title: [Decrement pattern of M-response amplitude in the low-frequency repetitive nerve stimulation in the muscles of patients with myasthenia gravis and Lambert-Eaton myasthenic syndrome].
abstract: OBJECTIVE
  To investigate the pattern of decrement in the muscles of patients with myasthenia gravis (MG) and Lambert-Eaton myasthenic syndrome (LEMS).
  
  
  METHODS
  Twenty-seven patients with MG and 39 patients with LEMS were studied using low frequency repetitive nerve stimulation (3/ sec).
  
  
  CONCLUSIONS
  The decrease of safety factor of neuromuscular transmission was equal in both groups. At the same time, a significant difference in the decrease of pattern of the amplitude compound of muscle action potential (CMAP) was found. In LEMS, by contrast with MG, another sequence of amplitude variability of CMAP from the second stimulus to the first and from the fifth stimulus to the fourth was noted. In LEMS patients, progressive decrement, manifesting by increasing ratios of late A9/A1 to early A4/A1 was found, whereas the MG patients showed retrogressive decrement expressed by the reduction in decrement ratio (from late to early). These differences reflect the mechanisms and status of acetylcholine mobilization and release from the axon terminal.
authors.affiliation: Moscow City Health Department, Moscow Myasthenia Center, SFHI Municipal Clinical Hospital No. 51, Moscow, Russia; Moscow Research and Clinical Center for Neuropsychiatry, Moscow, Russia.
authors.forename: D A
authors.initials: DA
authors.lastname: Tumurov
authors.affiliation: Moscow City Health Department, Moscow Myasthenia Center, SFHI Municipal Clinical Hospital No. 51, Moscow, Russia; Moscow Research and Clinical Center for Neuropsychiatry, Moscow, Russia; Pirogov Russian National Medical Research University, Moscow, Russia.
authors.forename: A G
authors.initials: AG
authors.lastname: Sanadze
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001369:Axons / Q000378:metabolism; D004576:Electromyography; D006801:Humans; D015624:Lambert-Eaton Myasthenic Syndrome / Q000503:physiopathology*; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000503:physiopathology*; D009460:Neurologic Examination; D009435:Synaptic Transmission; D004561:Transcutaneous Electric Nerve Stimulation; D055815:Young Adult
chemical_list: D000109:Acetylcholine