Objective: To reveal clinical and polysomnographic features in patients treated for restless leg syndrome, and to examine the compatibility of sleep data and clinical features.
Methods: The study was conducted at the Department of Neurology, Ankara Numune Training and Education Hospital, Ankara, Turkey, and comprised patients who presented to the outpatient clinic between January and July 2014 who were diagnosed with restless leg syndrome based on the International RestIess Leg Syndrome Study Group criteria. Patients underwent polysomnography test in spontaneous sleep in a single room. SPSS 18 was used for statistical analyses.
Results: Of the 18 patients, 13(72%)were females and 5(28%)were males. Overall mean age was 51.56±11.57years (range: 23-66 years). Fourteen (77.8%) patients reported insomnia; 10(55.5%) patients had excessive daytime sleepiness; 13(72.2%) reported snoring; and 3(17%) had apnoea. Mean International Restless Legs Syndrome Study Group Rating Scale score was 26.11±7.9 (range: 16-40).Mean Epworth Sleepiness Scale score was 9.17±5.1 (range: 0-20).
Conclusion: Restless leg syndrome was more common in women and the most common complaint was insomnia.
Keywords: Restless legs syndrome, Polysomnography, Sleep disorder. (JPMA 66: 568; 2016)
Restless legs syndrome (RLS) is a sensorimotor neurological disease which significantly affects the quality of life and manifests as a sensation of intolerable discomfort in the legs and paresthesia.1,2 Its reported incidences range between 5% and 15%, even reaching up to 25% in general Western population. RLS is more common in women by two folds than in men. Its incidence has been found to be lower in Asian societies.1-4 The disease is frequent and severe enough to require medical treatment in approximately 3% of the population.5 According to the International RestIess Leg Syndrome Study Group (IRLSSG), basic diagnostic criteria include: uncomfortable sensation in the legs, occurring or worsening of this sensation during sitting and rest, and resolution or alleviation of the symptoms with movement, further worsening of the symtoms in the evening and at night, and exluding the condition that may mimick RLS.2,6,7 Treatment strategies differ according to severity of the disease. Different treatment options are offered for the patient group with paroxysmal and mild symptoms, while other options are used for the constant and resistant symptoms. Non-pharmacological treatment can be used in the mild-symptoms group. Patients are advised to pay attention to sleep hygiene and avoid substances worsening the symptoms such as alcohol, nicotine and caffeine.8-10 Regular daily exercise and activities have been reported to be helpful in the mild-symptoms group.11 Non-pharmacological options are insufficient in the moderate and severe patient groups and these patients require pharmacological therapy. The first option in this group is dopa agonists.12 In addition, levodopa-carbidopa, gabapentin, low-potency opioids or opioids receptor agonists can be administered.8,9,13
RLS is frequently associated with insomnia.14 Polisomnography (PSG) is not recommended to be routinely used for the diagnosis of RLS. In the studies conducted with PSG, single-night tests in RLS patients yielded periodic limb movements of sleep (PLMS) by 70-80% and PLMS index by 5 or higher in adults. Using multiple PSGs, number of PLMSs per hour was found to be 5 or higher in 90% RLS patients. Some PLMSs cause arousals which may impair sleep hygiene.15
The current study was planned to reveal clinical and PSG features in RLS patients, and to examine the compatibility of sleep data and clinical features.
Patients and Methods
The study was conducted at the Department of Neurology, Ankara Numune Training and Education Hospital, Ankara, Turkey, and comprised patients who presented to the outpatient clinic between January and July 2014, and were diagnosed with RLS based on the IRLSSG criteria. After approval was obtained from the institutional ethics committee And written informed consent was obtained from the subjects, patients were asked to fill a questionnaire which included the following questions: "How old were you when the disease began?", "How do you describe your complaints?", "Do your complaints alleviate with movement?", "What time of day the complaints begin?", "How many days a week do you have these complaints?", "What do you do to relieve your complaints?", "Do you have similar complaints in your arms?" and "How was the course of disease over time?". Patients filled the International Restless Legs Syndrome Study Group Rating Scale (IRLS) proforma which consists of 10 questions (Table-1).
To assess the association between sleep disturbance and RLS, the Epworth Sleepiness Scale (ESS) was filled (Table-2).
