Muscle cramps are involuntary, painful contractions of a muscle or muscle group. For many individuals, these can be frequent and severe to the point of disabling. In fact, one study demonstrated that out of 365 outpatients aged 65 or older in the United Kingdom 50% of these patients reported frequent cramps. Another review of 515 elderly patients reported a similar prevalence of 56%, and one-half of these individuals experienced the cramps at least once per week. These cramps can have a significant impact on normal sleep patterns, which in and of itself can worsen chronic pain, and make depression and anxiety more difficult to treat in this population at risk for such psychological conditions.
If the motor system is stressed, muscle cramps become more frequent. Stressors can include neuromuscular disease, dehydration, and excessive exercise. The cramps themselves are caused by extra discharges from nerves or nerve terminals. Thus, neurologic conditions can cause cramps, as can many medical conditions such as low magnesium or calcium states, hypothyroidism, and kidney or liver disorders; not to mention pregnancy.
While there are many non-pharmacologic treatment regimens utilized by patients, there is also little evidence to support the use of any of these modalities. Hydration is used, particularly when cramping is associated with exercise; but there are no robust clinical studies supporting its use. A study comparing patients who stretched their calves three times a day to patients instructed in a sham exercise that involved only moving the legs without stretching them found no benefit of stretching on the frequency of cramps or the number of cramp-free nights; obvious flaws in this study included a problem with "blinding" patients as to which treatment they were receiving (how difficult is it to realize if you are stretching or not?), and the fact that moving the legs still might offer some benefit.
Regarding pharmacologic treatment, studies have shown that quinine derivatives are effective in reducing the frequency of muscle cramps, although the degree of the benefit is small. In addition, quinine agents are associated with potentially serious side effects, and therefore should probably be restricted to situations involving disabling cramping. The United States Food and Drug Administration issued an advisory in 2006 warning against the off-label use of quinine and its derivatives in the treatment of muscle cramps.
A study of only 28 patients demonstrated that vitamin B complex induced remission of muscle cramps in 86% of treated patients who were known to be vitamin deficient compared to placebo. But not only was this study flawed due to the low number of subjects, it also used severity as a study outcome measure; the overwhelming majority of studies use the frequency of cramps as the major outcome measure. A trial of vitamin E found no effect on the number of cramps, the number of nights with cramps, or sleep hygiene. A study of magnesium citrate was unable to conclude any improvement in the number of cramps; likewise, a study of magnesium sulfate found that there was no benefit over placebo regarding the number of cramps, severity, duration, or sleep disturbance.
Studies of prescription medications are likewise lacking in adequate patient numbers: A study involving only 13 patients concluded that the cardiovascular drug diltiazem reduced the intensity of cramps. An unblinded study showed a decrease in the frequency of cramps with gabapentin. Although muscle relaxants and agents such as baclofen, carbamazepine and oxcarbazepine are often used in clinical practice, there is a paucity of published clinical trials demonstrating their efficacy.
Given the lack of evidence for an overwhelmingly effective treatment for muscle cramps, more research is obviously needed. There are accompanying quality of life issues that will hopefully and subsequently be addressed, including an improvement in sleep hygiene and all the mental health benefits derived thereof.