Single photon emission tomography (SPET) imaging of dopamine D2 receptors in the course of dopamine replacement therapy in patients with nocturnal myoclonus syndrome (NMS)

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.

Short-interval intracortical inhibition is decreased in restless legs syndrome across a range of severity

BACKGROUND

Decreased short-interval intracortical inhibition (SICI) to transcranial magnetic stimulation (TMS) of the primary motor cortex was described in subjects with restless legs syndrome/Willis-Ekbom disease (RLS/WED). It remained to be determined whether the magnitude of SICI decrease would be similar across levels of RLS/WED severity. Moreover, it was unknown whether, in addition to decreases in SICI, changes in cortical thickness or area could be detected in subjects with RLS/WED compared to controls. The objective of this study was to compare SICI, cortical thickness, and cortical area in subjects with idiopathic mild to moderate RLS/WED, severe to very severe RLS/WED, and controls.

METHODS

The severity of RLS/WED was assessed by the International Restless Legs Syndrome Severity Scale (IRLSS). SICI and 3T magnetic resonance imaging (MRI) data of subjects with RLS/WED and controls were compared. A receiver operating characteristic curve for SICI was designed for discrimination of participants with RLS/WED from controls. Cortical thickness and area were assessed by automated surface-based analysis.

RESULTS

SICI was significantly reduced in patients with mild to moderate and severe to very severe RLS/WED, compared to controls (one-way analysis of variance: F = 9.62, p < 0.001). Receiver operating characteristic curve analysis predicted RLS/WED when SICI was above 35% (area under the curve = 0.79, 95% CI 0.67-0.91, p < 0.001). Analyses of the whole brain and of regions of interest did not reveal differences in gray matter thickness or area between controls and subjects with RLS/WED.

CONCLUSION

SICI is an accurate cortical biomarker that can support the diagnosis of RLS/WED even in subjects with mild symptoms, but cortical thickness and area were not useful for discriminating subjects with this condition from controls.

Restless Legs Syndrome and Parkinson Disease: A Causal Relationship Between the Two Disorders?

Restless Legs Syndrome/Willis-Ekbom Disease (RLS/WED) is a common sleep related movement disorder that can be idiopathic or occurs in comorbidity with other medical conditions such as polyneuropathy, iron deficiency anemia, multiple sclerosis, hypertension and cardiovascular diseases. In recent years, a growing body of literature investigated the association between RLS/WED and Parkinson's Disease (PD). Several questions regarding the comorbidity between these two disorders are still unanswered. If the insurgence of RLS/WED may precede the onset of PD, or if RLS/WED could represent a secondary condition of PD and if impaired dopaminergic pathway may represent a bridge between these two conditions are still debatable issues. In this review, we critically discuss the relationship between RLS/WED and PD by reviewing cross sectional and longitudinal studies, as well as the role of dopamine in these disorders. A twofold interpretation have to be taken into account: dopaminergic therapy may have a crucial role in the development of RLS/WED in PD patients or RLS/WED can be conceived as an early manifestation of PD rather than a risk factor. Several studies showed a high prevalence of RLS/WED in PD patients and several findings related to dopaminergic and iron alterations in both disorders, however up to now it is difficult to find a point of agreement between studies. A greater number of systematic and strongly controlled longitudinal studies as well as basic pathophysiological investigations particularly in RLS/WED are needed to clarify this complex relationship.

Neurophysiological mechanisms of circadian cognitive control in RLS patients - an EEG source localization study