It was also questioned whether they had any comorbid disease. Detailed neurological and otorhinolaryngologic examinations were carried out. Detailed neurological examination and electromyography (EMG) were performed in order to rule out additional pathologies such as peripheral neuropathy and radiculopathy. Serum levels of iron, iron-binding capacity, ferritin, calcium, sodium, magnesium, vitamin B12, folic acid, haemogram and thyroid function were studied. Patient with iron deficiency, vitamin deficiency, thyroid dysfunction, renal failure and peripheral neuropathy were excluded.
Patients underwent PSG in spontaneous sleep in a single room in the hospital\\\'s Sleep Center under the supervision of technicians. Audio and video recordings were taken through the whole night (Alice 5 Model PSG device). Four-channel electroencephalogram (EEG), electromyogram (EMG-submental and right-left tibialis), two-channel electrooculogram (EOG - right-left), electrocardiogram (ECG), nasal airflow, thorax and abdominal respiratory movements, pulse oximetry, blood oxygen saturation and body position data were recorded throughout the night during PSG. Data of all the patients were manually scored by the same specialist who had been certificated for sleep disorders. Scoring of PSG data was carried out in line with the second version of scoring guideline published by American Academy of Sleep Medicine (AASM) in 2012.16 Sleep efficiency, sleep latency, distribution of sleep stages, Apnoea Hypopnoea Index (AHI), AHI during the rapid eye movement (REM) stage, AHI during the non-REM stage, minimal oxygen saturation, duration of the oxygen saturation lower than 90%, number and index of the leg movement, number and index of the periodical leg movement and, number and index of the leg movement which led to arousal were recorded. Leg EMG activities observed during the respiratory events in obstructive sleep apnoea syndrome (OSAS) patients were not marked as legs movement, as specified in the AASM guidelines. Only EMG activities which should be marked as leg movement based on the criteria included in the AASM guideline which are independent of the respiratory events were marked in OSAS patients.
In addition, the patients were also asked about the treatments they had received, the length and dosage of the treatment and whether they had benefited from treatment.
Data obtained through patient history and the questionnaires was compared with PSG results statistically.
Statistical analysis was done using SPSS 18. Compliance of the variables with normal distribution was studied using visual (histogram and probability plots) and analytical methods (Kolmogorov-Simirnov, Shapiro-Wilk tests). Correlation coefficients and statistical significance was calculated through Pearson correlation analysis in case of both variables showed normal distribution. Spearman test was used to estimate coefficients and statistical significance for the correlation between variables at least one of which showed non-normal distribution or was ordinal. Correlation between the nominal-nominal and nominal-continuous variables was interpreted using phi and eta correlation coefficients. Level of statistical significance was accepted as type-1 error level of 5%.
Of the 18 patients, 13(72%) were females and 5(28%)were males. Overall mean age was 51.56±11.57years (range: 23-66 years). Ten (55.6%) patients had family history (55.6%), 6(33.3%) had hypertension (HT) and 2(11.1%) had arrhythmia. Complaints were localised only in the legs in 13(72.2%) patients, while 5(27.8%) had complaints in the arms also. Nine (50%) patients had complaints only at night. Complaints had begun in 10(55.6%) patients at age 45 years or less (mean: 35.20±11.94 years; range: 10-45 years) and at over 45 years in 8(44.4%) patients (mean: 56.75±5.49 years; range: 49-64 years).
Overall, 14(77.8%) patients reported insomnia; 10(55.6%) had excessive daytime sleepiness; 13(72.2%) had snoring; and 3(16.7%) had apnoea.
Mean IRLS score was 26.11± 7.9 (range: 16-40). Mean ESS score was 9.17± 5.1 (range: 0-20).
PSG data showed mean sleep efficiency to be 85.31± 9.9 (range: 54-96), mean REM sleep latency 124.5± 66.3 (range: 5.5-316), mean Stage N3 sleep latency 17±11.7 (range: 1.8-43.5), mean total sleep time 357.4 ±53.7 (range: 223-412.5), mean Stage N1 percentage 5.8±4.6 (range: 1.8-20.9), mean Stage N2 percentage 48.4±16.6 (range: 17-77), mean Stage N3 percentage 25.02±14.06 (range: 1.8- 51.5), mean REM percentage 20.1±9.2 (8.5-41.3), mean AHI value11.01±10.5 (range: 2-43), mean REM AHI 16.4±22.6 (range: 0-82.1), mean non-REM AHI 9.9 ±10.4 (range: 1.2-39.1); and mean oxygen saturation 85.1±7.6 (range: 64-94%).
