Restless legs syndrome and polyneuropathy

[Sleep disorders in patients with neuromuscular diseases]

Neuromuscular diseases (NMD) may affect skeletal muscles, peripheral nerves, or motor endplates. Clinical symptoms comprise muscle weakness, which is often progressive, but also sensory disturbances, and primary or secondary pain. Sleep disturbances in NMD may result from insomnia due to immobility, pain, or sleep-related leg muscle cramps, but also restless legs syndrome and sleep-disordered breathing. Many NMD predispose to obstructive sleep apnea or progressive respiratory muscle weakness, which first manifests as sleep-related hypoventilation and eventually leads to chronic hypercapnic respiratory failure. The latter is crucial for overall prognosis in muscular dystrophies and myopathies, but even more so in motor neuron diseases such as amyotrophic lateral sclerosis and spinal muscular atrophy.

Association between restless legs syndrome and peripheral neuropathy: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

The coexistence of peripheral neuropathy (PN) and restless legs syndrome (RLS) or Willis-Ekbom disease is relatively frequent, but its prevalence has shown a high variability across studies. In addition, several reports have shown data suggesting the presence of PN in patients with idiopathic RLS.

METHODS

A search was undertaken using the PubMed, Embase and Web of Science Databases, from 1966 to 6 December 2020, crossing the search term 'restless legs syndrome' with 'neuropathy', 'polyneuropathy' (PNP) and 'peripheral neuropathy', and the references of interest for this topic were identified; a meta-analysis was performed, according to PRISMA guidelines, and a calculation of pooled prevalences, where appropriate, was made using standard methods.

RESULTS

Restless legs syndrome has been reported in 5.2%-53.7% of patients with PN (average 21.5%; 95% confidence interval 18.6%-24.5%), and PN has been reported in 0%-87.5% of patients with RLS (average 41.8%; 95% confidence interval 39.9%-43.6%), both being significantly more frequent than in controls. The heterogeneity across studies could be due to differences in the diagnostic criteria used for both RLS and PN. RLS is a frequent clinical complaint in patients with PN of different aetiologies, mainly diabetic PN, uraemic PNP, familial amyloid PNP, Charcot-Marie-Tooth disease and chronic dysimmune inflammatory PNP. Recent neurophysiological findings suggest the presence of small sensory fibre loss in patients diagnosed with idiopathic RLS, but it remains to be determined whether RLS associated with small sensory fibre loss and idiopathic RLS are different clinical entities.

CONCLUSIONS

Future studies including clinical and neurophysiological assessment and skin biopsy involving a large series of patients with PN and RLS are needed for a better understanding of the association between these two entities.

Which Factors in Spinocerebellar Ataxia Type 3 Patients Are Associated with Restless Legs Syndrome/Willis-Ekbom Disease?

There is evidence of a higher prevalence of restless legs syndrome/Willis-Ekbom disease (RLS/WED) in individuals with spinocerebellar ataxia type 3 (SCA3), although the factors underlying this association remain unknown. The present study aimed to determine the prevalence of RLS/WED in SCA3 patients and to investigate which factors of SCA3 patients are associated with presence of RLS/WED. From February to August of 2006, we carried out clinical interviews in 40 controls and 40 SCA3 patients, diagnosed and followed up at Faculty of Medicine of Ribeirão Preto, University of São Paulo. Twenty-seven SCA3 patients were submitted to a detailed clinical protocol, electroneuromyography, blood work up, polysomnography (PSG), suggested immobilization test (SIT), and magnetic resonance image (MRI). RLS/WED was found in 27.5% of SCA3 patients and 2.5% of normal controls (p = 0.003). The factors related to RLS/WED in SCA3 patients were female gender, age at start of the symptoms of ataxia after 30 years, presence of peripheral neuropathy, and documented iron deficiency. Among SCA3 patients, those with RLS showed higher values of maximal discomfort level and discomfort level sum compared to non-RLS individuals on SIT. There is a relation between RLS/WED and SCA3, which seems to be resultant of different factors whose identification could improve the quality of assistance to those patients as well as to promote a better comprehension of the pathophysiology of both RLS/WED and SCA3.

