Effects of new PLM scoring rules on PLM rate in relation to sleep and resting wake for RLS and healthy controls.

PURPOSE: This study evaluates the differences in periodic leg movement (PLM) rates for Restless Legs Syndrome (RLS) and healthy controls when using the updated PLM scoring criteria developed by IRLSSG in 2016 versus the prior PLM scoring criteria developed by IRLSSG in 2006. Four major problems with the prior standards had been objectively identified, i.e. minimum inter-movement interval should be 10 not 5 s, non-PLM leg movements should end any preceding PLM sequence, a leg movement (LM) can be any length > 0.5 s, and a PLM should be a persisting movement not a couple or a series of closely spaced, very brief events. Each of these led to including, erroneously, various random leg movements as PLM. Correcting these problems was expected to increase specificity, reducing the number of PLM detected, particularly in situations producing relatively more random leg movements, e.g. wake vs. sleep and controls without PLMD vs. RLS patients. METHODS: This study evaluated the putative benefits of the updated, 2016-scoring criteria. The LMs from 42 RLS patients and 30 age- and gender-matched controls were scored for PLMS and PLMW from standard all-night PSG recordings using both 2006 and 2016 WASM criteria. RESULTS/CONCLUSION: The results confirmed that that the 2016 compared to the 2006 criteria generally decreased the PLM rates with particularly large decreases for the conditions with more random non-PLM events, e.g. wake times and normal healthy controls. This supported the view that the new criteria succeeded in increasing the specificity of PLM detection. Moreover, the changes in PLM rates were generally small for the conditions with relatively few random LM, e.g. RLS and sleep. Thus the bulk of existing PLMS research does not require reconsideration of results, with possible exception of special situations with relatively more random leg movements than periodic leg movements, e.g. wake, healthy normals and children.

Diurnal variations in brain iron concentrations in BXD RI mice.

Under normal and dietary iron deficiency conditions, the BXD recombinant inbred (RI) strains of mice show large variations in regional brain iron concentration, particularly in the ventral midbrain (VMB). In a study utilizing just one of the BXD strains, diurnal changes in subregional brain iron concentration were found, which were dependent on the brain region and sex of the mice. The focus of this study was to determine if diurnal changes in VMB can be found across other BXD RI strains and whether a diurnal effect would be common to all strains or variable across strains similar to the large strain variability in iron concentrations determined during the first part of the light phase. Eight RI (BXD type) strains of mice of both sexes were selected for this study. Mice were sacrificed at postnatal day 120: half in the light phase (LP) and half in the dark phase (DP) of the light-dark cycle. Iron concentrations were determined in VMB, which was the primary region of interest, and five other brain regions. Exploratory analysis was also done on liver and spleen iron concentrations to assess for diurnal changes. Three strains showed clear diurnal variation in iron in the VMB and the others strains showed diurnal variations in other regions. These changes were not equally apparent in both sexes. Exploratory analysis also found strain×sex-dependent diurnal differences in spleen and liver iron. In conclusion, significant brain-regional-specific diurnal changes in total iron concentrations were found in a selection of BXD RI mice. Sex and strain are functional determinates of which regions will be affected and in what direction the affect will be. The study provides an animal model for future work into determining the biological and genetic basis of circadian influences on VMB iron homeostasis.

Iron deficiency alters expression of dopamine-related genes in the ventral midbrain in mice.

