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P1041: Is home video telemetry-polysomnography (HVT-P) feasible?
Abstracts of Poster Presentations / Clinical Neurophysiology 125, Supplement 1 (2014) S1–S339
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P1037 Neurophysiological evaluation of spinal excitability in patients affected by primary restless legs syndrome
P1039 Polycardiorespiratory polygraphy diagnostic accuracy in mild to moderate obstructive sleep apnea hypopnea syndrome
P. Congiu 1 , G. Milioli 2 , G. Gioi 1 , P. Tacconi 3 , M.L. Fantini 4 , F. Marrosu 3 , L. Parrino 2 , M. Puligheddu 1 1 University of Cagliari, Sleep Center, Neurophysiology Unit, Monserrato, Cagliari, Italy; 2 University of Parma, leep Disorder Center, Parma, Italy; 3 University of Cagliari, Neurology Unit, Monserrato -CA, Italy; 4 EA7890, University of Auvergne, Clermont-Ferrande, France
K. Rahnama 1 , A. Ferre 1 , J. Vila 2 , O. Romero 1 1 Vall d’Hebron Hospital, Neurophysiology, Barcelona, Spain; 2 Vall d’Hebron Hospital, Otorhinolaryngologist, Barcelona, Spain
Question: Restless legs syndrome (RLS) is a frequent condition, but its pathophysiology is not completely understood. The dopaminergic system has a primary role, and some studies have highlighted a condition of spinal hyper-excitability. The aim of our study is to explore this hypothesis through the electrophysiological evaluation of patients affected by primary RLS. Methods: 15 women affected by primary RLS and 17 age-matched females (controls) were selected. All subjects underwent nerve conduction studies (NCS) evaluation to exclude any secondary causes of lower limb paresthesias and to evaluate spinal excitability. According to a previous study, we considered two parameters, the duration of F waves (FWD) of the tibial and ulnar nerves, and the ratio between FWD and the duration of the corresponding compound muscle action potential (FWD/CMAPD). Results: None of the subjects (both RLS and controls) included in our study showed alterations in the nerve conduction velocities. Compared to the control group, significantly higher values were found in RLS patients for the mean FWD for both ulnar (p<0.05) and tibial (p<0.01) nerves and for the mean FWD/CMAPD ratio average (p<0.001). Conclusions: The results of our study indicate a widespread spinal motoneuronaI hyper-excitability. Such condition could be mainly due to an abnormal modulation within the interneuronal system. Presently, RLS diagnosis is based exclusively on clinical criteria. The FWD/CMAPD ratio can help to shed light on the pathogenesis of RLS, is easily obtainable and can represent an instrumental diagnostic tool especially in cases of evening lower leg discomfort of unclear interpretation.
P1038 Evaluation of H reflex excitability during motor imagery in patients with the restless legs syndrome and healthy individuals F. Yavlal 1 , R. Inan 2 , G. Benbir 3 , D. Karadeniz 3 , M. Kiziltan 3 1 Bahcesehir University Faculty of Medicine, Neurology, Istanbul, Turkey; 2 Lutfi Kirdar Kartal Training and Research Hospital, Neurology, Istanbul, Turkey; 3 Istanbul University Cerrahpasa Faculty of Medicine, Neurology, Istanbul, Turkey Questions: Motor Imagery (MI) is suggested that the neural processes associated with the motor imagery are similar to the realization of that particular movement. The increase of the excitability belonging to TMS, reflexes and the cycles related with the delayed responses has been shown. Restless Legs Syndrome (RLS) is a sleeping disorder characterized by an abnormal sensation, legs in particular. The relationship between the desire of walking and the temporary relief of patients is known. The increase of excitability through TMS and segmental reflexes at the different levels of the CNS has been reported. In our study we aimed to investigate the difference on the excitability of the H reflex during the imagery of walking in RLS patients and healthy individuals. Methods: 11 RLS (3 M, 8 F. Average Age: 41.2) and 15 (8 M, 7 F. Average Age: 38.4) gender and age matched control, in total 26 subjects were included to the study. HR is studied in the supine position, while 1: resting and 2: simulating of walking and the ratio of Hmax/Mmax were obtained. The Hmax/Mmax ratios of the two groups were compared. Results: There was no difference between M responses, HR latencies and resting Hmax/Mmax ratios in the RLS patients and control subjects. The Hmax/Mmax ratio during resting period was 44.6+ 26.6 and MI Hmax/Mmax ratio was 51.9+32.7 in the control group, whereas resting Hmax/Mmax ratio was 49.4+22.5 and MI Hmax/Mmax ratio was 40.1+23.1 in the RLS group. Conclusion: Hmax was increased during MI at the control group, whereas it was decreased at the RLS group. This finding was interpreted as the imagination of walking decreases the spinal excitability in patients with RLS.
