Recent work in our research consortium has raised internal validity concerns regarding the current IASP criteria for Complex Regional Pain Syndrome (CRPS), suggesting problems with inadequate sensitivity and specificity. The current study explored the external validity of these IASP criteria for CRPS. A standardized evaluation of signs and symptoms of CRPS was conducted by study physicians in 117 patients meeting IASP criteria for CRPS, and 43 patients experiencing neuropathic pain with established non-CRPS etiology (e.g. diabetic neuropathy, post-herpetic neuralgia). Multiple discriminant function analyses were used to test the ability of the IASP diagnostic criteria and decision rules, as well as proposed research modifications of these criteria, to discriminate between CRPS patients and those experiencing non-CRPS neuropathic pain. Current IASP criteria and decision rules (e.g. signs or symptoms of edema, or color changes or sweating changes satisfy criterion 3) discriminated significantly between groups (P < 0.001). However, although sensitivity was quite high (0.98), specificity was poor (0.36), and a positive diagnosis of CRPS was likely to be correct in as few as 40% of cases. Empirically-based research modifications to the criteria, which are more comprehensive and require presence of signs and symptoms, were also tested. These modified criteria were also able to discriminate significantly, between the CRPS and non-CRPS groups (P < 0.001). A decision rule, requiring at least two sign categories and four symptom categories to be positive optimized diagnostic efficiency, with a diagnosis of CRPS likely to be accurate in up to 84% of cases, and a diagnosis of non-CRPS neuropathic pain likely to be accurate in up to 88% of cases. These results indicate that the current IASP criteria for CRPS have inadequate specificity and are likely to lead to overdiagnosis. Proposed modifications to these criteria substantially improve their external validity and merit further evaluation.

The coordination of mastication, oral transport, and swallowing was examined during intake of solids and liquids in four normal subjects. Videofluorography (VFG) and electromyography (EMG) were recorded simultaneously while subjects consumed barium-impregnated foods. Intramuscular electrodes were inserted in the masseter, suprahyoid, and infrahyoid muscles. Ninety-four swallows were analyzed frame-by-frame for timing of bolus transport, swallowing, and phases of the masticatory gape cycle. Barium entered the pharynx a mean of 1.1 s (range -0.3 to 6.4 s) before swallow onset. This interval varied significantly among foods and was shortest for liquids. A bolus of food reached the valleculae prior to swallow onset in 37% of sequences, but most of the food was in the oral cavity at the onset of swallowing. Nearly all swallows started during the intercuspal (minimum gape) phase of the masticatory cycle. Selected sequences were analyzed further by computer, using an analog-to-digital convertor (for EMG) and frame grabber (for VFG). When subjects chewed solid food, there were loosley linked cycles of jaw and hyoid motion. A preswallow bolus of chewed food was transported from the oral cavity to the oropharynx by protraction (movement forward and upward) of the tongue and hyoid bone. The tongue compressed the food against the palate and squeezed a portion into the pharynx one or more cycles prior to swallowing. This protraction was produced by contraction of the geniohyoid and anterior digastric muscles, and occurred during the intercuspal (minimum gape) and opening phases of the masticatory cycle. The mechanism of preswallow transport was highly similar to the oral phase of swallowing. Alternation of jaw adductor and abductor activity during mastication provided a framework for integration of chewing, transport, and swallowing.

