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Abstract
AbstractElectroencephalography (EEG) and evoked potential studies are established monitoring tools in the neurological intensive care unit (ICU). These neurophysiologic techniques provide information on physiological state and response to therapy, and may aid diagnosis and prognosis. Serial studies or continuous monitoring may enable changes to be detected prior to irreversible deterioration in the patient's condition. Current computer technology allows simultaneous display and correlation of electrophysiologic parameters, cardiovascular state and intracranial pressure (ICP). Continuous EEG monitoring in the ICU has been shown to have a decisive or contributing impact on medical decision making in more than three-quarters of patients. In addition, continuous EEG monitoring has revealed previously unsuspected non-convulsive seizures in one-third of patients. SEPs and BAEPs can provide useful prognostic information in coma - however, these tests are etiologically nonspecific and must be carefully integrated into the clinical situation. Motor evoked potentials offer a potentially useful tool for evaluating motor system abnormalities in the ICU.
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Mikell CB, Dyster TG, Claassen J. Invasive seizure monitoring in the critically-Ill brain injury patient: Current practices and a review of the literature. Seizure 2016; 41:201-5. [PMID: 27364336 PMCID: PMC5505252 DOI: 10.1016/j.seizure.2016.05.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 05/27/2016] [Indexed: 01/17/2023] Open
Abstract
Seizures commonly occur in a variety of serious neurological illnesses, and lead to additional morbidity and worsened outcomes. Recently, it has become clear that not all seizures in the acute brain injury setting are evident on scalp EEG. To address this, we have developed a protocol for depth electrode placement in the neuro-intensive care unit for patients in whom the clinical suspicion of occult seizures is high. In the current manuscript, we review the literature on depth EEG monitoring for ictal events in critically-ill, unconscious patients, focusing on the incidence of seizures not detected with scalp EEG in various conditions. We critically discuss evidence in support of and against treating these events that are only detectable on depth recordings. We describe additional specific scenarios in which depth EEG recordings may be helpful, including for the detection of delayed cerebral ischemia following subarachnoid hemorrhage. We then describe current techniques for bedside electrode placement. Finally, we outline potential avenues for future investigations, including the use of depth electrodes to describe circuit abnormalities in acute brain injury.
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Affiliation(s)
- Charles B Mikell
- Functional and Cognitive Neurophysiology Lab, Columbia University Medical Center, Department of Neurological Surgery, New York Presbyterian Hospital, New York, NY, USA
| | - Timothy G Dyster
- Functional and Cognitive Neurophysiology Lab, Columbia University Medical Center, Department of Neurological Surgery, New York Presbyterian Hospital, New York, NY, USA
| | - Jan Claassen
- Columbia University Medical Center, Department of Neurology, Division of Critical Care and Hospitalist Neurology, New York Presbyterian Hospital, New York, NY, USA.
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André-Obadia N, Parain D, Szurhaj W. Continuous EEG monitoring in adults in the intensive care unit (ICU). Neurophysiol Clin 2015; 45:39-46. [PMID: 25639999 DOI: 10.1016/j.neucli.2014.11.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 11/03/2014] [Indexed: 11/26/2022] Open
Abstract
Continuous EEG monitoring in the ICU is different from planned EEG due to the rather urgent nature of the indications, explaining the fact that recording is started in certain cases by the clinical team in charge of the patient's care. Close collaboration between neurophysiology teams and intensive care teams is essential. Continuous EEG monitoring can be facilitated by quantified analysis systems. This kind of analysis is based on certain signal characteristics, such as amplitude or frequency content, but raw EEG data should always be interpreted if possible, since artefacts can sometimes impair quantified EEG analysis. It is preferable to work within a tele-EEG network, so that the neurophysiologist has the possibility to give an interpretation on call. Continuous EEG monitoring is thus useful in the diagnosis of non-convulsive epileptic seizures or purely electrical discharges and in the monitoring of status epilepticus when consciousness disorders persist after initial treatment. A number of other indications are currently under evaluation.
