Ovid: Electrophysiologic monitoring in neurointensive care. Main Search Page Ask A LibrarianDisplay Knowledge BaseHelpLogoff Full Text Save Article TextEmail Article TextPrint Preview Electrophysiologic monitoring in neurointensive care Procaccio, Francesco MD*†; Polo, Alberto MD*; Lanteri, Paola MD†; Sala, ISSN: Author(s): Francesco MD† 1070- 5295 Issue: Volume 7(2), April 2001, pp 74-80 Accession: Publication Type: [Neuroscience] 00075198- Publisher: © 2001 Lippincott Williams & Wilkins, Inc. 200104000- University and City Hospital Neuroanesthesia and Intensive Care, Department 00004 of Neurological Sciences and Vision, Divisions of *Neurology and Full †Neurosurgery, Verona, Italy. Institution(s): Text Correspondence to Francesco Procaccio, MD, Neuroanesthesia and Intensive (PDF) Care, University and City Hospital, Pz Stefani, 1, 37124 Verona, Italy; e-mail: 69 K [email protected] Email Jumpstart Table of Contents: Find ≪ Neurologic complications in intensive care. Citing ≫ Pediatric neurologic emergencies. Articles ≪ Abstract Table Links of Cumulative evidence of potential benefits of Contents Abstract electroencephalography (EEG) and evoked potentials in About Complete Reference the management of patients with acute cerebral this ExternalResolverBasic damage has been confirmed. Continuous EEG Journal Outline monitoring is the best method for detecting ≫ nonconvulsive seizures and is strongly recommended for the treatment of status epilepticus. Continuously displayed, ● Abstract validated quantitative EEG may facilitate early detection of secondary ● Electroencephalographic cerebral insults and may play a decision-making role in the management of monitoring in the neurointensive patients with head injury, stroke, or subarachnoid hemorrhage. Long-latency care unit auditory evoked potentials and cognitive components constitute a new field ❍ Rationale for of interest for the progress of comatose patients. Motor evoked potentials http://ovidsp.tx.ovid.com/spb/ovidweb.cgi (1 of 14) [6/12/2008 11:43:39 AM] Ovid: Electrophysiologic monitoring in neurointensive care. electroencephalographic may become clinically important both in acutely injured and elective monitoring postoperative patients. In the neurointensive care units adequate techniques can ❍ Rationale for continuous be selected to answer targeted clinical questions. The efficacy can be improved electroencephalographic by implementing educational projects based on ad hoc training of nurses monitoring and neurointensive care specialists. ❍ Quantitative electroencephalography ❍ Technical guidelines Abbreviations:BIS Bispectral Index, EEG electroencephalography, EP ● Clinical applications of evoked potential, MMN mismatch negativity, NICU neurointensive care unit, SE electroencephalographic monitoring in the neurointensive status epilepticus, TMS transcranial magnetic stimulation care unit ❍ Seizures Is electrophysiologic monitoring useful to improve the neurointensive care of ❍ Nonconvulsive status patients with acute cerebral damage? Management strategies and epilepticus monitoring guidelines have been extensively reviewed in recent years in parallel ❍ Stroke and subarachnoid hemorrhage with developing concepts of evidence-based medicine [1]. As yet, cerebral ❍ Head injury electrical activity is not routinely included with physiologic parameters for ❍ Control of the level of sedation monitoring in the acute phase. Scepticism due to the supposed vulnerability ❍ Prognosis: to artifacts has outweighed considerations as to its potential utility electroencephalographic and noninvasiveness [2]. With the advent of digital processing and variability and reactivity ❍ Impact of continuous automated analysis, including expert systems, more positive evidence has emerged electroencephalography on [3–6] in favor of the use of electroencephalographic (EEG) monitoring. A management new methodologic approach is increasingly being adopted in pilot centers with ● Evoked potentials and event- diffuse application of continuous EEG monitoring and evoked potentials related potentials (EPs). Cumulative evidence of its potential benefits has been ❍ Acoustic evoked potentials retrospectively confirmed, and targeted prospective studies on its ❍ Somatosensory evoked potentials efficacy, efficiency, and cost-effectiveness are in progress [7–9]. ● Motor evoked potentials: This short review focuses on practical EEG and EP applications based on prognostic value ❍ clinically relevant questions arising in the neurointensive care unit (NICU). Postoperative motor evoked potentials ❍ Motor evoked potentials in Electroencephalographic monitoring in the neurointensive care acute cerebral lesions unit Rationale for electroencephalographic monitoring ● Conclusions ● References and recommended Secondary