Introduction: The gold standard in OSAHS diagnosis is the nocturnal polysomnography (PSG). Nowadays is allowed to use polycardiorespiratory polygraphy (PCR) in patients with high pretest probability of OSAHS. The PCR has some limitations that can infraestimate the AHI; impossibility to score sleep time, respiratory effort related to arousal and hypopneas related to arousal without oxygen desaturation. Objective: Evaluate the polycarodiorespiratory poligraphy (CRP) diagnostic accuracy in patientes with mild to moderate OSAHS. Methods: We evaluate 96 patients with AHI <30 in PCR and compare with the conventional polysomnography (PSG). Results: We studied 96 patients 69% male 30% female with a mean age 52±12.5 years, mean body mass index (BMI) 27.7±3.6, mean Epworth sleepiness scale 7.54±4.8 and mean AHI in PCR 11.6±7.8. PCR show a OSAHS prevalence of 26% normal, 39.6% mild and 34.4 moderate in the selected patients. When we compare PSG with PCR we observe statistical differences in the compute the AHI (19.2±14.9 & 11.6±7.8)and RDI (22.1±14.8 & 11.6±7.8). The mean difference in AHI and RDI are 7.6±12.0 and 10.4±12.1 respectively. When we obtain normal results with PCR we observe in PSG a 76% (IAH) or 48% (RDI) of mild to moderate OSAHS. When we obtain mild OSAHS with PCR we observe in PSG 42.1% (IAH) or 47% (RDI) moderate and 15.7% (IAH) or 21% (RDI) sever OSAHS. When we obtain moderate OSAHS with PCR we observe in PSG 21.2% (IAH) or 18% (RDI) mild and 42.5% (IAH) or 51% (RDI) sever OSAHS. Conclusions: PCR in mild to moderate OSAHS patients can infraestimate significantly the degree of OSAHS severity.
P1040 Intracerebral study of cortical activation during dissociated arousals N. Frezel 1 , S. Boudet 2 , N. Reyns 3 , W. Szurhaj 1,4 1 CHRU Lille, clinical neurophysiology, Lille, France; 2 Faculé Libre de Médecine, Université Nord de France, Lille, France; 3 CHRU Lille, Neurosurgery, Lille, France; 4 Lille II University, EA 4559, Lille, France Background: Dissociated arousals are characterized by behavioural arousal and slow-waves on ElectroEncephaloGram, that suggest the persistence of sleep. Our purpose was to determine, with intracerebral recordings, the changes in electrical activity in different cortical areas (sensori-motor and non-sensori-motors areas) during dissociated arousal states, in comparison with normal arousals. Methods: Dissociated and normal arousals were recorded in a fifteen years-old male with drug-resistant right parietal epilepsy. We analyzed the activity from non epileptic areas, recorded in: pre- and post-central gyri, middle and superior frontal gyri, cingulated gyrus, hippocampus, middle temporal gyrus, superior and inferior parietal lobes. Time-frequency analyses were performed from 2 minutes before up 2 minutes after the beginning of the arousal. Results: Five dissociated arousals were compared with 3 normal arousals. In dissociated arousals, we observed a blockage of very low frequencies rhythms in all areas, suggesting an arousal of the whole cortex. In motor cortex, higher frequencies rhythms occurred, similarly to a normal arousal. In other areas, a synchronization around 1.8 Hz was observed during the dissociated arousal states. This synchronization was never observed in normal arousals. Conclusion: The slow-wave sleep is interrupted in all cortical areas during dissociated arousal state. The activity of motor cortex seem to be similar to normal arousals, whereas a probably pathologic 1.8 Hz synchronization is observed in non-motor areas.
