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Todd's Paresis – Lateralising Value — SCE Neurology MCQ

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EasyEpilepsy & Seizure DisordersTodd's Paresis – Lateralising ValueSCE Neurology

A 40-year-old man with known epilepsy presents with a seizure. His witness describes his eyes rolling up, generalised stiffening for 20 seconds (tonic phase), followed by bilateral rhythmic jerking for 90 seconds (clonic phase), then he was unresponsive for 10 minutes. He bit his tongue laterally and was incontinent. Post-ictally he has a right arm weakness (Todd's paresis) lasting 30 minutes. What does the Todd's paresis lateralise?

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Correct answer: B — Todd's paresis localises the seizure onset to the contralateral hemisphere — right arm weakness suggests left hemisphere seizure onset

Todd's paresis (post-ictal focal weakness) has strong lateralising value — it indicates that the seizure originated from (or maximally involved) the contralateral motor cortex. Right arm weakness → left hemisphere seizure focus. It results from transient neuronal exhaustion in the active cortex. Todd's paresis typically resolves within 24 hours. If it persists, a structural lesion must be excluded. A: Todd's paresis has strong lateralising value. C: The contralateral hemisphere is implicated. D: Todd's paresis indicates focal onset. E: Todd's can occur without a structural lesion.

Reference: NICE NG217; ILAE