A clear link exists between iron deficiency (ID) and nigrostriatal dopamine malfunction. This link appears to play an important role in at least restless legs syndrome (RLS) if not several other neurological diseases. Yet, the underlying mechanisms remain unclear. The effects of ID on gene expression in the brain have not been studied extensively. Here, to better understand how exactly ID alters dopamine functioning, we investigated the effects of ID on gene expression in the brain, seeking to identify any potential transcription-based mechanisms. We used six strains of recombinant inbred mice (BXD type) known to differ in susceptibility to ID in the brain. Upon weaning, we subjected mice from each strain to either an iron-deficient or iron-adequate diet. After 100 days of dietary treatment, we measured the effects of ID on gene expression in the ventral midbrain, a region containing the substantia nigra. The substantia nigra is the base of the nigrostriatal dopamine pathway and a region particularly affected by iron loss in RLS. We screened for ID-induced changes in expression, including changes in that of both iron-regulating and dopamine-related genes. Results revealed a number of expression changes occurring in ID, with large strain-dependent differences in the genes involved and number of expression changes occurring. In terms of dopamine-related genes, results revealed ID-induced expression changes in three genes with direct ties to nigrostriatal dopamine functioning, two of which have never before been implicated in an iron-dopamine pathway. These were stromal cell-derived factor 1 (Cxcl12, or SDF-1), a ferritin regulator and potent dopamine neuromodulator, and hemoglobin, beta adult chain 1 (Hbb-b1), a gene recently shown to play a functional role in dopaminergic neurons. The extent of up-regulation of these genes varied by strain. This work not only demonstrates a wide genetic variation in the transcriptional response to ID in the brain, but also reveals two novel biochemical pathways by which iron may potentially alter dopamine function.

Effects of IV iron isomaltoside-1000 treatment on regional brain iron status in an iron-deficient animal.

BACKGROUND: Iron deficiency has been documented to affect human cognitive function and conditions with brain iron compromise such as the restless legs syndrome (RLS). Intravenous (IV) iron treatment is used to reduce iron deficiency but its effects on brain iron are not known. It is not known if IV iron is effective in correcting regional brain iron deficiencies nor if it poses a risk of producing iron overload in some brain regions. Preclinical study of IV iron in the iron-deficient (ID) murine model is needed to evaluate and develop IV iron treatments for brain iron deficiency. METHODS: Response to tail vein injections of iron (iron isomaltoside-1000, dose equivalent to 1000 mg for 75 kg adult) or vehicle were evaluated for ID mice by microdialysis assessing non-transferrin bound (NTB) iron in the ventral midbrain (VMB) and autopsy at 3 and 10 days post-injection assessing iron content in critical brain regions. RESULTS: The ID mice showed marked circadian variation in NTB extracellular iron. After iron injection, NTB iron was rapidly increased in the VMB and then decreased over 12h to the levels observed for vehicle. Regional brain iron content at 3 and 10 days post-injection in the iron- compared to vehicle-treated group showed significantly more iron for the VMB and nucleus accumbens but not for the other regions (i.e. prefrontal cortex, caudate-putamen, cerebellum, and pons), which also did not show decreased iron content with the ID diet. CONCLUSION: Iron isomaltoside-1000 given IV corrects the regional brain iron deficiency in these ID mice without producing iron overload in any of the brain regions studied. This is the first demonstration of effects of IV iron in the brain and it provides a useful preclinical model for this assessment, particularly relevant for developing iron treatments for conditions with problematic iron deficiency, e.g. RLS.

Of mice and men, periodic limb movements and iron: how the human genome informs the mouse genome.

The gene, BTBD9, was recently linked to restless legs syndrome, periodic limb movements and iron status in humans. In a homologous region in mouse, an area containing btbd9 was also identified as being related to iron homeostasis. This finding is important as iron status in brain has been implicated in restless legs syndrome.

Medication use in patients with restless legs syndrome compared with a control population.

Primary restless legs syndrome (RLS) is a sensorimotor disorder causing chronic sleep deprivation in those with moderate to severe symptoms. It has been associated with other medical conditions, such as high blood pressure, depression and attention deficit hyperactive disorder (ADHD). If these conditions are more prevalent for RLS patients, then it would be expected RLS patients would use relatively more of the medications treating these conditions. Current medication use was obtained from 110 RLS patients and 54 age, race and gender-matched local-community controls. Each subject was diagnosed as primary RLS or having no indications for RLS by a clinician board-certified in sleep medicine. The RLS group used more medications than the control group even when medications used for treating RLS were excluded. Significantly more of the RLS patients than controls used anti-depressants, gastro-intestinal (GI) medications and asthma/allergy medications. RLS patients compared with those without RLS are more likely to use medications not related to treating RLS. Moreover they use medications for conditions that have not previously been considered related to RLS, i.e. GI and asthma/allergy conditions.

