A crossover study of gabapentin in treatment of restless legs syndrome among hemodialysis patients

Update on the management of restless legs syndrome: existing and emerging treatment options

Restless legs syndrome (RLS) is a sensorimotor disorder, characterized by a circadian variation of symptoms involving an urge to move the limbs (usually the legs) as well as paresthesias. There is a primary (familial) and a secondary (acquired) form, which affects a wide variety of individuals, such as pregnant women, patients with end-stage renal disease, iron deficiency, rheumatic disease, and persons taking medications. The symptoms reflect a circadian fluctuation of dopamine in the substantia nigra. RLS patients have lower dopamine and iron levels in the substantia nigra and respond to both dopaminergic therapy and iron administration. Iron, as a cofactor of dopamine production and a regulator of the expression of dopamine type 2-receptor, has an important role in the RLS etiology. In the management of the disease, the first step is to investigate possible secondary causes and their treatment. Dopaminergic agents are considered as the first-line therapy for moderate to severe RLS. If dopaminergic drugs are contraindicated or not efficacious, or if symptoms are resistant and unremitting, gabapentin or other antiepileptic agents, benzodiazepines, or opioids can be used for RLS therapy. Undiagnosed, wrongly diagnosed, and untreated RLS is associated with a significant impairment of the quality of life.

Gabapentin Enacarbil: Pharmacotherapy of Restless Legs Syndrome

Restless Legs Syndrome (RLS) is a prevalent sleep-associated movement disorder greatly affecting patients’ quality of life (QoL). Several drugs can be used to control this condition although the first-line dopamine agents often cause adverse effects. Non-dopaminergic drugs such as oral gabapentin (GBP) have been more recently advocated. Despite ameliorating RLS symptoms, GBP’s pharmacokinetic limitations restrict its overall effectiveness. A novel specifically designed prodrug, gabapentin enacarbil (GE), has demonstrated successful RLS alleviation with a superior pharmacokinetic profile. This review aims to examine the efficacy and tolerability of both GBP and GE as pharmacotherapy for RLS. Despite some heterogeneity and limitations across research methodologies, GE appears to be a potential RLS therapy superior to GBP and other dopaminergic agents.

[Restless legs syndrome, periodic limb movements, and psychopharmacology]

Restless legs syndrome (RLS) and the often associated periodic limb movement disorder in sleep (PLMD) frequently occur in the general population as a primary disorder. In addition to organic disease, secondary forms are caused by psychotropic medication. Several antidepressants, antipsychotics, lithium, and opioid withdrawal have been shown to induce or exacerbate RLS and PLMD, while several antiepileptics used as mood stabilizers and some benzodiazepines demonstrate therapeutic potential for treating RLS/PLMD. Systematic or controlled studies for evaluating these side effects still do not exist. Among the antidepressants at higher risk of inducing this disorder are selective serotonin reuptake inhibitors, venlafaxine, and some tetracyclic antidepressants. Under medication with some tricyclic substances, periodic limb movements were observed more often. For some antidepressants with differing transmitter profiles such as bupropion RLS/PLMD ameliorating effects or at least neutral effects (Trazodon, Nortriptylin) have been described in small studies. In case of continued of or newly occurring insomnia a thorough history should be taken to identify a possible RLS/PLMD as an intolerable side effect of treatment. A change in medications should be considered if clinically feasible. In case of RLS/PLMD occurring in psychotic patients switching the antipsychotic and additionally using a second line medication such as antiepileptics or a benzodiazepine should be considered.

A randomized, double-blind, placebo-controlled, crossover study of XP13512/GSK1838262 in the treatment of patients with primary restless legs syndrome

STUDY OBJECTIVE

To evaluate the efficacy and tolerability of XP13512/ GSK1838262, an investigational nondopaminergic agent for the treatment of moderate-to-severe primary restless legs syndrome (RLS).

DESIGN

Randomized, double-blind, placebo-controlled, crossover trial.

SETTING

Nine US clinical sites.

PATIENTS

Thirty-eight treatment-naive subjects with RLS (mean +/- SD age 50.1 +/- 13.2 years).