The circadian variation of sensory and motor symptoms with increasing severity in the evening and at night is a key diagnostic feature/symptom of the restless legs syndrome (RLS). Even though many neurological diseases have shown a strong nexus between motor and cognitive symptoms, it has remained unclear whether cognitive performance of RLS patients declines in the evening and which neurophysiological mechanisms are affected by the circadian variation. In the current study, we examined daytime effects (morning vs. evening) on cognitive performance in RLS patients (n = 33) compared to healthy controls (n = 29) by analyzing flanker interference effects in combination with EEG and source localization techniques. RLS patients showed larger flanker interference effects in the evening than in the morning (p = .023), while healthy controls did not display a comparable circadian variation. In line with this, the neurophysiological data showed smaller N1 amplitudes in RLS patients compared to controls in the interfering task condition in the evening (p = .042), but not in the morning. The results demonstrate diurnal cognitive changes in RLS patients with intensified impairments in the evening. It seems that not all dopamine-regulated cognitive processes are altered in RLS and thus show daytime-dependent impairments. Instead, the daytime-related cognitive impairment emerges from attentional selection processes within the extra-striate visual cortex, but not from later cognitive processes such as conflict monitoring and response selection.

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RLS patients have larger flanker interference effect in the evening.

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RLS patients have enhanced impairment of attentional selection in the evening.

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Nocturnal attentional impairment relies on the extra-striate visual cortex.

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Conflict monitoring and response selection are not affected by RLS.

Brain imaging and networks in restless legs syndrome

Several studies provide information useful to our understanding of restless legs syndrome (RLS), using various imaging techniques to investigate different aspects putatively involved in the pathophysiology of RLS, although there are discrepancies between these findings. The majority of magnetic resonance imaging (MRI) studies using iron-sensitive sequences supports the presence of a diffuse, but regionally variable low brain-iron content, mainly at the level of the substantia nigra, but there is increasing evidence of reduced iron levels in the thalamus. Positron emission tomography (PET) and single positron emission computed tomography (SPECT) findings mainly support dysfunction of dopaminergic pathways involving not only the nigrostriatal but also mesolimbic pathways. None or variable brain structural or microstructural abnormalities have been reported in RLS patients; reports are slightly more consistent concerning levels of white matter. Most of the reported changes were in regions belonging to sensorimotor and limbic/nociceptive networks. Functional MRI studies have demonstrated activation or connectivity changes in the same networks. The thalamus, which includes different sensorimotor and limbic/nociceptive networks, appears to have lower iron content, metabolic abnormalities, dopaminergic dysfunction, and changes in activation and functional connectivity. Summarizing these findings, the primary change could be the reduction of brain iron content, which leads to dysfunction of mesolimbic and nigrostriatal dopaminergic pathways, and in turn to a dysregulation of limbic and sensorimotor networks. Future studies in RLS should evaluate the actual causal relationship among these findings, better investigate the role of neurotransmitters other than dopamine, focus on brain networks by connectivity analysis, and test the reversibility of the different imaging findings following therapy.

The effect of memantine on sleep architecture and psychiatric symptoms in patients with Alzheimer's disease

OBJECTIVE

Behavioural and psychological symptoms of dementia (BPSD) are commonly present in patients with Alzheimer's disease (AD). Disturbed sleep quality is also observed in AD patients. However, the effects of memantine on sleep architecture have not been investigated. The purpose of this study was to investigate the effects of memantine on polysomnography (PSG) variables and BPSD.

METHODS

In total, 12 patients with AD (mean age: 79.0±4.1 years old) were enrolled in this study. The following tests were performed: the Neuropsychiatric Inventory for the assessment of BPSD, the Mini-Mental State Examination (MMSE) for cognitive function, and PSG for evaluation of sleep architecture. After baseline examinations, patients were treated with memantine according to a standard prescription protocol. After being treated with 20 mg/day of memantine for 4 weeks, examinations were carried out again.

RESULTS

All subjects completed the trial. The mean MMSE and NPI scores were 22.6±3.4 and 13.8±12.9, respectively. Treatment with memantine significantly decreased the NPI score (5.8±4.3, p<0.01). There were significant decreases in the scores of subscales for anxiety (p=0.04) and irritability/lability (p=0.04). PSG demonstrated a longer total sleep time (TST) (p<0.01), increases in sleep efficiency (p<0.01) and time spent in stage II (% TST, p=0.02), and decreases in nocturnal awakening (p<0.01), the periodic limb movement index (p<0.01), and time spent in stage I (% TST, p=0.02).

