EEG and clinical neurophysiology in psychiatry — MEQ

(i) Indications and normal EEG. Order EEG when organic differentials matter: atypical new psychosis, fluctuating cognition, suspected seizures, unexplained catatonia with medical concern, spell characterisation pathway. Routine EEG is not a universal screen for uncomplicated depression or anxiety. A normal EEG does not exclude epilepsy, encephalitis, or primary psychiatric illness; abnormal non-specific slowing is common and requires clinical correlation. Write a clear clinical question and drug list on the request. [1][2]

(ii) NCSE approach. Suspect NCSE with impaired awareness, fluctuating responsiveness, or mutism without full recovery — convulsions are not required. Escalate to urgent/continuous EEG with neurology/ICU rather than labelling pure functional mutism. Salzburg-style criteria combine EEG patterns with clinical context. Continuous EEG detects electrographic seizures missed on brief records in critically ill patients. Treat as medical emergency pathways while investigating cause. [3][4]

(iii) Clozapine. Clozapine is associated with higher rates of EEG abnormalities than many other antipsychotics and with clinically important dose-related seizures in large cohorts. Management: acute seizure care; review dose escalation, plasma level, smoking/cessation and interactions; consider dose adjustment and antiseizure prophylaxis discussion; do not abandon uniquely effective therapy without a joint plan. [5][6]

(iv) Research tools. Routine clinical EEG is a diagnostic aid for organic/epilepsy differentials. MMN reduction is a robust group finding in schizophrenia research on automatic auditory processing; P300 relates to attention/context updating research. qEEG spectral maps are not standalone DSM/ICD diagnostic tests in ordinary care. [1][7]

(v) Extreme delta brush. Distinctive pattern described in anti-NMDA receptor encephalitis; supportive not pathognomonic. Action: neurology pathway, antibody testing, imaging/LP as indicated, immunotherapy consideration — not primary schizophrenia closure. [8]