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94. ERP modulation in patients with disorders of consciousness
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Society Proceedings / Clinical Neurophysiology 124 (2013) e189–e223
The goal of this study was to assess the effect of GPi-DBS in a homogeneous population of dystonic patients and to compare the clinical outcome using two different stimulation settings: a constant-current stimulation versus a constant-voltage stimulation. 22 patients affected by primary generalized or multisegmental dystonia underwent bilateral GPi-DBS. 13 patients were stimulated using a voltage-controlled setting while in the other 9 patients we used a current-controlled setting. Clinical features were evaluated for each patient at baseline, 6 months and 12 months after surgery by means of the Burke–Fahn–Marsden Dystonia Rating Scale (BFMDRS). In all the patients we found a statistically significant improvement both in motor and disability scores of BFMDRS. Moreover, we didn’t find any significant difference between current- and voltage-controlled stimulation at 6 and 12 months after surgery in comparison to baseline while a better improvement occured in the last 6 months follow-up in the current-controlled group. Our study shows that current-controlled stimulation could be more effective than voltage-controlled stimulation over long-term follow-up in dystonia. doi:10.1016/j.clinph.2013.06.120
94. ERP modulation in patients with disorders of consciousness— M. Cavinato, C. Volpato, M. Sacchetto, F. Piccione (Venice, Asolo TV) The limited evidence and inconsistency of purposeful behaviors in patients in a minimally conscious state (MCS) asks for objective electrophysiological marker of the level of consciousness. Here, a comparison between event-related potentials (ERPs) was investigated using different level of stimulus complexity. ERPs were recorded in 17 patients, 11 of which in vegetative state (VS), 6 in MCS, and 10 controls. Three oddball paradigms with different level of complexity were applied: sine tones, the subject’s own name vs. sine tones and other first names. Latencies and amplitudes of N1 and P3 waves were compared using a semi-automated peak detection algorithm. Cortical responses were found in all MCS patients, and in 6 of 11 patients in VS. Healthy controls and MCS patients showed a progressive increase of P3 latency in relation to the level of stimulus complexity. No modulation of P3 latency was observed in the vegetative patients. These results suggest that the modulation of P3 latency related to stimulus complexity may represent an objective index of higher-order processing integration that predicts the recovery of consciousness from VS to MCS when clinical manifestations are inconsistent. P3 latency modulation may help differentiate between different states of consciousness. doi:10.1016/j.clinph.2013.06.121
95. Detection of short-term habituation (STH) in patients with disorder of consciousness (DOC): Our results and potential clinical implications—A. Comanducci, M. Spalletti, C. Martinelli, G. Lanzo, R. Carrai, F. Pinto, A. Amantini, A. Grippo (Florence) Short-term habituation (STH) represents a “bottom-up” filter for salient stimuli and a prerequisite for a subsequent “top-down” processing. Our aim was to ascertain if STH is preserved in patients with different levels of disorder of consciousness (DOC). We recorded 35 DOC patients assessed with Coma Recovery Scale-Revised. We delivered trains of stimuli (S1–S2–S3): S1 and S2 always belongs to the same sensory modality (auditory/somatosensory) whereas S3 can belong either to the same modality, (triplet“same”) or to the other modality (triplet “different”). S1/S2/S3-related N1–P2 amplitudes were compared in order to detect any significant STH. STH was detected in each emerging and MCS patient, whereas it was found
absent only in VS patients (10 out of 19): until now, none of these 10 patients has regained consciousness. Among the 9 VS patients showing STH, 4 have subsequently become MCS. STH could represent a new potential diagnostic/prognostic neurophysiological indicator in DOC. We have found STH in every patient with a preserved level of consciousness. It remains to be determined whether the presence/absence of STH in an early DOC stage could have a prognostic value and whether the absence of STH in chronic VS could assume significance of a diagnostic confirmation. doi:10.1016/j.clinph.2013.06.122