P1041 Is home video telemetry-polysomnography (HVT-P) feasible? P. Muthinji, N. Mullatti, D. Amin, F. Brunnhuber King’s College Hospital, Clinical Neurophysiology, London, United Kingdom Background: HVT at King’s College Hospital has been successfully used
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Abstracts of Poster Presentations / Clinical Neurophysiology 125, Supplement 1 (2014) S1–S339
in patients referred to Telemetry Unit for seizure disorders evaluation. Some of the patients referred to Telemetry unit are for assessment of Non-Respiratory Sleep Disorders (NRSDs) and can benefit from HVT-P. Question: Can HVT-P be performed successfully at the patients’ own homes? Methods: An observational study comprising of eleven adult patients with NRSDs was carried out. Patients underwent 2-3 nights of HVT-P at their homes. Recorded data was retrieved daily for analysis. Data acquisition included Video synchronised with sleep staging parameters consisting of 27 channels (19 EEGs, 2 EOGs, 5 EMGs and 1 ECG). Conventional parameters for duration, continuity and quality of Sleep Period Time (SPT) were applied for sleep scoring. Video quality was graded according to its ability to characterise behavioural events occurring during sleep period. Results: Duration and continuity were good in 10/11. The EEG and Chin EMG signal were good in 10/11. The EOG signal was good in 9/11 and satisfactory in 1/11. Video was good in 6/11 and satisfactory in 5/11. Audio was good in 7/11 and satisfactory in 4/11. Conclusions: Previous studies indicate that that sleep staging signals are most susceptible to quality loss making sleep analysis difficult. This study shows an overall quality of 91% for EEG/EMG signals and 82% for EOG signals. This suggests HVT-P can successfully be performed at the patients’ home and compares favourably with laboratory based recordings.
P1042 Relation of sleep stages and sleep period to the cortical excitability in Parkinson’s disease J. Antczak, M. Rakowicz, K. Latuszynski, J. Phelps, A. Sobanska, E. Inglot, U. Zalewska, T. Jakubczyk Institute of Psychiatry and Neurology, Clinical Neurophysiology, Warsaw, Poland Question: Sleep problems are reported by up to 98% of Parkinson’s disease (PD) patients. The mechanisms of disordered sleep in PD are not fully understood. Increased cortical excitability (CE) is associated with poor sleep quality in insomniacs. As some specific alterations of CE were identified in PD, we pursued the question if CE is related to sleep also in PD. Methods: 27 PD patients (10 women, mean age 62.7±8.4) underwent examination of CE with transcranial magnetic stimulation (TMS), nocturnal polysomnography and examination with the motor part of the Unified Parkinson’s Disease Rating Scale (UPDRS III). Recorded CE parameters included the resting motor threshold (RMT), the motor evoked potential (MEP) and the central silent period (CSP). CE parameters were labelled as initial (ini) when recorded after the TMS of the hemisphere where the disease began and as secondary (sec) otherwise. Bayesian model choice methodology and LASSO were used to choose the best fitting linear models for the main polysomnographic parameters. Results: The Bayesian approach and LASSO both yield the same conclusions, i.e.: The best fitting linear model for total sleep time consists of one explanatory variable, RMTsec. The best model for wake after sleep onset uses RMTsec and RMTini, whereas the amount of NREM2 was best modelled by RMTsec and UPDRSIII. Our data did not support modelling other sleep parameters with linear models using CE parameters or UPDRSIII as explanatory variables. Conclusions: The results indicate there may be an association between sleep disorders and CE changes in PD.
