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EP 144. Detection of cerebral vasospasm following aneurysmal subarachnoid hemorrhage using motor evoked potentials
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Abstracts / Clinical Neurophysiology 127 (2016) e210–e303
the ‘‘resting” condition, where the muscle tone was visually minimized, linear and non-linear modeling of CSE independent of possible left-over preinnervation should yield similar results (Darling et al. 2006). Methods: Trains of single pulses of navigated TMS (nTMS) were applied to the dominant ‘‘hot-spot” of the first dorsal interosseous muscle (FDI) in healthy volunteers (4 f., 3 m.). In the ‘‘active” condition, subjects performed an isometric flexion of the index finger with three pre-defined force levels in a randomized order. In the ‘‘resting” condition, relaxation was visually monitored in the surface EMG of the FDI. Preinnervation was defined by the area-under-the-curve in 100, 200 and 300 ms time bins in the EMG prior to a stimulus. The amount of variability of motor evoked potentials explained by these measures of preinnervation was assessed with a simple linear and a non-linear regression using a sigmoidal fit. Results: In the ‘‘active” condition, the predictive validity of preinnervation steadily increased with longer time bins, starting at about 60% (p < 0.001) using a 100 ms time bin and a linear fit to about 70% (p < 0.001) using a 300 ms time bin and a sigmoidal fit. In subjects at rest, no significant difference between the fitting algorithm and different time bins was found. Conclusions: In line with previous studies, preinnervation validly predicted CSE in both linear (Schmidt et al. 2015) and non-linear (Darling et al. 2006) regression. Across different levels of muscle activity, a sigmoidal fit might reflect the input-output properties of the stimulated cortico-spinal networks and thus yield higher predictive validity (Devanne et al. 1997). In the resting motor state, we suggest linear regression as a valid method to measure and correct for preinnervation. doi:10.1016/j.clinph.2016.05.181
EP 143. Test-retest reliability of single and paired pulse transcranial magnetic stimulation parameters in healthy men and women—A. Hermsen a,b, A. Haag b, C. Duddek b, K. Balkenhol b, H. Bugiel b, S. Bauer a,b, V. Mylius b, K. Menzler b, F. Rosenow a,b (a Universitätsklinikum Frankfurt, Epilepsiezentrum Frankfurt b Rhein-Main, Frankfurt, Germany, Universitätsklinikum Marburg, Epilepsiezentrum Hessen, Marburg, Germany)
Question: To determine the influence of different factors on testretest reliability of frequently used transcranial magnetic stimulation (TMS) parameters while controlling for potential confounders in healthy subjects. Methods: TMS was applied in 93 healthy volunteers (61% male) twice (mean retest interval of 34.0 ± 25.6 (SD) days) between 7 am and 2 pm by four investigators (sessions n investigator A = 47, investigator B = 95, investigator C = 28, investigator D = 16). Women were assessed only in their follicular phase. Test stimulus (TS), resting motor threshold (RMT), short latency intracortical inhibition (SICI), intracortical facilitation (ICF) and cortical silent period (SCP) were analyzed. CSP was analyzed visually and automatically. Results: Good test-retest reliabilities were observed for TS (r = .880) and RMT (r = .826), moderate for visual and automated analyzed CSP durations (resp. r = .466, r = .486), and poor for ICF (r = .159). Gender (eg. automated CSP women: r = .538 vs. men: r = .422), re-test interval and method of CSP-analysis did not influence reliabilities. Reliable change indices are reported. Conclusions: In a large sample of healthy volunteers we found good to moderate test-retest reliabilities in all but one TMSparameter. Automated analysis of the CSP did not prove to be more
reliable than visual determination. For the first time it presents reliable change indices for all frequently used TMS parameters. These data can be helpful to determine the significance of observed changes in cortical excitability as well as for study design and sample size calculation in future research, in healthy populations. doi:10.1016/j.clinph.2016.05.182
EP 144. Detection of cerebral vasospasm following aneurysmal subarachnoid hemorrhage using motor evoked potentials— S. Grossauer a,*, K. Koeck a,*, J. Kraschl b, G.H. Vince b (a University of California San Francisco, Department of Neurological Surgery Helen Diller Cancer Research Building, San Francisco, United States, b Akademisches Lehrspital Klagenfurt, Neurochirurgie, Klagenfurt, Austria) ⇑
Corresponding authors.
