Update of the pathophysiology of the restless-legs-syndrome

Microstructural changes of basal ganglia in migraine with restless legs syndrome: findings from a neuroimaging study

In this study, it is planned to investigate the integrity of the basal ganglia structures in migraineurs with restless legs syndrome (RLS) to explore this relationship. In this study, 58 patients who were diagnosed migraine and 51 healthy controls (HCs) were included. Patients diagnosed with migraine were divided into two groups: Group I (migraine without RLS) and Group II (migraine with RLS). The integrity of basal ganglia was evaluated with region of interest diffusion tensor imaging method which allows us to assess microstructural changes of the tissue. The mean age of the patients was 35.98 ± 7.92 years, and the mean age of the HCs was 33.84 ± 11.06. 84.5% (n = 49) of the patients were female and 15.5% (n = 9) were male. 82.4% (n = 42) of the HCs were female, 17.6% (n = 9) were male. The number of  the patients without RLS was 41 (Group I), and the number of the patients with RLS was 17 (Group II). When basal ganglia structures were compared between groups of the patients with and without RLS, the fractional anisotropy (FA) value of the left putamen differed (Group I: 0.30 ± 0.06 vs. Group II: 0.25 ± 0.7, p = 0.01). The significant relationship was found attack frequency and presence of RLS with left putamen FA values according to multiple regression analysis. It was determined in this study that the changes in the microstructure of putamen, one of the basal ganglia structures, may be associated with the presence of RLS in migraineurs.

NonREM Disorders of Arousal and Related Parasomnias: an Updated Review

Parasomnias are abnormal behaviors and/or experiences emanating from or associated with sleep typically manifesting as motor movements of varying semiology. We discuss mainly nonrapid eye movement sleep and related parasomnias in this article. Sleepwalking (SW), sleep terrors (ST), confusional arousals, and related disorders result from an incomplete dissociation of wakefulness from nonrapid eye movement (NREM) sleep. Conditions that provoke repeated cortical arousals, and/or promote sleep inertia, lead to NREM parasomnias by impairing normal arousal mechanisms. Changes in the cyclic alternating pattern, a biomarker of arousal instability in NREM sleep, are noted in sleepwalking disorders. Sleep-related eating disorder (SRED) is characterized by a disruption of the nocturnal fast with episodes of feeding after arousal from sleep. SRED is often associated with the use of sedative-hypnotic medications, in particular the widely prescribed benzodiazepine receptor agonists. Compelling evidence suggests that nocturnal eating may in some cases be another nonmotor manifestation of Restless Legs Syndrome (RLS). Initial management should focus upon decreasing the potential for sleep-related injury followed by treating comorbid sleep disorders and eliminating incriminating drugs. Sexsomnia is a subtype of disorders of arousal, where sexual behavior emerges from partial arousal from nonREM sleep. Overlap parasomnia disorders consist of abnormal sleep-related behavior both in nonREM and REM sleep. Status dissociatus is referred to as a breakdown of the sleep architecture where an admixture of various sleep state markers is seen without any specific demarcation. Benzodiazepine therapy can be effective in controlling SW, ST, and sexsomnia, but not SRED. Paroxetine has been reported to provide benefit in some cases of ST. Topiramate, pramipexole, and sertraline can be effective in SRED. Pharmacotherapy for other parasomnias continues to be less certain, necessitating further investigation. NREM parasomnias may resolve spontaneously but require a review of priming and predisposing factors.