INTERVENTIONS

XP13512 1800 mg/day followed by placebo or placebo followed by XP13512 1800 mg/day for 14 days, with a 7-day washout between treatment periods.

MEASUREMENTS AND RESULTS

The primary endpoint was mean change from baseline International RLS Study Group rating scale (IRLS) total score on Day 14, analyzed using analysis of variance with sequence, period, and treatment as fixed effects and subjects within sequence as a random effect. XP13512 significantly reduced IRLS total score on Day 14 compared with placebo (mean +/- SD: XP13512 -12.1 +/-6.5, placebo -1.9 +/- 6.3; P < 0.0001). Polysomnographic data showed that XP13512 significantly improved sleep architecture on Day 14 compared with placebo (mean +/- SD change from baseline sleep time [minutes]: stage 1: XP13512 -9.8 +/- 23.9, placebo 0.4 +/-23.2; adjusted P<0.0054, nominal P<0.0001; stage 3/4 (slow-wave sleep): XP13512 22.8 +/- 40.8, placebo 1.4 +/- 34.3; adjusted P=0.0092, nominal P=0.0002). The most frequently reported adverse events were somnolence (XP13512 30.6%, placebo 2.8%) and dizziness (XP13512 27.8%, placebo 5.6%).

CONCLUSIONS

XP13512 1800 mg/day significantly reduced RLS symptoms, improved sleep, and was generally well tolerated in subjects with moderate-to-severe primary RLS across 14 days of treatment.

Restless legs syndrome: pathophysiology, diagnosis and treatment

Restless legs syndrome (RLS) is clinically defined by the presence of (i) an urge to move the legs with or without an actual paraesthesia; (ii) a worsening of symptoms with inactivity; (iii) improvement with activity; and (iv) a worsening of symptoms in the evening and at night. Patients may use a variety of semantic phrases to describe their symptoms but all must have an urge to move. Most people with RLS also have periodic limb movements during sleep, although this is not part of the clinical diagnostic criteria. RLS is very common. About 10% of all Caucasian populations have RLS, although it may be mild in the majority of cases. Women generally outnumber men by about 2:1. As a general rule, RLS severity worsens through the first seven to eight decades of life, but may actually lessen in old age. The aetiology of RLS is only partly understood. There is a strong genetic component, and several genetic linkages and three causative genes have been identified worldwide. Several medical conditions, including renal failure, systemic iron deficiency and pregnancy, and possibly neuropathy, essential tremor and some genetic ataxias, are also associated with high rates of RLS. In all cases to date, the actual CNS pathology of RLS demonstrates reduced iron stores, in a pattern that suggests that the homeostatic control of iron is altered, not just that there is not enough iron entering the brain. The relationship between reduced CNS iron levels and the clinical phenotype or treatment response to dopaminergics is not known but generates promising speculation. Treatment of RLS is usually rewarding. Most patients respond robustly to dopamine receptor agonists. Over time, response may lessen, or the patients may develop 'augmentation', whereby they have a worsening of symptoms, usually in the form of an earlier onset. Other treatment options include gabapentin, or similar antiepileptic drugs, and opioids. High-dose intravenous iron is a promising but still experimental approach.

Restless Legs Syndrome

Restless legs syndrome is a symptomatic urge to move the legs, usually accompanied or caused by uncomfortable/ unpleasant sensations deep within the legs that begin or are worsened during periods of rest or inactivity in the evening or night and are partially or totally relieved by movement. It can occur intermittently or daily. Nonpharmacologic treatments include moderate exercise; good sleep hygiene; elimination of alcohol, caffeine, and nicotine; and hot baths, massage, and stretching. Activities promoting mental alertness may improve symptoms. Moderate exercise and use of nasal continuous positive airway pressure are the only nonpharmacologic treatments with proven benefit. For intermittent restless legs syndrome, carbidopa/levodopa and nonpharmacologic therapy are recommended as primary treatments. For daily restless legs syndrome, dopamine agonists, particularly ropinirole and pramipexole, are suggested as the drugs of choice. Carbidopa/levodopa could be considered for daily restless legs syndrome, but augmentation is a significant drawback to its use. Carbamazepine and gabapentin have limited data to support their use.