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Affiliation(s)
- N André-Obadia
- Service de neurophysiologie et d'épileptologie, hôpital Neurologique P.-Wertheimer, hospices civils de Lyon, 59, boulevard Pinel, 69677 Bron cedex, France; Inserm U 1028, NeuroPain team, centre de recherche en neuroscience de Lyon (CRNL), université Lyon 1, 69677 Bron cedex, France.
| | - D Parain
- Service de neurophysiologie clinique, CHU Charles-Nicolle, 76031 Rouen cedex, France
| | - W Szurhaj
- Service de neurophysiologie clinique, hôpital Roger-Salengro, CHRU, 59037 Lille cedex, France; Faculté de médecine Henri-Warembourg, université Lille 2, 59045 Lille cedex, France
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[French guidelines on electroencephalogram]. Neurophysiol Clin 2014; 44:515-612. [PMID: 25435392 DOI: 10.1016/j.neucli.2014.10.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2014] [Accepted: 10/07/2014] [Indexed: 12/11/2022] Open
Abstract
Electroencephalography allows the functional analysis of electrical brain cortical activity and is the gold standard for analyzing electrophysiological processes involved in epilepsy but also in several other dysfunctions of the central nervous system. Morphological imaging yields complementary data, yet it cannot replace the essential functional analysis tool that is EEG. Furthermore, EEG has the great advantage of being non-invasive, easy to perform and allows control tests when follow-up is necessary, even at the patient's bedside. Faced with the advances in knowledge, techniques and indications, the Société de Neurophysiologie Clinique de Langue Française (SNCLF) and the Ligue Française Contre l'Épilepsie (LFCE) found it necessary to provide an update on EEG recommendations. This article will review the methodology applied to this work, refine the various topics detailed in the following chapters. It will go over the summary of recommendations for each of these chapters and underline proposals for writing an EEG report. Some questions could not be answered by the review of the literature; in those cases, an expert advice was given by the working and reading groups in addition to the guidelines.
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Stone JL, Fino J, Patel K, Calderon-Arnulphi M, Suss N, Hughes JR. Modified brain stem auditory evoked potentials in patients with intracranial mass lesions. Clin EEG Neurosci 2012. [PMID: 23185089 DOI: 10.1177/1550059412452688] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The authors report their experience utilizing a recently described rapid rate, binaural click and 1000-Hz tone burst modification of the brain stem auditory evoked potentials (BAEP), modified (MBP), in 27 symptomatic patients with non-brain stem compressive space-taking cerebral lesions (22), hydrocephalus (4), and pseudotumor cerebri (1). Many presented with clinical signs suggestive of increased intracranial pressure (ICP) and focal neurological deficits. The cerebral lesions, mostly large tumors with edema, had very substantial radiological signs of mass effect. Fourteen patients were also studied following surgical decompression. A number of significant changes in the wave V and Vn latency/intensity and less so amplitude/intensity function was found in the 27 patients, compared to normal volunteers, as well as those studied pre- and postoperatively. Similar MBP changes had been noted in normal volunteers placed in a dependent head position. Possible mechanisms to explain these findings are discussed. The MBP methodology shows promise and further development could make neuro-intensive care unit monitoring practical.
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Affiliation(s)
- James L Stone
- Department of Neurosurgery and Neurology, University of Illinois Medical Center at Chicago, IL 60612, USA.