Unraveling the Mysteries of Restless Leg Syndrome

Restless leg syndrome (RLS) or Willis-Ekbom disease (WED) is an under-diagnosed, chronic, and progressive primary sensory-motor disorder. It is characterized by an uncontrollable urge to move the legs due to uncomfortable and sometimes painful sensations, with a diurnal variation. RLS can lead to severe sleep disturbances, a usual cause of consultation. The pathophysiology is known partially, and it is believed that there is an association between the different variants of genetic mutations combined with dopaminergic and brain iron dysregulation, which plays an important role. The data used for this study were extracted from the articles found in the PubMed database that discuss different gene variants, pathophysiology, and various methods of treatment. They also highlight the role of iron in the pathogenesis of RLS as it is required for the synthesis of tyrosine hydroxylase, which is the rate-limiting step for dopamine synthesis. This review article provides a clinically useful overview of RLS in terms of pathophysiological findings, its genetic associations, and therapeutic options by using the currently available literature. Because RLS presents with vague symptoms and shares similarities with many other diseases, it might be overlooked by many physicians resulting in underdiagnosis and under-treatment. While these discoveries provide a breakthrough in understanding the details of RLS, further studies are recommended as these studies are limited to animal models and provide a limited representation of the general population.

Restless Legs Syndrome: From Pathophysiology to Clinical Diagnosis and Management

Restless legs syndrome (RLS), a common neurological sensorimotor disorder in western countries, has gained more and more attention in Asian countries. The prevalence of RLS is higher in older people and females. RLS is most commonly related to iron deficiency, pregnancy and uremia. The RLS symptoms show a significant circadian rhythm and a close relationship to periodic limb movements (PLMs) in clinical observations, while the pathophysiological pathways are still unknown. The diagnostic criteria have been revised in 2012 to improve the validity of RLS diagnosis. Recent studies have suggested an important role of iron decrease of brain in RLS pathophysiology. Dopaminergic (DA) system dysfunction in A11 cell groups has been recognized long ago from clinical treatment and autopsy. Nowadays, it is believed that iron dysfunction can affect DA system from different pathways and opioids have a protective effect on DA system. Several susceptible single nucleotide polymorphisms such as BTBD9 and MEIS1, which are thought to be involved in embryonic neuronal development, have been reported to be associated with RLS. Several pharmacological and non-pharmacological treatment are discussed in this review. First-line treatments of RLS include DA agents and α2δ agonists. Augmentation is very common in long-term treatment of RLS which makes prevention and management of augmentation very important for RLS patients. A combination of different types of medication is effective in preventing and treating augmentation. The knowledge on RLS is still limited, the pathophysiology and better management of RLS remain to be discovered.

[Geriatric inpatients with iron deficiency-associated Restless Legs Syndrome. A retrospective analysis]

OBJECTIVE

The Restless Legs Syndrome (RLS) is a clinically relevant condition in geriatric patients. An association between iron deficiency and RLS is largely acknowledged. The clinical and therapeutic management of iron deficiency-associated RLS has been, however, poorly evaluated in geriatric patients.

METHODS

Data from all RLS inpatients admitted to a geriatric unit between 2009 and 2011 were retrospectively collected on demographics and clinical characteristics, iron status, drug treatment including iron substitution, as well as comprehensive geriatric assessment (CGA) scores.

RESULTS

RLS was diagnosed in 56 of the 4,063 admitted patients during the two years. Of the RLS cases, 20 (36%) showed iron deficiency. Thirteen of these were treated with iron substitution according to the existing guidelines. Both RLS patients with and without iron deficiency showed a significant clinical improvement between admission to discharge according to the CGA scores.

CONCLUSION

Iron substituted geriatric patients with iron deficiency-associated RLS substantially benefited from the treatment, similarly to RLS patients without iron deficiency. A multidimensional assessment, careful iron metabolism examination and adequate treatment choice should be equally importantly considered in geriatric patients with RLS.

Restless Bladder in an Elderly Woman: An Unusual Feature or a Variant of Restless Legs Syndrome?

We herein report an elderly patient with a history of restless legs syndrome (RLS) who developed unpleasant sensations in the lower abdomen and perineum. The patient' s symptoms occurred during the evening and at rest and forced the patient to void, resulting in some symptom relief. Urological examinations and spinal magnetic resonance imaging findings were unremarkable. The adjunctive use of rotigotine resolved her symptoms. The symptoms were considered to be "restless bladder". Further studies are required to elucidate whether restless bladder is an identical condition to the clinical entities of other RLS variants or whether it represents an unusual feature of RLS.