High-Resolution Nerve Ultrasound and Electrophysiological Findings in Restless Legs Syndrome

BACKGROUND AND PURPOSE

Restless legs syndrome (RLS) is a multifactorial network disorder of a sensorimotor system extending from dopaminergic and glutamatergic cerebral structures to the spinal neurons and peripheral nerves. The role of peripheral nerve damage in the causality and severity progression for RLS patients remains unclear.

METHODS

We performed a clinical and epidemiological study on a cohort of 34 RLS patients focusing on RLS risk factors and disease severity. We investigated the peripheral nerves with nerve conduction studies and with high-resolution nerve ultrasound (HRUS).

RESULTS

In 18 of the 34 patients (mean age 67.4 ± 15 years old), a sensorimotor axonal neuropathy was diagnosed. These patients presented with late-onset RLS were treated with membrane stabilizing agents, whereas no neuropathy predisposing comorbidity could be identified for the majority of them. We could show an inverse correlation between the amplitudes of the tibial nerve for the patients with polyneuropathy and the RLS severity index. Neuropathy patients were characterized by an increase of the cross-sectional area (CSA) of the tibial nerve in the popliteal fossa and by increased intranerve and internerve variability values showing an asymmetry of CSA distribution. This pattern resembles previous studies on diabetic neuropathy.

CONCLUSIONS

Early diagnosis, characterization, and treatment of neuropathy are increasingly relevant for RLS patients as it correlates with disease severity. HRUS revealed a pattern resembling diabetic neuropathy, which implies a similar pathophysiology with metabolic and ischemic origin of RLS-related axonal neuropathy.

New steps forward in the neuroactive steroid field

Evidence accumulated in recent years suggests that the systemic treatment with neuroactive steroids, or the pharmacological modulation of its production by brain cells, represent therapeutic options to promote neuroprotection. However, new findings, which are reviewed in this paper, suggest that the factors to be considered for the design of possible therapies based on neuroactive steroids are more complex than previously thought. Thus, although as recently reported, the nervous system regulates neuroactive steroid synthesis and metabolism in adaptation to modifications in peripheral steroidogenesis, the neuroactive steroid levels in the brain do not fully reflect its levels in plasma. Even, in some cases, neuroactive steroid level modifications occurring in the nervous tissues, under physiological and pathological conditions, are in the opposite direction than in the periphery. This suggests that the systemic treatment with these molecules may have unexpected outcomes on neural steroid levels. In addition, the multiple metabolic pathways and signaling mechanisms of neuroactive steroids, which may change from one brain region to another, together with the existence of regional and sex differences in its neural levels are additional sources of complexity that should be clarified. This complexity in the levels and actions of these molecules may explain why in some cases these molecules have detrimental rather than beneficial actions for the nervous system. This article is part of a Special Issue entitled 'Steroid Perspectives'.

Increased prevalence of restless legs syndrome in patients with Crohn's disease

OBJECTIVE

To determine (a) the incidence of restless legs syndrome (RLS) in patients with Crohn's disease (CD), (b) whether and how the occurrence and severity of RLS is related to severity of CD, and (c) how RLS influences the quality of life of CD patients.

BASIC METHODS

We carried out a cross-sectional questionnaire study in a random selection of 144 CD patients and 80 controls. Differences were calculated using a χ-test (categorical data), an independent T-test (continuous data, normal distribution), or a Mann-Whitney U-test (continuous data, non-normal distribution). Logistic regression analysis was carried out to establish the relation between CD and RLS after adjusting for risk factors.

