Suxamethonium myalgia in relation to fasciculations, serum electrolytes and CPK changes

The relation between fasciculations, serum electrolytes and CPK changes and myalgia has been studied in 120 patients divided into four groups [n = 40 in each]. The first group [control] received normal saline, the second, third and fourth groups received atracurium in a dose of 0.04 mg/kg, 0.05 mg/kg and 0.06 mg/kg respectively. Saline or atracurium was given 3 min. before suxamethonium. There was no correlation between the intensity and incidence of visible muscle fasciculations and post-suxamethonium muscle pains. Not all patients with severe type of fasciculations complained of severe type of pain and not all patients who showed no fasciculations, did not complain of pain post operatively. All patients who complained of myalgia in the control group showed a significant [P < 0.001] rise in serum K+. Patients who were symptom free showed the least rise in serum K+. Also the greater the intensity of myalgia, the greater was the rise in serum K+ values. No relation between serum Na+ values and incidence and intensity of myalgia. The changes in serum Ca++ level was found to be related to the presence of myalgia. Patients complaining of myalgia showed a highly significant [P < 0.001] decrease in serum Ca[++] values. Also severe type of myalgia was associated with more decrease in serum Ca[++] in all groups of patients. The serum CPK was found to be the most markedly affected with the presence or absence of myalgia. The rise in CPK values was also found to be related to the severity of post suxamethonium myalgia. In conclusion, positive relation was found between the severity of pain and the degree of rise in serum K+ and CPK values and the degree of hypocalcaemia. On the other hand no relation could be detected between myalgia and serum Na[+] changes and fasciculations