Sleep-related eating disorder and its associated conditions

Sleep-related eating disorder (SRED) is a condition characterized by recurrent episodes of eating at the transition from night-time sleep to arousal. SRED patients describe eating in an out-of-control manner with preference for high-caloric foods and sometimes with inedible or toxic items. Level of consciousness during SRED episodes ranges from partial consciousness to dense unawareness typical of somnambulistic episodes. SRED is sometimes associated with psychotropic medication, in particular sedative hypnotics, and other sleep disorders, including parasomnias, narcolepsy, and restless legs syndrome. Night eating syndrome (NES) is another important condition in the disordered night-time eating spectrum showing hyperphagia episodes at full arousal from nocturnal sleep without accompanying amnesia. NES could be considered an abnormality in the circadian rhythm of meal timing with a normal circadian timing of sleep onset. The two conditions often overlap and possibly share a common pathophysiology. Studies have suggested that central nervous system serotonin modulation may lead to an effective treatment of NES, while the anti-seizure medication topiramate may be an effective SRED treatment.

Association between restless legs syndrome and migraine: a population-based study

BACKGROUND AND PURPOSE

A higher prevalence of restless legs syndrome (RLS) in migraineurs has been reported in clinical samples and in two large-scale clinical trials performed on healthcare workers but general population-based studies on this topic are lacking. The aim of this study was to assess the association between migraine and RLS in an Italian rural adult population-based setting.

METHODS

The presence of migraine and RLS was assessed via a computer-assisted personal interview and self-administered questionnaires according to current diagnostic criteria in 1567 participants of a preliminary phase of an adult population-based study performed in South Tyrol, Italy.

RESULTS

Migraineurs had an increased risk of having RLS also after adjustment for confounding factors such as age, sex, major depression, anxiety and sleep quality (odds ratio 1.79; confidence interval 1.00-3.19; P = 0.049). This association was not modified by aura status and possible causes of secondary RLS. RLS was not significantly associated with tension-type headache.

CONCLUSIONS

Restless legs syndrome and migraine were associated in our rural adult population. This association could be explained by a possible shared pathogenic pathway which would implicate new management strategies of these two disorders.

Restless Eating, Restless Legs, and Sleep Related Eating Disorder

Restless legs syndrome (RLS) often presents with a primary complaint of sleep initiation difficulty with only ambiguous allusions to motor symptoms. This may result in the condition being misdiagnosed as a psychophysiological insomnia. Further, nocturnal eating is common in RLS and like the classic motor symptoms, patients will describe an inability to initiate sleep until their urge (to eat) is addressed. Restless nocturnal eating arises, intensifies, and subsides in parallel to motor symptoms. Once misdiagnosed as psychophysiological insomnia, RLS patients are frequently treated with benzodiazepine receptor agonists. The CNS actions of these sedating agents, suppression of memory and executive function, unleash predisposed amnestic behaviors. In the case of RLS this would be expected to include the inappropriate ambulatory and eating behaviors of sleep related eating disorder (SRED). The evidence and implications of a link between the restless eating of RLS and SRED is presented here.

The relationship between depressive symptoms and restless legs syndrome in two prospective cohort studies

OBJECTIVE

Cross-sectional studies suggest a strong association between depression and restless legs syndrome (RLS); however, the temporal relationship between the two disorders remains unknown. We tested whether the presence of clinically relevant depressive symptoms (CRDS) is a risk factor for subsequent RLS in the general population. The relationship between prevalent RLS and incident CRDS was also examined.

METHODS

Two independent, prospective cohort studies with representative, age-stratified random samples, the Dortmund Health Study (DHS; n = 1312/1122 [baseline/follow-up], median follow-up time = 2.1 years) and the Study of Health in Pomerania (SHIP; n = 4308/3300, median follow-up time = 5.0 years) were analyzed. RLS was assessed in both studies according to the RLS minimal criteria, at baseline and at follow-up. CRDS were assessed by the Center for Epidemiologic Studies-Depression scale (a score of ≥16) in DHS only at baseline and by the Munich-Composite International Diagnostic-Screener in SHIP at baseline and at follow-up.

