Objective: To study the ultrastructural changes of neuromuscular junction (NMJ) in patients with lambert-Eaton myasthenia syndrome (LEMS) and mitochondrial encephalomyopathy (MEMS).
Methods: The MMJ of internal intercostal muscles from patients with LEMS, MEMS or cardiac disease (control group) was labelled by HRP-BuTx and was quantitatively studied using image analysis system on electron microscopic photo.
Results: The ratio of nerve terminal area with postsynaptic membrane of NMJ was less in the MEMS group than controls. Both the length of presynaptic membrane and the ratio of the length of postsynaptic memberane to presynaptic membrane was larger in the LEMS group than in the MEMS group and controls, but the ratio of nerve terminal area with postsynaptic memberane area was less in the LEMS patients than in the MEMS group and controls.
Conclusion: The areas of nerve terminal in the MEMS patients shrink because of mitochondrial damage. In LEMS patients however, the major change is the elongation of postsynaptic memberane and increasing of Ach receptors.