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Epilepsy surgery
Drug-resistant epilepsy — failure of two appropriate, well-tolerated drugs — requires referral to an epilepsy centre, and when the focus is unilateral mesial temporal sclerosis, anterior temporal lobectomy achieves seizure freedom in about 60% versus under 10% with continued medication.
Why it matters in the exam
Questions test the ILAE definition of drug resistance, the pre-surgical work-up (video-EEG, epilepsy-protocol MRI, PET showing hypometabolism, neuropsychological assessment, and fMRI or the Wada test to lateralise language and memory), and the semiology of a mesial temporal seizure: a rising epigastric aura or déjà vu, oral and ipsilateral hand automatisms and contralateral dystonic posturing. MRI shows hippocampal atrophy and increased T2 or FLAIR signal. The randomised Wiebe trial showed seizure freedom in 58% of operated patients versus 8% on medication alone.
The commonest complication after temporal resection is a visual field defect — a contralateral superior quadrantanopia from injury to Meyer's loop; on the dominant side there is a risk of decline in verbal memory and naming. When there is no resectable focus, options are vagus nerve stimulation (VNS) — which halves seizures in about half of patients — DBS of the anterior thalamic nucleus or responsive neurostimulation (RNS). Corpus callosotomy is for atonic drop attacks and interrupts seizures that spread between hemispheres; it can be followed by a disconnection syndrome with transient mutism. Functional hemispherectomy suits a child with single-hemisphere disease such as Rasmussen encephalitis or hemimegalencephaly. LITT (MRI-guided laser ablation) is a minimally invasive alternative for mesial sclerosis.
Key points
- Resistance: failure of two appropriate drugs.
- Mesial sclerosis — temporal lobectomy, about 60% seizure-free.
- Common complication: contralateral superior quadrantanopia.
- Drop attacks — corpus callosotomy.
- No focus — VNS, RNS or DBS.
Summary table
| Operation | Indication | Outcome | Typical complication |
|---|---|---|---|
| Anterior temporal lobectomy | Unilateral mesial temporal sclerosis | Seizure freedom about 60% | Contralateral superior quadrantanopia; verbal memory on the dominant side |
| LITT | Mesial sclerosis, small deep lesions | Slightly lower than resection | Visual field, oedema |
| Corpus callosotomy | Atonic drop attacks | Fewer falls, not cure | Disconnection syndrome, transient mutism |
| VNS | No resectable focus | Halves seizures in about half of patients | Hoarseness, cough |
| Functional hemispherectomy | Rasmussen, hemimegalencephaly | High seizure freedom in children | Hemiparesis expected in advance |
A free exam question
?מה מאפיין את הפעילות האפילפטית בהיפוקמפוס (the question as examined, in Hebrew)
- א. עלייה בפעילות תטא סינכרונית
- ב. עלייה בירי טוני של הנוירונים הגאבארגים
- ג. ירידה בפעילות.הנוירונים הגלוטמטרגים
- ד. ירידה בסינכרון התאים הפירמידליים
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Sources
- ILAE consensus definition of drug-resistant epilepsy, 2010 — Definition
- AAN/AES practice parameter: temporal lobe and localized neocortical resections for epilepsy, 2003 (reaffirmed) — Surgical outcomes
- Youmans and Winn Neurological Surgery, 8th edition (2022) — Surgical management of epilepsy
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.