Robinson J A, Naylor J M, Crichlow E C
Department of Veterinary Internal Medicine, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon.
Can J Vet Res. 1990 Oct;54(4):495-500.
The use of electromyography (EMG) as a diagnostic aid for equine hyperkalemic periodic paresis (EHPP) was investigated in seven affected and seven control horses. Affected horses were confirmed positive for EHPP either by elevated serum potassium concentration with clinical signs of myotonia, or by inducing hyperkalemia and clinical signs using oral potassium chloride challenge. All horses were asymptomatic at the time EMG was performed, using bipolar fine wire needle electrodes. The myopotentials were recorded on magnetic tape and displayed on paper charts for analysis. Insertional and resting activity were recorded from the right supraspinatus, triceps, extensor carpi radialis and gluteal muscles in standing horses. Myotonic discharges were seen in six of seven affected horses but not in any of the controls. All seven affected horses and two control horses had prolonged insertional activity. Five out of seven affected horses and one control horse displayed spontaneous motor unit discharges unrelated to recording electrode movement. Myoelectrical potentials containing closely timed muscle potentials, i.e. doublets, were found in all affected horses, with four of seven affected horses also showing triplets. These potentials were not observed in any of the controls. No obvious difference in activity was observed among the four muscle sites tested. It is concluded that EMG is a safe and useful tool for diagnosing EHPP in horses not currently displaying clinical signs. Myotonic discharges and doublets appear to be the most diagnostically significant electromyographic abnormalities in EHPP affected horses.
在7匹患病马和7匹对照马中研究了肌电图（EMG）作为马高钾性周期性麻痹（EHPP）诊断辅助手段的应用。患病马通过血清钾浓度升高伴肌强直临床症状确诊为EHPP阳性，或通过口服氯化钾激发试验诱导高钾血症和临床症状来确诊。在进行EMG检查时，所有马匹均无症状，使用双极细针电极。肌电位记录在磁带上，并显示在纸质图表上进行分析。在站立的马匹中，从右侧冈上肌、三头肌、桡侧腕伸肌和臀肌记录插入活动和静息活动。7匹患病马中有6匹出现肌强直放电，而对照马均未出现。所有7匹患病马和2匹对照马的插入活动均延长。7匹患病马中有5匹和1匹对照马出现与记录电极移动无关的自发运动单位放电。在所有患病马中均发现含有紧密同步肌肉电位（即双峰）的肌电电位，7匹患病马中有4匹还出现了三峰。在任何对照马中均未观察到这些电位。在所测试的四个肌肉部位之间未观察到明显的活动差异。结论是，EMG是诊断当前未表现出临床症状的马匹EHPP的一种安全且有用的工具。肌强直放电和双峰似乎是EHPP患病马中最具诊断意义的肌电图异常。
