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P30.1 Binocular beat visual evoked potentials in early strabismus
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Posters / Clinical Neurophysiology 117 (2006) S121–S336
subjects), as well as conventional EMG revealed high amplitude long duration motor unit potentials and moderately decreased recruitment but without denervation activity. Conclusions: Subclinical electrophysiologic abnormalities (including axonal damage) may be revealed in individuals after several months of complete recovery from GBS. doi:10.1016/j.clinph.2006.06.490
tribute to the understanding of binocularity in early strabismus. doi:10.1016/j.clinph.2006.06.491
P30.2 Diagnostic accuracy of early clinical signs,somatosensory evoked potentials and electroencephalography in predicting outcome of hypoxic coma in adults Y.C. Lee 1, D.A. Ingram 1, T.G. Phan 2 1
P30.1 Binocular beat visual evoked potentials in early strabismus N. Alexandri 1, A. Magot 2, V. Capart 3, A. Pechereau 3, S. Nguyen 2, Y. Pereon 2 1
Explorations Fonctionnelles, Hopital Bichat, France 2 Laboratoire d’Explorations Fonctionnelles, Hotel Dieu, France 3 Clinique Ophtalmologique, Hotel Dieu, France Background: Clinical methods that measure binocularity are widely used, especially in strabismic children at risk of amblyopia. However, they provide no objective approach and may be difficult in young children. Objectives: The aim of this study was to assess the use of binocular beat visual evoked potentials (BB-VEPs) as an electrophysiological tool for deficient binocular function detection. Patients and methods: BB-VEPs were recorded in 38 children presenting with severe early strabismus (9 months–14 years mean: 4 years old). Eyes were stimulated by red light emitting diode goggles flickering sinusoidally at rates of 10 Hz (left, Fq1) and 12 Hz (right, Fq2). Fast Fourier Transformation was computed on 2-s epochs of BB-VEP recording (Oz-Fz, Oz-Cz, Oz-left earlobe, twice 25 averaged sweeps). BB-VEP normal responses appear as peaks at Fq1, Fq2 and Fq1 + Fq2 Hz (sum response). The latter is known to represent non-linear interactions between the stimulation frequencies and to reflect binocular integration at the occipital cortex. Quantitative analysis of the data (FFT peaks) was performed. Results: BB-VEPs were obtained in all patients. Seven patients had no sum response (FFT peak-to-noise ratio >1.5) in any of the montages, 22 showed sum response in more than one montage and nine had always sum responses. There was a significant correlation between sum response and visual acuity. Baseline characteristics, type, duration, age of onset of binocular visual disturbances or degree of deviation did not differ among the three groups. Discussion and conclusion: Binocular VEP is an easily performed, low-cost test providing unambiguous evidence of cortical binocular integration. It can be used in very young patients lacking fusion vergence. Through qualitative and quantitative result analysis it can con-
Barts and The London NHS Trust, Department of Clinical Neurophysiology, UK 2 Monash Medical Centre, Department of Neurology, Australia Background and objective: Attempts to identify the best prognostic markers for the outcome of hypoxic coma using traditional analysis of sensitivity and specificity have yielded a range of results partly due to the heterogeneity of the study population and the diagnostic threshold. We have therefore performed a meta-analysis of 39 publications in the world literature using summary receiver operating characteristic curves (SROC) and compared the diagnostic accuracy of pupil responses, motor responses, Glasgow Coma Score (GCS), bilateral absence of somatosensory evoked potentials (SEP) and electroencephalographic findings in predicting outcome of hypoxic coma. Methods: PubMed (1966–2005), Medline (1966–2005) and Embase (1966–2005) were searched for reports in English, German and French. Manual review of article reference lists was conducted for additional studies. Raw data was extracted into a 2 · 2 table such that patients with positive and negative ’test’ results and their eventual clinical outcome were clearly demonstrated. A SROC curve was plotted for each test, thus allowing the comparison of the different tests using the calculated odds ratio (OR) and area under curve (AUC). Results: The AUCs of SROCs (indicative of diagnostic accuracy) for absent pupillary and graded motor responses (M1, M < 2, M < 3) for each of the 3 days post-coma showed an incremental pattern with optimal results on day 3. The AUCs of SROCs for absent pupillary and motor responses (M1) were generally larger than those for bilaterally absent SEP throughout the 3 days postcoma. Conclusions: These results provide support for the notion that diagnostic accuracy of coma outcome improves with time after the onset of coma, being optimal on day 3. Further, the overall diagnostic accuracies for absent pupillary response and motor response (M1) are superior to that of absent somatosensory evoked potentials throughout the first 3 days post-coma. doi:10.1016/j.clinph.2006.06.492