RESULTS

Clinically relevant depressive symptoms at baseline were associated new-onset RLS in both studies (DHS: odds ratio [OR] = 1.94, 95% confidence interval [CI] = 1.09-3.44; SHIP: OR = 2.37, 95% CI = 1.65-3.40) after adjustment for age, sex, education, body mass index, smoking, physical activity, and the presence of various comorbidities. RLS at baseline was an independent risk factor of incident CRDS in SHIP (OR = 1.82, 95% CI = 1.10-3.00).

CONCLUSIONS

The presence of CRDS may be a risk factor for subsequent RLS. The relationship between the two disorders might be bidirectional because RLS also predicts incident depressive symptoms.

Parasomnias: an updated review

Parasomnias are abnormal behaviors emanating from or associated with sleep. Sleepwalking and related disorders result from an incomplete dissociation of wakefulness from nonrapid eye movement (NREM) sleep. Conditions that provoke repeated cortical arousals, or promote sleep inertia lead to NREM parasomnias by impairing normal arousal mechanisms. Changes in the cyclic alternating pattern, a biomarker of arousal instability in NREM sleep, are noted in sleepwalking disorders. Sleep-related eating disorder (SRED) is characterized by a disruption of the nocturnal fast with episodes of feeding after an arousal from sleep. SRED is often associated with the use of sedative-hypnotic medications; in particular, the widely prescribed benzodiazepine receptor agonists. Recently, compelling evidence suggests that nocturnal eating may in some cases be a nonmotor manifestation of Restless Legs Syndrome (RLS). rapid eye movement (REM) Sleep Behavior Disorder (RBD) is characterized by a loss of REM paralysis leading to potentially injurious dream enactment. The loss of atonia in RBD often predates the development of Parkinson's disease and other disorders of synuclein pathology. Parasomnia behaviors are related to an activation (in NREM parasomnias) or a disinhibition (in RBD) of central pattern generators (CPGs). Initial management should focus on decreasing the potential for sleep-related injury followed by treating comorbid sleep disorders. Clonazepam and melatonin appear to be effective therapies in RBD, whereas paroxetine has been reported effective in some cases of sleep terrors. At this point, pharmacotherapy for other parasomnias is less certain, and further investigations are necessary.

Small fiber function in drug naïve patients with idiopathic restless legs syndrome

To assess whether idiopathic restless legs syndrome (RLS) is associated with small fiber abnormalities, we evaluated somatic and autonomic small fiber function in 56 patients with idiopathic RLS and 36 age-matched and sex-matched healthy controls using quantitative sensory testing and quantitative sudomotor axon reflex tests. The warm detection thresholds (WDT) of the hands (p=0.017) and feet (p=0.008) were higher in patients with RLS than in controls. Cooling detection thresholds (CDT) were higher in the feet of patients with RLS than controls (p<0.001), but CDT in the hands did not differ between groups (p=0.161). There were no significant between-group differences in total sweat volume and sweat production in the forearms, proximal legs, distal legs, and feet (p>0.1 each). These findings suggest that abnormal sensory perception in patients with idiopathic RLS may result from impairment of central somatosensory processing rather than small fiber neuropathy.

Restless legs syndrome and all-cause mortality in four prospective cohort studies

OBJECTIVES

To evaluate the association between restless legs syndrome (RLS) and all-cause mortality.

DESIGN

Four prospective cohort studies.

SETTING

The Dortmund Health Study (DHS) and the Study of Health in Pomerania (SHIP) from Germany. The Women's Health Study (WHS) and the Physicians' Health Study (PHS) from the USA.

PARTICIPANTS

In DHS: a random sample (n=1 299) from the population of Dortmund; in SHIP: a sample (n=4 291) from residents living in West Pomerania were drawn by multistage random sampling design; in WHS: female healthcare professionals (n=31 370); in PHS: male physicians (n=22 926)

MAIN OUTCOME MEASURES

All-cause mortality.