CONCLUSION

Memantine was effective for reducing fragmented sleep and improving BPSD, and was well tolerated.

DTI and VBM reveal white matter changes without associated gray matter changes in patients with idiopathic restless legs syndrome

BACKGROUND AND PURPOSE

We evaluated cerebral white and gray matter changes in patients with iRLS in order to shed light on the pathophysiology of this disease.

METHODS

Twelve patients with iRLS were compared to 12 age- and sex-matched controls using whole-head diffusion tensor imaging (DTI) and voxel-based morphometry (VBM) techniques. Evaluation of the DTI scans included the voxelwise analysis of the fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD).

RESULTS

Diffusion tensor imaging revealed areas of altered FA in subcortical white matter bilaterally, mainly in temporal regions as well as in the right internal capsule, the pons, and the right cerebellum. These changes overlapped with changes in RD. Voxel-based morphometry did not reveal any gray matter alterations.

CONCLUSIONS

We showed altered diffusion properties in several white matter regions in patients with iRLS. White matter changes could mainly be attributed to changes in RD, a parameter thought to reflect altered myelination. Areas with altered white matter microstructure included areas in the internal capsule which include the corticospinal tract to the lower limbs, thereby supporting studies that suggest changes in sensorimotor pathways associated with RLS.

The sleep-immunity relationship

Research models show a strong interrelationship between sleep quality and immune function. The proinflammatory cytokines, interleukin-1, interleukin-6, and tumor necrosis factor α are classified as official sleep-regulatory substances. However, sleep-promoting properties are also possessed by several other immune and proinflammatory cellular classes. This article reviews the current physiologic evidence for the prominent somnogenic and sleep-regulatory properties inherent to these immune substances. Clinical examples of this relationship are discussed from the perspective of infectious and primarily immune-related conditions associated with significant sleep disruption and from the perspective of immune dysregulation associated with several primary sleep disorders.

Increased synaptic dopamine in the putamen in restless legs syndrome

STUDY OBJECTIVES

Prior studies using positron emission tomography (PET) or single-photon emission computed tomography techniques have reported inconsistent findings regarding differences between patients with restless legs syndrome (RLS) and control patients in the striatal dopamine-2 receptor (D2R) binding potentials (BP). D2R-BP does reflect receptor-ligand interactions such as receptor affinity (K(d)) and density (β(max)) or neurotransmitter synaptic concentrations. Thus, differences in D2R-BP reflect changes in these primary factors. PET techniques are currently available to estimate D2R β(max) and K(d).

DESIGN

Separate morning and evening PET scans were performed. The D2R-BP were measured in basal ganglia using [(11)C]raclopride.

SETTING

Academic medical center.

PATIENTS OR PARTICIPANTS

Thirty-one patients with primary RLS and 36 age- and sex-matched control patients completed the study.

MEASURES AND RESULTS

Patients with RLS had lower D2R-BP in putamen and caudate but not the ventral striatum. A subgroups analysis of those RLS patients who had not previously taken dopaminergic medications continued to show a significantly lower D2R-BP in the posterior putamen. D2R-BP did not differ between night and day for either group. D2R β(max) and K(d) did not differ significantly between patients with RLS and control patients but did show a strong and significant increase at night in the ventral striatum. Primary and secondary clinical measures of disease status failed to show any relation to D2R in any brain region.

CONCLUSIONS

Given the lack of any difference in either β(max) or K(d) and the prior studies supporting an increase in presynaptic dopaminergic activity, the current changes found in D2R-BP likely reflect an increase in synaptic dopamine.