MAIN RESULTS

The prevalence of RLS was 25.7% (37/144) in CD patients compared with 12.5% (10/80) in the control group (P=0.02). CD patients using caffeine and patients with arthralgias had a higher risk for RLS. A higher score on the modified Harvey Bradshaw Index and CD-related surgery were also associated with a higher risk for RLS. CD-related surgery was also associated with a more severe course of RLS. Patients and controls with RLS had a lower score on 'physical functioning', one of the subcategories of the RAND-36 quality-of-life questionnaire.

PRINCIPAL CONCLUSION

RLS occurs more frequently in patients with CD compared with healthy individuals. A more severe course of CD seems to be associated with a higher risk for RLS. The presence of RLS has a negative influence on quality of life, mainly interfering with physical activities of daily life.

Restless Legs Syndrome among Pakistani Population: A Cross-Sectional Study

Objective. Restless leg syndrome (RLS) is a chronic distressing disease characterized by an urge to move the legs with an unpleasantsensation during periods of rest. The global prevalence estimates of RLS range from 2.5% to 15%. Method. This cross-sectional study was conducted at various hospitals in Karachi during August 13 to March 14. The visitors who had accompanied patients to Outpatient Department or had come to visit admitted patients were approached conveniently. Subjects were interviewed regarding the essential criteria of RLS and its attributes. Results. The sample size was 390 with 56% being females. The point prevalence of RLS was estimated to be 23.6%. The prevalence in females was twice as high as compared to males. Smoking and low level of education were associated with RLS (P < 0.001). Among RLS positive individuals, 50.1% reported frequency of their symptoms to be greater than 16 days per month and 64.1% graded their symptom severity as mild to moderate. About 37% of RLS positive individuals consulted a general physician for their symptoms. Conclusion. RLS is highly prevalent and underdiagnosed condition among Pakistani population. Efforts must be directed to raise the awareness of this condition among physicians and general population.

Depolarized inactivation overcomes impaired activation to produce DRG neuron hyperexcitability in a Nav1.7 mutation in a patient with distal limb pain

Sodium channel Nav1.7, encoded by SCN9A, is expressed in DRG neurons and regulates their excitability. Genetic and functional studies have established a critical contribution of Nav1.7 to human pain disorders. We have now characterized a novel Nav1.7 mutation (R1279P) from a female human subject with distal limb pain, in which depolarized fast inactivation overrides impaired activation to produce hyperexcitability and spontaneous firing in DRG neurons. Whole-cell voltage-clamp recordings in human embryonic kidney (HEK) 293 cells demonstrated that R1279P significantly depolarizes steady-state fast-, slow-, and closed-state inactivation. It accelerates deactivation, decelerates inactivation, and facilitates repriming. The mutation increases ramp currents in response to slow depolarizations. Our voltage-clamp analysis showed that R1279P depolarizes channel activation, a change that was supported by our multistate structural modeling. Because this mutation confers both gain-of-function and loss-of-function attributes on the Nav1.7 channel, we tested the impact of R1279P expression on DRG neuron excitability. Current-clamp studies reveal that R1279P depolarizes resting membrane potential, decreases current threshold, and increases firing frequency of evoked action potentials within small DRG neurons. The populations of spontaneously firing and repetitively firing neurons were increased by expressing R1279P. These observations indicate that the dominant proexcitatory gating changes associated with this mutation, including depolarized steady-state fast-, slow-, and closed-state inactivation, faster repriming, and larger ramp currents, override the depolarizing shift of activation, to produce hyperexcitability and spontaneous firing of nociceptive neurons that underlie pain.

Diagnosis, comorbidities, and management of restless legs syndrome

OBJECTIVE

This narrative review describes the differential diagnosis of restless legs syndrome, and provides an overview of the evidence for the associations between RLS and potential comorbidities. Secondary causes of RLS and the characteristics of pediatric RLS are also discussed. Finally, management strategies for RLS are summarized.