RESULTS

The prevalence of RLS ranged between 7.4% and 11.9% at baseline. During follow-up (ranging between 6 and 11 years) RLS was not associated with increased risk of all-cause mortality in any of the four cohorts. The multivariable-adjusted HRs (95% CI) for all-cause mortality ranged from 0.21 (0.03 to 1.53) to 1.07 (0.93 to 1.23) across the four studies. The HRs for all-cause mortality did not differ according to gender.

CONCLUSIONS

In these four independently conducted large prospective cohort studies from Germany and the USA, RLS did not increase the risk of all-cause mortality. These findings do not support the hypothesis that RLS is a risk factor for mortality of any cause.

A comparison of gray matter density in restless legs syndrome patients and matched controls using voxel-based morphometry

BACKGROUND

Restless legs syndrome (RLS) is a common neurological disorder the pathophysiology of which is incompletely understood. Four studies have examined structural differences between the brains of RLS patients and healthy controls, using voxel-based morphometry (VBM). All 4 studies have provided different results.

METHODS

Optimized VBM was used to search for structural differences in gray matter density. Sixteen RLS patients naïve to dopaminergic drugs and 16 age- and sex-matched controls received structural T1-weighted MR scans. Structural data were analyzed using FSL-VBM.

RESULTS

No difference in gray matter density was detected between the two groups (voxel-wise significance: no significant voxels at P= .89 (whole brain Family Wise Error (FWE) corrected); no significant voxels at P < .05 (whole brain False Discovery Rate (FDR) corrected; smallest achievable FDR threshold .99).

CONCLUSION/DISCUSSION

The present study did not replicate (confirm) previous findings of structural brain changes in RLS, but instead supported the findings of a recent study showing a lack of gray matter alteration in an elderly RLS population. More specifically, the results do not support neuronal loss as an underlying disease mechanism in RLS. Potential limitations in the application of VBM are also discussed.

Investigation of unmedicated early onset restless legs syndrome by voxel-based morphometry, T2 relaxometry, and functional MR imaging during the night-time hours

BACKGROUND AND PURPOSE

The pathophysiology of eRLS has not yet been elucidated. The purpose of the study was to assess, in patients with eRLS, the volume, iron content, and activation of the brain during night-time episodes of SLD and PLMs.

MATERIALS AND METHODS

Eleven right-handed unmedicated patients with eRLS (mean age, 55.3 ± 8.4 years; disease duration, 17.5 ± 14.05 years) and 11 matched control subjects were studied with a T1-weighted high-resolution 3D spoiled gradient-echo sequence used for VBM and a multisection spin-echo T2-weighted sequence used for T2 relaxometry. Additionally, a single-shot multisection gradient echo-planar sequence was used for fMRI. Brain activation was recorded during spontaneous SLD and PLMs. SPM software was used for analysis of the functional data.

RESULTS

The patients showed no regional brain volume change, but T2 relaxometry revealed decreased T2 relaxation time in the right globus pallidus internal and the STN, indicating increased iron content. The patients were observed to activate the following areas: in the left hemisphere, the primary motor and somatosensory cortex, the thalamus, the pars opercularis, and the ventral anterior cingulum; and in the right hemisphere, the striatum, the inferior and superior parietal lobules, and the dorsolateral prefrontal cortex. Bilateral activation was observed in the cerebellum, the midbrain, and the pons.

CONCLUSIONS

eRLS is associated with increased iron content of the globus pallidus internal and STN, suggesting dysfunction of the basal ganglia. Activation of the striatofrontolimbic area may represent the neurofunctional substrate mediating the repetitive compulsive movements seen in RLS.

Pathological gambling plus hypersexuality in restless legs syndrome: a new case

Emerging clinical data indicate that dopaminergic agonists used to treat restless legs syndrome may be associated with dopamine dysregulation syndrome, particularly pathological gambling. We report a new case with pathological gambling plus hypersexuality and impotence in an old patient treated with a small dose (0.18 mg daily at bedtime) of pramipexole for restless legs syndrome for 5 months. The time relationship and the resolution upon discontinuation of dopaminergic agonists suggest a causative association. Our new case confirms that restless legs syndrome patients should be cautioned about potential dopamine dysregulation syndrome coinciding with dopaminergic agonists, as it can be reversed by drug withdrawal.

