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Current Practice Of Clinical Electroencephalogr...

Policies of administration and availability of EEG offered during nonbusiness hours vary widely among EEG laboratories. The authors surveyed medical directors of accredited EEG laboratories (n = 84) to determine the ranges of availability and clinical indications for approval of continuously available emergent EEG (E-EEG). Of 46 respondents, 37 (80%) offered E-EEG. Two centers recently lost funding for E-EEG. Availability was not associated with the total number of EEGs performed annually. The mean estimated response time from request to expert interpretation was 3 +/- 4 hours (range, 1-24 hours). The five clinical indications for which most respondents approved E-EEGs were possible nonconvulsive status epilepticus (100%), treatment of status epilepticus (84%), cerebral death exam (81%), diagnosis of convulsive status epilepticus (79%), and diagnosis of coma or encephalopathy (70%). Respondents disagreed widely when asked which clinical situations merited E-EEG, with some approving all requests and others denying all except for nonconvulsive status epilepticus. The wide range of current practice suggests that research focused on outcomes of aggressive, EEG-aided patient evaluation and treatment are needed to define better the costs and benefits of a continuously available EEG service.

Current Practice of Clinical Electroencephalogr...

Processed electroencephalography (pEEG) is widely used in clinical practice. Few clinicians utilize the full potential of these devices. This brief review will address the improvements in patient management available from the utilization of all pEEG data.

Monitoring of sedation levels by pEEG in critical care environments was proposed recently as a rational method for managing limited pharmaceutical resources during the COVID-19 pandemic [70]. However, a meta-analysis of data from studies in more controlled circumstances found no benefit of BIS monitoring on clinical outcomes or resource utilization [71]. Continuous EEG monitoring placed and interpreted by a neurophysiologist has utility in critical care practice for diagnosis and prognosis in a range of clinical conditions. Caution has been urged when using processed EEG devices for applications other than sedation monitoring in this environment [72].

The goals of this book are to provide a brief historical perspective of EEG in psychi- atric practice; to provide an understanding of the physiologic bases of the EEG signal and of the basic elements of EEG recording; to review normal and abnormal EEG patterns; and to provide the psychiatrist with a clear understanding of both the value and limitations of EEG testing and its clinical indications in the diagnostic work up as it applies to psychiatric patients.

Historically, the early EEG discoveries occurring with epilepsy, structural lesions and encephalopathies were of considerable clinical value and were often used in assessing what were sometimes life-threatening events. Thus these were the early uses of EEG which had the highest visibility and recognition and because of this EEG came to be increasingly identified with neurology. Gradually, over ensuing years, most (but not all) EEG laboratories became housed within neurology departments or neurology practices.

The neurology discipline appreciates hard EEG data with well-documented and strongly supported diagnostic relevance. Psychiatry must of necessity (at least at the current state of knowledge) be concerned with EEG findings that are associated with a variety of altered behaviours and not necessarily with diagnostic categories defined by current classification systems. The value of EEG findings in psychiatry must be determined from within the field of psychiatry and cannot be evaluated in terms of the clinical conditions deemed important by neurologists.

The current Diagnostic and Statistical Manual (DSM-IV-TR) nomenclature for di- agnosis of ADHD describes the syndrome in terms of either partial or full expression: ADHD Predominantly Inattentive Type, ADHD Predominantly Hyperactive-Impulsive Type and ADHD Combined Type. Such distinctions are useful in delineating correlated neurological disorders presenting with hyperactive, impulsive or inattentive symptoms. Further, different subtypes of ADHD may predominate during distinct periods of child and adolescent development, aiding differential diagnosis. Pre-school children with ADHD most often present with the hyperactive-impulsive (HI) form of the disorder; whereas in contrast, older adolescents will largely manifest a predominantly Inattentive subtype with only residual restlessness. A child must meet six out of nine inattentive symptoms for diagnosis of the inattentive type, and/or six of the hyperactive-impulsive symptoms for the HI type. Six symptoms from each list must be present for diagnosis of the combined type. The range of potential symptom combinations within each type, as well as across individuals, highlights the heterogeneity in clinical presentation for diagnostic assessment. Although the DSM-IV remains the most commonly referenced diagnostic system for ADHD in the US, it must be noted that the ICD-10 system most commonly used in Europe and elsewhere in diagnosis of hyperkinetic disorder confronts similar issues of complexity and heterogeneity, although the symptom list has been described as more restrictive than what is published in the DSM-IV.