Background: Early detection of vasospasm (VS) following aneurysmal subarachnoid hemorrhage (aSAH) is vital to trigger therapy and to prevent infarction and subsequent permanent neurological deficit. Although motor evoked potentials (MEPs) are a well-established method for intraoperative detection of cerebral VS and cerebral ischemia during aneurysm surgery, there are no studies investigating the diagnostic value of MEPs for detecting delayed VS following aSAH in an intensive care unit. Objective: A prospective study was conceived to assess the diagnostic accuracy of MEPs in comparison with digital subtraction angiography. Methods: MEP threshold changes were determined in patients both with and without angiographic VS following high-grade aSAHs. Sensitivity, specificity, and the positive and negative predictive values of significant MEP threshold increases, which indicate angiographic VS, were calculated. Results: In all patients experiencing VS of the arteries supplying cerebral motor areas, a minimal MEP threshold increase of 50 mA (mean 66.25 mA) was observed, whereas a maximum MEP threshold increase of 30 mA was observed in patients without VS. Therefore, an increase from a baseline of P50 mA was considered significant and resulted in a sensitivity of 0.83, a specificity of 0.92, a positive predictive value of 0.83, and a negative predictive value of 0.92. Conclusion: VS following aSAH can be detected accurately by using MEPs. MEPs are a feasible bedside tool for online VS detection in an intensive care unit and, therefore, may complement existing diagnostic tools. Abbreviations: aSAH, aneurysmal subarachnoid hemorrhageDSA, digital subtraction angiographyICU, intensive care unitMEP, motor evoked potentialPCT, perfusion computed tomographyTCD, transcranial DopplerVS, vasospasm. doi:10.1016/j.clinph.2016.05.183
EP 145. Neuropeptide Y and the cellular effects of transcranial magnetic theta-burst stimulation in rat neocortex—D. Jazmati, U. Neubacher, V. Aliane, K. Funke * (Ruhr-Universität Bochum, Neurophysiologie, Bochum, Germany) ⇑
Corresponding author.
Questions: High-frequency transcranial magnetic stimulation with theta-burst stimulation (TBS) induces strong and highly synchronous cortical network activity principally able to trigger
Abstracts / Clinical Neurophysiology 127 (2016) e210–e303
the ‘‘resting” condition, where the muscle tone was visually minimized, linear and non-linear modeling of CSE independent of possible left-over preinnervation should yield similar results (Darling et al. 2006). Methods: Trains of single pulses of navigated TMS (nTMS) were applied to the dominant ‘‘hot-spot” of the first dorsal interosseous muscle (FDI) in healthy volunteers (4 f., 3 m.). In the ‘‘active” condition, subjects performed an isometric flexion of the index finger with three pre-defined force levels in a randomized order. In the ‘‘resting” condition, relaxation was visually monitored in the surface EMG of the FDI. Preinnervation was defined by the area-under-the-curve in 100, 200 and 300 ms time bins in the EMG prior to a stimulus. The amount of variability of motor evoked potentials explained by these measures of preinnervation was assessed with a simple linear and a non-linear regression using a sigmoidal fit. Results: In the ‘‘active” condition, the predictive validity of preinnervation steadily increased with longer time bins, starting at about 60% (p < 0.001) using a 100 ms time bin and a linear fit to about 70% (p < 0.001) using a 300 ms time bin and a sigmoidal fit. In subjects at rest, no significant difference between the fitting algorithm and different time bins was found. Conclusions: In line with previous studies, preinnervation validly predicted CSE in both linear (Schmidt et al. 2015) and non-linear (Darling et al. 2006) regression. Across different levels of muscle activity, a sigmoidal fit might reflect the input-output properties of the stimulated cortico-spinal networks and thus yield higher predictive validity (Devanne et al. 1997). In the resting motor state, we suggest linear regression as a valid method to measure and correct for preinnervation. doi:10.1016/j.clinph.2016.05.181
EP 143. Test-retest reliability of single and paired pulse transcranial magnetic stimulation parameters in healthy men and women—A. Hermsen a,b, A. Haag b, C. Duddek b, K. Balkenhol b, H. Bugiel b, S. Bauer a,b, V. Mylius b, K. Menzler b, F. Rosenow a,b (a Universitätsklinikum Frankfurt, Epilepsiezentrum Frankfurt b Rhein-Main, Frankfurt, Germany, Universitätsklinikum Marburg, Epilepsiezentrum Hessen, Marburg, Germany)