injury frequently occurs and negatively influences the outcome of reading patients with acute cerebral damage [10]. Thus, prevention and early detection ● Section Description of cerebral insults are major aims of neurointensive care. Despite http://ovidsp.tx.ovid.com/spb/ovidweb.cgi (2 of 14) [6/12/2008 11:43:39 AM] Ovid: Electrophysiologic monitoring in neurointensive care. increasingly sophisticated brain monitoring, subclinical seizures may be detected only by EEG, which provides invaluable information on the cerebral blood flow to metabolism ratio and may serve as a warning of ischemic insults, as a guide to treatment, and as a prognostic factor. EEG is sensitive to ischemia and can detect neuronal dysfunction at a reversible stage. Rationale for continuous electroencephalographic monitoring In the past, obvious limitations of analog recordings made EEG impractical for continuous monitoring. Nevertheless, a number of techniques for assessing EEG changes over time became very popular more than 20 years ago. The compressed spectral array [11,12], the cerebral function monitor [13], and the cerebral function analyzing monitor [14] have been extensively used. On-line continuous digital EEG recording and automatic processing have radically changed our perspective. In a recent review, techniques, evidence-based clinical recommendations, and caveats regarding misleading use have been addressed [15]. Quantitative electroencephalography Quantitative EEG transforms the EEG signal into a wide range of frequency and amplitude measurements. These continuous quantitative EEG outputs are easier for non-EEG experts and more “user friendly” than raw EEG. The advantages include data compression and visual display capability as bar graphs, compressed spectral arrays, or scalp maps [9]. Most data are derived from the fast Fourier transform (FFT) and displayed as measurement trends, including the percentage of alpha range activity (relative alpha), the total power or overall amplitude, and the alpha:delta ratio. The clinical scenario dictates the type of information that may be most significant; combinations of formats with raw EEG are possible. If clinical decisions are made on the basis of quantitative EEG, raw EEG and expert supervision must be available at the same time for quantitative EEG validation and artifact discrimination [15]. Technical guidelines Team training and continuous education are key factors. Continuous EEG monitoring should become part of the curricula of clinical neurophysiologists and neurointensive care specialists [16]. Particular methodologic and logistic strategies are needed [17•]. Standards of monitoring must be strictly observed [18]. When time is critical, “stick-on” electrocardiographic electrodes can be applied in a “subhairline” bipolar montage by house staff [19]. Artifacts can be avoided or detected by trained nurses [20]. Most artifacts are related to responses to nursing and other interventions; automatic methods for context-related artifact detection in prolonged EEG recordings have been tested with good performance against human observers [21,22••]. Nursing notes are of paramount importance [16,23]. Continuous EEG should be incorporated in the single bedside monitor or personal computer; thus, relationships between physiologic parameters and EEG could be obtained at a glance. Clinical applications of electroencephalographic monitoring in the neurointensive care unit http://ovidsp.tx.ovid.com/spb/ovidweb.cgi (3 of 14) [6/12/2008 11:43:39 AM] Ovid: Electrophysiologic monitoring in neurointensive care. Seizures Seizures constitute a common and probably underestimated complication in the NICU. Continuous EEG is necessary to detect subtle seizures and titrate drugs and should probably be considered standard in the treatment of status epilepticus (SE) [15]. On the other hand, continuous EEG can help to discriminate seizures from involuntary movements, spasms and tremors, eye deviations, and posturing that are common clinical features in the NICU [9]. Nonconvulsive status epilepticus Nonconvulsive SE includes three clinical situations: complex partial SE, absence SE, and electrographic SE [24]. Nonconvulsive SE represents an epileptic state lasting more than 30 minutes with two principal components: (1) some clinically evident alteration in mental status or behavior versus baseline, and (2) seizure activity on the EEG [25], including comatose patients in the NICU [26]. The reported proportion of SE patients who have nonconvulsive SE ranges from 4 to 20%. The incidence of absence SE compared with complex partial SE ranges from 3:1 to 1:3 [27–29]. A group of 127 patients with illnesses of various etiologies had an NICU continuous EEG; nonconvulsive seizures were documented in about 30%[30].