96. Triplet protocol for Short Term Habituation: Methodological issues—C. Martinelli, B. Gori, A. Comanducci, A. Amantini, F. Pinto, A. Grippo (Florence) In patients with Disorder of Consciousness (DOC) Event Related Potentials have been used for prognosis of recovery of the state of consciousness. The component that have been more studied were Mismatch Negativity and P300 but they have the limitation of low sensitivity due to pitfalls of recording and analysis during repetitive stimuli. N100 is a more robust component and change in amplitude is an index of Short-term Habituation. We designed a protocol which includes administration of a series of three stimuli (triplets) of two sensory modalities: acoustic (A) and electric (E). The triplets are of two types: triplet “same” with three identical acoustic (A1-A2-A3) and electrical stimuli (E1-E2-E3) given with a ITI of 8–12 s; triplet “different” with the first two identical stimuli and a third sensory ”different” (A1-A2-Ed or E1-E2-Ad). In order to obtain average of the single stimuli we used an EEG triggered acquisition (ERP-GALNT). We collected normative data in healthy subjects and we recorded also a group of patients with DOC. The data collected in healthy controls allow a classification of finding in single patients. In order to obtain interpretable data a series of expedients have to be used by Technician for recordings in patients with DOC. doi:10.1016/j.clinph.2013.06.123
97. Transcranial direct current stimulation increases long-range fronto-parietal connections in patients with disorders of consciousness: A preliminary study—S. Campostrini, M. Cavinato, F. Piccione (Venice) The aim of the present study was to assess the effect of transcranial direct current stimulation (TDCS) applied to the dorso-lateral prefrontal cortex (DLPF) on the behavioral responses and brain oscillations in 15 patients in vegetative (VS) and minimally conscious state (MCS). 10 daily sessions of anodal tcds were applied to the left dlpf. A sham stimulation was used as a control condition. 19-channels EEG was recorded before and after stimulation. The EEG coherence and spectral pattern differences before and after each treatment were analyzed. EEG data analysis showed a significant increase of coherence over the frontal and fronto-parietal areas in beta and gamma frequencies after tdcs. No significant effects were observed after sham stimulation. Clinical assessment of patients showed no significant changes. However all caregivers reported a reduction of oscillations of arousal level. Our study suggests that tdcs could influence the EEG coherence of rapid frequencies allowing the interaction between frontal and parietal areas. This interaction represents a fundamental prerequisite for all conscious perception mechanisms. TDCS may represent an useful new tool for cognitive rehabilitation. doi:10.1016/j.clinph.2013.06.124
Society Proceedings / Clinical Neurophysiology 124 (2013) e189–e223
The goal of this study was to assess the effect of GPi-DBS in a homogeneous population of dystonic patients and to compare the clinical outcome using two different stimulation settings: a constant-current stimulation versus a constant-voltage stimulation. 22 patients affected by primary generalized or multisegmental dystonia underwent bilateral GPi-DBS. 13 patients were stimulated using a voltage-controlled setting while in the other 9 patients we used a current-controlled setting. Clinical features were evaluated for each patient at baseline, 6 months and 12 months after surgery by means of the Burke–Fahn–Marsden Dystonia Rating Scale (BFMDRS). In all the patients we found a statistically significant improvement both in motor and disability scores of BFMDRS. Moreover, we didn’t find any significant difference between current- and voltage-controlled stimulation at 6 and 12 months after surgery in comparison to baseline while a better improvement occured in the last 6 months follow-up in the current-controlled group. Our study shows that current-controlled stimulation could be more effective than voltage-controlled stimulation over long-term follow-up in dystonia. doi:10.1016/j.clinph.2013.06.120
94. ERP modulation in patients with disorders of consciousness— M. Cavinato, C. Volpato, M. Sacchetto, F. Piccione (Venice, Asolo TV) The limited evidence and inconsistency of purposeful behaviors in patients in a minimally conscious state (MCS) asks for objective electrophysiological marker of the level of consciousness. Here, a comparison between event-related potentials (ERPs) was investigated using different level of stimulus complexity. ERPs were recorded in 17 patients, 11 of which in vegetative state (VS), 6 in MCS, and 10 controls. Three oddball paradigms with different level of complexity were applied: sine tones, the subject’s own name vs. sine tones and other first names. Latencies and amplitudes of N1 and P3 waves were compared using a semi-automated peak detection algorithm. Cortical responses were found in all MCS patients, and in 6 of 11 patients in VS. Healthy controls and MCS patients showed a progressive increase of P3 latency in relation to the level of stimulus complexity. No modulation of P3 latency was observed in the vegetative patients. These results suggest that the modulation of P3 latency related to stimulus complexity may represent an objective index of higher-order processing integration that predicts the recovery of consciousness from VS to MCS when clinical manifestations are inconsistent. P3 latency modulation may help differentiate between different states of consciousness. doi:10.1016/j.clinph.2013.06.121