Mean total number of leg movement was 108.2±150.6 (range: 3-593), mean leg movement index was 18.9±28.3 (range: 0.5-115.5), mean number of leg movement causing arrousals was 32.3±57.6 (range: 0-214), and mean arousal-related legs movement index was 5.76±10.7 (range: 0-41.7).
Accordingly, OSAS was identified in 9(50%) patients.
Mean periodical leg movement index was 15.7±28.9 (range: 0-114.9).
All the 18(100%) patients were receiving medical treatment. Among them, 17(94.4%) patients were using pramipexole and 1(5.6%) patient gabapentin. Dose of pramipexole was 2 mg/day in 1(5.6%) patient, 1mg/day in 2(11.3%), 0.5mg/day in 9(50%), 0.250mg/day in 4(45%), and 0.125mg/day in 1(5.6%) patient. Eleven (61%) patients stated that they had a lot of benefit from the treatment, while 3(16.7%) patients had not benefited.
On statistical comparison, a moderately significant negative correlation was found between sleep efficiency and IRLS scores. Sleep efficiency decreased as did IRLS scores, meaning that subjective complaints of patients increased (p=0.044).
A perfect correlation between sleep efficiency and insomnia variables was identified. It was found that sleep efficiency was lower in patients who had complaints of insomnia (p=0.029).
A perfect correlation between Stage N3 and REM percentage variables was identified. It was observed in objective PSG recordings that State N3 and REM sleep decreased in patients who had complaints of insomnia (p=0.021, p=0.030).
A moderately significant positive correlation was found between REM sleep latency and ESS variables REM sleep latency prolonged as ESS score increased (p=0.049).
A perfect correlation between REM sleep latency and insomnia variables was identified at a significant level. REM sleep latency was longer in patients who had complaints of insomnia (p=0.032).
Stage N3 percentage was moderately negatively correlated with total number of leg movements (p=0.044), total leg movement index (p=0.035), number of periodical leg movements (p=0.033), periodical leg movements index (p=0.43) and total time of periodical leg movement (p=0.032). According to these parameters, deep sleep statistically decreased with worsening of all the leg movement parameters obtained on PSG.
A moderately significant positive correlation was found between IRLS and leg movements associated with arousal. Leg movements associated with arousal increased as IRLS scores worsened (p=0.042).
A moderately significant negative correlation was found between IRLS scores and age variables. IRLS scores were better in advanced ages (p=0.019).
A correlation between "age of the complaint onset" and "complaints in the arms?" variables was identified at a significant level. That is, presence of complaints elsewhere out of legs differed with aging with more common complaints in the patients in whom complaints had begun at a younger age (p=0.015).
"Complaints in the arms?" variable was correlated with sleep efficiency, Stage N3 sleep latency, Stage N 1-2-3 percentages and total sleep time at significant levels. Presence of complaints in the arms were found to significantly affect almost all sleep data, while significant disturbances were observed in the sleep paterns of these patients (p=0.046, p=0.007, p=0.037).
Drug benefits were found to be strongly negatively correlated with the number and total time of episodes of the periodical leg movements. In objective PSG data, number of leg movements was less in patients who specified that they had benefited from treatment (p=0.004, p=0.035).
Diagnosis of RLS can be established based on the IRLSSG diagnostic criteria. Basic criteria that should be found in RLS patients include uncomfortable sensation in the legs, occurring or worsening of this sensation during sitting and rest and resolution or alleviation of the symptoms with movement, further worsening of the symptoms in the evening and at night, and excluding the condition that may mimick RLS.2,6,7 We also set the diagnosis of RLS based on these criteria.
RLS disease may begin in all age groups. Data in literature indicates that the disease may be seen between the age range of 6 and 80 years.15-19 In our patients, onset of the complaints was between 10 and 64 years of age.
