Descriptors of restless legs syndrome sensations

Sensory aspects of restless legs syndrome: Clinical, neurophysiological and neuroimaging prospectives

Restless Legs Syndrome (RLS) is a complex sensorimotor disorder, classified among the sleep-related movement disorders. Although sensory symptoms appear as key features of the disorder, they are still poorly characterized from a clinical perspective and conceptualized from a pathophysiological point of view. In this review, we aim to describe the clinical and functional substrates of RLS, focusing mainly on its sensory symptoms and on their neurophysiological and anatomical correlates. Knowledge of both subjective sensory symptoms and objective sensory signs are still controversial. Current data also indicate that the sensory component of RLS seems to be subserved by anomalies of sensorimotor integration and by mechanism of central sensitization. Overall, electrophysiological findings highlight the involvement of multiple generators in the pathogenesis of RLS, eventually resulting in an increased nervous system excitability and/or alterations in inhibition within the somatosensory and nociceptive pathways. Structural and functional neuroimaging data show the involvement of several crucial areas and circuits, among which the thalamus appears to play a pivotal role. A holistic approach looking at brain connectivity, structural or functional abnormalities, and their interplay with molecular vulnerability and neurotransmitter alterations is warranted to disentangle the complex framework of RLS.

Potential therapeutic benefit of spinal cord stimulation in restless legs syndrome: scoping review and mechanistic considerations

BACKGROUND

Restless legs syndrome (RLS) is a prevalent sensorimotor disorder that can dramatically impair sleep quality, daytime function, and quality of life. Although many patients benefit from standard pharmacological therapy, some patients suffer from insufficient treatment response or medication intolerance. Novel treatment approaches are therefore necessary.

OBJECTIVE

Given the overlap between RLS and pain syndromes in both pathophysiological mechanisms and certain treatment options, we aimed to perform a scoping review of the available evidence on spinal cord stimulation (SCS) for RLS and discuss potential mechanistic implications.

METHODS

We identified a total of 16 cases of patients with RLS who underwent SCS, all from case reports or case series.

DISCUSSION

The published evidence is insufficient to assess SCS efficacy in patients with RLS, but SCS remains a promising investigational therapy in RLS on the basis of its potential mitigatory effects in the central hyperexcitability of the sensorimotor cortex through neuromodulation of spinal, subcortical, and cortical areas. A call for further research in this field is presented, with suggestions for future directions and trial designs.

"Unvoluntary" Movement Disorders: Distinguishing between Tics, Akathisia, Restless Legs, and Stereotypies

Tics, stereotypies, akathisia, and restless legs fall at different places on the spectrum of discrete, unwanted and potentially disabling motor routines. Unlike tremor, chorea, myoclonus, or dystonia, this subgroup of abnormal movements is characterized by the subject's variable ability to inhibit or release undesired motor patterns on demand. Though it may be sometimes clinically challenging, it is crucial to distinguish these "unvoluntary" motor behaviors because secondary causes and management approaches differ substantially. To this end, physicians must consider the degree of repetitiveness of the movements, the existence of volitional control, and the association with sensory symptoms, or cognitive-ideational antecedent. This review aims to summarize the current existing knowledge on phenomenology, diagnosis, and treatment of tics, stereotypies, akathisia, and restless leg syndrome.

Chronic testicular pain cured by low-dose pramipexole: is there an association with restless legs syndrome?

Restless legs syndrome (RLS) is characterized by an urge to move the legs, predominantly at night. About one quarter of the patients with RLS report painful symptoms in the legs. In this case report, the patient presented at the sleep clinic with a chief complaint of insomnia and the classical symptoms of RLS. He also mentioned a chronic testicular pain (CTP). For over a year, the patient had undergone urologic investigation and empiric treatments, with only mild improvement of the testicular pain. After 3 months of therapy with pramipexole, the RLS symptoms and the CTP were no longer present. Finding an etiology for CTP can be challenging and many cases are diagnosed as idiopathic. RLS may be a forgotten and unidentified etiology for CTP in typical urological care. Considering the high prevalence of RLS and CTP, it is relevant to clarify the possible association.

CITATION

Tedesco Silva LM, Lenz MCS, Martinez D. Chronic testicular pain cured by low-dose pramipexole: Is there an association with restless legs syndrome? J Clin Sleep Med. 2022;18(5):1467-1469.

Clinical Decision-Making: Restless Legs Syndrome and Dementia in Older Adults

Restless legs syndrome (RLS), one of the more prevalent sleep disturbances among older adults, impacts quality of life. Patients with dementia are at high risk for developing RLS and may be unable to describe their symptoms. Often underdiagnosed, RLS can contribute to discomfort, pain, nighttime agitation, disturbed sleep, and falls. Clinical assessment is crucial and should include a thorough evaluation with input from the patient and family, deprescribing medication if possible, and consideration of common sleep-disturbing factors. Evidence-based treatment in this population is limited; overall focus should center on relieving discomfort while identifying and treating bothersome sleep symptoms.

