• Sleep Medicine and Psychophysiology
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• v.30 no.1
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• pp.3-8
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• 2023

Periodic limb movement disorder (PLMD) is a sleep-related movement disorder characterized by involuntary, rhythmic limb movements during sleep. While PLMD itself is not considered life-threatening, its association with certain underlying health conditions raises concerns about mortality risks. PLMD has been found to be associated with cardiovascular diseases such as hypertension and cardiovascular disease. The fragmented sleep caused by the repetitive limb movements and associated arousals may contribute to sympathetic activation, chronic sleep disruption, sleep deprivation, and subsequent cardiovascular problems, which can increase mortality risks. The comorbidities and health factors commonly associated with PLMD, such as obesity, diabetes, and chronic kidney disease, may also contribute to increased mortality risks. PLMD is often observed alongside other neurological disorders, including restless legs syndrome (RLS) and Parkinson's disease. The presence of PLMD in these conditions may exacerbate the underlying health issues and potentially contribute to higher mortality rates. Further research is needed to elucidate the specific mechanisms linking PLMD to mortality risks and to develop targeted interventions that address these risks.

• Tuberculosis and Respiratory Diseases
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• v.45 no.5
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• pp.1039-1046
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• 1998

Background: Sleep-related breathing disorders(SRBD) and periodic leg movements disorder(PLMD) are both common, and are considered as separate sleep disorders. However, both disorders show high comorbidity. SRBD and PLMD can result in excessive daytime sleepiness and insomnia due to frequent sleep fragmentation. So, it is very important to consider the presence of PLMD, when we are dealing with the diagnosis and management of SRBD. The objectives of this study were to determine the incidence of PLMD in patients with SRBD, and to describe any differences between patients with and without PLMD. Method: The authors reviewed the sleep recordings of 106 patients with a final diagnosis of SRBD(obstructive sleep apnea or upper airway resistance syndrome), who underwent full nocturnal polysomnography, including the monitoring of the anterior tibialis electromyogram. All sleep records were recorded and scored using the standard criteria. The data was analyzed by the student t-test. Result: 106 patients(M=76, F=30) were included in the analysis. Data revealed a mean age of $49.5{\pm}13.6$ years, a respiratory disturbance index(RDI) of $22.3{\pm}25.4$/hour sleep, a lowest oxygen saturation of $84.9{\pm}11.3%$, a maximal esophageal pressure of $-41.0{\pm}19.1cmH_2O$, and PLM index(PLMI) of $13.1{\pm}22.4$movements/hour sleep. Forty four percent(47 of 106 patients) had a PLMI of greater than 5 on this study. The mean age of the patients with PLMD was significantly higher than that of the patients without PLMD(p<0.005). Female patients with SRBD accompanied more PLMD(p<0.05). The apnea index of the patients with PLMD was significantly lower than that of the patients without PLMD(p<0.01). The percentage of stage 1 sleep in the patients with PLMD was significantly lower than that of the patients without PLMD(p<0.05). Conclusion: The prevalence of PLMD in the patients with SRBD was high at 44.3%. The patients with PLMD were older and had more high RDI in comparison to the patients without PLMD, which was consistent with previous findings. The authors recommend that more careful consideration of PLMD is required when diagnosing and treating SRBD.

• Sleep Medicine and Psychophysiology
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• v.4 no.2
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• pp.164-171
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• 1997