Restless legs syndrome in Friedreich ataxia: a polysomnographic study

Friedreich ataxia (FA) is the most common type of hereditary ataxia. Frataxin deficiency due to a GAA expansion in the first intron of chromosome 9 results in intramitochondrial iron accumulation. On the basis of the patients' complaints about sleep disturbance and pathophysiological considerations, we systematically assessed sleep history and polysomnography in FA. We included 16 consecutive FA patients (11 men, 5 women; mean age, 35.4 ± 11.1 years) with a mean disease duration of 16.5 ± 7.0 years. All patients underwent a standardized protocol including a detailed sleep history and polysomnographic recordings. Eight out of 16 patients were diagnosed with restless legs syndrome (RLS). In seven patients, RLS onset was after the onset of FA. Interestingly, FA patients with RLS had significantly lower serum ferritin levels than FA patients without RLS (76.3 ± 56.0 μg/L vs. 176.3 ± 100.7 μg/L; P = 0.043 after correction for sex and age). Moreover, periodic leg movements in wakefulness (PLMW) indices were significantly higher in FA patients with RLS than FA patients without RLS (FA with RLS, 118.1 ± 50.7; FA without RLS, 65.6 ± 44.2; P = 0.028). There was an inverse correlation between serum ferritin levels and PLMW indices obtained in all FA patients (rho -0.538, P = 0.039). RLS is common in FA. Its frequency in this primarily spinal ataxia appears consistent with the concept of dysfunctional spinal sensorimotor integration in the pathophysiology of RLS. The finding that RLS is more frequent in the context of lower serum ferritin levels in FA is interesting, but requires further investigation in larger patient samples.

Restless legs syndrome is a common feature of adult celiac disease

Restless legs syndrome (RLS) is a common neurological condition, frequently idiopathic, sometimes associated with specific disorders such as iron deficiency. We investigated RLS prevalence in celiac disease (CD), an autoimmune disease characterized by several features such as malabsorption-related iron deficiency anemia and peripheral neuropathy. We screened a population of 100 adult CD patients for CD features, iron metabolism, clinical and neurological conditions, and enrolled 100 age- and sex-matched controls in the general population. RLS was ascertained in CD patients and controls by both the presence of the four essential International RLS Study Group diagnostic criteria and neurological examination. The International RLS Study Group rating scale was used to measure RLS severity. We found a 31% prevalence of RLS in the CD population that was significantly higher than the prevalence in the control population (4%; P < 0.001). The average severity of RLS in CD population was moderate (17 +/- 6.5). In the CD population, no significant correlation was found between RLS and either gluten-free diet or iron metabolism, despite hemoglobin levels were significantly lower in CD patients with RLS than without RLS (P = 0.003). We found no correlation between RLS and other possible causes of secondary RLS, including signs of peripheral neuropathy, pregnancy, end-stage renal disease, and pharmacological treatments.Our study broadens the spectrum of neurological disorders associated with CD and indicates that RLS should be sought for in all patients with CD.

Restless legs syndrome is frequent in narcolepsy with cataplexy patients

STUDY OBJECTIVES

To investigate the occurrence of restless legs syndrome (RLS) in narcolepsy with cataplexy (NC).

DESIGN

A case-control study assessing the frequency of comorbidity of RLS and NC in three European sleep disorder centers.

PATIENTS

Three sleep research centers recruited 184 NC patients and 235 age-matched controls.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

NC patients and controls underwent a face-to-face interview investigating demographics, medical and drug history, sleep habits, and sleep disorders, in particular RLS based on the 4 international criteria and on a frequency > or =2 times/week, with a detailed description of RLS symptoms when present. RLS was significantly more prevalent among NC patients (14.7%) than in controls (3.0%). The age at onset of RLS in NC patients fits with the age at onset in idiopathic RLS, and RLS appeared more than 10 years after NC onset. Unlike idiopathic RLS, RLS in NC subjects was not more prevalent in women and was less familial (15.4% of cases). Lastly, NC patients with RLS showed a moderate disease severity and an almost daily occurrence of symptoms, which were also diurnal in 35% of cases. Older age, higher blood ferritin levels, and sleep paralysis seem to have a predictive value for RLS in NC. The higher ferritin levels indicate that different pathophysiological mechanisms underlie secondary RLS associated with NC.