P1043 The quality of polysomnography recording in intensive care unit and the special requirements for the recordings set by ICU environment S. Leivo, M. Ritmala-Castrén, I. Virtanen, E. Liikanen Turku University Central Hospital, Department of Clinical Neurophysiology, Turku, Finland Polysomnography (PSG) is used for the diagnosis of sleep related disorders. This may not only be performed in a sleep laboratory but also in challenging circumstances at a hospital ward or in an intensive care unit (ICU). In the ICU, technical PSG problems arise that are beyond those experienced in a standard PSG laboratory. The aim of this study is to describe the quality of the PSG carried out in the ICU in cases where a trained PSG technician is not available throughout the recording process. A further aim is to describe the proportion of artifact-free signal in each of the measured traces, causes for the artifacts as well as to
find out if the recordings contain sufficient amounts of artifact-free signal for reliable analyses. We also wanted to compare the efficacy of the nasal pressure cannula with the respiratory inductance plethysmography sum signal (RIP) in detection of respiratory events in adult ICU-PSG. A total of 20 overnight PSG recordings performed at a university hospital in southern finland were analyzed for the study. The least artifact-free signal was to be found in the EEG-recording (78.5%) and most artifactfree in the ECG-recording (96.5%) and in the oxygen saturation-recording (SpO2 ) (96.3%). The most common sources of artifacts in the EEG-, EOGand ECG-recordings were body movement and poor electrode contact, in the EMG-recording ECG-artifacts, in SpO2 -recording body movement and in the thoraco-abdominal movement detection and the EMFit-signal the occasional inability of the sensors to detect respiratory movements. Over 90 minutes (which equals one sleep cycle) of completely artifact-free signal on every channel simultaneously was found in 65% of the recordings (fr =13). Respiratory events were scored twice in each study using a nasal pressure-signal and an RIP-signal. A statistically significant difference was detectable only in the amount of apneas/h. In one recording, the difference of the two analyses was significant. In the ICU environment, the quality of PSG recordings varies and the most disturbing artifacts last for last for a long period of time. In circumstances where a trained PSG technician is not available throughout the recording process it is reasonable to record EEG-signal on both sides in frontal, central and occipital head regions as well as to use both the tibialis-EMG-recording and EMFit-recording to detect limb-movements. Respiratory events can usually be diagnosed by using the RIP-signal in case the nasal pressure signal for some reason not usable.
P1045 Automatic sleep classification using a data-driven approach reveals six latent sleep states H. Koch 1,2 , J.A.E. Christensen 1,2 , R. Frandsen 1 , L. Arvastson 3 , S.R. Christensen 4 , P. Jennum 1,5 , H.B.D. Sorensen 2 1 Glostrup University Hospital, Danish Center for Sleep Medicine, Glostrup, Denmark; 2 Technical University of Denmark, Electrical Eng., Kgs. Lyngby, Denmark; 3 H. Lundbeck A/S, Biostatistics, Valby, Denmark; 4 H. Lundbeck A/S, Clinical Pharmacology, Valby, Denmark; 5 University of Copenhagen, Center for Healthy Ageing, Copenhagen, Denmark Question: Will a sleep classifier, which uses a data-driven approach, classify sleep according to the golden standard for manual sleep scoring? Which EEG/EOG characteristics will the model include in the latent sleep states? Methods: An automatic sleep classifier, which evaluates sleep using latent sleep states, was optimized using a data-driven approach. The model used spectral EEG and EOG measures and eye correlation in three seconds windows with one second resolution. Each thirty seconds epoch was expressed as mixture of probabilities of the latent sleep states. The model was applied to four groups to test the application: control subjects and patients with periodic leg movements represented a non-neurodegenerative group and patients with idiopathic REM sleep behavior disorder and Parkinsons Disease represented a neurodegenerative group. The model was optimized using 50 subjects and validated on 73 subjects. Results: The optimized sleep model gave a detailed description of sleep, used six latent sleep states indicating that sleep contains six diverse latent sleep states and the state transitions were expressed as continuous processes. Statistics of the latent sleep states showed accordance to the spectral EEG and EOG content as well as eye movements in the AASM stages. The sleep model performed similar across the four groups and the overall subject-specific accuracy reached (%) 68.3±7.5. Conclusions: Analysing sleep using a data-driven approach and inclusion of only EEG and EOG revealed six latent sleep states. The model is general applicable on subject groups and may contribute to the research in sleep and neurodegenerative diseases.
