[Neurogenic electromyographic activity in a patient with non-paraneoplasic Lambert-Eaton syndrome]. / Activité électromyographique neurogène dans un cas de syndrome de Lambert-Eaton non-paranéoplasique.

INTRODUCTION: Lambert-Eaton myasthenic syndrome (LEMS) is a rare presynaptic disorder of the neuromuscular junction. Electrodiagnosis is characterized by compound muscle action potentials of small amplitude at rest, normalizing immediately after brief exercise or high-rate nerve stimulation. Needle electromyographic (EMG) activity is classically described as normal or myogenic. CASE: We report the case of a young patient with a non-paraneoplastic LEMS in whom the initial electroneuromyographic examination showed neurogenic changes in needle EMG concomitant with typical features of presynaptic neuromuscular junction disorder at single and repetitive nerve stimulation. DISCUSSION: Neurogenic EMG abnormalities were not previously described in patients with LEMS and could result from "functional" reversible denervation, depending on the presence of anti-calcium channel antibodies at axon terminals. CONCLUSION: Neurogenic features in needle EMG examination in case of subacute motor deficiency should not eliminate the possibility of a presynaptic neuromuscular junction disorder, such as LEMS.

CSF isoelectrofocusing in a large cohort of MS and other neurological diseases.

The present study was performed in order to confirm the diagnostic value of isoelectrofocusing (IEF) in a large multiple sclerosis (MS) cohort and to evaluate the various neurological diseases probably to present a similar IEF profile. The cerebrospinal fluid (CSF) of 1292 patients with neurological diseases was studied by IEF. After a follow-up of 2-36 months, we only included patients with a definite MS or confirmed diagnosis of other neurological diseases (OND). MS was diagnosed in 407 patients and OND in 593 patients. For patients in whom three or more oligoclonal bands (OCB) were detected, IEF results showed a sensitivity of 85% and a specificity of 92% for the diagnosis of MS. The positive and negative predictive values were 86.5 and 90%, respectively. Inflammatory and infectious disorders of the central nervous system represented the main affections associated with OCB, including human immunodeficiency virus encephalitis, Lyme disease and less frequently Sjogren syndrome. Furthermore, when OCB were observed, 10 or more bands were more frequently found in MS than in OND (P < 0.0001). IEF of the CSF is a reliable method for the diagnosis of MS. The absolute number of bands may help to discriminate between MS and OND.