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175 ERPS and event-related frequency changes in vegetative state patients—diagnostic and prognostic implications
70
Abstracts
/International
Journal
I75 ERPS AND EVENT-RELATED FREQUENCY CHANGES IN VEGETATIVE STATE PATIENTS-DIAGNOSTIC AND PROGNOSTIC IMPLICATIONS K. Lindlar, U. Loeper, M. Wagner, P-W Schoenle and B. Rockstroh University of Konstartz, Konstanz, Germany The aim of the present study is to investigate the diagnostic and prognostic significance of ERPs and event-related frequency changes in vegetative state patients (DRS score 23 (22-25), VS duration 8 (l-96) months). These electrophysiological methods allow for an objective measure of the patient’s reactivity to different stimuli without necessitating an overt response. Three paradigms were used to evoke long-latency AEPs in vegetative state patients (n = 37). In addition, somatosensory evoked potentials and frequency changes in response to vibration stimuli were recorded (n = 231, which were applied to the palm of the hand with a new egg shaped apparatus. The EEG was recorded from Fz, Pz, C3, C4, Al, A2, using Cz as recording reference. In order to assessreliability, each patient was tested at least two times. Late auditory and somatosensory evoked potentials could be reliably recorded in about 50% of the examined VS patients. All the evoked potentials were, however, of substantially reduced amplitude in comparison with those in healthy subjects. Short lasting event-related frequency c@anges were evident in several patients. Replicating results from a previous study in another sample, the first data from a one year follow-up indicate that the amplitude of the NI is of prognostic significance. Since event-related potentials originate in the cerebral cortex, this finding is hard to reconcile with the concept of an “apalhc syndrome” or “vegetative state”, which implies the absence of any kind of cortical functions. Instead, the findings demonstrate that, in a sizeable subgroup of vegetative state patients, cortical processing of auditory and somatosensory stimuli takes place and that at least residual cognitive functioning (orienting and discrimination) may be present in apparently unconscious patients. This seems to be related with better outcome. The preliminary results for the event-related changes in EEG frequency demonstrate that this method also is a sensitive measure of cortical reactivity in patients in vegetative state.
176 ERPS IN LOCKED-IN
PATIENTS
Aldo Ragazzoni* Department of Neurological and Psychiatric Sciences, University of Florence, Viale Morgagni 85, Florence, 50134 Italy Locked-in syndrome LIS represents a rare but dramatic neurological condition, usually due to a lesion in the basis pontis, in which blinking and vertical eye movements are the only
of Psychophysiology
30 (1998)
7-94
voluntary motor responses remaining, whereas consciousness is preserved. Severe forms of polyradiculoneuropathies can produce a similar clinical condition. In the acute stage of the disease, vigilance is often fluctuating, making early identification of this state difficult. Electrophysiological studies are recommended, in addition to clinical and neuroradiological assessment, not only for diagnosing LIS, but mostly to define the extent of the brainstem lesion and to predict the functional outcome. A series of five adult patients in a locked-in-state were submitted to sequential electrophysiological recordings, including EEG, short-latency evoked potentials (BAEPs and median nerve SEPs) and auditory ERPs elicited with an oddball paradigm. Three patients had had a brainstem stroke; two suffered from an acute (“fulminant”) form of GuillainBarre syndrome (GBS). EEG showed normal, partially reactive alpha rhythm in three and a poorly modulated alpha/theta pattern in two. Short-latency EPs showed various degrees of abnormalities in all the patients, reflecting the impairment of nerve conduction either in the central sensory pathways or in the peripheral fibers. ERPs (peaks Nl, P2, N2, P3) could be recorded in three of the patients, all of which later on had a good neurological outcome. In one GBS patient, mismatch negativity (MMN) and CNV-like potentials could be obtained in the earlier phase of the disease. Two patients (one with GBS) presented only ERP peaks Nl and P2, whereas N2, P3 and MMN could never be observed, despite a long series of recordings: both patients died. ERPs allow monitoring the level of alertness and attention and are most valuable when clinical measures are scarce, as is the case with a number of patients in the Intensive Care Unit. They appear more specific than EEG in identifying a state of awareness in patients in which communication is severely impaired as a consequence of neurological disorders.