95. Detection of short-term habituation (STH) in patients with disorder of consciousness (DOC): Our results and potential clinical implications—A. Comanducci, M. Spalletti, C. Martinelli, G. Lanzo, R. Carrai, F. Pinto, A. Amantini, A. Grippo (Florence) Short-term habituation (STH) represents a “bottom-up” filter for salient stimuli and a prerequisite for a subsequent “top-down” processing. Our aim was to ascertain if STH is preserved in patients with different levels of disorder of consciousness (DOC). We recorded 35 DOC patients assessed with Coma Recovery Scale-Revised. We delivered trains of stimuli (S1–S2–S3): S1 and S2 always belongs to the same sensory modality (auditory/somatosensory) whereas S3 can belong either to the same modality, (triplet“same”) or to the other modality (triplet “different”). S1/S2/S3-related N1–P2 amplitudes were compared in order to detect any significant STH. STH was detected in each emerging and MCS patient, whereas it was found
absent only in VS patients (10 out of 19): until now, none of these 10 patients has regained consciousness. Among the 9 VS patients showing STH, 4 have subsequently become MCS. STH could represent a new potential diagnostic/prognostic neurophysiological indicator in DOC. We have found STH in every patient with a preserved level of consciousness. It remains to be determined whether the presence/absence of STH in an early DOC stage could have a prognostic value and whether the absence of STH in chronic VS could assume significance of a diagnostic confirmation. doi:10.1016/j.clinph.2013.06.122
96. Triplet protocol for Short Term Habituation: Methodological issues—C. Martinelli, B. Gori, A. Comanducci, A. Amantini, F. Pinto, A. Grippo (Florence) In patients with Disorder of Consciousness (DOC) Event Related Potentials have been used for prognosis of recovery of the state of consciousness. The component that have been more studied were Mismatch Negativity and P300 but they have the limitation of low sensitivity due to pitfalls of recording and analysis during repetitive stimuli. N100 is a more robust component and change in amplitude is an index of Short-term Habituation. We designed a protocol which includes administration of a series of three stimuli (triplets) of two sensory modalities: acoustic (A) and electric (E). The triplets are of two types: triplet “same” with three identical acoustic (A1-A2-A3) and electrical stimuli (E1-E2-E3) given with a ITI of 8–12 s; triplet “different” with the first two identical stimuli and a third sensory ”different” (A1-A2-Ed or E1-E2-Ad). In order to obtain average of the single stimuli we used an EEG triggered acquisition (ERP-GALNT). We collected normative data in healthy subjects and we recorded also a group of patients with DOC. The data collected in healthy controls allow a classification of finding in single patients. In order to obtain interpretable data a series of expedients have to be used by Technician for recordings in patients with DOC. doi:10.1016/j.clinph.2013.06.123
97. Transcranial direct current stimulation increases long-range fronto-parietal connections in patients with disorders of consciousness: A preliminary study—S. Campostrini, M. Cavinato, F. Piccione (Venice) The aim of the present study was to assess the effect of transcranial direct current stimulation (TDCS) applied to the dorso-lateral prefrontal cortex (DLPF) on the behavioral responses and brain oscillations in 15 patients in vegetative (VS) and minimally conscious state (MCS). 10 daily sessions of anodal tcds were applied to the left dlpf. A sham stimulation was used as a control condition. 19-channels EEG was recorded before and after stimulation. The EEG coherence and spectral pattern differences before and after each treatment were analyzed. EEG data analysis showed a significant increase of coherence over the frontal and fronto-parietal areas in beta and gamma frequencies after tdcs. No significant effects were observed after sham stimulation. Clinical assessment of patients showed no significant changes. However all caregivers reported a reduction of oscillations of arousal level. Our study suggests that tdcs could influence the EEG coherence of rapid frequencies allowing the interaction between frontal and parietal areas. This interaction represents a fundamental prerequisite for all conscious perception mechanisms. TDCS may represent an useful new tool for cognitive rehabilitation. doi:10.1016/j.clinph.2013.06.124