Literature review of the usefulness of repetitive nerve stimulation and single fiber EMG in the electrodiagnostic evaluation of patients with suspected myasthenia gravis or Lambert-Eaton myasthenic syndrome

A retrospective literature review of the electrodiagnosis of myasthenia gravis (MG) and Lambert--Eaton myasthenic syndrome (LEMS) through July 1998 was performed for the purpose of generating evidence-based practice parameters. There were 545 articles identified, of which 13 articles met at least three of the six criteria set previously by the American Association of Electrodiagnostic Medicine (AAEM). An additional 21 articles were identified from review articles or the references of these first 13 articles leading to a total of 34 articles. Results of studies utilizing repetitive nerve stimulation (RNS) showed that a 10% decrement in amplitude from the first to fourth or fifth intravolley waveform while stimulating at 2--5 HZ is valid for the diagnosis of MG. The degree of increment needed for the diagnosis of LEMS is at least 25% but most accurate when greater than 100%. Abnormal jitter or impulse blocking are the appropriate criteria for diagnosis of neuromuscular junction (NMJ) disorders when using single fiber electromyography (SFEMG). SFEMG is more sensitive than RNS for the diagnosis of disorders of neuromuscular transmission, but may be less specific and may not be available. Therefore, RNS remains the preferred initial test for MG and LEMS.     

Skin cancer diagnosis by dermatologists in the region of Champagne-Ardenne: a prospective study

INTRODUCTION: The exact incidence of skin cancers is not well established in France as in other european countries, except for cutaneous melanoma. It is the same for the part taken by dermatologists in the screening of skin malignancies. We have therefore planned a prospective study in the Champagne-Ardenne region to determine the incidence of the various types of skin cancers diagnosed by dermatologists.PATIENTS AND METHOD: A prospective study was performed within a 4-month period at the end of 1998 with the participation of the dermatologists of the Champagne-Ardenne and the south of Aisne. The new incident cases of skin cancers confirmed histologically were recorded using a questionnaire including the type of tumour, demographic data of the patient and type of practice of the dermatologist. Parallely, the pathology laboratories of the same region were asked about the number of squamous and basal cell carcinomas and melanomas diagnosed histologically during the same period of time.RESULTS: The rate of participation of dermatologists was 86 p. 100. During the study period, 898 skin cancers were diagnosed in 794 patients (408 women and 386 men; mean age 70.1 years) including 643 basal cell carcinomas, 123 squamous cell carcinomas, 48 Bowen diseases, 53 melanomas, 7 lymphomas and 24 other tumours. More than 80 p. 100 of patients were primarily seen in private practice. Ten of 13 pathology laboratories of the region replied to the inquiry. From these pathological data, 585 basal cell carcinomas, 125 squamous cell carcinomas and 44 melanomas were recorded during the same period of time.DISCUSSION: This study shows that the oncologic clinical practice of dermatologists in our region is considerable. Taking into account both participation and exhaustivity rates, one can estimate at more than 3,500 the annual number of skin cancers diagnosed by dermatologists in our region, with an expected distribution of the various types of cancers. The essential role of the dermatologists in screening skin malignancies is confirmed by data provided by pathology laboratories. This role is a french characteristic and cannot by applied to other industrialized countries.