Posters / Clinical Neurophysiology 117 (2006) S121–S336
subjects), as well as conventional EMG revealed high amplitude long duration motor unit potentials and moderately decreased recruitment but without denervation activity. Conclusions: Subclinical electrophysiologic abnormalities (including axonal damage) may be revealed in individuals after several months of complete recovery from GBS. doi:10.1016/j.clinph.2006.06.490
tribute to the understanding of binocularity in early strabismus. doi:10.1016/j.clinph.2006.06.491
P30.2 Diagnostic accuracy of early clinical signs,somatosensory evoked potentials and electroencephalography in predicting outcome of hypoxic coma in adults Y.C. Lee 1, D.A. Ingram 1, T.G. Phan 2 1
P30.1 Binocular beat visual evoked potentials in early strabismus N. Alexandri 1, A. Magot 2, V. Capart 3, A. Pechereau 3, S. Nguyen 2, Y. Pereon 2 1
Explorations Fonctionnelles, Hopital Bichat, France 2 Laboratoire d’Explorations Fonctionnelles, Hotel Dieu, France 3 Clinique Ophtalmologique, Hotel Dieu, France Background: Clinical methods that measure binocularity are widely used, especially in strabismic children at risk of amblyopia. However, they provide no objective approach and may be difficult in young children. Objectives: The aim of this study was to assess the use of binocular beat visual evoked potentials (BB-VEPs) as an electrophysiological tool for deficient binocular function detection. Patients and methods: BB-VEPs were recorded in 38 children presenting with severe early strabismus (9 months–14 years mean: 4 years old). Eyes were stimulated by red light emitting diode goggles flickering sinusoidally at rates of 10 Hz (left, Fq1) and 12 Hz (right, Fq2). Fast Fourier Transformation was computed on 2-s epochs of BB-VEP recording (Oz-Fz, Oz-Cz, Oz-left earlobe, twice 25 averaged sweeps). BB-VEP normal responses appear as peaks at Fq1, Fq2 and Fq1 + Fq2 Hz (sum response). The latter is known to represent non-linear interactions between the stimulation frequencies and to reflect binocular integration at the occipital cortex. Quantitative analysis of the data (FFT peaks) was performed. Results: BB-VEPs were obtained in all patients. Seven patients had no sum response (FFT peak-to-noise ratio >1.5) in any of the montages, 22 showed sum response in more than one montage and nine had always sum responses. There was a significant correlation between sum response and visual acuity. Baseline characteristics, type, duration, age of onset of binocular visual disturbances or degree of deviation did not differ among the three groups. Discussion and conclusion: Binocular VEP is an easily performed, low-cost test providing unambiguous evidence of cortical binocular integration. It can be used in very young patients lacking fusion vergence. Through qualitative and quantitative result analysis it can con-
Barts and The London NHS Trust, Department of Clinical Neurophysiology, UK 2 Monash Medical Centre, Department of Neurology, Australia Background and objective: Attempts to identify the best prognostic markers for the outcome of hypoxic coma using traditional analysis of sensitivity and specificity have yielded a range of results partly due to the heterogeneity of the study population and the diagnostic threshold. We have therefore performed a meta-analysis of 39 publications in the world literature using summary receiver operating characteristic curves (SROC) and compared the diagnostic accuracy of pupil responses, motor responses, Glasgow Coma Score (GCS), bilateral absence of somatosensory evoked potentials (SEP) and electroencephalographic findings in predicting outcome of hypoxic coma. Methods: PubMed (1966–2005), Medline (1966–2005) and Embase (1966–2005) were searched for reports in English, German and French. Manual review of article reference lists was conducted for additional studies. Raw data was extracted into a 2 · 2 table such that patients with positive and negative ’test’ results and their eventual clinical outcome were clearly demonstrated. A SROC curve was plotted for each test, thus allowing the comparison of the different tests using the calculated odds ratio (OR) and area under curve (AUC). Results: The AUCs of SROCs (indicative of diagnostic accuracy) for absent pupillary and graded motor responses (M1, M < 2, M < 3) for each of the 3 days post-coma showed an incremental pattern with optimal results on day 3. The AUCs of SROCs for absent pupillary and motor responses (M1) were generally larger than those for bilaterally absent SEP throughout the 3 days postcoma. Conclusions: These results provide support for the notion that diagnostic accuracy of coma outcome improves with time after the onset of coma, being optimal on day 3. Further, the overall diagnostic accuracies for absent pupillary response and motor response (M1) are superior to that of absent somatosensory evoked potentials throughout the first 3 days post-coma. doi:10.1016/j.clinph.2006.06.492