Neuroimaging insights into the pathophysiology of sleep disorders

Neuroimaging methods can be used to investigate whether sleep disorders are associated with specific changes in brain structure or regional activity. However, it is still unclear how these new data might improve our understanding of the pathophysiology underlying adult sleep disorders. Here we review functional brain imaging findings in major intrinsic sleep disorders (i.e., idiopathic insomnia, narcolepsy, and obstructive sleep apnea) and in abnormal motor behavior during sleep (i.e., periodic limb movement disorder and REM sleep behavior disorder). The studies reviewed include neuroanatomical assessments (voxel-based morphometry, magnetic resonance spectroscopy), metabolic/functional investigations (positron emission tomography, single photon emission computed tomography, functional magnetic resonance imaging), and ligand marker measurements. Based on the current state of the research, we suggest that brain imaging is a useful approach to assess the structural and functional correlates of sleep impairments as well as better understand the cerebral consequences of various therapeutic approaches. Modem neuroimaging techniques therefore provide a valuable tool to gain insight into possible pathophysiological mechanisms of sleep disorders in adult humans.

Restless Legs Syndrome

Restless legs syndrome (RLS) is a common and often disabling sensorimotor disorder. Epidemiologic studies suggest that RLS is an underrecognized and undertreated disorder affecting both children and adults. The diagnosis is based primarily on the following four essential criteria: (1) an urge to move, usually associated with paresthesias, (2) onset or exacerbation of symptoms at rest, (3) relief of symptoms with movement, and (4) symptoms manifesting in a circadian pattern. Supplemental workup including polysomnography, iron profile, and/or neuropathy screen can provide support for the diagnosis and aid in the treatment strategy. Behavioral techniques, dopaminergic agents, opiates, benzodiazepines, and antiepileptics all have potential value in treating this disorder. Dopaminergic agents continue to be the most effective RLS treatment. However, due to their potential long-term side effects, these agents should not be considered the sole treatment of choice. In the end, the therapeutic plan should be individualized to suit each patient's presentation and needs.

Circadian changes in CSF dopaminergic measures in restless legs syndrome

BACKGROUND AND PURPOSE

Restless legs syndrome (RLS) has a circadian component with symptoms being prominent at night. The dopaminergic (DAergic) system, which plays a role in RLS, entails circadian changes that parallel RLS symptom changes. The aim of this study was to look for relative and diurnal differences in DAergic activity.

PATIENTS AND METHODS

All RLS subjects were treated prior to their enrollment in the study but were all drug-free for at least 2 weeks prior to evaluation. Cerebrospinal fluid (CSF) collected at 10 p.m. was used to determine DA-related co-factors and metabolites. These were compared to CSF values collected in a previous study at 10 a.m.

RESULTS

The only significant finding from the 10 p.m. samples (30 RLS; 22 control) was increased 3-ortho-methyldopa (3OMD) for RLS compared to controls. A comparison of the 10 p.m. to 10 a.m. values (16 RLS; 9 controls) showed small, non-significant diurnal changes for controls but large diurnal changes in tetrahydrobiopterin (BH4), HVA:5HIAA ratio and 3OMD for RLS, with the 10 a.m. sample showing increases in all three CSF factors compared to the 10 p.m. sample.

CONCLUSIONS

The greater diurnal changes in RLS suggest greater fluctuations than normal in DAergic circadian dynamics. The increased 3OMD concentration in the absence of concurrent exogenous levodopa (l-dopa) suggests changes in synthesis or metabolism of l-dopa in RLS.

The restless legs syndrome

The restless legs syndrome (RLS) is one of the commonest neurological sensorimotor disorders at least in the Western countries and is often associated with periodic limb movements (PLM) during sleep leading to severe insomnia. However, it remains largely underdiagnosed and its underlying pathogenesis is presently unknown. Women are more affected than men and early-onset disease is associated with familial cases. A genetic origin has been suggested but the mode of inheritance is unknown. Secondary causes of RLS may share a common underlying pathophysiology implicating iron deficiency or misuse. The excellent response to dopaminegic drugs points to a central role of dopamine in the pathophysiology of RLS. Iron may also represent a primary factor in the development of RLS, as suggested by recent pathological and brain imaging studies. However, the way dopamine and iron, and probably other compounds, interact to generate the circadian pattern in the occurrence of RLS and PLM symptoms remains unknown. The same is also the case for the level of interaction of the two compounds within the central nervous system (CNS). Recent electrophysiological and animals studies suggest that complex spinal mechanisms are involved in the generation of RLS and PLM symptomatology. Dopamine modulation of spinal reflexes through dopamine D3 receptors was recently highlighted in animal models. The present review suggests that RLS is a complex disorder that may result from a complex dysfunction of interacting neuronal networks at one or several levels of the CNS and involving numerous neurotransmitter systems.

