Sleep-Related Leg Cramps

Restless Legs Syndrome and Other Common Sleep-Related Movement Disorders

OBJECTIVE

This article reviews common sleep-related movement disorders, including their clinical description, epidemiology, pathophysiology (if known), and evaluation and management strategies. This article will provide the reader with a good foundation for approaching concerns that are suggestive of sleep-related movement disorders to properly evaluate and manage these conditions.

LATEST DEVELOPMENTS

α2δ Ligands, such as gabapentin enacarbil, can be used for the initial treatment of restless legs syndrome (RLS) or in those who cannot tolerate, or have developed augmentation to, dopamine agonists. Another option is the rotigotine patch, which has a 24-hour treatment window and may be beneficial for those who have developed augmentation with short-acting dopamine agonists. IV iron can improve RLS symptoms even in those whose serum ferritin level is between 75 ng/mL and 100 ng/mL. At serum ferritin levels greater than 75 ng/mL, oral iron will likely have minimal absorption or little effect on the improvement of RLS. Research has found an association between RLS and cardiovascular disease, particularly in people who have periodic limb movements of sleep.

ESSENTIAL POINTS

RLS is the most common sleep-related movement disorder. Its pathophysiology is likely a combination of central iron deficiency, dopamine overproduction, and possibly cortical excitation. Treatment includes oral or IV iron. Dopaminergic medications can be very effective but often lead to augmentation, which limits their long-term use. Other sleep-related movement disorders to be aware of are sleep-related rhythmic movement disorder, nocturnal muscle cramps, sleep-related propriospinal myoclonus, sleep bruxism, and benign myoclonus of infancy.

Restless Legs Syndrome - Clinical Features

Restless legs syndrome (RLS) is one of the most common neurologic conditions, with an estimated prevalence in European and North American heritage populations of about 2% to 5%. Because RLS diagnosis is essentially clinical, a careful evaluation of the symptoms is mandatory. It is important to exclude RLS mimics and evaluate factors that could exacerbate RLS symptoms. It is mandatory to evaluate systemic iron parameters, because the initial treatment depends on this result. Other complementary tests could help support the diagnosis or exclude mimics. The decision about when and how to treat should be carefully tailored to each patient.

Restless Legs Syndrome and Other Common Sleep-Related Movement Disorders

PURPOSE OF REVIEW

In this article, the different sleep-related movement disorders are discussed with special attention given to restless legs syndrome (RLS).

RECENT FINDINGS

The differential diagnosis of sleep-related movement disorders can often be challenging; therefore, it is essential to have accurate information to make a correct diagnosis. This article focuses on RLS, highlighting the change in the paradigm of initial treatment, the role played by iron (pathophysiologic and therapeutic), and how to approach possible complications occurring with long-term treatment.

SUMMARY

RLS is one of the most common neurologic conditions, and it is common in clinical practice to find patients experiencing symptoms suggestive of RLS. Neurologists must be careful and thorough in the diagnosis, excluding RLS mimics. The decisions regarding which specific sleep-related movement disorder is present and how it should be treated are important because in certain cases, especially in RLS, adverse effects and long-term complications are frequently reported with the use of certain drugs.

Restless Legs Syndrome and Sleep-Related Movement Disorders

PURPOSE OF REVIEW

This article provides an update on six sleep-related movement disorders: restless legs syndrome (RLS), periodic limb movement disorder, sleep-related leg cramps, bruxism, rhythmic movement disorder, and propriospinal myoclonus, with an emphasis on RLS.

RECENT FINDINGS

RLS is a common sensorimotor disorder that impairs quality of life. RLS is frequently comorbid to neurologic, psychiatric, vascular, and inflammatory diseases. Accumulating evidence implicates the pathophysiology of RLS as a state of dopamine dysfunction and iron deficiency that occurs on a background of genetic susceptibility conferred by 6 gene polymorphisms. Multiple treatments approved by the US Food and Drug Administration (FDA) are available. Dopamine agonists and α2δ calcium channel ligands are considered first-line treatments, but these treatments have very different side effect profiles that should be taken into consideration.

SUMMARY

Sleep-related movement disorders are frequently encountered in clinical practice. For some disorders, particularly RLS and periodic limb movement disorder, our understanding of biology, epidemiology, and treatment is advanced. For others, much work is needed to determine optimal treatment strategies.

Nocturnal leg cramps: Prevalence and associations with demographics, sleep disturbance symptoms, medical conditions, and cardiometabolic risk factors

BACKGROUND

Nocturnal leg cramps (NLC) are common and poorly understood.

OBJECTIVE

To determine the prevalence of NLC and associations with cardiometabolic, sleep, and behavioral risk factors in the US population.

DESIGN

Cross-sectional epidemiology.

PARTICIPANTS

National Health and Nutrition Examination Survey, 2005-2006 and 2007-2008 waves.

MAIN OUTCOME(S) AND MEASURE(S)

NLC were assessed with, "In the past month, how often did you have leg cramps while trying to sleep?" Responses were categorized as None, Mild, or Moderate-Severe. Demographics, medical history, sleep disturbances, and cardiometabolic risk factors were evaluated using the 2005-2006 dataset. Variables that demonstrated significant relationships to NLC after adjusting for age, sex, education, and BMI were assessed in the 2007-2008 dataset. Variables that were still significant were entered into a forward stepwise regression model combining both waves, to determine which variables best explained the variance in NLC.

RESULTS

Prevalence was 24-25% reporting mild and 6% reporting moderate-severe NLC. NLC increased with age, lower education, unemployment, shorter sleep duration, all assessed sleep symptoms (nocturnal "leg jerks", snoring, snorting/gasping, difficulty falling asleep, difficulty maintaining sleep, non-restorative sleep, sleepiness, use of sleep medications), higher BMI, smoking, medical history (hypertension, heart failure, angina, stroke, arthritis, respiratory disease, and cancer), depression symptoms, and biomarkers (CRP, HbA1c, calcium, cadmium, red blood cells). Stepwise analysis showed that moderate-severe nocturnal leg cramps were associated with (in decreasing order of partial R2): leg jerks, poor overall health, arthritis, difficulty falling asleep, age, nonrestorative sleep, red blood cell count, lower education, angina, and difficulty maintaining sleep.

CONCLUSIONS AND RELEVANCE

Based on this first large, representative study, NLC occurring >5x per month are reported by 6% of the adult US population. Sleep disturbance symptoms and health conditions are associated with higher frequency of NLC, suggesting that NLC is a marker, and possibly contributor, to poor sleep and general health.

A review of nocturnal leg cramps in older people

Nocturnal leg cramps are common and troublesome, especially in later life, and have a significant impact on quality of life, particularly sleep quality. This article reviews the current state of knowledge regarding the diagnosis, frequency, pathophysiology and management of cramps. Recent evidence suggests that diuretic and long-acting beta-agonist therapy predispose to leg cramps. There is conflicting evidence regarding the efficacy of prophylactic stretching exercises in preventing cramps. Quinine remains the only medication proven to reduce the frequency and intensity of leg cramps. However, the degree of benefit from quinine is modest and the risks include rare but serious immune-mediated reactions and, especially in older people, dose-related side effects. Quinine treatment should be restricted to those with severe symptoms, should be subject to regular review and requires discussion of the risks and benefits with patients.