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Acute intraoperative EEG changes during cartoid endarterectomy
16P
Society proceedings
We studied neural mechanisms of attentional modulation of the ERP using laminar current source density (CSD), and multiunit activity profiles in monkeys, required to alternate attention across runs, between concurrent visual and auditory stimulus streams. Early attentional modulation (before the Pl peak) occurred in most structures, with an increase in amplitude across VI, V2 and V4. Early effects were poorly manifested in surface ERPs, but later effects appeared to contribute to ERP modulation starting at Pl peak. Modulation was smaller and earlier in parietal than in temporal stream areas, possibly weighting their contributions to earlier vs. Iater components. Also, modulation in parietal stream areas MT and STP generally reflected excitatory response enhancement, while that in temporal stream areas V4 and IT reflected a brief, initial enhancement, followed by a much longer and large epoch of modulation, primarily representing disinhibition. Local contributions to N2 were indicated by supragranular current sinks in nearly every area, consistent with the view that N2 reflects synchronous supragranular activation in multiple areas. Multiple areal contributions to P3 were also noted, but clear P3-related activity was less prominent and less widely distributed than that for N2, the largest being in V2. (MH47939 &James S. McDonnell Foundation). ElOl: Acute intraoperative EEG changes during cartoid endarterectomy *Eli M. Mizrahi, **Robert T. Simkins, **Konstadinos A. Plestis and **Jimmy F. Howell (*Section of Neurophysiology, Department of Neurology and **Section of Cardiovascular Surgery, Department of Surgery, Baylor College of Medicine and The Methodist Hospital, Houston, TX 77030) In this study the frequency, character and causes of EEG changes were assessed in 377 consecutive patients with atherosclerotic carotid stenosis undergoing endarterectomy. Eight EEG channels were continuously monitored intraoperatively utilizing a single bipolar montage with leads from frontal, central, occipital and temporal regions. EEG was assessed following carotid clamping for 50% reduction of amplitude of background activity and/or development of slowing of the dominant frequencies. Acute changes were observed in 43; 33, unilateral and ipsilateral to the side of clamping; 6, bilateral with the same degree of change on each side; 4, bilateral with greater degree of change ipsilateral to clamping. In 38 cases (30 unilateral, 8 bilateral) changes were attributable to vascular occlusion. An interluminal shunt was placed only in these patients. This resulted in prompt return to EEG baseline in 34; improvement in 3; no improvement in 1, In 5 cases (3 unilateral, 2 bilateral) changes were attributable to a decrease in systemic blood pressure and reversed with its restoration. Two of the 377 patients experienced stroke in the perioperative period; subsequent evaluation suggested an embolic etiology in both. In one, the ipsilateral EEG change following carotid clamping did not improve with shunting. In the other, with no EEG change following carotid clamping, the stroke occurred during a postoperative period of atrial fibrillation and in the hemisphere contralateral to the side of endarterectomy. E102: Remote carotid-endarterectomy monitoring (CEM) using 18channel telemetry and computer analysis - J.R. Ives, L.J. Gruber, S.A. McPeck, D.L. Martin, K.B. Krisbnamurthy, A.S. Blum, F.W. Drislane, S.L. Schachter and D.L. Schemer (Department of Neurology, Beth Israel Hospital and Harvard Medical School, Boston, MA) CEM is usually associated with the inefficient use of personnel and equipment. Based on experience with remote monitoring during a Wada (l), we have established a procedure using l8-channel cabletelemetry (2). The patient is set up on the telemetry system and connects into spectral OR cabling during the operation. This permits local monitoring as well as remote monitoring in the EEG lab. An EEG technologist attends an EEG machine fitted out with a computer and large
screen during the procedure in the OR. This system allows both traditional and paperless EEG monitoring to occur simultaneously as new computer displays are developed and introduced without compromising the monitoring information. At critical points during the operation, an electroencephalographer can be called to view the remote EEG and discuss the EEG with the technologist. (1) Ives JR, Martin DL, Coots JF, Schemer DL. The efficient use of cable-telemetry EEG during the Wada procedure. Am J EEG Technol 1993; 33: 192-197. (2) Ives JR, Mainwaring NR, Schemer DL. An 18-channel solid-state ambulatory event recorder for use in the home and hospital environment. Epilepsia 1992; 33: 63. E103:
EEG in the evaluation of acute confusional states - *N.R. Holland, **P.W. Kaplan, *G.J. Dal Pan, *D. Williamson and *N.C. Sacktor (*Department of Neurology, Johns Hopkins Hospital, Baltimore, MD 21287, **Department of Neurology, Johns Hopkins Bayview Medical Center, Baltimore, MD 21224)