Functional neuroimaging studies in restless legs syndrome

Functional neuroimaging studies may contribute to elucidate pathophysiological mechanisms of the restless legs syndrome (RLS) which still remain unclear. Studies in patients with RLS have been performed using functional magnetic resonance imaging (fMRI), single photon emission computed tomography (SPECT) and, more recently, positron emission tomography (PET). SPECT and PET studies revealed some controversial results of the pre- and postsynaptic dopaminergic neurotransmission system and cerebral metabolism in RLS probably reflecting a dysfunction of the central dopaminergic system. However, it still has to be determined whether these alterations affect the nigrostriatal and/or other central dopaminergic systems like the diencephalospinal or mesolimbic pathway and whether they are the primary mechanisms or only secondary phenomena within the manifestation of RLS symptoms. A subtle receptor dysfunction or a synaptic dopaminergic deficit may play a major role. fMRI investigations of RLS patients revealed an activation in the red nuclei and brainstem close to the reticular formation during the symptomatic period, suggesting that subcortical cerebral generators are involved in the pathogenesis of RLS. However, both techniques are not yet clinically relevant methods to differentiate RLS from other movement disorders during sleep. Further investigations, especially at night when RLS symptoms are most pronounced, will lead to a better understanding of the mechanisms underlying RLS.

Neuroimaging and sleep medicine

In sleep medicine, patients with sleep disorders are evaluated and treated. The primary assessment tool of the field has traditionally been polysomnography. While polysomnography has been helpful in the evaluation of some sleep disorders, such as sleep apnea syndrome and periodic limb movement disorder, it has been less helpful in others, such as the insomnias, or sleep disorders secondary to mental disorders. These disorders are presumed to stem from some alteration in brain function that disrupts sleep. The development of functional neuroimaging methods provides a means to understand brain function in patients with sleep disorders in a manner not accessible to polysomnography. This paper summarizes functional neuroimaging findings during healthy sleep, then, reviews available studies in sleep disorders patients, and studies addressing the pharmacology of sleep and sleep disorders. Areas in which functional neuroimaging methods may be helpful in sleep medicine, and in which future development is advised, include: (1) clarification of pathophysiology; (2) aid in differential diagnosis; (3) assessment of treatment response; (4) guiding new drug development; and (5) monitoring treatment response.

Normal striatal D2 receptor binding in idiopathic restless legs syndrome with periodic leg movements in sleep

Dopaminergic treatment is very effective in restless legs syndrome (RLS) and periodic leg movements in sleep (PLMS). However, neuroreceptor imaging studies that addressed altered striatal dopaminergic function have given controversial results. In this present study, 14 patients with idiopathic RLS (iRLS) and PLMS with a good response to dopaminergic and non-dopaminergic treatment and ten healthy sex- and age-matched controls were investigated off-medication by using 123I-IBZM and SPECT. RLS symptoms and sleep disturbances were evaluated using three nights of polysomnography, the Pittsburgh Sleep Quality Index, and the International RLS Study Group (IRLSSG) rating scale. The patients presented with sleep disturbances, a high PLMS index (56.2 +/- 33.1 per h), and severe RLS symptoms during SPECT (IRLSSG rating scale 23.1 +/- 8.0), and showed no significant differences in striatal to frontal IBZM binding to D2 receptors compared to controls (ratio striatum/frontal cortex, right side 1.60 +/- 0.10 vs 1.63 +/- 0.08, P = 0.35, NS; left side 1.61 +/- 0.11 vs 1.63 +/- 0.08, P = 0.51, NS). These findings show normal function of striatal D2 receptors in successfully treated patients with iRLS and PLMS. Dopaminergic and non-dopaminergic pretreatment does not appear to change striatal D2 receptor binding as compared to healthy controls. Structures other than striatal D2 receptors are discussed as possible causes of the treatment effects in RLS.