METHODS

The review began with a comprehensive PubMed search for 'restless legs syndrome/Willis-Ekbom disease' in combination with the following: anxiety, arthritis, attention-deficit hyperactivity disorder, cardiac, cardiovascular disease, comorbidities, depression, end-stage renal disease, erectile dysfunction, fibromyalgia, insomnia, kidney disease, liver disease, migraine, mood disorder, multiple sclerosis, narcolepsy, neuropathy, obesity, pain, Parkinson's disease, polyneuropathy, pregnancy, psychiatric disorder, sleep disorder, somatoform pain disorder, and uremia. Additional papers were identified by reviewing the reference lists of retrieved publications.

RESULTS AND CONCLUSIONS

Although clinical diagnosis of RLS can be straightforward, diagnostic challenges may arise when patients present with comorbid conditions. Comorbidities of RLS include insomnia, depressive and anxiety disorders, and pain disorders. Differential diagnosis is particularly important, as some of the medications used to treat insomnia and depression may exacerbate RLS symptoms. Appropriate diagnosis and management of RLS symptoms may benefit patient well-being and, in some cases, may lessen comorbid disease burden. Therefore, it is important that physicians are aware of the presence of RLS when treating patients with conditions that commonly co-occur with the disorder.

Gabapentin enacarbil for the treatment of moderate to severe primary restless legs syndrome (Willis-Ekbom disease): 600 or 1,200 mg dose?

Gabapentin enacarbil is a prodrug of the anticonvulsant gabapentin. The efficacy and safety of gabapentin enacarbil for the treatment of moderate to severe primary restless legs syndrome (RLS) has been evaluated in several clinical trials in the United States and Japan. Although most clinical trials assessed gabapentin enacarbil at doses greater than 600 mg/day and demonstrated the overall safety and efficacy (defined as improvements in the coprimary endpoints of the international RLS rating scale [IRLS] total score and Clinical Global Impression-Improvement response), the US Food and Drug Administration approved the 600 mg once-daily dosage because doses higher than 600 mg/day were considered to provide no additional benefits and were associated with higher rates of adverse events, such as somnolence and dizziness. Nonetheless, the results of clinical trials and post hoc meta-analyses have indicated that the 1,200 mg once-daily dosage was the most validated gabapentin enacarbil treatment for not only subjective RLS symptoms but also severe sleep disturbance associated with RLS. A Japanese dose-finding study showed that 900 mg/day, the intermediate dose between 600 and 1,200 mg, failed to show a significant improvement in IRLS total score, probably because many of the patients who discontinued treatment did so early, suggesting that a half-landing dose may cause more adverse effects than favorable ones in some RLS patients early in the treatment. Gabapentin enacarbil may have two distinct therapeutic doses for the treatment of RLS: 600 mg/day or lower doses for the treatment of subjective RLS symptoms and 1,200 mg/day or higher doses for the treatment of both subjective RLS symptoms and associated problems such as severe sleep disturbances.

Sleep measured by polysomnography in patients receiving high-dose chemotherapy for multiple myeloma prior to stem cell transplantation

PURPOSE/OBJECTIVES

To describe the objective sleep of patients receiving chemotherapy for multiple myeloma (MM) prior to stem cell transplantation.

DESIGN

A descriptive study with repeated measures.

SETTING

An international referral center in an urban area of the southern United States.

SAMPLE

A convenience sample of a subset of 12 patients with MM, recruited from a randomized, controlled trial.

METHODS

Objective sleep was assessed using two nights of polysomnography, one obtained before and one after a second cycle of high-dose chemotherapy prior to stem cell transplantation. Demographic and clinical data were obtained through a retrospective chart review.

MAIN RESEARCH VARIABLES

Objective sleep including sleep characteristics, sleep-related respiratory events, and periodic limb movements (PLMs) of sleep.

