Nocturnal Leg Cramps
Abstract & Commentary
By Michael Rubin, MD, Professor of Clinical Neurology, Weill Cornell Medical College. Dr. Rubin reports no financial relationships relevant to this field of study.
Synopsis: Nocturnal calf cramps are usually benign and respond to stretching and muscle-strengthening exercises.
Source: Hawke F, et al. Factors associated with night-time calf muscle cramps: A case-control study. Muscle Nerve 2013;47;339-343.
Present in nearly 50% of those older than 50 years of age, increasing in prevalence with increasing age, and affecting both sexes equally, nocturnal leg cramps occur at least thrice weekly in 40%, and nighty in 5-10% of affected patients, producing pain while disrupting sleep. Lasting seconds to minutes and most commonly affecting the foot, calf, or thigh, forceful stretching of the affected muscles offers relief, and workup for underlying causes is usually in vain. What factors are associated with nocturnal calf cramps that might be etiologically important and amenable to therapeutic intervention?
Between August 2010-October 2011, 160 adults — 80 with nocturnal calf cramps and 80 age- and gender-matched controls without nocturnal calf cramps — were recruited from the Newcastle, Central Coast, and Hunter Valley regions of New South Wales, Australia, to undergo clinical evaluation and completion of a self-report survey. Exclusionary criteria encompassed neuromuscular or neurologic disease, pregnancy, dialysis, dementia, or leg injury that precluded participation in clinical testing. Clinical evaluation included testing ankle and toe strength, ankle and knee flexibility, toe sensation to 10-g filament and 64-Hz/c128-Hz graded tuning fork, and measurement of hallux blood pressure. Self-reported survey items included, but were not limited to, smoking history, alcohol intake, diet, fluid consumption, exercise, showering and sleeping habits, presence of varicose veins, use of compression stockings or high heels, medication and surgical history as indicators of general health, presence of back pain or sciatica, depression, diabetes, renal failure, or rheumatoid arthritis. Statistical analyses encompassed the Kolmogorov-Smirnov test, parametric and nonparametric tests, Spearman rho, chi-square, and Fisher exact tests, and significance was set at the 95% confidence interval.
Ankle weakness (inversion, eversion, dorsi- and plantar flexion), hallux weakness, tip-toe walking difficulty, tight hamstrings, muscle twitches, feet or leg tingling, cold feet in bed at night, increased fluid consumption, calf pain, and decreased migraine prevalence were significantly associated with nocturnal calf cramps, and logistic regression modeling identified only muscle twitching, leg tingling, and weak ankle dorsiflexion, but not diabetes or sensory deficits, as independent correlates of nocturnal calf cramps. Intermittent claudication, smoking, or alcoholism were not associated with nocturnal calf cramps, supporting a neurologic origin of this phenomenon.
Commentary
Several non-pharmacologic therapies, including hydration, stretching, massage therapy, and herbal remedies are recommended for nocturnal calf cramps but none are of proven efficacy. Pharmacologic treatment traditionally included quinine, now in disfavor due to serious adverse effects in 2-4%, including thrombocytopenia, hemolytic uremic syndrome, cardiac arrhythmias, and hypersensitivity reactions. Gabapentin, diphenhydramine, vitamin E or B complex, and calcium channel blockers (verapamil or diltiazem) may be useful, but have limited data to support their use. Baclofen is a favorite among Canadian neurologists.1
Reference
1. Lim Fat MJ, et al. Neurologist practice patterns in treatment of muscle cramps in Canada. J Foot Ankle Res 2013;6:2. Available at: http://www.jfootankleres.com/content/6/1/2.
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