SYMPOSIUM
30: Drug Addiction
177 SEX DIFFERENCES OF NICOTINE
IN THE CENTRAL
ACTIONS
Sakire Pogun Ege University, Center for Brain Research and School of Medicine, Department of Physiology, Bornova, Izmir 35100, Turkey Tobacco use is accepted to be a form of addiction, which manifests gender differences. As gender is a factor that intluences a variety of neurotransmitter systems, it seems possible that gender differences seen in smoking patterns could, to some extent, reflect differences in how chronic nicotine interacts with nAChR, the substrate of the biological effects of nicotine. Smoking is reinforced by pharmacological effects produced by nicotine, as well as non-pharmacological, psycho-
Abstracts
/International
Journal
I75 ERPS AND EVENT-RELATED FREQUENCY CHANGES IN VEGETATIVE STATE PATIENTS-DIAGNOSTIC AND PROGNOSTIC IMPLICATIONS K. Lindlar, U. Loeper, M. Wagner, P-W Schoenle and B. Rockstroh University of Konstartz, Konstanz, Germany The aim of the present study is to investigate the diagnostic and prognostic significance of ERPs and event-related frequency changes in vegetative state patients (DRS score 23 (22-25), VS duration 8 (l-96) months). These electrophysiological methods allow for an objective measure of the patient’s reactivity to different stimuli without necessitating an overt response. Three paradigms were used to evoke long-latency AEPs in vegetative state patients (n = 37). In addition, somatosensory evoked potentials and frequency changes in response to vibration stimuli were recorded (n = 231, which were applied to the palm of the hand with a new egg shaped apparatus. The EEG was recorded from Fz, Pz, C3, C4, Al, A2, using Cz as recording reference. In order to assessreliability, each patient was tested at least two times. Late auditory and somatosensory evoked potentials could be reliably recorded in about 50% of the examined VS patients. All the evoked potentials were, however, of substantially reduced amplitude in comparison with those in healthy subjects. Short lasting event-related frequency c@anges were evident in several patients. Replicating results from a previous study in another sample, the first data from a one year follow-up indicate that the amplitude of the NI is of prognostic significance. Since event-related potentials originate in the cerebral cortex, this finding is hard to reconcile with the concept of an “apalhc syndrome” or “vegetative state”, which implies the absence of any kind of cortical functions. Instead, the findings demonstrate that, in a sizeable subgroup of vegetative state patients, cortical processing of auditory and somatosensory stimuli takes place and that at least residual cognitive functioning (orienting and discrimination) may be present in apparently unconscious patients. This seems to be related with better outcome. The preliminary results for the event-related changes in EEG frequency demonstrate that this method also is a sensitive measure of cortical reactivity in patients in vegetative state.
176 ERPS IN LOCKED-IN
PATIENTS
Aldo Ragazzoni* Department of Neurological and Psychiatric Sciences, University of Florence, Viale Morgagni 85, Florence, 50134 Italy Locked-in syndrome LIS represents a rare but dramatic neurological condition, usually due to a lesion in the basis pontis, in which blinking and vertical eye movements are the only
of Psychophysiology
30 (1998)
7-94
voluntary motor responses remaining, whereas consciousness is preserved. Severe forms of polyradiculoneuropathies can produce a similar clinical condition. In the acute stage of the disease, vigilance is often fluctuating, making early identification of this state difficult. Electrophysiological studies are recommended, in addition to clinical and neuroradiological assessment, not only for diagnosing LIS, but mostly to define the extent of the brainstem lesion and to predict the functional outcome. A series of five adult patients in a locked-in-state were submitted to sequential electrophysiological recordings, including EEG, short-latency evoked potentials (BAEPs and median nerve SEPs) and auditory ERPs elicited with an oddball paradigm. Three patients had had a brainstem stroke; two suffered from an acute (“fulminant”) form of GuillainBarre syndrome (GBS). EEG showed normal, partially reactive alpha rhythm in three and a poorly modulated alpha/theta pattern in two. Short-latency EPs showed various degrees of abnormalities in all the patients, reflecting the impairment of nerve conduction either in the central sensory pathways or in the peripheral fibers. ERPs (peaks Nl, P2, N2, P3) could be recorded in three of the patients, all of which later on had a good neurological outcome. In one GBS patient, mismatch negativity (MMN) and CNV-like potentials could be obtained in the earlier phase of the disease. Two patients (one with GBS) presented only ERP peaks Nl and P2, whereas N2, P3 and MMN could never be observed, despite a long series of recordings: both patients died. ERPs allow monitoring the level of alertness and attention and are most valuable when clinical measures are scarce, as is the case with a number of patients in the Intensive Care Unit. They appear more specific than EEG in identifying a state of awareness in patients in which communication is severely impaired as a consequence of neurological disorders.
SYMPOSIUM
30: Drug Addiction
177 SEX DIFFERENCES OF NICOTINE
IN THE CENTRAL
ACTIONS
Sakire Pogun Ege University, Center for Brain Research and School of Medicine, Department of Physiology, Bornova, Izmir 35100, Turkey Tobacco use is accepted to be a form of addiction, which manifests gender differences. As gender is a factor that intluences a variety of neurotransmitter systems, it seems possible that gender differences seen in smoking patterns could, to some extent, reflect differences in how chronic nicotine interacts with nAChR, the substrate of the biological effects of nicotine. Smoking is reinforced by pharmacological effects produced by nicotine, as well as non-pharmacological, psycho-