Investigation of Muscle Cramps in Patients With Cirrhosis Using Electrical Stimulation Cramp Threshold Frequency

Abstract

Introduction: Electrically stimulated cramp threshold frequency (TF) correlates well with occurrence of muscle cramps; i.e., lower TF represents increased predisposition to cramps. Higher frequency of muscle cramps in cirrhosis is associated with a poor quality of life. However, the etiology of muscle cramps in cirrhotic individuals is not well understood. In the current study, we tested the hypothesis that cirrhotic patients with muscle cramps have lower cramp TF. Methods: 36 participants were recruited: Group A: cirrhotic patients who experienced at least 3 episodes of cramps/week (n=14); Group B: cirrhotic patients without cramps (n=12) and Group C: healthy individuals without cramps (n=10). All groups were matched for age, gender and BMI whereas Groups A and B were matched for liver disease etiology and diuretic usage. Patients recorded cramps in a daily diary for 3 weeks and then underwent blood sampling and testing for cramp TF of tibial and ulnar nerves. Threshold frequency was determined by delivering a series of 8 shocks over 2 seconds. If no cramp occured, the frequency was increased by 2 Hz with a minimum of 60 seconds between the end of each stimulus until a cramp was induced. The shocks were delivered until max TF of 40 Hz was reached or patient requested to stop the test. Results: The study cohort comprised of 53% women, 86% Caucasian, BMI 32 ± 11 kg/m2 with mean age of 55 ± 9 years. Group A experienced an average of 5 ± 1 episodes of cramps per week. Cramps were induced in 43% of Group A, 50% of Group B, and 70% of Group C participants (P>0.05). Of those, 5 (14%) had induced cramps in both the tibial and ulnar nerve stimulation, whereas 10 (28%) patients had cramps induced only in the tibial nerve and 4 (11%) had cramps induced only at the ulnar nerve. The lowest TF required to induce cramps either with tibial or ulnar nerve stimulation was not significantly different among three groups: Group A (16 ± 6 Hz), Group B (15 ± 3 Hz) and Group C ( 17 ± 4 Hz) (P>0.05). Serum levels of magnesium (r= -0.71, P<0.05) and albumin (r=-0.52, P<0.05) had significant negative correlation with cramp TF. Conclusion: The frequency of electrically stimuted muscle cramps, or TF required to induce muscle cramps was not different in cirrhotics with cramps compared to other groups. The negative relationship between serum magnesium and albumin with cramp TF suggests therapeutic potential for magnesium and albumin for muscle cramps in cirrhotics.