Decreased transferrin receptor expression by neuromelanin cells in restless legs syndrome.

BACKGROUND: Restless legs syndrome (RLS) is a sensory-movement disorder affecting 5 to 10% of the population. Its etiology is unknown, but MRI analyses and immunohistochemical studies on autopsy tissue suggest the substantia nigra (SN) of patients with RLS has subnormal amounts of iron. METHODS: Neuromelanin cells from the SN of four RLS and four control brains were isolated by laser capture microdissection, and a profile of iron-management protein expression was obtained by immunoblot analysis. Binding assays for iron regulatory protein activity were performed on cell homogenates. RESULTS: Ferritin, divalent metal transporter 1, ferroportin, and transferrin receptor (TfR) were decreased in RLS neuromelanin cells compared with control. Transferrin was increased in RLS neuromelanin cells. This protein profile in RLS neuromelanin cells is consistent with iron deficiency with the exception that TfR expression was decreased rather than increased. The concentration and activity of the iron regulatory proteins (IRP1 and IRP2) were analyzed to determine whether there was a functional deficit in the post-transcriptional regulatory mechanism for TfR expression. Total IRP activity, IRP1 activity, and IRP1 protein levels were decreased in RLS, but total IRP2 protein levels were not decreased in RLS. CONCLUSION: Restless legs syndrome may result from a defect in iron regulatory protein 1 in neuromelanin cells that promotes destabilization of the transferrin receptor mRNA, leading to cellular iron deficiency.

Neuropathological examination suggests impaired brain iron acquisition in restless legs syndrome.

OBJECTIVE: To assess neuropathology in individuals with restless legs syndrome (RLS). METHODS: A standard neuropathologic evaluation was performed on seven brains from individuals who had been diagnosed with RLS. The substantia nigra was examined in greater detail for iron staining and with immunohistochemistry for tyrosine hydroxylase and proteins involved in iron management. Five age-matched individuals with no neurologic history served as controls. RESULTS: There were no histopathologic abnormalities unique to the RLS brains. Tyrosine hydroxylase staining in the major dopaminergic regions appeared normal in the RLS brains. Iron staining and H-ferritin staining was markedly decreased in the RLS substantia nigra. Although H-ferritin was minimally detected in the RLS brain, L-ferritin staining was strong. However, the cells staining for L-ferritin in RLS brains were morphologically distinct from those in the control brains. Transferrin receptor staining on neuromelanin-containing cells was decreased in the RLS brains compared to normal, whereas transferrin staining in these cells was increased. CONCLUSIONS: RLS may not be rooted in pathologies associated with traditional neurodegenerative processes but may be a functional disorder resulting from impaired iron acquisition by the neuromelanin cells in RLS. The underlying mechanism may be a defect in regulation of the transferrin receptors.

Increased CSF hypocretin-1 (orexin-A) in restless legs syndrome.

Hypocretin-1 levels were increased in evening CSF samples from subjects with restless legs syndrome, indicating altered hypocretin transmission in this sleep disorder. Increases in CSF hypocretin-1 levels were most striking in patients with early-onset restless legs syndrome.

Family history study of the restless legs syndrome.