Introduction : Periodic limb movement disorder (PLMD) is shown to common in patients with OSA and may become evident or worsened when treated with nasal continuous positive airway pressure (CPAP). Whether this is due to im proved sleep continuity. adverse nocturnal body positioning, uncovered by CPAP, or due to the CPAP stimulus is still debat-ed. We hypothesized that the increase in PLM activity following CPAP is associated with more supine-sleeping tendencies when being treated with CPAP. In the present work, we compared differences in the PLMD index (PLMI) and sleeping position of patients with sleep disordered breathing before and after CPAP treatment. Method : We studied 16 patients (mean age 46 yr, 9M, 7F) with OSA (11 patients) or UARS (5 patients) who either had PLMD on initial polysomnogram (baseline PSG) or on nasal CPAP trial (CPAP PSG). All periodic leg movements were scored on anterior tibialis EMG during sleep according to standard criteria (net duration; 0.5-5.0 seconds, intervals; 4-90 seconds. 4 consecutive movements). Paired t-tests compared PLMD index (PLMI), PLMD-related arousal index (PLMD-ArI), respiratory disturbance index (RDI), and supine sleeping position spent with baseline PSG and CPAP PSG. Results : Ten patients (63%) on baseline PSG and fifteen patients (94%) on CPAP PSG had documented PLMD ($PLMI{\ge}5$) respectively with significant increase on CPAP PSG(p<0.05). Ten patients showed the emergence (6/10 patients) or substantial worsening (4/10 patients) of PLMD during CPAP trial. Mean CPAP pressure was $7.6{\pm}1.8\;cmH_2O$. PLMI tended to increase from baseline PSG to CPAP PSG, and significantly increase when excluding 2 outlier (baseline PSG, $19.0{\pm}25.8/hr$ vs CPAP PSG, $29.9{\pm}12.5/hr$, p<0.1). PLMD-ArI showed no significant change, but a significant decrease was detected when excluding 2 outlier (p<0.1). There was no significant sleeping positional difference (supine vs non-supine) on baseline PSG, but significantly more supine position (supine vs non-supine, p<0.05) on CPAP PSG. There was no significant difference in PLMI during supine-sleeping and nonsupine-sleeping position on both of baseline PSG and CPAP PSG. There was also no significant difference in PLMI during supine-sleeping position between baseline PSG and CPAP PSG. With nasal CPAP, there was a highly significant reduction in the RDI (baseline PSG, $14.1{\pm}21.3/hr$ vs CPAP PSG, $2.7{\pm}3.9/hr$, p<0.05). Conclusion : This preliminary data confirms previous findings that CPAP is a very effective treatment for OSA, and that PLMD is developed or worsened with treatment by CPAP. This data also indicates that supine-sleeping position is more common when being treated with CPAP. However, there was no clear evidence that supine position is the causal factor of increased PLMD with CPAP. It is, however, suggested that the relative movement limitation induced by CPAP treatment could be a contributory factor of PLMD.

• Sleep Medicine and Psychophysiology
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• v.24 no.1
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• pp.24-31
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• 2017

Objectives: Periodic limb movement disorder (PLMD) has been debated with regard to its clinical significance and diagnostic criteria. The current diagnostic criterion for PLMD in adults has been changed from periodic limb movement index (PLMI) > 5/hour to PLMI > 15/hour by the International Classification of Sleep Disorders (ICSD). In this study, we aimed to investigate the changes in polysomnographic sleep variables according to PLMI and to determine the relevance of the diagnostic criterion for PLMD. Methods: Out of 4195 subjects who underwent standard polysomnography, we selected 666 subjects (370 males and 296 females, aged $47.1{\pm}14.8$) who were older than 17 years and were not diagnosed with primary insomnia, sleep apnea, narcolepsy, or REM sleep behavior disorder. Subjects were divided into three groups according to PLMI severity: group 1 ($PLMI{\leq}5$), group 2 (5 < $PLMI{\leq}15$), and group 3 (PLMI > 15). Demographic and polysomnographic sleep variables and Epworth sleepiness scale (ESS) were compared among the three groups. Results: There were significant differences among the three groups in age and gender. Sleep efficiency (SE) and stage 3 sleep percentage in group 1 were significantly higher than those in groups 2 and 3. The wake after sleep onset (WASO) score in group 1 was significantly lower than those in groups 2 and 3. However, there were no significant differences in SE, stage 3 sleep percentage, or WASO between groups 2 and 3. Sleep latency (SL) in group 1 was significantly lower than that in group 3, but there was no difference in SL between group 2 and group 3. ESS score in group 1 was significantly higher than that in group 3, but there was no difference between group 2 and group 3. Partial correlation analysis adjusted by age showed that PLMI was significantly related to SE and WASO. Conclusion: This study suggests that PLMI influences polysomnographic sleep variables. In addition, we found the individuals who did not have PLMD but had PLMI > 5 were not different in polysomnographic sleep variables from the individuals who had PLMD according to the current criterion. These results raise questions about the relevance of the current diagnostic criterion of PLMD.

