSION: Although the clinical history and findings from the physical examination do not allow the prediction of a normal or abnormal electrophysiological result in patients with LBP, the interview and some of the clinical tests do make it easier to select which patients should be referred for an EMG exploration, the purpose of which is to aid the diagnosis of a lumbar radiculopathy.
It is uncertain to what degree sensation and pain relating to the gut are influenced by sex. The aim of the study was to explore sex differences to experimental multimodal stimulation of the esophagus in 22 age-matched males and females. A probe was positioned in the lower part of the esophagus. Mechanical stimuli were applied as distensions with a bag using an impedance planimetric method. The distensions were done before and after relaxation of the smooth muscle. Thermal stimulation was done with recirculating water at 1 and 60 degrees C in the bag. The sensory intensities were assessed during the stimulations, and the referred pain area was drawn at maximum pain intensities. An increased sensation to mechanical stimuli was found in the males for volume, pressure, and tension (P = 0.003, P = 0.02, P = 0.005), whereas cross-sectional area and strain showed no sex difference (P = 0.06, P = 0.9). Sex differences were not found for the cold and warmth stimulations (P = 0.6, P = 0.1). The mean size of the referred pain areas to the different stimuli was 23.6 cm2 in males and 48.7 cm2 in females (P = 0.002). As strain is believed to be the major determinant for the sensory response to mechanical stimulation of the gut, we conclude that no robust sex differences were observed in the assessments of the multimodal stimulations. However, the larger referred pain area in females reflects sex differences in central pain processing, which may explain the female preponderance in functional disorders relating to the gut.
OBJECTIVE: This study reviews the clinical distinctions between fibromyalgia (FM) and myofascial pain syndrome (MPS), which represent two separate and distinct soft-tissue syndromes. The major aim of this article is to clarify the terminology associated with these syndromes and clearly define the parameters of differential diagnosis and treatment. DATA SOURCES: Pertinent articles in the chiropractic and medical literature are reviewed with an emphasis on the literature published from 1985-1994. STUDY SELECTION: Studies were selected that emphasized differential diagnosis of FM and MPS, as well as individual articles on either FM or MPS. DATA SYNTHESIS: The literature on fibromyalgia and myofascial pain syndromes has grown considerably since 1985. It is now clear that there are several important differences between FM and MPS. The most important criteria for differential diagnosis are the presence of tender points (TePs) and widespread, nonspecific, soft tissue pain in FM, compared with regional and characteristic referred pain patterns with discrete muscular trigger points (TrPs) and taut bands of skeletal muscle in MPS. The etiology of TePs is still unknown and it is uncertain which specific soft tissues are tender in FM patients. Myofascial TrPs are found within a taut band of skeletal muscle and have a characteristic "nodular" texture upon palpation. TrPs are thought to develop after trauma, overuse or prolonged spasm of muscles. Local treatment applied to TePs is ineffective, yet specific treatment of TrPs is often dramatically effective. CONCLUSION: FM and MPS are two different clinical conditions that require different treatment plans. FM is a systemic disease process, apparently caused by dysfunction of the limbic system and/or neuroendocrine axis. It often requires a multidisciplinary treatment approach including psychotherapy, low dose antidepressant medication and a moderate exercise program. MPS is a condition that arises from the referred pain and muscle dysfunction caused by TrPs, which often respond to manual treatment methods such as ischemic compression and various specific stretching techniques. Both of these conditions are seen routinely in chiropractic offices; therefore, it is important for field practitioners to understand these distinctions.
Neurons of T2 to T4 spinal segments were antidromically activated from the medullary reticular formation and the contralateral region in or near the ventral posterior lateral nucleus of the thalamus. Sixty-seven percent of the spinoreticular neurons projected to the ipsilateral, contralateral, or both ipsilateral and contralateral medullary reticular formation. In addition, 21% of the cells projected to the reticular formation and thalamus and 12% projected only to the thalamus. These cells received both visceral and somatic inputs. Electrical stimulation of cardiopulmonary sympathetic afferent fibers elicited an early peak of cell activity in 30 cells, an early and late peak in 38 cells, and only a late peak in 1 cell. Seventy-one percent of the cells had simple somatic receptive fields; these fields were localized to the left forelimb and left upper thorax. The remaining 29% of the cells had complex receptive fields that often extended to the hind limb as well as bilaterally. Classification of all cells according to threshold for activation of the somatic receptive field showed that 86% of the cells were high-threshold, 10% were wide dynamic range, and 4% were high-threshold but, in addition, were inhibited during hair movement. Viscerosomatic convergence onto these cells support Ruch's convergence projection theory for referred pain. These projecting neurons may be involved with referred pain associated with angina pectoris. In addition, they may also be involved with cardiovascular adjustments.
