Muscle cramp in pediatric Charcot-Marie-Tooth disease type 1A: prevalence and predictors.

OBJECTIVES: To identify correlates of calf cramp in children with Charcot-Marie-Tooth disease type 1A (CMT1A).

METHODS: Throughout Australia, 81 children aged 2-16 years with CMT1A were recruited. Measures of strength, ankle range, foot posture, balance, agility, endurance, gait, and neurophysiology were collected. Post hoc logistic regression analyses were performed to identify independent predictors of calf cramp.

RESULTS: Of the 81 children, 26 (32%) reported calf cramp, and 1 child each reported toe, quadriceps, or arm cramp. Calf cramp was associated (p < 0.05) with older age; the presence of hand tremor; stronger foot inversion, eversion, dorsiflexion, and plantarflexion; and better performance in long-jump and 9-hole peg tests. Logistic regression analysis revealed only increasing age (odds ratio [OR] 1.32, 95% confidence interval [CI] 1.11-1.58; p = 0.002) and the presence of hand tremor (OR 3.81, 95% CI 1.18-12.56; p = 0.028) as independent predictors of calf cramp.

CONCLUSION: Calf cramps are common in children with CMT1A and worsen with age. This study revealed a previously unrecognized link between cramp and hand tremor in children with CMT1A. Further investigation of proposed mechanisms and risk factors common to both cramp and tremor will contribute to our understanding of these common complications of CMT1A.