Epidemiology of restless legs syndrome: the current status

Epidemiological studies in restless legs syndrome (RLS) have often been limited by misdiagnosis and by the fact that affected individuals, even when their symptoms are severe, might not seek medical care. Some of these limitations have been overcome in the last years as population studies based on face to face interviews have been carried out with new standardized diagnostic criteria. According to these studies, and in contrast to earlier views, RLS has been shown to be a common disorder with prevalences ranging between 2.5 and 10% of the population. Although few studies performed outside Europe/North America have shown a low prevalence, a number of methodological issues have been raised that might question these results. Furthermore, once established, RLS usually follows a chronic course, and preliminary evidence shows that it might worsen over time in some patients. Endstage renal disease, increasing age, female gender, pregnancy, frequent blood donations, iron deficiency and neuropathy are considered to be risk factors for this disorder. The association to RLS is less definitely established for other conditions, such as PD or diabetes. In summary, epidemiological evidence suggests that RLS is a common neurological disorder-with high impact on many aspects of the life of those affected.

EFNS guidelines on management of restless legs syndrome and periodic limb movement disorder in sleep

In 2003, the EFNS Task Force was set up for putting forth guidelines for the management of the Restless Legs Syndrome (RLS) and the Periodic Limb Movement Disorder (PLMD). After determining the objectives for management and the search strategy for primary and secondary RLS and for PLMD, a review of the scientific literature up to 2004 was performed for the drug classes and interventions employed in treatment (drugs acting on the adrenoreceptor, antiepileptic drugs, benzodiazepines/hypnotics, dopaminergic agents, opioids, other treatments). Previous guidelines were consulted. All trials were analysed according to class of evidence, and recommendations formed according to the 2004 EFNS criteria for rating. Dopaminergic agents came out as having the best evidence for efficacy in primary RLS. Reported adverse events were usually mild and reversible; augmentation was a feature with dopaminergic agents. No controlled trials were available for RLS in children and for RLS during pregnancy. The following level A recommendations can be offered: for primary RLS, cabergoline, gabapentin, pergolide, ropinirole, levodopa and rotigotine by transdermal delivery (the latter two for short-term use) are effective in relieving the symptoms. Transdermal oestradiol is ineffective for PLMD.

Restless legs syndrome

PURPOSE

The signs and symptoms, epidemiology, etiology, pathophysiology, diagnosis, pharmacologic and nonpharmacologic treatments, and options and guidelines for the treatment of restless legs syndrome (RLS) are reviewed.

SUMMARY

RLS was first described in the 17th century and further characterized in 1945. RLS is a common disorder, occurring in about 10% of the population. Patients with RLS often describe the urge to move, uncomfortable sensations, and pain, which begin or worsen during rest or inactivity such as lying or sitting. Symptoms of RLS make sleeping difficult for many patients, and significant daytime difficulties result from the condition. RLS can either be primary or arise from secondary causes that lead to iron deficiency. There is a familial component in primary RLS, but its underlying mechanisms remain unknown. Of individuals with conditions associated with iron-deficiency states, including pregnancy, renal failure, and anemia, 25-30% may develop RLS. The goals of RLS treatment include improving its symptoms and the patient's quality of life. There are limited data on the treatment of RLS. Pharmacologic therapies include iron replacement, dopaminergic agents (e.g., levodopa), dopamine agonists, anticonvulsants, opioids, and benzodiazepines. There have been no systematic trials of nonpharmacologic therapies for RLS, but good sleep hygiene and avoidance of alcohol, caffeine, and nicotine may improve symptoms.

CONCLUSION

RLS is a common disorder thought to involve abnormal iron metabolism and dopaminergic systems. Nonpharmacologic therapy should be suggested for all patients with RLS, but pharmacologic therapy may be required, and evidence is strongest for levodopa and dopamine agonists.