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Brainstem auditory evoked potentials--a review and modified studies in healthy subjects. J Clin Neurophysiol 2009; 26:167-75. [PMID: 19424080 DOI: 10.1097/wnp.0b013e3181a76a6e] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The authors review the brainstem auditory evoked potential (BAEP), and present studies on 40 healthy subjects. In addition to the conventional click evoked BAEP, three modified BAEP examinations were performed. The modified BAEP tests include a 1,000 Hz tone-burst BAEP, and more rapid rate binaural click and 1,000 Hz tone-burst BAEPs-each of the last two studies performed at four diminishing moderate intensities. In addition to the usual parameters, the authors examined the Wave V to Vn interpeak latency, and stimulus intensity versus Wave V latency and amplitude functions in the rapid rate binaural studies. Studies were also repeated on healthy subjects in a dependant head position in an attempt to increase intracranial pressure. Discussion centers on the BAEP, its current utility in medicine, unique neurophysiology, and literature support that the above modifications could increase the practicality of the test in patients at risk with intracranial lesions and perhaps improve the feasibility for real-time continuous or frequent monitoring in the future.
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Affiliation(s)
- M R Nuwer
- Clinical Neurophysiology Department, Reed Neurological Research Center, 710 Westwood Plaza, Room 1-194, Los Angeles, CA 90095-6987, USA
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Vespa PM, Boscardin WJ, Hovda DA, McArthur DL, Nuwer MR, Martin NA, Nenov V, Glenn TC, Bergsneider M, Kelly DF, Becker DP. Early and persistent impaired percent alpha variability on continuous electroencephalography monitoring as predictive of poor outcome after traumatic brain injury. J Neurosurg 2002; 97:84-92. [PMID: 12134937 DOI: 10.3171/jns.2002.97.1.0084] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Early prediction of outcomes in patients after they suffer traumatic brain injury (TBI) is often nonspecific and based on initial imaging and clinical findings alone, without direct physiological testing. Improved outcome prediction is desirable for ethical, social, and financial reasons. The goal of this study was to determine the usefulness of continuous electroencephalography (EEG) monitoring in determining prognosis early after TBI, while the patient is in the intensive care unit. METHODS The authors hypothesized that the reduced percentage of alpha variability (PAV) in continuous EEG tracings indicates a poor prognosis. Prospective continuous EEG monitoring was performed in 89 consecutive patients with moderate to severe TBI (Glasgow Coma Scale [GCS] Scores 3-12) from 0 to 10 days after injury. The PAV was calculated daily, and the time course and trends of the PAV were analyzed in comparison with the patient's Glasgow Outcome Scale (GOS) score at the time of discharge. In patients with GCS scores of 8 or lower, a PAV value of 0.1 or lower is highly predictive of a poor outcome or death (positive predictive value 86%). The determinant PAV value was obtained by Day 3 after injury. Persistent PAV values of 0.1 or lower over several days or worsening of the PAV to a value of 0.1 or lower indicated a high likelihood of poor outcome (GOS Scores 1 and 2). In comparison with the combination of traditional initial clinical indicators of outcome (GCS score, pupillary response to light, patient age, results of computerized tomography scanning, and early hypotension or hypoxemia), the early PAV value during the initial 3 days after injury independently improved prognostic ability (p < 0.01). CONCLUSIONS Continuous EEG monitoring performed with particular attention paid to the PAV is a sensitive and specific method of prognosis that can indicate outcomes in patients with moderate to severe TBI within 3 days postinjury.
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Affiliation(s)
- Paul M Vespa
- Department of Neurology, School of Medicine, University of California at Los Angeles, 90095, USA.
