Electroencephalography

Electroencephalography (EEG) is the measurement of electric activity produced by the brain recorded by placing electrodes on the scalp. EEG measurement is useful to investigate various psychiatric disorders like Epilepsy, Schizophrenia, distinguish them from other disorders like Syncope, End-Stage Bipolar Disorder, Post-Traumatic Stress Disorder, Suicidality, Dissociative Identity Disorder and Obsessive-Compulsive Disorder, to characterize the disorder patterns for treatment, to monitor the depth of anaesthesia, to detect Cerebral Perfusions and to detect Brain Death.

EEG in Psychiatric Nurse Care

Drug and psychosocial nurse interventions for the symptoms of mental disorders contribute to a lower incidence and prevalence. Caring such patients undergoing therapy with antipsychotic drugs like clozapine and benzodiazepines involves careful monitoring due to marked side effects like Sedation, Hyper Salivation, increase in Transaminases, EEG changes, Cardiovascular Respiratory Dysregulation, Overweight, Mild Parkinsonism, Akathisia, Tardive Dysakinesia, increase of liver enzymes, Hypotension, Fever, ECG Alterations, Tachycardia and Delirious States. These drugs also pose the risk of seizures (Cochrane, 2006).

Published Evidence

Electroencephalogram slowing has been shown to be associated with clozapine side effects and can be used as a marker to predict treatment response during clozapine treatment (Wichniak A et.al, 2005). Patients with schizophrenia have been found to show N1, P3 and late slow wave abnormalities indicating impairment in early stimulus evaluation and subsequent working memory functions. Subsequent treatment with clozapine seems to induce normalization of the P3 and late slow waves, indicating improvement in working memory updating and executive processing. There also seems to be a partial normalization of N1 amplitude, suggesting improvement in early stimulus evaluation (Galletly et.al, 2005). In patients treated with Electro Convulsive Therapy along with parallel administration of antipsychotic medication, antipsychotic drugs have been found to influence both seizure threshold and seizure activity in different ways. Most of the antipsychotics like Olanzapine and Zuclopenthixol have been found to have epileptogenic properties (Gazdag, 2004).

The importance of Continuous EEG monitoring in the diagnosis and management of Convulsive and Nonconvulsive Status Epilepticus has been established and helps the early diagnosis and management of Precarious Cerebral Ischemia, including severe Acute Cerebral Infarctions and Post-SAH Vasospasms. It provides diagnostic and prognostic information in comatose patients which is otherwise impossible. More recently, it has also been found useful in the management of acute severe Head Trauma patients (Jordan and Kenneth, 1999). The changes of theta activity (3.5-7 Hz) in the Quantitative Electroencephalography (QEEG) and serum drug levels and their correlation with clinical response, measured by the positive and negative syndrome rating scale (PANSS) have been examined prospectively in patients and significant inverse correlations between the theta power increase and the changes in PANSS subscales for negative (P < 0.01) and positive (P < 0.05) symptoms at three weeks have been obtained indicating that the change in the theta frequency in QEEG, particularly in the midline electrodes over the fronto-central scalp area might be a more sensitive indicator for the evaluation of treatment adequacy than the serum drug levels (Gross, 2004). The probability of EEG abnormality has been found to be linearly dependent on the daily drug dose and patient's age. Such studies have shown that a substantial proportion of patients treated with drugs like Clozapine develop EEG abnormalities and the EEG abnormalities occur in a dose-dependent manner (Chung et.al, 2002). A study which investigated the incidence and nature of drug-associated electroencephalographic (EEG) abnormalities and the relationship between EEG abnormality and clozapine dosage in Korean schizophrenic patients has shown that the majority of EEG abnormalities presented as Non-Specific Slow Waves (SW), Spikes (Or Spike And Wave Complexes; SP) and Frontal Intermittent Rhythmic Delta Activity (FIRDA). Specific Electroencephalogram (EEG) changes during pharmacotherapy have also been studied with reference to serum level ranges. Patients in a typical study have shown EEG changes during the 10-week study period with seizures and slowing on EEG (Freudenreich, 1997). Topographic quantitative Electroencephalographic power and frequency indices have been recently studied in 17 treatment refractory; DSM-III diagnosed schizophrenic patients, before and after acute (single dose) and chronic (six weeks) treatment. Studies have shown that acute dosing increased total Spectrum Power globally, Slow Wave Power posteriorally, Mean Alpha Frequency and Beta Power anteriorally and Decreased Alpha Power posteriorally. Chronic treatment results in EEG slowing as shown by decrease in relative Alpha Power, Mean Beta/Total Spectrum Frequency and by widespread increases in Absolute Total and Delta/Theta Power suggesting that the brain electric profiling may be a promising tool for assessing and understanding the central impact of pharmacotherapeutic interventions (Knott, 2001). Recent studies on the effect of Clozapine treatment of patients with chronic Schizophrenia on the scalp topographic distribution of different frequency bands on EEG has shown that the topographic EEG features caused by clozapine are quite specific to it and can be differentiated from those of other neuroleptics (Joutsiniemi, 2001).