• Sleep Medicine and Psychophysiology
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• v.30 no.1
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• pp.9-12
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• 2023

Periodic limb movements during sleep (PLMS) are prevalent in various sleep disorders, such as restless legs syndrome (RLS), periodic limb movements disorder, obstructive sleep apnea (OSA), REM sleep behavior disorder (RBD), and narcolepsy. PLMS has been hypothesized to be related to the decline of dopaminergic transmission. In RLS, PLMS is suggested to be related to iron deficiency and symptom severity. PLMD is a rare sleep disorder, and the role of PLMS in PLMD has not been clearly investigated yet. PLMS in OSA, which remain after proper PAP therapy, may need further management. The clinical relevance of PLMS in RBD and narcolepsy have not been investigated thoroughly and need further studies. Whether PLMS are to be considered as a mere symptom of individual sleep disorders or not can be elucidated through studies investigating the efficacy of therapeutic approaches to reduce PLMS in various sleep disorders.

• Sleep Medicine and Psychophysiology
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• v.20 no.1
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• pp.35-40
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• 2013

Objectives: The aim of this study is to evaluate the polysomnographic characteristics and prescription status of restless legs syndrome (RLS) patients in naturalistic setting. Methods: We reviewed medical record of the patients over 18 years olds who (i) satisfied the clinical RLS diagnostic criteria and (ii) had the polysomnography and got treatment related thereto. As a baseline, we evaluated the four diagnostic criteria of the International Restless Legs Syndrome Study Group (IRLSSG) and the International Restless Legs Scale (IRLS) of the subjects. Then the polysomnography and the suggested immobilization test (SIT) were conducted and, after one month of pharmacotherapy using dopamine agonist, the IRLS was evaluated again. Results: A total of 211 subjects participated in this analysis and 94 (44.5%) of them were male and the other 117 (55.5%) were female and the average age of the 211 subjects was $46.9{\pm}14.2$. Out of such 211 subjects, 136 subjects (64.5%) also had the obstructive sleep apnea (OSA), and 53 subjects (25.1%) also had the periodic limb movement disorder (PLMD). 185 subjects (87.7%) out of the 211 subjects had some other sleep disorders except RLS. The results of the polysomnography were as follows : 78.0% of sleep efficiency, 86.8 min of wake after sleep onset, and 3.4% of N3. More specifically, 12.4/h of the average apnea hypopnea index, 14.8/h of the periodic limb movement during sleep (PLMS), 41.2/h of the periodic limb movement during wake during SIT and 21.6/h of total arousal index during sleep. Out of the total subjects, 149 (70.6%) of them took the ropinirole and 47 (22.3%) of them took the pramipexole, and the average dosage of ropinirole was 0.9mg(dosage range 0.125-5 mg) while the average dosage of pramipexole was 0.5 mg (dosage range 0.125-4 mg). The dosage of the ropinirole showed a significant positive correlation with the age (r=0.25, p=0.002) and also with the IRLS (r=0.23, p=0.038). The IRLS at the baseline was 24.9 while the same was decreased down to 13.4 after one month. Conclusions: Analyzing the result of this study, a majority of clinical RLS subjects demonstrated comorbidity with some other sleep disorder such as the OSA or PLMD. 25.1% of the subjects showed a PLMD, which was less than in previous researches and the average PLMS was not very high as 14.8/h. The dosage of dopamine agonist taken was often a bit more than the amount recommended in Korea. A prospective research using a large scale controlled subjects will be necessary with respect to this topic.

• Proceedings of the Membrane Society of Korea Conference
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• 1993.10a
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• pp.46-51
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• 1993

Poly(vinyl chloride) was modified by reacting with sodium N-methyldithiocarbamate or N-methyl-N-carboxymethyldithiocarbamate to obtain crosslinked dithiocarbamated PVC(PMD, PSDC). In addition PSDC were substituted with metal ions of $Ma^+, Li^+$ and $Cs^+$. PLMD and PSDC were reacted with copper ions in alcohol or aqueous solution to produce chelate complexes of dithiocarbanated PVC, respectively(PMD-$Cu^{2+}$, PSDC-$Cu^{2+}$). PSDC was irradiated by ultraviolet light to enhance crosslinking(PSDC-UV).