FINDINGS

Sleep was characterized by a relatively short sleep time, excessive time spent awake after the onset of sleep, and poor sleep efficiency (objective sleep quality). Patients spent more than the expected percent of time in non-rapid eye movement sleep and less in rapid eye movement sleep. Arterial oxyhemoglobin saturation nadirs reflected episodes of low arterial oxygen saturation. PLMs during sleep were in the mildly elevated range.

CONCLUSIONS

Findings suggest that patients had poor sleep efficiency (objective sleep quality) and were slightly better sleepers after receiving a second cycle of high-dose chemotherapy. A number of patients also demonstrated obstructive sleep apnea and frequent PLMs.

IMPLICATIONS FOR NURSING

Findings support the need for additional investigation of sleep in patients with MM, particularly poor sleep efficiency and PLMs. Improving sleep may improve quality of life by decreasing associated symptoms such as pain, fatigue, and depression.

KNOWLEDGE TRANSLATION

Oncology nurses should consider assessing patients with MM for insomnia symptoms, excessive daytime sleepiness, obstructive sleep apnea, and a history of jerking or kicking their legs when asleep. Those symptoms may suggest the need for additional investigation of a possible sleep disorder, which may negatively influence mood and function.

No association between neuropathy and restless legs in Parkinson's disease

BACKGROUND

The prevalence of restless legs syndrome (RLS) has been studied extensively in Parkinson's disease (PD), with conflicting findings. More recently, both neuropathy and leg motor restlessness (LMR) have been found to be significantly more prevalent in PD patients than in controls.

AIMS

Our objective was to determine whether RLS or LMR may be secondary to neuropathy, or its currently postulated determinants, cumulative levodopa usage and vitamin B(12) metabolism, in patients with PD.

MATERIALS AND METHODS

We compared prevalence of RLS, LMR and neuropathy in 37 PD patients and 37 age- and gender-matched controls. Correlations between RLS/LMR and neuropathy and symptomatic neuropathy, cumulative levodopa usage and vitamin B(12) levels were ascertained.

RESULTS

RLS prevalence was comparable in PD patients and controls (16.2% vs 10.8%; P = 0.30). LMR was significantly more common in PD patients than in controls (40.5% vs 16.2%; P = 0.038), as was neuropathy (37.8% vs 8.1%; P = 0.005). Neither RLS, nor LMR correlated with neuropathy or symptomatic neuropathy, cumulative levodopa exposure or serum vitamin B(12) levels in patients with PD. There was a non-significant trend for a correlation between LMR and earlier age of onset of PD (P = 0.069).

CONCLUSIONS

RLS and LMR appear unrelated to neuropathy or symptomatic neuropathy, cumulative levodopa usage, or serum vitamin B(12) levels in patients with PD. The occurrence of LMR may relate to the earlier onset of PD, raising the possibility of common pathophysiological mechanisms for PD and RLS, of which LMR may be an early manifestation in some patients.

Strategies for the treatment of restless legs syndrome

Restless legs syndrome (RLS) is a common neurological disorder of unknown etiology that is managed by therapy directed at relieving its symptoms. Treatment of patients with milder symptoms that occur intermittently may be treated with nonpharmacological therapy but when not successful, drug therapy should be chosen based on the timing of the symptoms and the needs of the patient. Patients with moderate to severe RLS typically require daily medication to control their symptoms. Although the dopamine agonists, ropinirole and pramipexole have been the drugs of choice for patients with moderate to severe RLS, drug emergent problems like augmentation may limit their use for long term therapy. Keeping the dopamine agonist dose as low as possible, using longer acting dopamine agonists such as the rotigotine patch and maintaining a high serum ferritin level may help prevent the development of augmentation. The α2δ anticonvulsants may now also be considered as drugs of choice for moderate to severe RLS patients. Opioids should be considered for RLS patients, especially for those who have failed other therapies since they are very effective for severe cases. When monitored appropriately, they can be very safe and durable for long term therapy. They should also be strongly considered for treating patients with augmentation as they are very effective for relieving the worsening symptoms that occur when decreasing or eliminating dopamine agonists.

