American Journal of Clinical Neurology and Neurosurgery
Articles Information
American Journal of Clinical Neurology and Neurosurgery, Vol.1, No.3, Nov. 2015, Pub. Date: Dec. 14, 2015
Evoked Electric Responses of the Muscle in Myasthenia Gravis Diagnostics
Pages: 164-168 Views: 2966 Downloads: 771
Authors
[01] Kvirkvelia N., Petre Sarajishvili Institute of Neurology, Tbilisi, Georgia.
[02] Shakarishvili R., Petre Sarajishvili Institute of Neurology, Tbilisi, Georgia.
[03] Khizanishvili N., Petre Sarajishvili Institute of Neurology, Tbilisi, Georgia.
Abstract
Analysis of the M-responses parameters of the muscles by means of indirect maximal stimulation with different frequencies is a very important method for diagnostic of Myasthenia gravis (MG). As an indicator of degree of neuromuscular transmission damage, a difference expressed in percents (decrement) between the first- and fifth M-responses was used. To define the dynamic of the release of a neurotransmitter and its interaction with acetylcholine receptor of the postsynaptic membrane in 265 MG patients with 3 imp/sec stimulation in a series of five responses’, we have determined the decrement (%) of the size of every following M-responses amplitude in correlation with amplitude of M-response of the previous. 265 MG patients were investigated, out of which 148 (55.9%) were female and 117 (44.1%) were male aged from 10 to 75. MG was diagnosed according to clinical and electromyographic (EMG) data, the level of antibodies against Acetylcholine receptors (AChR), Titin and MuSK, and results of pharmacologic tests. CT of chest was done to reveal pathology of the thymus. The most significant decrement of the M-responses at 3 imp/sec stimulation in a series of five responses was found between the second- and the first M-responses and between the third- and second responses. These data correlate with classically evaluated decrements between the first- and the fifth responses (r=0.64; p<0.001). The difference between the fifth- and the fourth M-responses was minimal. Thus, during the stimulation, the efficiency of released neurotransmitter interaction with receptors gradually decreases until the third impulse, when the physiologic decrement of neurotransmitter release takes place but from the fourth impulse mobilization of neurotransmitter begins. It is characterized for Lambert-Eaton myasthenic syndrome (LEMS) that as a response to the fourth and fifth stimulus, M-response amplitudes (area) continue to decrease compared with the third- and the fourth M-responses, while this difference is minimal in MG, and all these indicate to the differences in character between the neurotransmitter release and its interaction with AChR of postsynaptic membrane in different synaptic diseases, and this will facilitate to determine the character of the synaptic damage.
Keywords
M-Response, Negative Phase Amplitude, Area, Duration, Neuromuscular Transmission, Post-Tetanic Facilitation, Post-Tetanic Depression, Myasthenia Gravis, Antibodies Against Acetylcholine Receptors (Achr), Titin and Musk
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