Mutational analysis of neurotensin in familial restless legs syndrome

A susceptibility locus for restless legs syndrome (RLS) has been identified recently on chromosome 12q. This region contains several transcribed genes including neurotensin (NTS), which, as an important modulator of the dopaminergic transmission, represents a strong functional and positional candidate in the context of RLS. In this study, NTS was evaluated for mutational analysis. A panel of 19 individuals from 4 families supporting linkage to 12q was investigated using a combined denaturing high-performance liquid chromatography (dHPLC) and direct sequencing method. Analysis of the NTS genomic sequence revealed 2 intronic polymorphisms and 1 variant located in the 5' untranslated region (UTR). None of the observed variants co-segregated with RLS and no disease-associated polymorphisms were detected in any of the analyzed families. Based on these results, it is unlikely that NTS is the gene responsible for RLS in chromosome 12-linked families.

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

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

Restless legs syndrome: clinical features and treatment

Restless legs syndrome (RLS), widely recognized as a definite clinical entity, has an estimated prevalence of 1 to 15% in different ethnic populations. However, it remains an underdiagnosed condition and its symptoms are frequently ascribed to stress and anxiety. Advancement in modern imaging techniques and clinical drug trials provide evidence of an impaired dopaminergic system in RLS. Management involves investigating and correcting treatable secondary causes, avoidance of aggravating factors, and pharmacologic therapy. Recent controlled trials have demonstrated the effectiveness of dopamine agonists such as pramipexole and pergolide. Additional research is needed to further elucidate the pathophysiology of RLS, through obtaining post-mortem specimens and refinement of neuroimaging and neurophysiologic techniques. Isolation of specific genetic loci in familial cases would enable better characterization of distinct clinical and genetic subsets of RLS and result in better understanding of this disease at the molecular level.

Can chronic neuroleptic treatment promote sleep disturbances in elderly schizophrenic patients?

It has been proposed that sleep disturbances, especially reduced delta sleep, are related to a poor outcome in schizophrenia. To determine whether long-term treatment with neuroleptics can promote sleep disturbances by increasing the risk of a nocturnal myoclonus syndrome (NMS) (=periodic movements in sleep) related insomnia, we performed all-night polysomnography in 10 chronically ill schizophrenic patients who had been under neuroleptic therapy for a mean of 27 years. NMS-related insomnia was detected in all 10 patients. Potential pathophysiological relationships between long-term neuroleptic therapy and NMS occurrence are discussed. Our findings suggest that long-term administration of neuroleptics favours the appearance of insomnia.

Treatment of periodic leg movement disorder and restless leg syndrome with talipexole

In order to investigate the bedtime dose of talipexole, a D2 and alpha2 stimulant, on patients with periodic leg movement disorder (PLMD) and restless leg syndrome (RLS), we made a comparison of polysomnographic findings and subjective symptom ratings before and during 4 weeks of the treatment on five cases with RLS and PLMD. A significant decrease in both the frequencies of periodic leg movements and subjective symptom ratings and significant improvement of sleep composition were recognized during the treatment. We speculate that the combination of the agonistic action of D2 and alpha2 receptor with the drug might not only suppress PLMD and RLS but also improve sleep quality.

Pergolide: treatment of choice in restless legs syndrome (RLS) and nocturnal myoclonus syndrome (NMS). A double-blind randomized crossover trial of pergolide versus L-Dopa

A double-blind randomized crossover study of 0.125 mg Pergolide (Lilly) at bedtime versus 250mg L-Dopa + Carbidopa (Roche) was conducted in 16-day phases in 11 patients with idiopathic restless legs syndrome. Two patients reported a partial and 9 patients a complete relieve of motor restlessness while receiving Pergolide. Only 1 patient experienced an improvement of restlessness after L-Dopa. The patients showed polysomnographically a mean decrease in NMS cluster disturbed time by 45% from control on L-Dopa (p < 0.025) and by 79% from control on Pergolide (p < 0.001). In addition, Pergolide increased the total sleep time compared to L-Dopa (p < 0.05). In conclusion, the dopamine agonist Pergolide is superior to L-Dopa in the treatment of RLS and NMS.