A positive correlation between Reactive Oxygen Species production of Blood Monocytes (R(2) = 0.929, p < 0.05) for nonstimulated MO, and (R(2) = 0.907, p < 0.001) for stimulated MO and theta-power values in the central frontal electrode (F(z)) have been obtained recently giving rise a speculation that the EEG slowing is a result of the modulatory action of the activated microglial cells in the central nervous system via production of ROS or Cytokines or both (Gross, 2003). EEG coherence in slow (delta and theta) frequencies has been assessed in people with Schizophrenia and the results show that EEG coherence can be an index of Brain Regional Coupling (Knott, 2002).

A study on the relationships between serum drug level, quantitative EEG parameters and performance in vigilance and memory tasks have shown that the atypical antipsychotics cause EEG alterations indicating memory impairments due to anticholinergic properties. Negative correlations between serum drug levels and the amount of high-frequency EEG activity and positive correlations between high-frequency EEG activity and memory performance obtained suggest that treatment brings about dose-dependent impairments of vigilance and memory indicated by reduction of high-frequency EEG activity (Adler et.al, 2002). A descriptive study to describe the various findings of Electroencephalography in assessing diseases encountered in clinical practice, to audit the use of EEG in a tertiary teaching hospital and to describe the diagnostic categories in which EEG can be helpful as diagnostic tool has shown that Electroencephalography is helpful in assessing the diagnosis of epilepsy and delirium. 

Conclusion

Although the Electroencephalogram is a reliable test to assess cerebral function, its value in diagnosis and evaluation of neurological conditions apart from epilepsy has been largely controversial. But recent research studies have proved that the utilization of EEG in psychiatric nurse practice can help investigation of conditions like Schizophrenia. Hence, it should be possible to investigate and monitor end-stage bipolar disorder, post-traumatic stress disorder, suicidality, dissociative identity disorder and obsessive-compulsive disorder that are posing a challenge to psychiatric nurse care. EEG recording has been proved especially useful in tracing and monitoring changes in patients undergoing therapy with antipsychotic drugs.

Reference

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• Gross A, Joutsiniemi SL, Rimon R, Appelberg B (2004). Clozapine-Induced QEEG Changes Correlate with Clinical Response in Schizophrenic Patients: A Prospective, Longitudinal Study. Pharmacopsychiatry. 37(3):119-22.
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• Knott VJ, LaBelle A, Jones B, Mahoney C (2002). EEG Coherence Following Acute and Chronic Clozapine in Treatment-Resistant Schizophrenics. Exp Clin Psychopharmacol. 10(4):435-44.
• Muir-Cochrane (2006). Medical Co-Morbidity Risk Factors and Barriers to Care for People with Schizophrenia. J Psychiatr Ment Health Nurs. 13(4):447-52.
• Wichniak A, Szafranski T, Wierzbicka A, Waliniowska E, Jernajczyk W.(2006). Electroencephalogram Slowing, Sleepiness and Treatment Response in Patients with Schizophrenia during Olanzapine Treatment. J Psychopharmacol. 20 (1):80-85.

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