S325
P1037 Neurophysiological evaluation of spinal excitability in patients affected by primary restless legs syndrome
P1039 Polycardiorespiratory polygraphy diagnostic accuracy in mild to moderate obstructive sleep apnea hypopnea syndrome
P. Congiu 1 , G. Milioli 2 , G. Gioi 1 , P. Tacconi 3 , M.L. Fantini 4 , F. Marrosu 3 , L. Parrino 2 , M. Puligheddu 1 1 University of Cagliari, Sleep Center, Neurophysiology Unit, Monserrato, Cagliari, Italy; 2 University of Parma, leep Disorder Center, Parma, Italy; 3 University of Cagliari, Neurology Unit, Monserrato -CA, Italy; 4 EA7890, University of Auvergne, Clermont-Ferrande, France
K. Rahnama 1 , A. Ferre 1 , J. Vila 2 , O. Romero 1 1 Vall d’Hebron Hospital, Neurophysiology, Barcelona, Spain; 2 Vall d’Hebron Hospital, Otorhinolaryngologist, Barcelona, Spain
Question: Restless legs syndrome (RLS) is a frequent condition, but its pathophysiology is not completely understood. The dopaminergic system has a primary role, and some studies have highlighted a condition of spinal hyper-excitability. The aim of our study is to explore this hypothesis through the electrophysiological evaluation of patients affected by primary RLS. Methods: 15 women affected by primary RLS and 17 age-matched females (controls) were selected. All subjects underwent nerve conduction studies (NCS) evaluation to exclude any secondary causes of lower limb paresthesias and to evaluate spinal excitability. According to a previous study, we considered two parameters, the duration of F waves (FWD) of the tibial and ulnar nerves, and the ratio between FWD and the duration of the corresponding compound muscle action potential (FWD/CMAPD). Results: None of the subjects (both RLS and controls) included in our study showed alterations in the nerve conduction velocities. Compared to the control group, significantly higher values were found in RLS patients for the mean FWD for both ulnar (p<0.05) and tibial (p<0.01) nerves and for the mean FWD/CMAPD ratio average (p<0.001). Conclusions: The results of our study indicate a widespread spinal motoneuronaI hyper-excitability. Such condition could be mainly due to an abnormal modulation within the interneuronal system. Presently, RLS diagnosis is based exclusively on clinical criteria. The FWD/CMAPD ratio can help to shed light on the pathogenesis of RLS, is easily obtainable and can represent an instrumental diagnostic tool especially in cases of evening lower leg discomfort of unclear interpretation.
P1038 Evaluation of H reflex excitability during motor imagery in patients with the restless legs syndrome and healthy individuals F. Yavlal 1 , R. Inan 2 , G. Benbir 3 , D. Karadeniz 3 , M. Kiziltan 3 1 Bahcesehir University Faculty of Medicine, Neurology, Istanbul, Turkey; 2 Lutfi Kirdar Kartal Training and Research Hospital, Neurology, Istanbul, Turkey; 3 Istanbul University Cerrahpasa Faculty of Medicine, Neurology, Istanbul, Turkey Questions: Motor Imagery (MI) is suggested that the neural processes associated with the motor imagery are similar to the realization of that particular movement. The increase of the excitability belonging to TMS, reflexes and the cycles related with the delayed responses has been shown. Restless Legs Syndrome (RLS) is a sleeping disorder characterized by an abnormal sensation, legs in particular. The relationship between the desire of walking and the temporary relief of patients is known. The increase of excitability through TMS and segmental reflexes at the different levels of the CNS has been reported. In our study we aimed to investigate the difference on the excitability of the H reflex during the imagery of walking in RLS patients and healthy individuals. Methods: 11 RLS (3 M, 8 F. Average Age: 41.2) and 15 (8 M, 7 F. Average Age: 38.4) gender and age matched control, in total 26 subjects were included to the study. HR is studied in the supine position, while 1: resting and 2: simulating of walking and the ratio of Hmax/Mmax were obtained. The Hmax/Mmax ratios of the two groups were compared. Results: There was no difference between M responses, HR latencies and resting Hmax/Mmax ratios in the RLS patients and control subjects. The Hmax/Mmax ratio during resting period was 44.6+ 26.6 and MI Hmax/Mmax ratio was 51.9+32.7 in the control group, whereas resting Hmax/Mmax ratio was 49.4+22.5 and MI Hmax/Mmax ratio was 40.1+23.1 in the RLS group. Conclusion: Hmax was increased during MI at the control group, whereas it was decreased at the RLS group. This finding was interpreted as the imagination of walking decreases the spinal excitability in patients with RLS.