This is a multisite study examining the internal validity and comprehensiveness of the International Association for the Study of Pain (IASP) diagnostic criteria for Complex Regional Pain Syndrome (CRPS). A standardized sign/symptom checklist was used in patient evaluations to obtain data on CRPS-related signs and symptoms in a series of 123 patients meeting IASP criteria for CRPS. Principal components factor analysis (PCA) was used to detect statistical groupings of signs/symptoms (factors). CRPS signs and symptoms grouped together statistically in a manner somewhat different than in current IASP/CRPS criteria. As in current criteria, a separate pain/sensation criterion was supported. However, unlike in current criteria, PCA indicated that vasomotor symptoms form a factor distinct from a sudomotor/edema factor. Changes in range of motion, motor dysfunction, and trophic changes, which are not included in the IASP criteria, formed a distinct fourth factor. Scores on the pain/sensation factor correlated positively with pain duration (P<0. 001), but there was a negative correlation between the sudomotor/edema factor scores and pain duration (P<0.05). The motor/trophic factor predicted positive responses to sympathetic block (P<0.05). These results suggest that the internal validity of the IASP/CRPS criteria could be improved by separating vasomotor signs/symptoms (e.g. temperature and skin color asymmetry) from those reflecting sudomotor dysfunction (e.g. sweating changes) and edema. Results also indicate motor and trophic changes may be an important and distinct component of CRPS which is not currently incorporated in the IASP criteria. An experimental revision of CRPS diagnostic criteria for research purposes is proposed. Implications for diagnostic sensitivity and specificity are discussed.

We have demonstrated that subjects with complex regional pain syndrome (CRPS) have asymmetric venous pool plasma concentrations of norepinephrine (NE) when affected and unaffected limbs are compared, with most demonstrating decreased NE levels in the affected limb. This pilot study explored whether systemic venous plasma catecholamine levels in CRPS subjects with sympathetically maintained pain (SMP) differ from those found in healthy volunteers. We also explored whether catecholamine levels were correlated with scores on psychometric measures of depression, anxiety, and personality. Venous blood samples from 33 CRPS/SMP patients (from unaffected limbs) and 30 healthy control subjects were assayed for plasma NE and epinephrine (E) concentrations. Plasma NE levels were significantly higher in the CRPS group (P < 0.001). Statistical comparisons of E levels across groups did not achieve significance (P < 0.06), although 52% of CRPS/SMP patients had E levels exceeding the 95% confidence interval based on control data. Significant positive correlations were found between E levels and scores on the Beck Depression Inventory and Scales 1, 3, and 6 on the Minnesota Multiphasic Personality Inventory-2 (all P < 0.05). This preliminary work suggests that increased NE and E levels in CRPS/SMP patients may result from the pain of CRPS, consequent affective distress, or both. Alternatively, our findings could reflect premorbid adrenergic hyperactivity caused by affective, endocrine, or other pathology, which might predispose these individuals to develop the syndrome. Definitive studies are needed to examine these hypotheses in detail.

Myofascial pain syndrome (MPS) and fibromyalgia (FM) are complex conditions and pose significant challenges to clinicians and patients. This chapter explores available treatments for MPS and FM in the context of pathophysiology, clinical evidence, and experimental support. This information may prove to be helpful in designing individualized treatment for patients with these complex syndromes. New treatments should be critically and carefully evaluated as they appear.

Hypermobility spectrum disorders (HSDs) encompass an array of connective tissue disorders characterized by joint instability and chronic pain. Fatigue and other systemic symptoms that affect daily functioning may occur, as well. Accurate data on incidence and prevalence of HSDs is hampered by lack of awareness of these conditions and the wide heterogeneity of their clinical presentation. Identifying which type of HSD is present is important in guiding appropriate care. In particular, making the diagnosis of hypermobile Ehlers-Danlos syndrome (hEDS) is important, as individuals with hEDS may be at risk for more significant multisystem involvement. Diagnostic criteria for hEDS include measures of joint hypermobility, skin and other connective tissue findings, and lack of evidence of a different type of Ehlers-Danlos syndrome. Beyond accurate diagnosis, HSDs pose many challenges for primary care providers, as ongoing patient education, patient empowerment, and coordination of a multidisciplinary treatment team are integral to proper care. This article describes the incidence and prevalence, pathophysiology, diagnosis, and management of HSDs, including clinical cases exemplifying how joint hypermobility might present within a primary care setting.

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