CONCLUSIONS

This study highlights the association between RLS and NC. The nature of this association is still investigational, but it does indicate that RLS must be addressed in the evaluation and management of nocturnal sleep impairment in NC patients.

[Pathophysiology of restless legs syndrome]

Restless legs syndrome (RLS) could be the consequence of sensorimotor dysfunction. Dopaminergic treatment has been successful in RLS, suggesting dopaminergic abnormalities. The specific pathophysiology of idiopathic RLS is not well known but recent studies have raised the hypothesis of diencephalospinal pathway dysfunction. This pathway includes spinal, subcortical and cortical structures. In idiopathic RLS, an implication of A11 neurons has been evoked, but further studies are needed to confirm this hypothesis. Brain iron is reduced in RLS. This decrease plays a major role in RLS occurrence. Genetic analyses are necessary to better understand the pathophysiological mechanisms of RLS.

New approaches for the treatment of sleep disorders

Epidemiological studies have established that sleep disorders are common and often untreated. Besides having a negative impact on overall health, these conditions can significantly disrupt normal daily functions. While a number of drugs are employed in the treatment of sleep disorders, safety, tolerability, and variable efficacy limit their utility. Clinical developments in the area have been facilitated especially by advances in neurobiology and neuropharmacology. In this regard, a wide array of neuroactive substances has been found to be responsible for regulating sleep and wakefulness. Advances in the understanding of neurotransmitter and hormone receptor mechanisms and classifications have led to new opportunities for developing novel therapeutics for treating sleep disorders. Provided in this report is an overview of some of the more prevalent sleep disorders, including narcolepsy, insomnia, obstructive sleep apnea syndrome, and restless legs syndrome, with a summary and critique of medications used to treat these conditions. For each disorder, information is provided on recent approaches taken to develop novel therapeutics based on laboratory findings relating to the underlying biological abnormalities associated with the condition, in addition to approaches that leverage existing therapeutics to develop new treatment options for patients. Significant advances in the future await a better understanding of the underlying pathophysiology of these conditions and of the neurobiological alterations associated with these disorders. It is hoped that some of the research directions described herein will stimulate additional research in this area and thereby help foster the discovery of novel agents for treating major sleep disorders.

Restless legs syndrome: differential diagnosis and management with pramipexole

Restless legs syndrome (RLS) is a condition characterized by discomfort at rest and urge to move focused on the legs. RLS may occur as an idiopathic, often hereditary condition (primary RLS), or in association with medical conditions (secondary RLS) including iron deficiency, uremia, and polyneuropathy. Current understanding of the pathophysiology of RLS points to the involvement of three interrelated components: dopaminergic dysfunction, impaired iron homeostasis, and genetic mechanisms. The diagnosis of RLS is made according to the consensus criteria by a National Institutes of Health panel: 1) an urge to move the legs, usually accompanied by uncomfortable sensations; 2) beginning or worsening during rest; 3) relieved by movement; and 4) worse, or only occurring, in the evening or at night. The differential diagnosis of RLS aims to: 1) distinguish RLS from other disorders with RLS-like symptoms and 2) identify secondary forms, with investigation of underlying diseases. The treatment of RLS demands a clinical evaluation to rule out and cure causes of secondary RLS, including iron supplementation when deficient, and to eliminate the triggering factors. The presence of neuropathy should be especially investigated in nonhereditary, late-onset RLS, in view of a possible treatment of the underlying disease. The first line treatment for idiopathic RLS is represented by dopamine agonists, in particular nonergot-derived ropinirole and pramipexole, whereas ergot dopamine agonists (cabergoline and pergolide) are no longer in first-line use given the risks of cardiac valvulopathy. Although no comparative trials have been published, a meta-analysis of pramipexole versus ropinirole suggests differences in efficacy and tolerability favoring pramipexole.