Self-reported subjective sleep quality and fatigue in patients with peritoneal dialysis treatment at home

The aim of this study was to describe habitual sleep, daytime symptoms, sleep-disturbing factors, current sleep during 1 week and fatigue in patients with peritoneal dialysis treatment at home and also discover predictions for sleep quality outcome. The knowledge should increase possibilities for supportive nursing health care. Fifty-five patients answered two mailed questionnaires and filled in a sleep diary. Of these, 60% had moderate, persistent sleep problems combined with daytime symptoms. Nocturnal awakenings with difficulties falling asleep again and a sleep duration predicted as 57% of sleep quality. Nocturnal pruritus and 'difficulties finding a comfortable sleeping position' were significant sleep-disturbing factors. Sleep quality predictors means progress in knowledge about the complexity of the situation for peritoneal dialysis patients. Poor sleep, daytime symptoms, sleep-disturbing factors and chronic fatigue need to be enlightened, especially for the nephrology nurses who are in a unique position to give supportive nursing health care.

Emerging drugs for restless legs syndrome

Restless legs syndrome (RLS) is a common, but often underdiagnosed, neurological disorder, which is characterised by an imperative urge to move the extremities associated with paraesthesias, worsening of symptoms at rest and in the evening or at night, and, as a consequence, sleep disturbances. RLS affects 1-10% of the population. The aetiology of RLS is unknown, but besides genetic factors the dopaminergic and opioidergic system may play a crucial role and new developments also point to an exciting iron-dopamine connection in the pathophysiology of this burdening disorder. Due to the limited disease-specific knowledge, current treatment strategies are not curative, but nevertheless may produce an effective and lasting relief of symptoms. Although clinically based treatment has focused on levodopa, opioids and benzodiazepines for a long time, evidence-based and clinical guidelines identify dopamine agonists as a first-line treatment for daily restless legs symptoms. These substances are now in the process of registration for this indication. Ropinirole is the first dopamine agonist that has been approved by the FDA in May 2005. In addition, several promising new therapies with nondopamine profiles are under development for RLS.

Management of Restless Legs Syndrome in Patients on Dialysis

Restless legs syndrome (RLS) is characterised by an urge to move the legs, uncomfortable sensations in the legs and worsening of these symptoms during rest with at least temporary relief brought on by activity. RLS occurs in 3-15% of the general population and in 10-30% of patients on maintenance dialysis. RLS may lead to severe sleep onset or maintenance insomnia, and greatly impaired quality of life. Current recommendations suggest dopaminergic therapy (levodopa or dopamine receptor agonists: pramipexol, ropinirole, pergolide or cabergoline) as the first-line treatment for RLS. This group of medications is effective in reducing RLS symptoms in the general population; limited information is available on the effect of these drugs in patients with renal failure. However, it must be noted that most published studies in uraemic patients had short treatment periods and insufficient statistical power because of small sample size. Frequent adverse effects of levodopa, seen mainly with continuous use, may limit its use significantly. Rebound and augmentation, problems relatively frequently seen with levodopa, seem to be less prevalent with the use of dopamine receptor agonists, although properly designed comparative trials are still needed to address this question. Alternative treatment options for RLS are gabapentin, benzodiazepines and opioids. For all of these medications, there are only very limited data available on their effectiveness and safety profile in patients on maintenance dialysis. Referral to a specialist for RLS management should be considered for patients with refractory RLS.

[Neurophysiological and neuroimaging studies for restless legs syndrome and periodic leg movement disorder]

The restless legs syndrome (RLS) is a clinical diagnosis based on the four essential criteria defined by the International Restless Legs Syndrome Study Group (IRLSSG). An idiopathic form can be separated from a symptomatic form. Neurophysiological studies have investigated the pathophysiology of the idiopathic RLS or have been used to exclude a symptomatic cause, in particular polyneuropathy. So far cortical excitability changes, corticomotor, somatosensory and auditory pathways, spinal cord excitability, B-wave rhythm and cycling alternating pattern, as well as reflex mechanisms have been investigated by electroencephalography, evoked potentials, Bereitschaftspotentials, nerve conduction and thermal threshold measurements, electromyography, transcranial Doppler sonography, measurements of the spinal flexor reflex as well as neuroimaging techniques. The etiology of the RLS cannot be revealed by these methods, neurophysiological studies in RLS are, however, useful for a better understanding of the pathophysiology and for exclusion of a polyneuropathy or other symptomatic causes. In addition to neurophysiological investigations, small fiber neuropathy, which seems to be a more common finding in RLS patients than expected to date, may need biopsy for confirmation. This review will focus on investigations of the different systems involved with diverse neurophysiological methods.