Family recurrence and oligo-anuria predict uremic restless legs syndrome

OBJECTIVES

To determine clinical and laboratory predictors of restless legs syndrome (RLS) in patients with end-stage kidney disease (ESKD) undergoing long-term hemodialysis (HD).

MATERIALS AND METHODS

One hundred and sixty-two consecutive patients were assessed. History of sleep disturbances, neurological examination, clinical, and laboratory data were collected. Patients with and without RLS were compared, and a logistic regression model described the relations between independent predictors and RLS.

RESULTS

Fifty-one patients (32%) currently had RLS (RLS+). RLS+ vs RLS- patients were more frequently women (49% vs 29%, P = 0.012), had first-degree relative with RLS (22% vs 6%, P = 0.004), insomnia (59% vs 36%, P = 0.007), peripheral neuropathy (41% vs 21%, P = 0.006), and low residual diuresis (92% vs 68% with below 500 ml/24 h, P = 0.001). Low (OR = 8.71, CI = 2.27-33.41; P = 0.002) and absent (OR = 4.96, CI = 1.52-16.20; P = 0.008) residual diuresis, peripheral neuropathy (OR = 4.00, CI = 1.44-11.14; P = 0.008), and first-degree relative with RLS (OR = 3.82, CI = 1.21-12.13; P = 0.023) significantly predicted RLS in ESKD patients undergoing HD.

CONCLUSION

Positive family history for RLS together with reduced/absent residual renal function and peripheral neuropathy predicts the risk for RLS in ESKD patients undergoing HD. Longitudinal studies are warranted to correlate RLS occurrence with genetic and environmental factors.

Restless legs syndrome--theoretical roles of inflammatory and immune mechanisms

Theories for restless legs syndrome (RLS) pathogenesis include iron deficiency, dopamine dysregulation and peripheral neuropathy. Increased prevalence of small intestinal bacterial overgrowth (SIBO) in controlled studies in RLS and case reports of post-infectious RLS suggest potential roles for inflammation and immunological alterations. A literature search for all conditions associated with RLS was performed. These included secondary RLS disorders and factors that may exacerbate RLS. All of these conditions were reviewed with respect to potential pathogenesis including reports of iron deficiency, neuropathy, SIBO, inflammation and immune changes. A condition was defined as highly-associated if there was a prevalence study that utilized an appropriate control group. Small case reports were recorded but not included as definite RLS-associated conditions. Fifty four diseases, syndromes and conditions have been reported to cause and/or exacerbate RLS. Of these, 38 have been reported to have a higher prevalence than age-matched controls, 9 have adequate sized reports and have general acceptance as RLS-associated conditions and 7 have been reported in case report form. Overall, 42 of the 47 RLS-associated conditions (89%) have also been associated with inflammatory and/or immune changes. In addition, 43% have been associated with peripheral iron deficiency, 40% with peripheral neuropathy and 32% with SIBO. Most of the remaining conditions have yet to be studied for these factors. The fact that 95% of the 38 highly-associated RLS conditions are also associated with inflammatory/immune changes suggests the possibility that RLS may be mediated or affected through these mechanisms. Inflammation can be responsible for iron deficiency and hypothetically could cause central nervous system iron deficiency-induced RLS. Alternatively, an immune reaction to gastrointestinal bacteria or other antigens may hypothetically cause RLS by a direct immunological attack on the central or peripheral nervous system.

Restless Legs Syndrome in Behçet's Disease

The prevalence of restless legs syndrome (RLS) and its association with the clinical features of Behçet's disease (BD) has not previously been elucidated. The inflammatory character, central nervous system involvement and neuropathies of BD led to this investigation of RLS risk in BD patients. A total of 116 BD patients and 104 healthy control subjects were included; seven BD patients were excluded because of concurrent diseases, pregnancy or alcohol misuse that might cause RLS symptoms, and the remaining 109 BD patients were included in the analysis. The prevalence of RLS was significantly higher in patients with BD (32/109; 29.4%) than in controls (5/104; 4.8%). No significant differences were found between BD patients with and without RLS with regard to the clinical features of BD. RLS severity positively correlated with age in BD patients. In conclusion, BD-related RLS should be considered in symptomatic RLS secondary to rheumatological disorders and BD patients should be examined for RLS. Further studies are needed to clarify the pathogenetic mechanisms underlying BD-related RLS.

