Dyspnea and pulmonary function in the L-tryptophan-associated eosinophilia-myalgia syndrome

Does the 'oxygen cost diagram' reflect changes in six minute walking distance in follow up studies?

The oxygen cost diagram (OCD) is a simple scale for quantifying a patient's evaluation of his tolerance to exercise frequently used in clinical trials; it has been shown to be well correlated with objective measures of capacity of ambulation such as the 6 min walk test (6' W). This study aimed to determine whether the OCD accurately depicts changes in capacity of ambulation either quantitatively or qualitatively. OCD ratings were analysed at baseline and after a 1 yr follow-up, in patients treated by non-invasive home mechanical ventilation, as well as objective measurements of pulmonary function [forced expiratory volume in 1 sec (FEV1), forced vital capacity (FVC), arterial blood gases], physical autonomy (6' W), resting dyspnoea (Borg scale) and scores for anxiety or depressive disorders (HAD). Forty-five patients (24 male, 21 female, aged 62 +/- 16 years, mean FEV1: 38 +/- 17% of predicted) were evaluated at baseline. OCD ratings were significantly correlated with 6 min walking distance (P < 0.0001)--although with a large variability around the regression line--but not with resting dyspnoea (Borg). Patients were re-evaluated after 352 +/- 90 days. Changes in OCD ratings were not significantly correlated with changes in FFV1 FVC, PaO2, PaCO2, 6' W, HAD scores or resting dyspnoea; furthermore--albeit for Borg scores--changes in OCD did not reflect the trend of changes in these parameters. These results show that although OCD ratings are well correlated with results of a 6' W test, they cannot be used to extrapolate individual performances, because of a large variability around the regression line, furthermore, changes in the OCD over 1 yr did not depict objective changes in 6' W test results, either quantitatively or qualitatively. The use of the OCD in clinical trials should be limited to the description of the patient's perception of exercise tolerance, as a component of health-related quality of life, with the awareness of possible discrepancies between changes in objective performances and changes in OCD ratings.

Clinical features of eosinophilia myalgia syndrome and related disorders

EMS, EF, and TOS are all relatively rare disorders. There are considerable data to suggest that most (if not all) of these cases may be due to toxin exposure, although the precise etiologic agent(s) has yet to be identified. It is likely that the pathogenic mechanisms responsible for disease are similar in these entities, and thus the distinctions between these illnesses may be largely semantic. Rational therapy includes the removal of an inciting agent if identified, and the application of symptom-based treatment based on the organ or tissue involved, and whether there is evidence of active inflammation is present.

Head and neck manifestations of eosinophilia-myalgia syndrome

Eosinophilia-myalgia syndrome (EMS) is a multisystemic disease that occurs in patients who have consumed products containing L-tryptophan. Prominent features include incapacitating myalgias, arthralgias, neuropathies, and eosinophilia. Despite the frequent association of dysphagia, dyspnea, and the potential for aspiration, the otolaryngology literature is devoid of information on EMS. In order to determine the frequency of otolaryngic symptoms, questionnaires were distributed to patients with EMS in 33 different US states. Among the 28 various head and neck manifestations studied, 70% of EMS patients complained of generalized muscle spasms, 66% xerostomia, 62% dyspnea, and 56% dysphagia. In addition, the epidemiology, clinical presentation, diagnostic criteria, and treatment options are discussed. This paper assesses the frequency of otolaryngic manifestations of EMS, as well as introduces this syndrome to the otolaryngologist-head and neck surgeon. It is important for the otolaryngologist to be aware of EMS and its manifestations and treatments so that patients with this potentially lethal disease can receive appropriate evaluation and expeditious treatment.

A murine model of the eosinophilia-myalgia syndrome induced by 1,1'-ethylidenebis (L-tryptophan)

The eosinophilia-myalgia syndrome (EMS) is a recently described disease that has been associated with the ingestion of L-tryptophan containing trace amounts of several impurities. The first such contaminant to be identified and linked epidemiologically to the EMS epidemic was 1,1'-ethylidenebis(L-tryptophan) (EBT), but its role in the etiology and pathogenesis of the syndrome has been controversial. We report the development of inflammation and fibrosis affecting the dermis and subcutis, including the fascia and perimyseal tissues, after the daily intraperitoneal administration of EBT to female C57BL/6 mice. Such changes are accompanied by increased numbers of mast cells, many of which appear to be degranulating. Plasma levels of quinolinic acid, a metabolic product of L-tryptophan via the kynurenine pathway, are reduced initially, and then become elevated when inflammation and fibrosis are more pronounced. The nature and location of the inflammatory cell infiltrate and fibrosis, as well as the presence of mast cells and alterations of L-tryptophan metabolism, are consistent with findings reported in patients with EMS. This murine model suggests that EBT may have been one of the mediators of EMS and should facilitate studies of the pathogenesis of EMS.

Chronicity of the eosinophilia-myalgia syndrome. A reassessment after three years

OBJECTIVE

To define the natural history and outcome of eosinophilia-myalgia syndrome (EMS) among a cohort of patients followed up at one center since the onset of their disease.

METHODS

Fifty-seven patients with well-characterized EMS were evaluated prospectively at a university hospital for 21-64 months (mean 36 months).

RESULTS

Eighty-eight percent of the patients continue to have symptomatic disease with > 3 clinical manifestations. Fatigue (91%), muscle cramping (75%), myalgia (70%), paresthesias with objectively demonstrated hypesthesias (62%), articular symptoms (54%), scleroderma-like skin changes (44%), and proximal muscle weakness (40%) are the most common features of chronic EMS. New findings identified among this cohort include cognitive symptoms in 86% of the study group, tremor, and myoclonus.

CONCLUSION

The recognition of new manifestations in EMS and ongoing clinical disease in 88% of patients highlights the chronic nature of this disorder. Continued prospective followup of a large patient base is warranted to further define the natural history of this newly recognized illness.