The restless legs syndrome

The restless legs syndrome is a common disorder that encompasses an idiopathic form of genetic or unknown origin and symptomatic forms associated with many causes. Symptomatic forms occur during pregnancy and are coincident with uraemia, iron depletion, polyneuropathy, spinal disorders, and rheumatoid arthritis. For the hereditary forms, at least three gene loci, located on chromosomes 12, 14, and 9, have been traced so far. Prevalence in the general population is between 3% and 9%, increases with age, and is higher in women than in men. Treatment is needed only in the moderate to severe forms of the disorder and mostly in elderly people. Pathophysiology and treatment may be closely linked to the dopaminergic system and iron metabolism. Dopaminergic treatment with levodopa and dopamine agonists is the first choice in idiopathic restless legs syndrome, but augmentation and rebound should be monitored in long-term treatment. Various other drugs, such as opioids, gabapentin, and benzodiazepines, provide alternative treatment possibilities.

Gabapentin-Induced Myopathy in 2 Patients on Short Daily Hemodialysis

Gabapentin is an antiepileptic medication that also has been used for restless legs syndrome. The mechanism of action is unknown. The most commonly reported adverse effects of this medication include somnolence, dizziness, ataxia, fatigue, nystagmus, and tremor. Myalgia has been reported in 2% of gabapentin users compared with 1.9% of patients in placebo-controlled add-on trials. Two patients on short daily hemodialysis therapy developed neuromuscular symptoms and an elevation in creatine kinase levels after starting gabapentin therapy. To our knowledge, this is the first case report of an increase in creatine kinase level after the administration of gabapentin.

Restless legs syndrome

In the past 10 years, restless legs syndrome (RLS) has gained recognition as a common sleep disorder. There are several therapeutic options in treating patients with RLS. RLS causes significant sleep disturbance and negatively impacts on patient quality of life. Pharmacologic treatment can result in improved sleep and quality of life issues. RLS patients should be evaluated for iron deficiency anemia; iron replacement in deficient patients may lead to a resolution of symptoms or may reduce the severity of their symptoms. For patients with daily symptoms, the initial therapy is dopamine agonists. Low doses given in the evening or 2 hours before bed provide adequate relief of symptoms for many RLS patients. Augmentation can be seen with all dopamine agents, but is most prevalent with levodopa. Levodopa therapy is best used for milder intermittent symptoms or in aggravating situations, such as long car rides. Opiates and antiepileptics remain a beneficial therapy for RLS and are useful in patients who experience pain as part of their RLS. Newer anticonvulsants may provide additional treatment options, but they have yet to undergo clinical trials. Intravenous iron also may provide relief of RLS symptoms; however, dosing and safety issues have not been fully evaluated in a RLS population.

Restless legs symptoms among incident dialysis patients: Association with lower quality of life and shorter survival

BACKGROUND

Symptoms of restless legs are common among patients treated with long-term hemodialysis. We investigated the relation between symptoms of restless legs, quality of life, and survival among incident hemodialysis and peritoneal dialysis patients.

METHODS

This report includes 894 dialysis patients who responded to an item regarding severity of restless legs symptoms in the Choices for Healthy Outcomes in Caring for End-Stage Renal Disease Study. We examined participant responses both as categorized by the 5-point symptoms of restless legs item and classified with severe symptoms of restless legs if they reported they were very or extremely bothered by symptoms. Independent predictors of restless legs symptoms were estimated using logistic regression. The association of restless legs symptoms with quality of life was examined by means of mixed-model regression, and adjusted mortality risk was estimated by means of Cox proportional hazards.