Introduction: The gold standard in OSAHS diagnosis is the nocturnal polysomnography (PSG). Nowadays is allowed to use polycardiorespiratory polygraphy (PCR) in patients with high pretest probability of OSAHS. The PCR has some limitations that can infraestimate the AHI; impossibility to score sleep time, respiratory effort related to arousal and hypopneas related to arousal without oxygen desaturation. Objective: Evaluate the polycarodiorespiratory poligraphy (CRP) diagnostic accuracy in patientes with mild to moderate OSAHS. Methods: We evaluate 96 patients with AHI <30 in PCR and compare with the conventional polysomnography (PSG). Results: We studied 96 patients 69% male 30% female with a mean age 52±12.5 years, mean body mass index (BMI) 27.7±3.6, mean Epworth sleepiness scale 7.54±4.8 and mean AHI in PCR 11.6±7.8. PCR show a OSAHS prevalence of 26% normal, 39.6% mild and 34.4 moderate in the selected patients. When we compare PSG with PCR we observe statistical differences in the compute the AHI (19.2±14.9 & 11.6±7.8)and RDI (22.1±14.8 & 11.6±7.8). The mean difference in AHI and RDI are 7.6±12.0 and 10.4±12.1 respectively. When we obtain normal results with PCR we observe in PSG a 76% (IAH) or 48% (RDI) of mild to moderate OSAHS. When we obtain mild OSAHS with PCR we observe in PSG 42.1% (IAH) or 47% (RDI) moderate and 15.7% (IAH) or 21% (RDI) sever OSAHS. When we obtain moderate OSAHS with PCR we observe in PSG 21.2% (IAH) or 18% (RDI) mild and 42.5% (IAH) or 51% (RDI) sever OSAHS. Conclusions: PCR in mild to moderate OSAHS patients can infraestimate significantly the degree of OSAHS severity.
P1040 Intracerebral study of cortical activation during dissociated arousals N. Frezel 1 , S. Boudet 2 , N. Reyns 3 , W. Szurhaj 1,4 1 CHRU Lille, clinical neurophysiology, Lille, France; 2 Faculé Libre de Médecine, Université Nord de France, Lille, France; 3 CHRU Lille, Neurosurgery, Lille, France; 4 Lille II University, EA 4559, Lille, France Background: Dissociated arousals are characterized by behavioural arousal and slow-waves on ElectroEncephaloGram, that suggest the persistence of sleep. Our purpose was to determine, with intracerebral recordings, the changes in electrical activity in different cortical areas (sensori-motor and non-sensori-motors areas) during dissociated arousal states, in comparison with normal arousals. Methods: Dissociated and normal arousals were recorded in a fifteen years-old male with drug-resistant right parietal epilepsy. We analyzed the activity from non epileptic areas, recorded in: pre- and post-central gyri, middle and superior frontal gyri, cingulated gyrus, hippocampus, middle temporal gyrus, superior and inferior parietal lobes. Time-frequency analyses were performed from 2 minutes before up 2 minutes after the beginning of the arousal. Results: Five dissociated arousals were compared with 3 normal arousals. In dissociated arousals, we observed a blockage of very low frequencies rhythms in all areas, suggesting an arousal of the whole cortex. In motor cortex, higher frequencies rhythms occurred, similarly to a normal arousal. In other areas, a synchronization around 1.8 Hz was observed during the dissociated arousal states. This synchronization was never observed in normal arousals. Conclusion: The slow-wave sleep is interrupted in all cortical areas during dissociated arousal state. The activity of motor cortex seem to be similar to normal arousals, whereas a probably pathologic 1.8 Hz synchronization is observed in non-motor areas.