Association of proton pump inhibitor and histamine H2-receptor antagonists with restless legs syndrome

Restless legs syndrome (RLS) is a common sensorimotor disorder, which can disrupt sleep and is thought to be caused in part by low cellular iron stores. Proton pump inhibitors (PPI) and histamine H₂-receptor antagonists (H₂A) are among the most commonly used drugs worldwide and show evidence of causing iron deficiency. We conducted a case/non-case observational study of blood donors in the United States (N = 13,403; REDS-III) and Denmark (N = 50,323; Danish Blood Donor Study, DBDS), both of which had complete blood count measures and a completed RLS assessment via the Cambridge–Hopkins RLS questionnaire. After adjusting for age, sex, race, BMI, blood donation frequency, smoking, hormone use, and iron supplement use, PPI/H₂A use was associated with RLS (odds ratio [OR] = 1.41; 95% confidence interval [CI], 1.13–1.76; p = 0.002) in REDS-III for both PPI (OR = 1.43; CI, 1.03–1.95; p = 0.03) and H₂A (OR = 1.56; CI, 1.10–2.16; p = 0.01). DBDS exhibited a similar association with PPIs/H₂As (OR = 1.29; CI, 1.20–1.40; p < 0.001), and for PPIs alone (OR = 1.27; CI, 1.17–1.38; p < 0.001), but not H₂As alone (OR = 1.18; CI, 0.92–1.53; p = 0.2). We found no evidence of blood iron stores mediating this association. The association of PPI, and possibly H₂A, consumption with RLS independent of blood iron status and other factors which contribute to RLS risk suggest the need to re-evaluate use of PPI/H₂A in populations at particular risk for RLS.

Sensory symptoms in body-focused repetitive behaviors, restless legs syndrome, and Tourette syndrome: An overlap?

Tourette syndrome (TS) is a neurodevelopmental condition characterized by multiple tics. Sensory symptoms play a key role in the clinical phenomenology and pathophysiology of TS, as most patients report premonitory urges driving tic expression. Interestingly, sensory symptoms have also been reported in other conditions characterized by repeated behaviors. This review explores the nature of sensory symptoms reported by patients with body focused repetitive behaviors (BFRBs, especially trichotillomania and skin picking disorder) and restless legs syndrome (RLS) in comparison to TS. A sense of mounting inner tension and reinforcement mechanisms driven by gratification and relief on expression of the tic or repetitive behavior appear to be implicated across all conditions. Subjective urges can be temporarily suppressed by patients with TS and selected BFRBs, whereas patients with RLS tend to report dysesthesia more frequently than a suppressible urge to move. The observed similarities in the phenomenology of sensory symptoms across these conditions raise the possibility of a comparable underlying pathophysiology. Preliminary findings suggest an overlap of neural pathways encompassing the insula, basal ganglia (putamen), and posterior cingulate cortex.

Emerging Concepts of the Pathophysiology and Adverse Outcomes of Restless Legs Syndrome

Restless legs syndrome (RLS), also known as Willis-Ekbom disease (WED), is a common neurological disorder affecting up to 5% to 10% of the population, but it remains an underdiagnosed condition. RLS/WED is characterized by uncomfortable sensations, mainly in the legs, which appear during inactivity and worsen in the evening or at night. The prevalence of RLS/WED and periodic leg movements (PLMs) is increased in patients with sleep-disordered breathing, particularly in those with OSA, the most common sleep disorder encountered in sleep centers. New advances in the pathophysiology of RLS/WED have shown important implications for various genetic markers, neurotransmitter dysfunction, and iron deficiency. A practical approach to RLS/WED management includes an accurate diagnosis, the identification of reversible contributing factors, and the use of nonpharmacological therapies, including iron substitution (oral or IV) therapy. Many pharmacological agents are effective for the treatment of RLS/WED. Until recently, the first-line treatment of RLS/WED consisted of low-dose dopamine agonists (DA). However, given the fact that DAs cause high rates of augmentation of symptoms, international guidelines recommend that whenever possible the initial treatment of choice should be an α2δ ligand, and avoidance of dopaminergic agents unless absolutely necessary. If necessary, the lowest effective dose should be used for only the shortest possible time. The symptoms of RLS/WED can disrupt the quality of sleep as well as the quality of life. IV iron therapy may be considered in patients with refractory RLS. A better understanding of RLS/WED pathophysiology will allow patients to receive tailored therapy, resulting in an improved quality of life.

