From the Guidelines
An electroencephalogram (EEG) is not routinely indicated for patients with impulsive symptoms and abnormal behavior unless there is clinical suspicion of an underlying seizure disorder or organic brain pathology. EEG should be considered when patients exhibit episodic behavioral changes, altered consciousness, automatisms, or other features suggestive of seizure activity, particularly temporal lobe epilepsy which can sometimes present with behavioral disturbances 1. It may also be warranted if the patient has a history of head trauma, unexplained cognitive decline, or if symptoms emerged suddenly without psychological precipitants.
Before ordering an EEG, clinicians should first conduct a thorough psychiatric and neurological evaluation, as most impulsive behaviors and conduct disturbances stem from primary psychiatric conditions rather than neurological disorders. If an EEG is performed, both routine and sleep-deprived recordings may be necessary to maximize detection of abnormalities, as some epileptiform discharges only appear during sleep transitions. The absence of EEG abnormalities does not definitively rule out neurological contributions to behavioral symptoms, and clinical correlation remains essential for proper diagnosis and treatment planning. Key considerations include:
- Clinical suspicion of seizure disorder or organic brain pathology
- Episodic behavioral changes or altered consciousness
- History of head trauma or unexplained cognitive decline
- Sudden onset of symptoms without psychological precipitants
- The role of EEG in detecting nonconvulsive seizure activity, as highlighted in guidelines for ICU patients 1, may also inform decision-making in certain cases. However, the primary consideration should be the clinical presentation and suspicion of underlying neurological pathology, rather than the presence of impulsive symptoms and abnormal behavior alone.
From the Research
Impulsive Symptoms and Abnormal Behavior
- EEG is not directly indicated for impulsive symptoms and abnormal behavior, but it can be useful in certain cases where epilepsy or other cerebral diseases are suspected 2.
- In patients with newly occurring psychoses or conditions with fluctuating or progressive loss of cognitive function, EEG should be considered 2.
- EEG can also be useful in cases where seizure symptoms or rapid changes in affective states are present, as epileptiform activity during EEG can be a specific sign of epileptic etiology or comorbidity 2.
Diagnostic Yield of EEG
- Early EEG in the emergency room setting can have a high diagnostic yield in patients with suspected new-onset seizures 3.
- Abnormal EEG and abnormal MRI can significantly contribute to decision-making regarding treatment 3.
- However, the diagnostic yield of EEG may be lower in patients with developmental disabilities or mental retardation, and other diagnostic criteria may be needed 4, 5.