Hashimoto S, Akai F, Semba E, Sakatani K, Hiruma S, Nagaoka M, Hukuda K, Imada A
J Neurol Sci. 1980 Jan;44(2-3):169-79. doi: 10.1016/0022-510x(80)90125-2.
Hypokalemic myopathy has been observed in various clinical conditions. There are many studies of the pathomorphological changes of muscle fibers but alterations in intramuscular nerves and motor end-plates are seldom mentioned. The present authors observed biopsied muscle from a 51-year-old housewife who had suffered from gradually increasing muscle weakness. Laboratory examinations revealed a severe hypokalemia of 1.5 mEq/1, 18304 U/1 of CPK, 1300 U/1 of LDH, 343 U/1 of SGOT and 297 IU/1 of adolase. Light-microscopic examination showed changes previously described, including twin-peaked distribution in the histogram of type I, IIA and IIB fibers, ballooning and thickening of terminal axon, and 2 or 3 end-plates closely spaced along the length of muscle fibers. The electron-microscopic examination revealed empty folds of basement membrane in end-plate regions, reduced secondary synaptic clefts, interposition of Schwann cell processes between nerve ending and primary synaptic cleft, and an increase of disarranged microtubules and neurofilaments in terminal axons. The findings suggest that severe hypokalemia primarily produces structural alterations of intramuscular peripheral nerves and motor end-plates as well as of muscle fibers.
低钾性肌病已在多种临床情况下被观察到。关于肌纤维病理形态学改变的研究有很多，但肌内神经和运动终板的改变很少被提及。本文作者观察了一名51岁家庭主妇的活检肌肉，她患有逐渐加重的肌无力。实验室检查显示严重低钾血症，血钾为1.5 mEq/1，肌酸磷酸激酶（CPK）为18304 U/1，乳酸脱氢酶（LDH）为1300 U/1，谷草转氨酶（SGOT）为343 U/1，醛缩酶为297 IU/1。光镜检查显示出先前描述的变化，包括I型、IIA型和IIB型纤维直方图中的双峰分布、终末轴突的气球样变和增粗，以及沿肌纤维长度紧密排列的2或3个终板。电镜检查显示终板区域基底膜空泡化、次级突触间隙减少、施万细胞突起插入神经末梢与初级突触间隙之间，以及终末轴突中排列紊乱的微管和神经丝增加。这些发现表明，严重低钾血症主要导致肌内周围神经和运动终板以及肌纤维的结构改变。