• Sleep Medicine and Psychophysiology
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• v.17 no.1
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• pp.16-20
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• 2010

Objectives: We review the sleep problems of the alcohol dependence patients. Especially we are interested in the prevalence, the severity of symptoms, anxiety, depression, and sleep quality of restless legs syndrome (RLS) in the alcohol dependence patients. Methods: We recruit 86 alcohol dependence patients who were admitted from October 6th, 2008 to October 17th, 2008. We interviewed each patient and evaluated sleep questionnaires such as the Sleep Disorder Questionnaire (SDQ), the Pittsburgh Sleep Quality Index (PSQI) and the International Restless Legs Syndrome Study Group (IRLSSG) rating scale. The presence of RLS and its severity were assessed using the IRLSSG diagnostic criteria and the IRLSSG severity scale, respectively. Depression and anxiety were evaluated by the Beck Depression Inventory (BDI) and the Beck anxiety inventory (BAI). Results: Of all 86 patients, 59 patients have insomnia, 33 patients have RLS, 30 patients have Periodic limb movement disorder (PLMD), 29 patients have nightmare. RLS patients have more high score in the BAI ($21.70{\pm}10.36$ vs $14.67{\pm}11.98$), and their sleep quality was poor in the PSQI ($11.09{\pm}4.08$ vs $7.92{\pm}3.91$) than non-RLS patients. Conclusion: This study shows that alcohol dependence patients show many sleep problems such as insomnia and RLS. So we should notice that the sleep problems of alcohol dependence patients are important in clinical approach and treatment.

• Sleep Medicine and Psychophysiology
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• v.14 no.2
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• pp.86-91
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• 2007

Background: Actigraphy is a reliable and valid method for assessing sleep in normal, healthy populations, but it may be less reliable and valid for detecting disturbed sleep in patients. In this study, we attempted to assess the utility of actigraphy in the estimation of sleep quality in patients with obstructive sleep apnea syndrome (OSAS), a major sleep disorder. Method: We analyzed the data of patients who underwent polysomnography (PSG) and actigraphy simultaneously for one night at the Center for Sleep and Chronobiology, Seoul National University Hospital from November 2004 to March 2006. Eighty-nine subjects with OSAS alone and 21 subjects with OSAS and periodic limb movement disorder (PLMD) were included for final data analyses between groups. Polysomnographic and actigraphic data were also compared. Results: In subjects with mild OSAS (RDI<15), modretae ($15{\leq}RDI$<30), and OSAS with PLMD, PSG and actigraphy did not show significant difference in total sleep time and sleep efficiency. However in severe ($30{\leq}RDI$) OSAS subjects, PSG and actigraphy showed significant difference in total sleep time and sleep efficiency. In all patients, no correlations were found between sleep parameters from PSG and from those using actigraphy. Conclusions: We suggest that in severe OSAS patients, PSG is the diagnostic tool. In mild and moderate cases, actigraphy might be used as a screening tool.

• Sleep Medicine and Psychophysiology
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• v.12 no.1
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• pp.58-63
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• 2005

Objectives: REM sleep behavior disorder (RBD), characterized by excessive motor activity during REM sleep, is associated with loss of muscle atonia. In recent years, it has been reported that RBD has high co-morbidity with CNS disorders (especially, Parkinson's disease, dementia, multiple system atrophy, etc.). We aimed to assess differences in clinical and polysomnographic findings among RBD patients, depending on the presence or absence of central nervous system (CNS) disorders. Methods: The medical records and polysomnographic data of 81 patients who had been diagnosed as having RBD were reviewed. The patients were classified into two groups: associated RBD (aRBD, i.e., with a clinical history and/or brain MRI evidence of CNS disorder) and idiopathic RBD (iRBD, i.e., without a clinical history and/or brain MRI evidence of CNS disorder) groups. Twenty-one patients (25.9%) belonged to the aRBD group and 60 patients (74.1%) belonged to the iRBD group. The clinical characteristics and polysomnographic findings of the two groups were compared. Results: Periodic limb movement disorder (PLMD), i.e., PLMI (periodic limb movement index)>5, was observed more frequently in the aRBD group than in the iRBD group (p<0.001, Fisher's exact test). Also, obstructive sleep apnea syndrome (OSAS), i.e., RDI (respiratory disturbance index)>5, was found more frequently in the aRBD group (p=0.0042, Fisher's exact test). The percentages for slow wave sleep and sleep efficiency were significantly lower in the aRBD group than in the iRBD group. Conclusion: We found that 1 out of 4 RBD patients had associated CNS disorders, warranting more careful neurological evaluation and follow-up in this category of RBD. In this category of RBD patients, we also found more frequent PLMD and OSAS. These patients were also found to have lower slow wave sleep and sleep efficiency. In summary, RBD patients with associated CNS disorders suffer from more disturbed sleep than those without them.