BACKGROUND: Although there is a relatively high rate of occurrence of sporadic cases of restless legs syndrome (RLS), the systematic study of family history of RLS in populations of RLS patients has been very limited. The objective of the present study was to determine the risk of RLS for first- and second-degree relatives of a population of primary RLS patients not selected for the number of affected relatives in their families and to obtain an estimate of the degree of genetic involvement in RLS. METHODS: Consecutively consenting patients from two different sites who met the criteria for RLS completed a worksheet that asked them to indicate their current age, the date of their earliest RLS symptoms, and the names and RLS status of all of their first- and second-degree relatives. Controls with no clinical history of RLS also completed the worksheet. RESULTS: First- and second-degree relatives of patients with RLS had a significantly greater risk of RLS than the first- (P<0.001) and second-degree relatives (P<0.003) of controls. The risk of RLS was found to be greater for first-degree relatives of early-onset, rather than late-onset, RLS probands (P<0.001). CONCLUSIONS: This study provides a complete systematic examination of the risk of RLS among relatives of RLS probands and controls using the same assessment methodology. Although the results are consistent with a genetic etiology for RLS, they do not support the presence of one simple, Mendelian-inherited major gene in most RLS families.

Associations of aortic Windkessel function with age, gender and cardiovascular risk factors.

Aortic Windkessel function is thought to represent a potential cardiovascular risk factor. As an indicator for the function, we have recently introduced the decay index (DI). DI is the coefficient of an exponential function applied to the postpeak portion of internal carotid artery Doppler waveform, and is inversely associated with the function. This study compares DI with age, gender and traditional cardiovascular risk factors in 220 apparently healthy volunteers (59 +/- 16 years). DI increased linearly with age (r = 0.51, p < 0.001), and was higher in women than in men at all ages (p < 0.001). Also, DI was positively associated with systolic blood pressure (beta = 0.17, p < 0.01) and diabetic medication (beta = 0.14, p < 0.05), independent of age (beta = 0.49, p < 0.0001), gender (beta = 0.27, p < 0.0001) and other traditional cardiovascular risk factors (model r(2) = 0.36). Based on the present results, the Windkessel function as assessed by DI declines with age and is lower in women. However, the associations with cardiovascular risk factors need to be established on a larger sample at higher cardiovascular risk.

Restless legs syndrome: a review of clinical and pathophysiologic features.

Restless legs syndrome (RLS), although long ignored and still much underdiagnosed, disrupts the life and sleep considerably of those who have it. Recent clinical and basic research provides for better definition and pathophysiologic understanding of the disorder. The body of knowledge about this disorder has been expanding rapidly during the past decade and it has altered our concepts of this disorder. This review of RLS covers history, diagnosis, morbidity of sleep disturbance, relation to periodic limb movements in both sleep and waking, secondary causes, severity assessment methods, phenotypes for possible genetic patterns, epidemiology, pathophysiology, and medical treatment considerations. The emphasis on pathophysiology includes consideration of central nervous system localization, neurotransmitter and other systems involved, and the role of iron metabolism. Studies to date support the authors' recently advanced iron-dopamine model of RLS.

Validation of the Johns Hopkins restless legs severity scale.

Determine reliability and validity of the Johns Hopkins restless legs severity scale (JHRLSS), an easily used clinical scale assessing severity of the restless legs syndrome (RLS). There is, prior to this study, no validated scale assessing the wide range of RLS severity. The JHRLSS has been used in prior studies to assess RLS severity, but has not previously been validated in relation to direct measures of the morbidity associated with RLS. A consecutive case series of 31 RLS patients was used in the study. The JHRLSS was validated by its correlation with objective measures by a polysomnogram of the sleep disturbances associated with RLS (periodic leg movements of sleep per hour (PLMS/h), and sleep efficiency). Reliability was determined from the independent ratings of two clinicians. Reliability measures for the JHRLSS based on inter-rater agreement were 0.91 (Spearman Rho) and 0.87 (Cramers V). The subjective JHRLSS correlated significantly with both objective measures of sleep: sleep efficiency (R=0.60, P<0.01) and PLMS/h (R=0.45, P=0.01). The JHRLSS provides a reliable, valid, easily used clinical assessment of RLS severity.