Question: To determine the influence of different factors on testretest reliability of frequently used transcranial magnetic stimulation (TMS) parameters while controlling for potential confounders in healthy subjects. Methods: TMS was applied in 93 healthy volunteers (61% male) twice (mean retest interval of 34.0 ± 25.6 (SD) days) between 7 am and 2 pm by four investigators (sessions n investigator A = 47, investigator B = 95, investigator C = 28, investigator D = 16). Women were assessed only in their follicular phase. Test stimulus (TS), resting motor threshold (RMT), short latency intracortical inhibition (SICI), intracortical facilitation (ICF) and cortical silent period (SCP) were analyzed. CSP was analyzed visually and automatically. Results: Good test-retest reliabilities were observed for TS (r = .880) and RMT (r = .826), moderate for visual and automated analyzed CSP durations (resp. r = .466, r = .486), and poor for ICF (r = .159). Gender (eg. automated CSP women: r = .538 vs. men: r = .422), re-test interval and method of CSP-analysis did not influence reliabilities. Reliable change indices are reported. Conclusions: In a large sample of healthy volunteers we found good to moderate test-retest reliabilities in all but one TMSparameter. Automated analysis of the CSP did not prove to be more
reliable than visual determination. For the first time it presents reliable change indices for all frequently used TMS parameters. These data can be helpful to determine the significance of observed changes in cortical excitability as well as for study design and sample size calculation in future research, in healthy populations. doi:10.1016/j.clinph.2016.05.182
EP 144. Detection of cerebral vasospasm following aneurysmal subarachnoid hemorrhage using motor evoked potentials— S. Grossauer a,*, K. Koeck a,*, J. Kraschl b, G.H. Vince b (a University of California San Francisco, Department of Neurological Surgery Helen Diller Cancer Research Building, San Francisco, United States, b Akademisches Lehrspital Klagenfurt, Neurochirurgie, Klagenfurt, Austria) ⇑
Corresponding authors.
Background: Early detection of vasospasm (VS) following aneurysmal subarachnoid hemorrhage (aSAH) is vital to trigger therapy and to prevent infarction and subsequent permanent neurological deficit. Although motor evoked potentials (MEPs) are a well-established method for intraoperative detection of cerebral VS and cerebral ischemia during aneurysm surgery, there are no studies investigating the diagnostic value of MEPs for detecting delayed VS following aSAH in an intensive care unit. Objective: A prospective study was conceived to assess the diagnostic accuracy of MEPs in comparison with digital subtraction angiography. Methods: MEP threshold changes were determined in patients both with and without angiographic VS following high-grade aSAHs. Sensitivity, specificity, and the positive and negative predictive values of significant MEP threshold increases, which indicate angiographic VS, were calculated. Results: In all patients experiencing VS of the arteries supplying cerebral motor areas, a minimal MEP threshold increase of 50 mA (mean 66.25 mA) was observed, whereas a maximum MEP threshold increase of 30 mA was observed in patients without VS. Therefore, an increase from a baseline of P50 mA was considered significant and resulted in a sensitivity of 0.83, a specificity of 0.92, a positive predictive value of 0.83, and a negative predictive value of 0.92. Conclusion: VS following aSAH can be detected accurately by using MEPs. MEPs are a feasible bedside tool for online VS detection in an intensive care unit and, therefore, may complement existing diagnostic tools. Abbreviations: aSAH, aneurysmal subarachnoid hemorrhageDSA, digital subtraction angiographyICU, intensive care unitMEP, motor evoked potentialPCT, perfusion computed tomographyTCD, transcranial DopplerVS, vasospasm. doi:10.1016/j.clinph.2016.05.183
EP 145. Neuropeptide Y and the cellular effects of transcranial magnetic theta-burst stimulation in rat neocortex—D. Jazmati, U. Neubacher, V. Aliane, K. Funke * (Ruhr-Universität Bochum, Neurophysiologie, Bochum, Germany) ⇑
Corresponding author.
Questions: High-frequency transcranial magnetic stimulation with theta-burst stimulation (TBS) induces strong and highly synchronous cortical network activity principally able to trigger