Restless legs and substantia nigra hypoechogenicity are common features in Friedreich's ataxia

Friedreich's ataxia (FA) is a multisystemic degenerative disease, but the prevalence of restless legs syndrome (RLS) is unknown. FA patients might be particularly susceptible to develop RLS as FA presents with features commonly associated with RLS, e.g. multisystemic network dysfunction, peripheral neuropathy and disturbances in subcellular brain iron homeostasis. In this work, we assessed the following: (1) the prevalence of RLS; (2) the prevalence of sonographic hypoechogenicity of the substantia nigra (SN), which is known to be associated with idiopathic RLS; and (3) the relation between both in 28 FA patients. Thirty-two percent of the patients suffered from RLS, thus clearly exceeding the prevalence rate in the general population. SN hypoechogenicity was more frequent in FA patients (61%) compared to healthy controls (7%) and was significantly associated with RLS. However, as SN echogenicity also correlated inversely with disease severity, it seems to be related not only to RLS, but also to the neurodegenerative process in FA itself. The high prevalence of RLS in FA patients warrants specific assessment by neurologists involved in the care of FA patients as treatments are readily available. Similar to patients with idiopathic RLS, reduced SN echogenicity is a frequent finding in FA, possibly indicating regional changes in subcellular brain iron regulation in FA.

Restless legs syndrome is associated with irritable bowel syndrome and small intestinal bacterial overgrowth

BACKGROUND

Restless legs syndrome (RLS) is linked to gastrointestinal disorders. The prevalence of irritable bowel syndrome (IBS) and small intestinal bacterial overgrowth (SIBO) in RLS patients was determined.

METHODS

RLS subjects were recruited from unbiased ads that did not mention gastrointestinal symptoms. RLS diagnosis was confirmed by a neurologist and utilized the International RLS Study Group criteria. General population controls (GPC) were spouses of gastrointestinal clinic patients and were excluded for RLS. Completely healthy controls (CHC) were excluded for RLS and gastrointestinal symptoms. IBS was diagnosed by Rome II criteria. SIBO was diagnosed by the lactulose breath test (LBT).

RESULTS

There were 32 RLS subjects (23F/9M; 57 yo), 25 GPC (13F/12M; 58 yo) and 30 CHC (19F/11M; 44 yo). Twenty-nine had RLS unassociated with other GI diseases, one had celiac disease, and two had gastric resections. IBS was diagnosed in 28% of RLS subjects compared to 4% GPC (p=0.0317). SIBO was diagnosed in 69% of RLS subjects compared to 28% of GPC (p=0.0033) and 10% of CHC. Using a false positive rate of 10%, 59% of positive LBT results are associated with RLS.

CONCLUSIONS

IBS and SIBO are common in RLS. Three hypotheses developed are (a) RLS patients are selectively immunocompromised or genetically predisposed and thus more subject to SIBO; (b) SIBO leads to autoimmune changes, and subsequent auto-antibodies attack brain and/or peripheral nerves and (c) SIBO inflammation leads to increased hepcidin and CNS iron deficiency which, in turn, leads to RLS. These hypotheses bear further investigation.

