Functional seizures: differentials

Generalized tonic-clonic seizures

• These have a consistent semiology
• The movements are synchronous
• There is no pelvic thrusting
• There are no side-to-side head or body movements
• The eyes are open during the episodes
• There may be lateral tongue biting
• They are less likely to last >5minutes unlike in psychogenic seizures
• There is post-ictal stertorous breathing: this strongly suggests organic seizures
• There is postictal amnesia for the episodes
• There is post-ictal confusion
• The course is not fluctuating

References

1. Avbersek A, Sisodiya S. Does the primary literature provide support for clinical signs used to distinguish psychogenic nonepileptic seizures from epileptic seizures? JNNP2010; 81: 719-725.
2. Muthusamy S, Seneviratne U, Ding C, Phan TG. Using semiology to classify epileptic seizures vs psychogenic nonepileptic seizures: a meta-analysis. Neurol Clin Pract 2022; 12:234-247. 
3. Seneviratne U, Minato E, Paul E. How reliable is ictal duration to differentiate psychogenic nonepileptic seizures from epileptic seizures? Epilepsy Behav 2017; 66:127-131. 
4. Sen A, Scott C, Sisodiya SM. Stertorous breathing is a reliably identified sign that helps in the differentiation of epileptic from psychogenic non-epileptic convulsions: an audit. Epilepsy Res 2007; 77:62-64. 
5. Azar NJ, Tayah TF, Wang L, Song Y, Abou-Khalil BW. Postictal breathing pattern distinguishes epileptic from nonepileptic convulsive seizures. Epilepsia 2008; 49:132-137.
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Related checklists

• Functional seizures: risk factors
• Functional seizures: clinical patterns
• Functional seizures: clinical features
• Functional seizures: course and complications
• Functional seizures: outcomes