RESULTS

Fifteen percent of dialysis patients were classified as having severe restless legs. Those characterized by severe restless legs were significantly more likely to be administered benzodiazepines, antidepressants, and antiepileptics. Age and diabetes mellitus were independently associated with severe symptoms of restless legs. Symptoms of restless legs were associated with lower Physical and Mental Component Scores, vitality, bodily pain, and sleep quality (all P < 0.001). After adjustment, severe symptoms of restless legs were significantly associated with an increased mortality hazard ratio of 1.39 (95% confidence interval, 1.08 to 1.79).

CONCLUSION

Symptoms of restless legs were associated with lower quality of life and increased risk for death. The effect of treatment for symptoms of restless legs on quality of life and survival awaits additional study.

Restless legs syndrome in patients on dialysis

The past decade has seen an explosion of interest in both idiopathic and secondary restless legs syndrome (RLS). Secondary RLS occurs in patients with uremia, pregnancy, and iron deficiency. Patients experience an irresistible urge to move the legs that is worse during inactivity and at night. RLS affects 6.6% to 62% of patients on long-term dialysis therapy and is associated with a greater mortality risk. The wide range of reported prevalence is explained in part by variations in methods of diagnosis. The International Restless Legs Syndrome Study Group defined diagnostic criteria that have improved the quality of RLS research. Advanced neurological imaging techniques suggest the pathophysiological state of idiopathic RLS involves dysfunction of subcortical areas of the brain. Dopaminergic pathways and neuronal iron handling have been implicated. Limited studies of patients with uremic RLS suggested similar mechanisms, but anemia, hyperphosphatemia, and psychological factors also may have a role. The few clinical trials in uremic RLS suggest that treatment should involve the reduction of potential exacerbating agents (tricyclic antidepressants, selective serotonin uptake inhibitors, lithium, and dopamine antagonists), correction of anemia (with erythropoietin and iron), and use of levodopa or dopamine agonists. Other agents shown to be of benefit in idiopathic RLS can be tried, but may be limited by side effects in patients with uremia (benzodiazepines, opioids, gabapentin, carbamazepine, and clonidine). Symptoms of uremic RLS will disappear within a few weeks of successful renal transplantation. The progress made to date in unraveling the pathophysiological state of uremic RLS should stimulate additional research toward targeted therapy.

Analgesia in patients with ESRD: a review of available evidence

Moderate to severe pain frequently accompanies chronic diseases in general and end-stage renal disease (ESRD) in particular. Several analgesic agents and associated metabolites show altered pharmacokinetics in the presence of reduced glomerular filtration rate. Drug-related side effects may exacerbate symptoms frequently observed in persons with chronic kidney disease (CKD; eg, fatigue, nausea, vomiting, and constipation) or those often attributed to hemodialysis therapy (eg, orthostatic hypotension and impaired cognition). Persons with advanced CKD and ESRD are at increased risk for adverse effects of analgesic agents because of enhanced drug sensitivity, comorbid conditions, and concurrent medication use. Dose adjustment and avoidance of certain analgesics may be required in patients with advanced CKD and ESRD. We review the available evidence on pharmacokinetics and adverse drug effects of various analgesic agents commonly used in patients with advanced CKD and ESRD. Determining an optimal approach to the control of pain in patients with advanced CKD and ESRD will require additional research.