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 in chronic inflammatory demyelinating polyneuropathy

The prevalence of restless legs syndrome (RLS) is unknown in chronic inflammatory demyelinating polyneuropathy (CIDP). We prospectively studied 28 patients with CIDP. Prevalence of RLS in CIDP was ascertained by face-to-face interview using validated criteria and compared with that in 28 age- and gender-matched controls. Eleven (39.3%) CIDP patients were diagnosed with RLS, compared with 2 (7.1%) controls (P < 0.01). A significant correlation was ascertained between presence of RLS and lower limb weakness, functional disability, and summated compound muscle action potential (CMAP). The prevalence of RLS in CIDP was significantly higher than in controls in our study population, approaching 40%. Screening for RLS in CIDP patients may be appropriate, particularly in those with weakness, disability, and motor axonal loss in the lower limbs. Our findings may otherwise suggest the existence of peripheral components to the pathophysiology of RLS in patients with CIDP.

Restless legs syndrome and painful neuropathy-retrospective study. A role for nociceptive deafferentation?

OBJECTIVES

Restless legs syndrome (RLS) occurs in polyneuropathy with small fiber involvement, possibly as a peculiar form of neuropathic pain; however, the relationship between pain and RLS has been poorly investigated in polyneuropathy.

DESIGN, SETTING, AND PATIENTS

We evaluated retrospectively the occurrence of RLS in 102 consecutive patients with polyneuropathy manifesting with neuropathic pain or dysesthesia, referred to the Neuromuscular Center, using the National Institutes of Health criteria for RLS. The patients were classified in subgroups characterized respectively by allodynia (hyperphenomena), with reported unpleasant sensations evoked by tactile stimuli, and hypoalgesia (hypophenomena), with absent pain sensation to pinprick, according to putative mechanisms of pain.

RESULTS

RLS was present in 41/102 patients (40.2%). It was significantly more frequent in the "hypoalgesia" (23/37) than in the "allodynia" subgroup (9/31; P = 0.008) and in the not classifiable cases (9/34; P = 0.004).

CONCLUSIONS

RLS is frequent in painful polyneuropathy and is significantly associated with decreased small fiber input, thus nociceptive deafferentation may represent a factor interacting with RLS "generators," possibly at spinal level. We suggest that overactivity of the spinal structures implicated in RLS may be triggered by nociceptive deafferentation in a subgroup of patients with painful polyneuropathy. Our findings, prompting a mechanistic characterization of RLS associated with painful polyneuropathy, have to be confirmed in a prospective study.

Sex-specific therapeutic strategies based on neuroactive steroids: In search for innovative tools for neuroprotection

Different pathologies of the central and peripheral nervous system show sex differences in their incidence, symptomatology and/or neurodegenerative outcome. These include Parkinson's disease, Alzheimer's disease, Huntington's disease, multiple sclerosis, traumatic brain injury, stroke, autism, schizophrenia, depression, anxiety disorders, eating disorders and peripheral neuropathy. These sex differences reveal the need for sex-specific neuroprotective strategies. This review article and other manuscripts published in this issue of Hormones and Behavior analyze possible sex-specific therapeutic strategies based on neuroactive steroids. In particular in our introductory article, the possibility that sex differences in the levels or in the action of neuroactive steroids may represent causative factors for sex differences in the incidence or manifestation of pathologies of the nervous system is considered.

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.

Sonographic substantia nigra hypoechogenicity in polyneuropathy and restless legs syndrome

Substantia nigra (SN) hypoechogenicity assessed by transcranial B-mode sonography (TCS) is typical for idiopathic restless legs syndrome (RLS). Here, we investigated whether SN hypoechogenicity may differentiate between polyneuropathy (PNP) patients with and without RLS. Seventy-five patients with PNP, 65 healthy controls, and 75 patients with idiopathic RLS were investigated. A total of 41.2% patients with PNP additionally suffered from RLS. A total of 44.1% patients with PNP, 10.2% of healthy controls, and 91.2% of patients with idiopathic RLS exhibited SN hypoechogenicity. SN echogenicity did not differ significantly between PNP patients with and without RLS. Thus, TCS seems not suitable for the diagnosis of RLS in patients with PNP.