MRI measurement of brain iron in patients with restless legs syndrome.

Brain iron insufficiency in the restless legs syndrome (RLS) has been suggested by a prior CSF study. Using a special MRI measurement (R2'), the authors assessed regional brain iron concentrations in 10 subjects (five with RLS, five controls). R2' was significantly decreased in the substantia nigra, and somewhat less significantly in the putamen, both in proportion to RLS severity. The results show the potential utility of this MRI measurement, and also indicate that brain iron insufficiency may occur in patients with RLS in some brain regions.

CSF dopamine, serotonin, and biopterin metabolites in patients with restless legs syndrome.

PURPOSE: To evaluate the role of CNS dopaminergic systems in Restless Legs Syndrome (RLS), homovanillic acid (HVA), tetrahydrobiopterin (BH4), and neopterin (NEOP), were assayed in CSF from RLS patients. The serotonin metabolite, 5-hydroxyindoleacetic acid (5-HIAA), was also measured. METHODS: CSF was taken from 16 RLS patients after 2 weeks off medication and from 14 control subjects. The CSF metabolites were determined using HPLC techniques. RESULTS: There was no significant difference in HVA or 5-HIAA, but NEOP and BH4 were higher in RLS patients. The RLS group was significantly older than the control group (64.2 +/- 9.2 years vs. 51.4 +/- 6.3 years; P < 0.001). A multiple regression analysis showed a strong correlation between age and 5-HIAA (r = 0.46, P = 0.04) and between age and NEOP (r = 0.61, P < 0.01). To eliminate the potential error created by the age difference between groups, an age-adjusted subgroup of RLS and control subjects were compared. There was still no difference found for HVA; however, 5-HIAA was now significantly lower (P < 0.01) in the RLS subgroup. Age-adjustment eliminated the differences previously found for NEOP, (P = 0.12), but BH4 continued to remain higher in the RLS group (P < 0.01). CONCLUSION: Differences in CSF HVA concentrations were not found. The changes in 5-HIAA and BH4 are of unclear clinical significance and require further assessment with appropriate age-matched controls.

Alcohol intake, type of beverage, and the risk of cerebral infarction in young women.

BACKGROUND AND PURPOSE: The relationship between alcohol consumption and cerebral infarction remains uncertain, and few studies have investigated whether the relationship varies by alcohol type or is present in young adults. We examined the relationship between alcohol consumption, beverage type, and ischemic stroke in the Stroke Prevention in Young Women Study. METHODS: All 59 hospitals in the greater Baltimore-Washington area participated in a population-based case-control study of stroke in young women. Case patients (n=224) were aged 15 to 44 years with a first cerebral infarction, and control subjects (n=392), identified by random-digit dialing, were frequency matched by age and region of residence. The interview assessed lifetime alcohol consumption and consumption and beverage type in the previous year, week, and day. ORs were obtained from logistic regression models controlling for age, race, education, and smoking status, with never drinkers as the referent. RESULTS: Alcohol consumption, up to 24 g/d, in the past year was associated with fewer ischemic strokes (<12 g/d: OR 0.57, 95% CI 0. 38 to 0.86; 12 to 24 g/d: OR 0.38, 95% CI 0.17 to 0.86; >24 g/d: OR 0.95, 95% CI 0.43 to 2.10) in comparison to never drinking. Analyses of beverage type (beer, wine, liquor) indicated a protective effect for wine consumption in the previous year (<12 g/wk: OR 0.58, 95% CI 0.35 to 0.97; 12 g/wk to <12 g/d: OR 0.55, 95% CI 0.28 to 1.10; >/=12 g/d: OR 0.92, 95% CI 0.23 to 3.64). CONCLUSIONS: Light to moderate alcohol consumption appears to be associated with a reduced risk of ischemic stroke in young women.

Insight into the pathophysiology of restless legs syndrome.