P1041 Is home video telemetry-polysomnography (HVT-P) feasible? P. Muthinji, N. Mullatti, D. Amin, F. Brunnhuber King’s College Hospital, Clinical Neurophysiology, London, United Kingdom Background: HVT at King’s College Hospital has been successfully used
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Abstracts of Poster Presentations / Clinical Neurophysiology 125, Supplement 1 (2014) S1–S339
in patients referred to Telemetry Unit for seizure disorders evaluation. Some of the patients referred to Telemetry unit are for assessment of Non-Respiratory Sleep Disorders (NRSDs) and can benefit from HVT-P. Question: Can HVT-P be performed successfully at the patients’ own homes? Methods: An observational study comprising of eleven adult patients with NRSDs was carried out. Patients underwent 2-3 nights of HVT-P at their homes. Recorded data was retrieved daily for analysis. Data acquisition included Video synchronised with sleep staging parameters consisting of 27 channels (19 EEGs, 2 EOGs, 5 EMGs and 1 ECG). Conventional parameters for duration, continuity and quality of Sleep Period Time (SPT) were applied for sleep scoring. Video quality was graded according to its ability to characterise behavioural events occurring during sleep period. Results: Duration and continuity were good in 10/11. The EEG and Chin EMG signal were good in 10/11. The EOG signal was good in 9/11 and satisfactory in 1/11. Video was good in 6/11 and satisfactory in 5/11. Audio was good in 7/11 and satisfactory in 4/11. Conclusions: Previous studies indicate that that sleep staging signals are most susceptible to quality loss making sleep analysis difficult. This study shows an overall quality of 91% for EEG/EMG signals and 82% for EOG signals. This suggests HVT-P can successfully be performed at the patients’ home and compares favourably with laboratory based recordings.
P1042 Relation of sleep stages and sleep period to the cortical excitability in Parkinson’s disease J. Antczak, M. Rakowicz, K. Latuszynski, J. Phelps, A. Sobanska, E. Inglot, U. Zalewska, T. Jakubczyk Institute of Psychiatry and Neurology, Clinical Neurophysiology, Warsaw, Poland Question: Sleep problems are reported by up to 98% of Parkinson’s disease (PD) patients. The mechanisms of disordered sleep in PD are not fully understood. Increased cortical excitability (CE) is associated with poor sleep quality in insomniacs. As some specific alterations of CE were identified in PD, we pursued the question if CE is related to sleep also in PD. Methods: 27 PD patients (10 women, mean age 62.7±8.4) underwent examination of CE with transcranial magnetic stimulation (TMS), nocturnal polysomnography and examination with the motor part of the Unified Parkinson’s Disease Rating Scale (UPDRS III). Recorded CE parameters included the resting motor threshold (RMT), the motor evoked potential (MEP) and the central silent period (CSP). CE parameters were labelled as initial (ini) when recorded after the TMS of the hemisphere where the disease began and as secondary (sec) otherwise. Bayesian model choice methodology and LASSO were used to choose the best fitting linear models for the main polysomnographic parameters. Results: The Bayesian approach and LASSO both yield the same conclusions, i.e.: The best fitting linear model for total sleep time consists of one explanatory variable, RMTsec. The best model for wake after sleep onset uses RMTsec and RMTini, whereas the amount of NREM2 was best modelled by RMTsec and UPDRSIII. Our data did not support modelling other sleep parameters with linear models using CE parameters or UPDRSIII as explanatory variables. Conclusions: The results indicate there may be an association between sleep disorders and CE changes in PD.