Characterization of painful Restless Legs Syndrome sensations in an English-speaking South African population

Background and aims Restless Legs Syndrome (RLS) is characterised by unusual sensations in the legs which can be described as painful in up to 60% of RLS patients. The purpose of this study was to characterise and examine whether the presence of pain influenced the words used to describe the sensations of RLS in an English speaking population. Methods RLS participants (n=55) were divided according to whether or not painful RLS sensations were reported upon questioning. They completed the McGill Pain Questionnaire (MPQ), the International Restless Legs Syndrome Severity Scale (IRLS) and selected descriptors from a list of previously published RLS terms. Results Thirty-five percent of the RLS patients had painful sensations. The participants with painful RLS had higher Pain Rating Index (PRI) scores [median (interquartile range) 21 (17-28) vs. 14 (7.5-21) p=0.0008] and IRLS scores [23 (17-28) vs. 18 (11.5-22.5) p=0.0175] than the participants with non-painful RLS. Patients with painful RLS symptoms selected more pain-related literature terms, chose significantly different words in eight of the MPQ subclasses (both sensory and affective) and selected more intense descriptors from certain MPQ subclasses than the non-painful RLS group. The terms that characterised painful RLS were "aching", "painful", "cramping" and "unbearable". Conclusions Descriptors of RLS sensations are changed by the presence of pain, which may indicate an aetiological difference in the patients who have painful RLS. Clinically, patients complaining of cramping and painful sensations may be diagnosed with a condition that mimics RLS. Thus, it is important that the most accurate set of descriptors for RLS are used to enable recognition of RLS and optimised treatment according to the RLS phenotype. Implications The diagnosis of RLS may be improved by overcoming language and cultural barriers and obtaining differential diagnostic terms for painful conditions mimicking RLS.

Prevalence and clinical characteristics of patients with restless legs syndrome with painful symptoms

BACKGROUND

The complaint of pain has largely been ignored in the diagnostic criteria for restless legs syndrome (RLS). The purpose of this study was to investigate the prevalence of painful symptoms in RLS, and to compare sleep-related characteristics between the patients who experienced the painful symptoms and those who did not.

METHODS

The patients with RLS were retrospectively screened from July 2011 to December 2013 at a tertiary-care sleep center. For classifying those with pain and those without pain, more than three specialists separately observed the patients' reports and complaints of symptoms, and the final decision was made through consensus. The demographics and clinical characteristics, including sleep, psychiatric-related scales, and polysomnographic data were reviewed for the study.

RESULTS

One hundred and sixty patients with RLS were selected, and 23.8% of them reported painful symptoms of RLS. Patients with RLS who experienced painful sensations were found to have lower ferritin levels, more severe RLS symptoms, anxiety and depressive symptoms, and a lower quality of life. The polysomnography data found that patients with RLS who experienced painful sensations had a longer latency to sleep onset and a lower periodic limb movement index (PLMI) (p <0.05).

CONCLUSIONS

Patients who experienced painful sensations had more severe RLS symptoms and a trend toward lower PLMI during sleep. According to these results, an inference can be made that painful sensations may be one important point in determining the severity of RLS.

Restless legs syndrome: clinical presentation diagnosis and treatment

Restless legs syndrome (RLS) is a circadian disorder of sensory-motor integration that may be related to genetically determined dysregulation of iron transport across the blood-brain barrier. Dopamine agonists (DAs) have been considered the first-line therapy, but with the growing appreciation of problems associated with long-term treatment, particularly augmentation and impulse control disorder, alpha-2-delta drugs, such as gabapentin, are now considered the first line of treatment in patients with troublesome RLS. Opioids can be considered as an alternative therapy, particularly in patients with DA-related augmentation. In more severe cases, a combination therapy may be required. Intravenous iron therapy may be considered on those patients with refractory RLS.

Brazilian consensus on guidelines for diagnosis and treatment for restless legs syndrome

The Consensus on restless legs syndrome is an effort of neurologists from several Brazilian states, which tirelessly reviewed the literature of recent years in search of evidence, both in regard to diagnosis and treatment, according to the Oxford Centre for Evidence-based Medicine.

An update on restless legs syndrome (Willis-Ekbom disease): clinical features, pathogenesis and treatment

PURPOSE OF REVIEW

In recent years, there have been a number of advances in the field of restless legs syndrome (RLS) or Willis-Ekbom disease (WED). Here, we review recent studies pertaining to the diagnosis and clinical features, pathogenesis, and treatment of RLS/WED.

RECENT FINDINGS

Recent studies have added a temporal dimension to RLS/WED epidemiology by examining both the incidence and persistence rates in different populations. Diagnostic criteria have been modified to increase sensitivity, and new guidelines take into account recently published studies of different drug classes.