Restless Legs Syndrome (RLS) is a disorder of sensation with a prevalence of around 2-5% of the population. Relevant to understanding the possible pathophysiological mechanism is the fact that RLS is extremely responsive to dopaminergic agents. A second issue is that iron deficiency states may precipitate RLS in as much as 25-30% of people with iron deficiency. Studies looking at basal ganglia dopaminergic function using PET and SPECT techniques have shown a decrease in binding potential for the dopamine receptor and transporter. Similar phenomena occurs in iron-deficient animals. Using MRI techniques and CSF analysis of iron-related protein, studies have suggested a reduction in brain iron concentration occurs in RLS patients. The relevance of CNS iron metabolism to the pathophysiology of RLS is discussed.

Subclinical sensory neuropathy in late-onset restless legs syndrome.

OBJECTIVE: To determine the prevalence of different forms of peripheral neuropathy in patients with restless legs syndrome (RLS) and correlate the findings with other clinical characteristics. BACKGROUND: RLS is characterized by a desire to move the extremities, often associated with paresthesias or dysesthesias, motor restlessness, worsening of symptoms with rest with relief by activity, and worsening of symptoms in the evening or night. The association between RLS and peripheral neuropathy remains controversial. The observation that many patients with small-fiber neuropathy also complain of RLS prompted this prospective case series. METHODS: Twenty-two consecutive patients with RLS were evaluated for evidence of large-fiber neuropathy (LFN) and small sensory fiber loss (SSFL). RESULTS: In eight of the 22 (36%) patients, neuropathy was identified. Three patients had pure LFN; two had mixed LFN and SSFL; and three had isolated SSFL. The SSFL group had a later onset of RLS (p < 0.009), reported pain in their feet with RLS more frequently (p < 0.001), and tended to have no family history of RLS (p < 0.078). Patients with LFN did not have similar associations with age at onset, family history status, or presence of pain. CONCLUSION: The results suggest that two forms of RLS exist: one is triggered by painful dysesthesias associated with SSFL, has later onset, and no family history; and one without involvement of SSF, with an earlier onset age, positive family history for RLS, and no pain. The authors hypothesize that patients with the SSFL subtype of RLS will preferentially respond to neuropathic pain medications.

Lipoprotein (a) and the risk of ischemic stroke in young women.

BACKGROUND AND PURPOSE: lipoprotein (a) (lp (a)) is a lipid-containing particle similar to LDL which has been found in atherosclerotic plaque. The role of lp (a) in ischemic stroke remains controversial, but some studies suggest lp (a) is particularly important as a risk factor for stroke in young adults. We investigated the role of lp (a) as a risk factor for stroke in young women enrolled in the Stroke Prevention in Young Women Study. METHODS: subjects were participants in a population-based, case-control study of risk factors for ischemic stroke in young women. Cases were derived from surveillance of 59 regional hospitals in the central Maryland, Washington DC, Pennsylvania and Delaware area. Lp (a) was measured in 110 cases and 216 age-matched controls. Demographics, risk factors, and stroke subtype were determined by interview and review of medical records. RESULTS: lp (a) values were higher in blacks than whites, but within racial groups, the distribution of lp (a) values was similar between cases and controls. After adjustment for age, race, hypertension, diabetes, cigarette smoking, coronary artery disease, total cholesterol and HDL cholesterol, the odds ratio for an association of lp (a) and stroke was 1.36 (95% CI 0.80-2.29). There was no dose-response relationship between lp (a) quintile and stroke risk. Among stroke subtypes, only lacunar stroke patients had significantly elevated lp (a) values compared to controls. CONCLUSIONS: we found no association of lp (a) with stroke in a population of young women with ischemic stroke. Small numbers of patients limit conclusions regarding risk in ischemic stroke subtypes, but we could not confirm previous suggestions of an association of lp (a) with atherosclerotic stroke in young adults.