RESUMEN
INTRODUCTION: Several studies have reported high diagnostic sensitivity and specificity for the ice test in myasthenia gravis. All of the studies employed a case-control design, in which the diagnosis was already known at the time of the test for both patients and controls, leading to case selection bias. This suggests that the available literature substantially overestimates the diagnostic utility of these tests. METHODS: A retrospective cohort study without selection bias was performed to examine the sensitivity and specificity of the ice test. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the ice test were determined by means of a 2 × 2 table. RESULTS: The ice test has a sensitivity of 0.92 (95% CI 0.62-1.00), specificity of 0.79 (95% CI 0.56-1.00), PPV of 0.73 (95% CI 0.48-0.90), and NPV of 0.94 (95% CI 0.70-1.00). CONCLUSIONS: Due to its high negative predictive value the ice test is still a reliable and useful bed-side test.
Asunto(s)
Blefaroptosis/complicaciones , Blefaroptosis/diagnóstico , Hielo , Miastenia Gravis/complicaciones , Miastenia Gravis/diagnóstico , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Estudios de Cohortes , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estimulación Física/métodos , Estudios Retrospectivos , Sensibilidad y Especificidad , Adulto JovenRESUMEN
BACKGROUND/AIMS: Little is known about the distribution of electromyographic (EMG) abnormalities in myositis even though this is relevant in daily practice. METHODS: A retrospective semiquantitative analysis of needle EMG findings was performed in a group of 98 patients with myositis. The frequency, type, and distribution of abnormalities were studied. The influence of the use of corticosteroids and the stage of the disease were evaluated. RESULTS: In most patients, a myopathic pattern with spontaneous activity was found, although several clinically relevant exceptions were noted. Long-duration motor unit potentials were found in all three diagnostic groups and were not associated with disease duration. In the lower extremity a distal to proximal gradient was present, adding to the diagnostic confusion with neurogenic diseases, and spontaneous activity was absent in a relatively large group although none of the patients in the acute stage of the disease had a normal EMG. The use of corticosteroids reduced the number of abnormal findings in dermatomyositis and polymyositis, but not in inclusion body myositis. CONCLUSION: A myopathic pattern with spontaneous activity was most frequently found, although several clinically relevant exceptions were noted. These results illustrate the spectrum of EMG findings in myositis, and may aid the clinician in the interpretation of the EMG in these patients.