The observation of a clinical seizure, preceded by the unusual nocturnal and daytime behavioural history in the above case, suggest the importance of close continuing be- havioural observation and consideration of an anticonvulsant trial, with follow-up EEG monitoring. Both seizure and ADHD may be treated concurrently and safely, although stimulant treatment is advised only in the context of well controlled seizure disorder. Clinicians must be alert and suspicious of the possibility of seizure in atypical presenta- tions of behavioural disturbance labelled ADHD, and must be prepared to pursue more careful diagnostic assessment, including behaviour logs, rating scales and EEG.

one child proved to have Landau-Kleffner syndrome (LKS). They still concluded that strong consideration should be given to genetic testing and EEG studies. They felt that a full metabolic and neuroimaging work up for screening are not justified based on current knowledge. On the other hand, Steiner et al. [47] applied a protocol of clinical and laboratory evaluations to 103 outpatients with PDD. The protocol included chromosomal analysis, screening for inborn errors of metabolism, EEG, SPECT and MRI. Eighty-four subjects were included and fell into three clinical categories: autism, atypical autism or Asperger syndrome. Imaging and EEG abnormalities occurred in similar proportions amongst the three groups. Genetic factors were more prevalent in the two autism groups.

Whether the appearance of an abnormal EEG predicts a favourable therapeutic re- sponse to anticonvulsant medications is currently unknown. Monroe [22] showed that anticonvulsants can block electroencephalographic epileptiform discharges and can lead to dramatic clinical improvement in individuals exhibiting repeated and frequent ag- gressive behaviour. An earlier study by Boelhouwer et al. [23] found adolescents or young adults exhibiting the 14 and 6 positive spikes to respond favourably to the com- bination of anticonvulsants and antipsychotic medications. With a maximum of 8 week trials comparing thioridazine, diphenylhydantoin or combination of the two against placebo, they reported that the PS spike group responded best to the combination of drugs. These investigators then assessed the EEGs for the presence of the posterior temporal lobe slowing. They noted that patients with both abnormalities did least well

r In Italy, training in clinical neurophysiology is clearly defined only for the postgrad- uate schools of specialisation in neurophysiopathology. The status of this speciality is very uncertain at the present time, and the possibility that training schools in neurophysiopathology disappear to become part of the neurology training schools is being discussed. So far, the medical doctor with this specialisation must have acquired knowledge in the field of physiology and pathology of the nervous system, with special reference to instrumental diagnostic of nervous and muscle pathology and to techniques relevant to the ascertainment of cerebral death and to the pathophysiology of vigilance and consciousness. The majority of Italian psychiatrists never receive a training in electrophysiology and therefore are unfamiliar with EEG and its clinical applications in psychiatry. Neurologists are in many, but not in all, cases trained in EEG procedures and clinical applications. The standardisation of recording procedures is not yet satisfactory. No specific degree, obtained from any school of medicine, is mandatory for EEG recording and interpretation. Different medical doctors, if experi- enced in the field, can take the responsibility of recording and interpretation of clinical neurophysiology tests. No clear recommendations are available about the practice of recording and interpreting neurophysiological data.

Contrary to the current trend to reduce the EEG education, the core curriculum of psychiatrists should include training in electrophysiology, at least covering the basic aspects described in this book. We would also advocate the creation of a subspecialty of clinical electrophysiology within psychiatry, based on the availability of:

As can be seen from the above figure, areas of overlap exist that could represent potential grounds for conflicts of interests in territorial disagreements. The current field of sleep disorders medicine is heavily focused on evaluating and treating sleep disordered breathing. Where psychiatric interest in sleep studies is focused is in the ability of sleep EEGs to differentiate between psychiatric disorders (e.g. delusional depression vs. schizophrenia), and identify neuropsychiatric disorders (e.g. nocturnal panic attacks). The psychiatric questions remain largely in the research arena while the sleep medicine issues are all widely accepted clinically. Another, and even perhaps more contentious area of overlap is with clinical neurophysiology and the standard EEG (which is the focus of this entire text. Indeed if the two disciplines of neurology and psychiatry fully recognise the significant overlap of the fields (both being related to brain disorders), then such conflict may not have grounds as current clinical neurophysiology labs would provide the service and be nourishing environments for research in both neurophysiology and psychiatric electrophysiology. As of the writing of this text, this scenario does not seem very likely. Indeed, as of now, psychiatrists in the USA are not eligible to sit for either of the two mainstream CN boards. This obvious overlap need not create major conflict as psychiatric electrophysiology labs would provide clinical services only for patients presenting with psychiatric complaints. A parallel board should also be developed for PhDs with significant training in psychiatry. 041b061a72


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