BACKGROUND: Chronic neck pain can be a difficult problem to evaluate and treat, as it can have several different causes. We studied a series of patients with neck pain near the superomedial aspect of the scapula that was referred pain from inflammation of the shoulder secondary to chronic impingement. We postulate that some patients with specific clinical findings and neck pain can benefit from treatment of shoulder impingement. METHODS: We conducted a retrospective review of the charts of thirty-four patients with neck pain who met three criteria for the diagnosis of shoulder impingement syndrome: (1) a positive impingement sign with pain referred to the neck, (2) radiographic abnormalities, and (3) relief of neck pain after injection of lidocaine and cortisone into the subacromial space. Subjective pain scores were determined before and after the injection. RESULTS: Thirty of the thirty-four patients obtained immediate relief of the neck pain following injection into the subacromial space, and the remaining four had substantial pain relief when they were evaluated three weeks following the injection. Avoidance of the shoulder impingement position (forward elevation of the arm above 90 degrees ) subsequently minimized recurrences. CONCLUSIONS: In selected patients, chronic neck pain may be caused by shoulder impingement, which can be easily diagnosed with standard techniques. The difficulty in making this diagnosis is that the patient presents with neck pain rather than with the typical shoulder pain. The differential diagnosis of chronic lower neck pain should include shoulder impingement syndrome, which can be identified by classic physical and radiographic signs and can be treated with injection into the subacromial space and avoidance of the shoulder impingement position.
Evidence gathered from our studies and the work of others appears to support the presence of two distinct nerve pain pathways in the dental pulp, represented by fast conducting A-delta and slow conducting C-fibers. Each of these types of fibers has different pain characteristics: A-delta fibers evoke a rapid, sharp, lancinating pain reaction, and C-fibers cause a slow, dull, crawling pain. Pain response thresholds vary in different regions of the tooth, and thermal, osmotic, ionic, and electric stimuli involve different mechanisms to provoke nerve excitation of the dental pulp. Evidence also points to the fact that the incidence of pain increases as the histopathosis worsens. On interrogation, patients who manifest severe or referred pain almost always give a previous history of pain in the tooth with the ache. Eighty percent of patients who give a previous history of pain manifest histopathologic evidence of chronic partial pulpitis with partial necrosis, the untreatable category, for which endodontics or extraction is indicated. The other 20% exhibit histopathosis of the pulp with slight inflammation to chronic partial pulpitis without necrosis, a treatable category. Clinically, one can determine the degree of pulp histopathosis by asking the patient about a previous history of pain in the involved tooth. This history of previous pain adds another dimension in diagnosis for the clinician as to whether the painful pulpitis is reversible. This information also aids in referred pain localization.
This article reports a prospective, randomized, multicentered study documenting changes in the intensity and location of low-back and referred pain to repeated end-range lumbar flexion and extension movements performed first while standing and then while recumbent during a single clinical patient evaluation. Significant and rapid changes in central and distal pain intensity and location of peripheral pain resulted from the performance of these movements. For the mean in both protocols, regardless of the order of spinal movements, end-range extension significantly decreased central and distal pain intensity and centralized referred pain. Flexion spinal movements, however, significantly increased mean central and distal pain intensity and peripheralized the pain. Forty percent of individual subjects had a clear preference for extension and 7% a clear preference for flexion.
Myofascial pain syndrome is a disease of muscle that produces local and referred pain. It is characterized by a motor abnormality (a taut or hard band within the muscle) and by sensory abnormalities (tenderness and referred pain). It is classified as a musculoskeletal pain syndrome that can be acute or chronic, regional or generalized. It can be a primary disorder causing local or regional pain syndromes, or a secondary disorder that occurs as a consequence of some other condition. When it becomes chronic, it tends to generalize, but it does not change to fibromyalgia. It is a treatable condition that can respond well to manual and injection techniques, but requires attention to postural, ergonomic, and structural factors, and toxic or metabolic factors that impair muscle function.