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Smith MC. Quantification of neurologic function. Crit Care Med 2001; 29:2036-7. [PMID: 11588486 DOI: 10.1097/00003246-200110000-00039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ruiz-López MJ, Martínez de Azagra A, Serrano A, Casado-Flores J. Brain death and evoked potentials in pediatric patients. Crit Care Med 1999; 27:412-6. [PMID: 10075069 DOI: 10.1097/00003246-199902000-00051] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To define the evoked potential responses (auditory and somatosensory) obtained from pediatric brain-dead patients. DESIGN Prospective study over an 8-yr period (1988-1996). SETTING A 14-bed pediatric intensive care unit in a multidisciplinary regional referral center (teaching hospital). PATIENTS Fifty-one pediatric patients with clinically established brain death. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Auditory brainstem and somatosensory evoked potentials were performed with a mean evolution time of 24 hrs after clinical brain death. The first brainstem auditory evoked potential recording was compatible with the diagnosis in 45 patients (90%): 27 patients (53%) did not respond, wave I was patent in 16 (7 bilateral, 6 from the left side, and 3 from the right side), and 2 patients evoked waves I and II in one or both ears. Gross anomalies were found in the remaining six patients. Sixteen patients were tested for somatosensory evoked potentials. N13 identifiable wave (62.5% of the patients) or a flat record were the obtained findings. Electric silence was noted initially on the electroencephalogram (EEG) in only 14 of 29 patients. Later flattening was observed in seven patients. Missing brainstem evoked response was noted earlier than cortical electric silence (range, 12-144 hrs). Any central wave could be pointed out in the evoked potentials of patients with an isoelectric EEG. CONCLUSIONS Evoked potential is useful in confirming the diagnosis of brain death in infants and in children as well as in adults. The test can be performed at bedside without interfering with patient care, and results are similar to those obtained in adult patients. Flattening of the EEG requires more time than achieving compatible evoked-potential responses.
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Affiliation(s)
- M J Ruiz-López
- Department of Pediatrics, Hospital Infantil del Niño Jesús, Autonomous University of Madrid, Spain
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Chiappa KH, Hill RA. Evaluation and prognostication in coma. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY 1998; 106:149-55. [PMID: 9741776 DOI: 10.1016/s0013-4694(97)00118-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Electroencephalography (EEG) and evoked potential (EP) studies are neurophysiologic techniques which provide information on physiological state and response to therapy, and may aid diagnosis and prognosis. Serial studies or continuous monitoring may enable changes to be detected prior to irreversible deterioration in the patient's condition. Current computer technology allows simultaneous display and correlation of electrophysiologic parameters, cardiovascular state and ICP. Continuous EEG monitoring in the ICU has been shown to have a decisive or contributing impact on medical decision making in more than three-quarters of patients. In addition, continuous EEG monitoring has revealed previously unsuspected non-convulsive seizures in two-thirds of patients. Somatosensory and auditory EPs can provide useful prognostic information in coma patients, however, these tests are etiologically non-specific and must be carefully integrated into the clinical situation. Motor EPs offer a potentially useful tool for evaluating motor system abnormalities in the ICU. Thus, neurophysiologic tests are established monitoring tools in the neurological intensive care unit.
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Affiliation(s)
- K H Chiappa
- Massachusetts General Hospital, EEG Laboratory, Boston 02114, USA
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Litscher G, Schwarz G, Jobstmann R, Kehl G, Kleinert R. Brain-stem auditory evoked potential monitoring. The increase of the stimulus artifact in the development of brain death: a biological phenomenon? Int J Neurosci 1997; 91:95-103. [PMID: 9394218 DOI: 10.3109/00207459708986368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Brain-stem auditory evoked potentials (BAEPs) were recorded in 12 dead subjects (mean age, 72.6 +/- 14.8 years), 30.6 +/- 19.5 hours (range 9-70) after abolished systemic circulation. Death was due to cardiac failure (n = 10), intracerebral hemorrhage (n = 1) and larynx cancer (n = 1). The presence and amplitude of the stimulus artifact were evaluated. The mean (+/- SD) amplitudes of the stimulus artifact was 0.03 +/- 0.02 microV on the left side and 0.01 +/- 0.02 microV on the right side. These findings in accordance with previous studies on comatose patients and brain dead subjects confirm that the increase of the stimulus artifact in the development of brain death, in spite of stimulation with alternating polarity, seems to reflect a biological phenomenon which is not found in dead subjects after complete cessation of systemic circulation.