SUMMARY

Recent epidemiological findings have shown that RLS/WED is a common neurological disorder that affects up to 5% of the adult population in Western countries. In moderate and severe cases, RLS/WED has a strong impact on sleep and quality of life and can involve an increased cardiovascular risk. Diagnosis is made clinically by confirming the presence of the five essential criteria. However, in difficult cases objective tests such as the multiple suggested immobilization test (m-SIT) can be used. The pathophysiology is partially known, with several risk polymorphisms (BTBD-9 (BTB (POZ) domain containing 9), MEIS-1 (Meis homeobox 1), protein tyrosine phosphatase, receptor type, D, and others) playing an important role, along with dopaminergic and iron dysfunctions. The disorder frequently requires long-term treatment with low-dose dopamine agonists or α2δ ligands. Dopamine agonists are usually effective but the main complication, RLS/WED augmentation, can arise.

Restless legs syndrome/Willis-Ekbom disease diagnostic criteria: updated International Restless Legs Syndrome Study Group (IRLSSG) consensus criteria--history, rationale, description, and significance

BACKGROUND

In 2003, following a workshop at the National Institutes of Health, the International Restless Legs Syndrome Study Group (IRLSSG) developed updated diagnostic criteria for restless legs syndrome/Willis-Ekbom disease (RLS/WED). These criteria were integral to major advances in research, notably in epidemiology, biology, and treatment of RLS/WED. However, extensive review of accumulating literature based on the 2003 NIH/IRLSSG criteria led to efforts to improve the diagnostic criteria further.

METHODS

The clinical standards workshop, sponsored by the WED Foundation and IRLSSG in 2008, started a four-year process for updating the diagnostic criteria. That process included a rigorous review of research advances and input from clinical experts across multiple disciplines. After broad consensus was attained, the criteria were formally approved by the IRLSSG executive committee and membership.

RESULTS

Major changes are: (i) addition of a fifth essential criterion, differential diagnosis, to improve specificity by requiring that RLS/WED symptoms not be confused with similar symptoms from other conditions; (ii) addition of a specifier to delineate clinically significant RLS/WED; (iii) addition of course specifiers to classify RLS/WED as chronic-persistent or intermittent; and (iv) merging of the pediatric with the adult diagnostic criteria. Also discussed are supportive features and clinical aspects that are important in the diagnostic evaluation.

CONCLUSIONS

The IRLSSG consensus criteria for RLS/WED represent an international, interdisciplinary, and collaborative effort intended to improve clinical practice and promote further research.

Sensory aspects of movement disorders

Movement disorders, which include disorders such as Parkinson's disease, dystonia, Tourette's syndrome, restless legs syndrome, and akathisia, have traditionally been considered to be disorders of impaired motor control resulting predominantly from dysfunction of the basal ganglia. This notion has been revised largely because of increasing recognition of associated behavioural, psychiatric, autonomic, and other non-motor symptoms. The sensory aspects of movement disorders include intrinsic sensory abnormalities and the effects of external sensory input on the underlying motor abnormality. The basal ganglia, cerebellum, thalamus, and their connections, coupled with altered sensory input, seem to play a key part in abnormal sensorimotor integration. However, more investigation into the phenomenology and physiological basis of sensory abnormalities, and about the role of the basal ganglia, cerebellum, and related structures in somatosensory processing, and its effect on motor control, is needed.

Motor restlessness, sleep disturbances, thermal sensory alterations and elevated serum iron levels in Btbd9 mutant mice

Restless legs syndrome (RLS), also known as Willis-Ekbom disease, is a sensory-motor neurological disorder with a circadian component. RLS is characterized by uncomfortable sensations in the extremities, generally at night or during sleep, which often leads to an uncontrollable urge to move them for relief. Recently, genomic studies identified single-nucleotide polymorphisms in BTBD9, along with three other genes, as being associated with a higher risk of RLS. Little is known about the function of BTBD9 or its potential role in the pathophysiology of RLS. We therefore examined a line of Btbd9 mutant mice we recently generated for phenotypes similar to symptoms found in RLS patients. We observed that the Btbd9 mutant mice had motor restlessness, sensory alterations likely limited to the rest phase, and decreased sleep and increased wake times during the rest phase. Additionally, the Btbd9 mutant mice had altered serum iron levels and monoamine neurotransmitter systems. Furthermore, the sensory alterations in the Btbd9 mutant mice were relieved using ropinirole, a dopaminergic agonist widely used for RLS treatment. These results, taken together, suggest that the Btbd9 mutant mice model several characteristics similar to RLS and would therefore be the first genotypic mouse model of RLS. Furthermore, our data provide further evidence that BTBD9 is involved in RLS, and future studies of the Btbd9 mutant mice will help shine light on its role in the pathophysiology of RLS. Finally, our data argue for the utility of Btbd9 mutant mice to discover and screen novel therapeutics for RLS.