RLS is more commonly seen in women. It has been reported in literature that incidence of RLS is two times higher in women compared to men.1-3 In our study, consistent with the literature incidence of RLS was higher in female patients by a F/M rate of 2.2/1.
Family history is accepted as a supportive criteron for RLS diagnosis. Family histories between 3.2% and 50% have been reported in literature.18,21 Family history reaches 77% especially in RLS patients in whom onset of the complaints had begun in the childhood period.19 In our study, family history was found by 44.4%.
Apart from the legs, complaints of RLS may also be seen in the arms. This condition has been reported between 42.8% and 48.7% in literature.21,22 In this study, complaints in the arms were observed in 5(27.8%)patients.
Complaints of sleep disorders, failure to sleep enough and insomnia are among the most common complaints. Complaints of sleep problems have been reported in literature between 47.9% and 53%.23,24 Of our patients, 77.8% had complaints of sleep disorders.
Although daytime sleepiness is among the most encountered complaints, ESS scores have been reported within the normal limits. In this study, we found ESS scores between 0 and 20 (mean 9.17±5.19).25,26
Iron deficiency, pregnancy and renal failure are the most important conditions that may cause RLS. Patients having these conditions are considered as secondary RLS. We excluded the patients with additional pathologies that may lead to RLS.
IRLS scores are a gold standard scale with proven validation.27,28 The scores between 31 and 40 are accepted as very severe, 21-30 as severe, 11-20 as moderate and 1-10 as mild. In this study, we found the IRLS scores between 16 and 40 with a mean value of 26.11±7.95.
PSG is not necessary to establish diagnosis of RLS. However, PSG provides valuable information for determination of additional sleep disturbances like OSAS, differential diagnosis of parasomnia or for assessment of the correlation of subjective findings. Some studies demonstrated impaired sleep patterns, decreased sleep efficiency, prolongation of the sleep latency and increase in the number of awakenings in RLS patients, while others reported that no significant difference was found in terms of PSG measurements (total sleep time, sleep efficiency, sleep and wakefulness time). In this study, significant decreases were observed especially in N3 sleep. It was found that deepness in sleep statistically decreased with worsening of all leg movement parameters. We also observed that sleep efficiency was correlated with IRLS scores and sleep efficiency was lower in patients with subjectively poor questionnaire outcomes.29,30
Among the sleep data, IRLS was significantly correlated especially with sleep efficiency and the number of leg movements associated with arousal (p=0.044 and p=0.042; respectively).
Periodical leg movement are common in RLS. In the studies conducted with single-night PSG, periodical leg movements were reported in 70-90% of RLS patients.15 In our study group, periodical leg movement index was found as minimal 0 and maximal 114.9 with a mean value of 15.7±28.9 and all patients were under treatment.
It was found that patients who had complaints also in the arms were more affected and this condition caused significant decrease in many PSG parameters (sleep efficiency, N3 sleep latency, REM sleep latency, N1, N2, N3 percentages, REM percentage and total sleep time).
OSAS may be seen in association with RLS and the incidence of this association has been reported in literature as 55.4%.23 In some studies, OSAS patients have been excluded, considering they have secondary RLS. However, in PSG scoring periodical leg movements which are independent of respiratory events during sleep must be used. If patients with periodical leg movements independent of respiratory events meet diagnostic criteria of RLS in addition to OSAS, they should be considered OSAS in addition to RLS. In our study, rate of patients with OSAS in addition to RLS was 50%, consistently with the literature.23
Dopamin agonists, levodopa-carbidopa, gabapentin, low-potency opioids or opioids receptor agonists are used in treatment of RLS.8,9,12,13 In this study, dopamin agonist (pramipexole) was used in 17 patients and gabapentin in 01 patient. Subjective evaluation of drug efficacy was statistically compatible withthe leg movements identified on PSG.
Consistent with literature, it was found in our study that RLS was more common in women, family history was frequently observed, and the most common complaint was insomnia. Disturbances in sleep efficiency and sleep patterns was found in PSG examination of RLS patients. Complaints of the patients and disturbances in the sleep patterns in PSG were correlated with the questionnaire outcomes. Further disturbance was found in the sleep data in patients who had additional complaints in the arms. Association of RLS and OSAS may be commonly encountered. If this association is found, then evaluation with PSG must be made.
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