EEG has long been used in the evaluation of agitated and confused patients to differentiate psychiatric from organic problems. We received 57 sequentially hospitalized patients referred for EEG because of sudden change from baseline mentation. An abnormal EEG was defined as generalized or focal slowing, or epileptiform activity. Five of 15 patients with normal EEGs had psychiatric diagnoses; the other 10 had organic problems: medications (5). stroke (2), metabolic (I), and dementia (I). The 42 patients with abnormal EEGs had the following organic etiologies: multifactorial (17) (including 6 with dementia), medications (5). dementia alone (5). metabolic (4). infections (3) stroke (2), and other (6). No patient with an abnormal EEG was felt to have a primary psychiatric diagnosis. Thus, routine EEG was of greatest benefit in distinguishing organic from psychiatric confusional states. EEG remains helpful in the evaluation of patients with acutely altered mental status. E104: Atypical tripbasic waves associated with the use of pentobarbital - Marcel0 E. Lancman, Stephen Marks, and Kbalid Mahmood (Comprehensive Epilepsy Program, Department of Neurology, Westchester County Medical Center, New York Medical College, Valhalla, NY 10595) Objective: to report a case in which triphasic waves developed during pentobarbital treatment. Background: Pentobarbital coma is indicated in status epilepticus refractory to other anticonvulsants, and in certain neurologic conditions in order to decrease brain metabolism. At high doses of pentobarbital, the EEG shows a typical burst-suppression pattern, while at low doses diffuse slowing. Triphasic waves have not been reported in association with pcntobarbital. Case report: a 54 year old female underwent surgery for giant ophthalmic aneurysm clipping. Due to tearing and bleeding of the carotid artery, a clamp was placed and an external-internal carotid artery by-pass was done and the patient was started on pentobarbital. Patient remained comatose, the EEG showed a burst-suppression pattern, and pentobarbital level was 30S~gldl. One week later, the patient was still comatose, the EEG showed generalized triphasic waves with anterior predominance, and pentobarbital level was 1 I ygldl. One day later, the patient was awake, and the EEG was normalized. The patient recovered. having a left I I1 nerve palsy sequelae. Conclusion: triphasic waves may be seen in patients on pentobarbital. It is important to recognized this finding in patients on pentobarbital due to status epilepticus. This pattern should not be misinterpreted as ‘electrical’ status epilepticus. El05
EEG rhythms produced by three chemically dissimilar sedative drugs - Vladimir A. Feshchenko, Robert A. Veselis, Ruth A. Reinsel (Dept. of Anesthesiology & Crit. Care Med., Memorial Sloan-Kettering Cancer Center & Cornell Univ. Medical College, New York, NY 10021)
Society proceedings
We studied neural mechanisms of attentional modulation of the ERP using laminar current source density (CSD), and multiunit activity profiles in monkeys, required to alternate attention across runs, between concurrent visual and auditory stimulus streams. Early attentional modulation (before the Pl peak) occurred in most structures, with an increase in amplitude across VI, V2 and V4. Early effects were poorly manifested in surface ERPs, but later effects appeared to contribute to ERP modulation starting at Pl peak. Modulation was smaller and earlier in parietal than in temporal stream areas, possibly weighting their contributions to earlier vs. Iater components. Also, modulation in parietal stream areas MT and STP generally reflected excitatory response enhancement, while that in temporal stream areas V4 and IT reflected a brief, initial enhancement, followed by a much longer and large epoch of modulation, primarily representing disinhibition. Local contributions to N2 were indicated by supragranular current sinks in nearly every area, consistent with the view that N2 reflects synchronous supragranular activation in multiple areas. Multiple areal contributions to P3 were also noted, but clear P3-related activity was less prominent and less widely distributed than that for N2, the largest being in V2. (MH47939 &James S. McDonnell Foundation). ElOl: Acute intraoperative EEG changes during cartoid endarterectomy *Eli M. Mizrahi, **Robert T. Simkins, **Konstadinos A. Plestis and **Jimmy F. Howell (*Section of Neurophysiology, Department of Neurology and **Section of Cardiovascular Surgery, Department of Surgery, Baylor College of Medicine and The Methodist Hospital, Houston, TX 77030) In this study the frequency, character and causes of EEG changes were assessed in 377 consecutive patients with atherosclerotic carotid stenosis undergoing endarterectomy. Eight EEG channels were continuously monitored intraoperatively utilizing a single bipolar montage with leads from frontal, central, occipital and temporal regions. EEG was assessed following carotid clamping for 50% reduction of amplitude of background activity and/or development of slowing of the dominant frequencies. Acute changes were observed in 43; 33, unilateral and ipsilateral to the side of clamping; 6, bilateral with the same degree of change on each side; 4, bilateral with greater degree of change ipsilateral to clamping. In 38 cases (30 unilateral, 8 bilateral) changes were attributable to vascular occlusion. An interluminal shunt was placed only in these patients. This resulted