Functional seizures (dissociative/non-epileptic seizures)
Definition and scope
Functional seizures are paroxysmal motor, sensory or behavioural episodes that resemble epileptic seizures but arise from disordered nervous‑system functioning rather than epileptic electrical discharges. They are common in emergency departments, may coexist with epilepsy, and require a management approach that balances immediate safety, careful diagnostic reasoning and sensitive communication (NICE NG127; RCEM).
Terminology - use plain, non‑stigmatising language
- Preferred terms: “functional seizures” or “dissociative seizures.” These terms convey that symptoms are real, involuntary and due to altered brain function.
- Avoid pejorative or misleading labels such as “pseudoseizure,” “hysterical,” “conversion disorder” or “psychogenic seizure.”
- “Non‑epileptic seizure/attack” (NES/NEAD) is descriptive but negative; diagnosis should be positive - based on features of functional neurological disorder (FND) rather than only on exclusion of epilepsy (NICE NG127).
Key pathophysiology concepts
- Functional seizures reflect altered brain network function involving motor, attentional and limbic systems.
- Dissociation may be present - a transient disruption of integration of awareness, memory and movement.
- Psychological stressors or prior illness can be contributing factors but are neither necessary nor sufficient for diagnosis.