Restless legs syndrome in the older adult: diagnosis and management

Restless legs syndrome (RLS) is common in the elderly, with an estimated prevalence of 10 to 35% in individuals over 65 years of age. RLS is characterised by paraesthesias and dysaesthesias of the legs, typically occurring in the evening. The symptoms occur at rest and result in motor restlessness; movement often temporarily relieves the symptoms. Patients with poorly controlled RLS may develop related problems including insomnia (due to sleep-onset restlessness or periodic limb movements or related sleep fragmentation) and depression. RLS can be a primary disorder that develops in the young and includes familial cases. Secondary RLS occurs in association with iron-deficiency anaemia, uraemia and polyneuropathies. Typically, RLS is misdiagnosed or undiagnosed for years. In the elderly, both primary and secondary types of the disorder are common. It is thought that RLS represents lower CNS levels of, or reduced responsiveness to, dopamine. The symptoms improve with dopaminergic therapy. Ergotamine dopamine-receptor agonists such as pergolide, and the non-ergotamine dopamine-receptor agonists pramipexole and ropinirole, are becoming more commonly used to treat RLS. The dopamine precursor levodopa, in combination with carbidopa, is another effective therapeutic agent. An advantage of levodopa is lower cost than non-ergotamine and ergotamine dopamine-receptor agonists. However, the adverse effect of symptom augmentation appears to develop more frequently with levodopa than dopamine-receptor agonists; therefore, levodopa may currently be used somewhat less often as first-line therapy. Patients with painful symptoms may respond favourably to the anticonvulsants gabapentin and carbamazepine. Opioids and hypnosedatives are helpful in selected patients; however, these agents may have troubling adverse effects in the elderly. Correction of iron deficiency improves symptoms in patients with low ferritin levels. Lifestyle modification may also be helpful. Therapy is directed at symptoms, and most symptomatic patients benefit from treatment. It is important to consider RLS in the differential diagnosis of any patient with paraesthesias of the limbs.

Clinical and psychological aspects of restless legs syndrome in uremic patients on hemodialysis

BACKGROUND

The pathogenesis of restless legs syndrome (RLS) is still unclear. The purpose of this study is to determine relationships of the presence of RLS in uremic patients regularly undergoing hemodialysis (HD) with demographic, clinical, and psychological factors.

METHODS

In 490 uremic patients on HD therapy in Japan, RLS was diagnosed based on diagnostic criteria established by the International Restless Legs Syndrome Study Group. Data were compared between patients with and without RLS.

RESULTS

There were univariately significant (P < 0.05) differences in serum phosphorus levels, anxiety levels determined using the Hospital Anxiety and Depression Scale, and degrees of emotion-oriented and avoidance-oriented coping determined using the Coping Inventory for Stressful Situations. In multivariate analyses, low hemoglobin levels, high serum phosphorus levels, high anxiety levels, and a great degree of emotion-oriented coping were independently related to the presence of RLS in uremic patients on HD therapy, with statistical significance (P < 0.05).

CONCLUSION

Hyperphosphatemia, anxiety, and a great degree of emotion-oriented coping with stress were independently related to the presence of RLS in uremic patients on HD therapy. The pathogenesis of RLS seems to involve more than one mechanism, which leads to restless legs as the final common pathway. These findings may provide new clues to the pathogenesis of RLS.

Restless legs syndrome and periodic limb movements of sleep: fact, fad, and fiction

Restless legs syndrome (RLS) and periodic limb movements of sleep (PLMS) are common disorders seen in sleep disorder centers. Although RLS in universally thought to cause daytime sleepiness, the role of PLMS in causing sleepiness (or any symptom!) has been more controversial. Recent publications have show that PLMS do not cause either subjective or objective sleepiness, but may be a marker for respiratory effort related arousals. In regards to patients with end-stage renal disease, PLMS may mark mortality. In this same group of patients, gabapentin and normalization of hematocrit may be effective therapies for RLS/PLMS. Melatonin may prove to be an alternative therapy for PLMS.

Restless legs syndrome: a sensorimotor disorder of sleep/wake motor regulation

Restless legs syndrome (RLS) remains an underappreciated sensorimotor disorder of sleep/wake regulation. It is one of the few sensorimotor disorders that is provoked by rest and that also follows a clear circadian pattern. Recent epidemiologic studies have verified that the condition is common in populations derived from the north and west of Europe, and have begun to uncover some of the genetic substrate of the disorder. New instruments have been developed to facilitate diagnosis and assessment of severity. The pathogenesis of the condition remains uncertain, but recent discoveries implicate areas of the nervous system from the spinal cord up to the basal ganglia. A current hypothesis undergoing vigorous exploration is that the condition results from a deficiency of dopaminergic function based on abnormalities of iron transport and storage. Therapeutically, studies have shown the dopamine agonists to be the most reliable treatment for severe cases, whereas other recent studies have successfully utilized a number of other medications, including levodopa, opioids, and anticonvulsants. New standards provide guidelines for management of RLS and make specific pharmacotherapeutic recommendations.