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Affiliation(s)
- G Litscher
- Department of Anesthesiology and Intensive Care Medicine, University of Graz, Austria
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Chatrian GE, Bergamasco B, Bricolo A, Frost JD, Prior PF. IFCN recommended standards for electrophysiologic monitoring in comatose and other unresponsive states. Report of an IFCN committee. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY 1996; 99:103-22. [PMID: 8761047 DOI: 10.1016/0013-4694(96)96059-9] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- G E Chatrian
- Department of Neurology, University of Washington Medical Center, Seattle 98195, USA
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Litscher G. Middle latency auditory evoked potentials in intensive care patients and normal controls. Int J Neurosci 1995; 83:253-67. [PMID: 8869431 DOI: 10.3109/00207459508986342] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Evoked potentials have been introduced into intensive care unit to objectively measure parameters of coma. In particular, auditory brainstem evoked potentials have been useful for localizing brainstem dysfunction in comatose patients. The middle latency auditory evoked potentials (MLAEPs) believed to be a response of subcortical auditory radiations and the primary auditory cortex. MLAEPs were measured in 40 adults (mean age 24.9 +/- 2.9 years; range: 19-34 years) with normal hearing and in 102 intensive care patients (mean age: 48.4 +/- 18.9 years; range: 14-86 years) under the influence of biological variables. Latencies (control group, mean +/- SD: V = 5.74 +/- .29 ms, N0 = 9.11 +/- 1.74 ms, P0 = 12.94 +/- 1.87 ms, Na = 17.23 +/- 1.77 ms, and Pa = 29.22 +/- 3.43 ms), amplitudes (control group, mean +/- SE: N0-P0 = 2.00 +/- .34 microV, P0-Na = 3.88 +/- .67 microV, Na-Pa = 2.83 +/- .29 microV) and the amplitude ratio (control group, mean +/- SE: P0-Na/Na-Pa = 1.53 +/- .39) were calculated. In the control group in both females and males, right-sided stimulation produced shorter average MLAEP latencies and higher amplitudes than left-sided stimulation (Pa-right 28.26 +/- 3.53 ms; Pa-left 30.17 +/- 3.33 ms). MLAEPs showed significant differences according to sex but did not depend significantly on age. A temperature dependence was found for the latency of wave V (short latency AEP), which was prolonged at lower temperatures and for the amplitude Na-Pa, which was increased at decreased temperatures between 38.9 and 35.4 degrees C. There was a significant association between the amplitude Na-Pa and PO2 (P = .017). Alterations of PCO2 in the range of 26 to 54 mmHg did not influence the MLAEPs. Also, renal dysfunction or hepatic dysfunction and alterations of mean arterial pressure (range: 50-102 mmHg) did not affect MLAEP latencies and amplitudes significantly. Increases in latencies and decreases in amplitude were seen in sedated patients. These results in intensive care patients suggest that the combination of early AEP (acute phase) and MLAEP (post acute phase) may be useful to monitor comatose patients.
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Affiliation(s)
- G Litscher
- Department of Anesthesiology, University of Graz, Austria
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Litscher G, Schwarz G, Kleinert R. Brain-stem auditory evoked potential monitoring. Variations of stimulus artifact in brain death. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY 1995; 96:413-9. [PMID: 7555915 DOI: 10.1016/0168-5597(95)00045-t] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Brain-stem auditory evoked potentials (BAEPs) were recorded in 20 subjects with brain death (mean age, 33.2 +/- 15.1 years) and 20 healthy volunteers (mean age, 29.8 +/- 6.8 years). Brain death was due to head injury (n = 14), encephalitis (n = 3), brain-stem hemorrhage (n = 1), cerebellar hemorrhage (n = 1) or cerebral infarction (n = 1). The presence, latency and amplitude of the individual BAEP components and variations of the stimulus artifact were evaluated. The mean (+/- S.D.) amplitude of the stimulus artifact was 0.26 +/- 0.12 microV in the brain-dead subjects and 0.09 +/- 0.05 microV in the control group (P < 0.001, t test). The causes of the phenomenon of increasing stimulus artifacts in the evolution of brain death remain unclear.
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Affiliation(s)
- G Litscher
- Department of Anesthesiology, University of Graz, Austria
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