in prompt return to EEG baseline in 34; improvement in 3; no improvement in 1, In 5 cases (3 unilateral, 2 bilateral) changes were attributable to a decrease in systemic blood pressure and reversed with its restoration. Two of the 377 patients experienced stroke in the perioperative period; subsequent evaluation suggested an embolic etiology in both. In one, the ipsilateral EEG change following carotid clamping did not improve with shunting. In the other, with no EEG change following carotid clamping, the stroke occurred during a postoperative period of atrial fibrillation and in the hemisphere contralateral to the side of endarterectomy. E102: Remote carotid-endarterectomy monitoring (CEM) using 18channel telemetry and computer analysis - J.R. Ives, L.J. Gruber, S.A. McPeck, D.L. Martin, K.B. Krisbnamurthy, A.S. Blum, F.W. Drislane, S.L. Schachter and D.L. Schemer (Department of Neurology, Beth Israel Hospital and Harvard Medical School, Boston, MA) CEM is usually associated with the inefficient use of personnel and equipment. Based on experience with remote monitoring during a Wada (l), we have established a procedure using l8-channel cabletelemetry (2). The patient is set up on the telemetry system and connects into spectral OR cabling during the operation. This permits local monitoring as well as remote monitoring in the EEG lab. An EEG technologist attends an EEG machine fitted out with a computer and large
screen during the procedure in the OR. This system allows both traditional and paperless EEG monitoring to occur simultaneously as new computer displays are developed and introduced without compromising the monitoring information. At critical points during the operation, an electroencephalographer can be called to view the remote EEG and discuss the EEG with the technologist. (1) Ives JR, Martin DL, Coots JF, Schemer DL. The efficient use of cable-telemetry EEG during the Wada procedure. Am J EEG Technol 1993; 33: 192-197. (2) Ives JR, Mainwaring NR, Schemer DL. An 18-channel solid-state ambulatory event recorder for use in the home and hospital environment. Epilepsia 1992; 33: 63. E103:
EEG in the evaluation of acute confusional states - *N.R. Holland, **P.W. Kaplan, *G.J. Dal Pan, *D. Williamson and *N.C. Sacktor (*Department of Neurology, Johns Hopkins Hospital, Baltimore, MD 21287, **Department of Neurology, Johns Hopkins Bayview Medical Center, Baltimore, MD 21224)
EEG has long been used in the evaluation of agitated and confused patients to differentiate psychiatric from organic problems. We received 57 sequentially hospitalized patients referred for EEG because of sudden change from baseline mentation. An abnormal EEG was defined as generalized or focal slowing, or epileptiform activity. Five of 15 patients with normal EEGs had psychiatric diagnoses; the other 10 had organic problems: medications (5). stroke (2), metabolic (I), and dementia (I). The 42 patients with abnormal EEGs had the following organic etiologies: multifactorial (17) (including 6 with dementia), medications (5). dementia alone (5). metabolic (4). infections (3) stroke (2), and other (6). No patient with an abnormal EEG was felt to have a primary psychiatric diagnosis. Thus, routine EEG was of greatest benefit in distinguishing organic from psychiatric confusional states. EEG remains helpful in the evaluation of patients with acutely altered mental status. E104: Atypical tripbasic waves associated with the use of pentobarbital - Marcel0 E. Lancman, Stephen Marks, and Kbalid Mahmood (Comprehensive Epilepsy Program, Department of Neurology, Westchester County Medical Center, New York Medical College, Valhalla, NY 10595) Objective: to report a case in which triphasic waves developed during pentobarbital treatment. Background: Pentobarbital coma is indicated in status epilepticus refractory to other anticonvulsants, and in certain neurologic conditions in order to decrease brain metabolism. At high doses of pentobarbital, the EEG shows a typical burst-suppression pattern, while at low doses diffuse slowing. Triphasic waves have not been reported in association with pcntobarbital. Case report: a 54 year old female underwent surgery for giant ophthalmic aneurysm clipping. Due to tearing and bleeding of the carotid artery, a clamp was placed and an external-internal carotid artery by-pass was done and the patient was started on pentobarbital. Patient remained comatose, the EEG showed a burst-suppression pattern, and pentobarbital level was 30S~gldl. One week later, the patient was still comatose, the EEG showed generalized triphasic waves with anterior predominance, and pentobarbital level was 1 I ygldl. One day later, the patient was awake, and the EEG was normalized. The patient recovered. having a left I I1 nerve palsy sequelae. Conclusion: triphasic waves may be seen in patients on pentobarbital. It is important to recognized this finding in patients on pentobarbital due to status epilepticus. This pattern should not be misinterpreted as ‘electrical’ status epilepticus. El05
EEG rhythms produced by three chemically dissimilar sedative drugs - Vladimir A. Feshchenko, Robert A. Veselis, Ruth A. Reinsel (Dept. of Anesthesiology & Crit. Care Med., Memorial Sloan-Kettering Cancer Center & Cornell Univ. Medical College, New York, NY 10021)