Striatal D2 receptor binding in sleep bruxism: a controlled study with iodine-123-iodobenzamide and single-photon-emission computed tomography

The neurochemical mechanisms underlying sleep bruxism are little understood at present. However, recent pharmacologic evidence suggests that the central dopaminergic system may be involved in the pathophysiology of sleep bruxism. This possibility was further assessed by means of functional neuroimaging of dopamine D2 receptors with single-photon-emission computed tomography (SPECT). Ten controls and ten patients with polysomnographically confirmed sleep bruxism were injected intravenously with 185 MBq (5 mCi) iodine-123-iodobenzamide, a specific D2 receptor antagonist radioligand, and data acquisition was performed 90 min post-injection. Following image reconstruction, it was found that striatal D2 receptor binding potential (basal ganglia/background ratio) did not differ significantly between bruxism patients and controls. However, side-to-side differences between unilateral values of the striatal D2 binding potential ("highest side" values minus "lowest side" values) were significantly larger for the bruxism patients (p < 0.001, by two-independent-samples t test with pooled variances). It was concluded that an abnormal side imbalance in striatal D2 receptor expression can be associated with sleep bruxism. This reinforces the possibility that the central dopaminergic system plays a role in the pathophysiology of this disorder.

Lamotrigine in the treatment of nocturnal myoclonus syndrome (NMS): two case reports

In previous investigations we found an increase of D2 dopamine receptors in the striatum of patients with nocturnal myoclonus syndrome (NMS) after treatment with dopamimetics. Under the hypothesis, that, according to animal experiments, the glutamatergic system could be involved in this atypical dopaminergic up-regulation in NMS. The glutamate release inhibitor lamotrigine was tested in up to now two NMS patients. The results and the success of this approach and its implications are discussed.

[123I]IBZM SPET analysis of dopamine D2 receptor occupancy in narcoleptic patients in the course of treatment

Elevated levels of central D2 dopamine receptors were found on postmortem examination in cases of human narcolepsy. In vivo investigations using positron emission tomography (PET) and single photon emission tomography (SPET) found no changes of D2 binding in the striatal structures. To investigate whether the elevated D2 receptors in postmortem investigations are due to long-term treatment effects, we applied 123I-labeled (S)-2-hydroxy-3-iodo-6-methoxy-([1-ethyl-2-pyrrolidinyl]methyl) benzamide (IBZM) ([123I]IBZM, a highly selective CNS D2 dopamine receptor ligand) and SPET in narcoleptic patients in the course of treatment with stimulants and/or antidepressants. Before treatment we found no changes in D2 binding in 10 patients (in comparison to 10 normal controls). After treatment (performed in five patients for 3 months) we found changes in D2 binding in four of them, indicating that the results of the postmortem studies could have been influenced by long-term medications. Human narcolepsy seems not to be related to a striatal D2 dopaminergic disturbance.

Effects of chronic treatment with methadone and naltrexone on sleep in addicts

Previous studies have described sleep disturbance secondary to chronic opiate use and abuse. Drug-dependency insomnia is of interest because chronic sleep disturbances can promote depressive symptoms which could lead to a drug relapse. For the first time we compared the polysomnographic parameters of 10 methadone-substituted outpatients and 10 naltrexone-treated outpatients. Methadone (mu-opioid agonist) produced a marked fragmentation of the sleep architecture with frequent awakenings and a decrease in EEG arousals. In comparison with methadone and controls, the naltrexone (mu-opioid antagonist) group showed the shortest sleep latency and the longest total sleep time. These data indicate that mu-agonists and mu-antagonists have different effects on sleep. The implications, especially the involvement of opioid-dopamine interactions on sleep and movements during sleep, are discussed.