P1043 The quality of polysomnography recording in intensive care unit and the special requirements for the recordings set by ICU environment S. Leivo, M. Ritmala-Castrén, I. Virtanen, E. Liikanen Turku University Central Hospital, Department of Clinical Neurophysiology, Turku, Finland Polysomnography (PSG) is used for the diagnosis of sleep related disorders. This may not only be performed in a sleep laboratory but also in challenging circumstances at a hospital ward or in an intensive care unit (ICU). In the ICU, technical PSG problems arise that are beyond those experienced in a standard PSG laboratory. The aim of this study is to describe the quality of the PSG carried out in the ICU in cases where a trained PSG technician is not available throughout the recording process. A further aim is to describe the proportion of artifact-free signal in each of the measured traces, causes for the artifacts as well as to
find out if the recordings contain sufficient amounts of artifact-free signal for reliable analyses. We also wanted to compare the efficacy of the nasal pressure cannula with the respiratory inductance plethysmography sum signal (RIP) in detection of respiratory events in adult ICU-PSG. A total of 20 overnight PSG recordings performed at a university hospital in southern finland were analyzed for the study. The least artifact-free signal was to be found in the EEG-recording (78.5%) and most artifactfree in the ECG-recording (96.5%) and in the oxygen saturation-recording (SpO2 ) (96.3%). The most common sources of artifacts in the EEG-, EOGand ECG-recordings were body movement and poor electrode contact, in the EMG-recording ECG-artifacts, in SpO2 -recording body movement and in the thoraco-abdominal movement detection and the EMFit-signal the occasional inability of the sensors to detect respiratory movements. Over 90 minutes (which equals one sleep cycle) of completely artifact-free signal on every channel simultaneously was found in 65% of the recordings (fr =13). Respiratory events were scored twice in each study using a nasal pressure-signal and an RIP-signal. A statistically significant difference was detectable only in the amount of apneas/h. In one recording, the difference of the two analyses was significant. In the ICU environment, the quality of PSG recordings varies and the most disturbing artifacts last for last for a long period of time. In circumstances where a trained PSG technician is not available throughout the recording process it is reasonable to record EEG-signal on both sides in frontal, central and occipital head regions as well as to use both the tibialis-EMG-recording and EMFit-recording to detect limb-movements. Respiratory events can usually be diagnosed by using the RIP-signal in case the nasal pressure signal for some reason not usable.
P1045 Automatic sleep classification using a data-driven approach reveals six latent sleep states H. Koch 1,2 , J.A.E. Christensen 1,2 , R. Frandsen 1 , L. Arvastson 3 , S.R. Christensen 4 , P. Jennum 1,5 , H.B.D. Sorensen 2 1 Glostrup University Hospital, Danish Center for Sleep Medicine, Glostrup, Denmark; 2 Technical University of Denmark, Electrical Eng., Kgs. Lyngby, Denmark; 3 H. Lundbeck A/S, Biostatistics, Valby, Denmark; 4 H. Lundbeck A/S, Clinical Pharmacology, Valby, Denmark; 5 University of Copenhagen, Center for Healthy Ageing, Copenhagen, Denmark Question: Will a sleep classifier, which uses a data-driven approach, classify sleep according to the golden standard for manual sleep scoring? Which EEG/EOG characteristics will the model include in the latent sleep states? Methods: An automatic sleep classifier, which evaluates sleep using latent sleep states, was optimized using a data-driven approach. The model used spectral EEG and EOG measures and eye correlation in three seconds windows with one second resolution. Each thirty seconds epoch was expressed as mixture of probabilities of the latent sleep states. The model was applied to four groups to test the application: control subjects and patients with periodic leg movements represented a non-neurodegenerative group and patients with idiopathic REM sleep behavior disorder and Parkinsons Disease represented a neurodegenerative group. The model was optimized using 50 subjects and validated on 73 subjects. Results: The optimized sleep model gave a detailed description of sleep, used six latent sleep states indicating that sleep contains six diverse latent sleep states and the state transitions were expressed as continuous processes. Statistics of the latent sleep states showed accordance to the spectral EEG and EOG content as well as eye movements in the AASM stages. The sleep model performed similar across the four groups and the overall subject-specific accuracy reached (%) 68.3±7.5. Conclusions: Analysing sleep using a data-driven approach and inclusion of only EEG and EOG revealed six latent sleep states. The model is general applicable on subject groups and may contribute to the research in sleep and neurodegenerative diseases.