Temporal Lobe and Focal Epilepsy
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Direct answer
Temporal lobe epilepsy is focal epilepsy arising from the mesial temporal structures, most often the hippocampus, and it is a common cause of drug-resistant focal epilepsy in adults. Typical features are an epigastric aura, automatisms such as lip smacking, and impaired awareness, usually with hippocampal sclerosis on MRI. Surgical resection is considered when two appropriately chosen drugs have failed and the findings concordantly localise the seizure focus.
What you must remember
- Aura: A rising epigastric sensation, fear, déjà vu or an unpleasant smell, which is itself a focal seizure with preserved awareness.
- Automatisms: Lip smacking, chewing or fumbling movements, with impaired awareness and amnesia for the event.
- Hippocampal sclerosis: The commonest pathology in mesial temporal epilepsy, seen on MRI as hippocampal atrophy with raised T2 or FLAIR signal.
- Febrile seizures: Prolonged or complex febrile seizures in childhood are a classic risk factor for mesial temporal sclerosis.
- Drug resistance: Failure of two appropriately chosen and tolerated antiseizure drugs defines drug-resistant epilepsy.
- Surgical candidacy: Requires concordance between EEG, MRI and the clinical seizure semiology, with a clear seizure-onset zone.
- Wada test: Used to lateralise language and memory before surgery, when the findings are unclear.
A pathway from drug resistance to surgery
Surgery can offer lasting seizure freedom in carefully selected drug-resistant temporal lobe cases. The steps below show how candidacy is established before any operation is planned. Each step filters out patients who would not benefit or who carry an unacceptable risk of deficit.
- Confirm drug resistance: Two properly chosen and tolerated drugs, used at adequate doses, must have failed to control the seizures.
- Characterise the seizures: Video-EEG captures the aura, automatisms and ictal onset to confirm a focal origin.
- Image the brain: An epilepsy-protocol MRI looks for hippocampal sclerosis, tumours or malformations, and PET or SPECT is added when MRI is normal.
- Assess function: Neuropsychological testing and fMRI or the Wada test establish language and memory dominance before resection.
- Choose the operation: Anterior temporal lobectomy or selective amygdalohippocampectomy is selected when the findings concord.
- Plan follow-up: Seizure freedom is reviewed over time, and many patients still need antiseizure medication afterwards.
Where the exam tries to catch you
Examiners test whether you recognise focal semiology and do not operate on a single abnormal finding.
- Trap: Calling a dreamy epigastric aura a psychiatric disorder Correct: an epigastric aura followed by automatisms and impaired awareness indicates temporal lobe epilepsy until proven otherwise.
- Trap: Assuming an MRI lesion automatically means surgery Correct: surgery needs concordance between EEG, MRI and seizure semiology, not any single finding alone.
- Trap: Confusing temporal lobe seizures with absence seizures because both involve staring Correct: temporal lobe seizures show automatisms and post-ictal confusion, while absence seizures are brief and generalised on EEG.
Frequently asked questions
What is the commonest pathology in mesial temporal lobe epilepsy?
Hippocampal sclerosis is the commonest pathology in mesial temporal lobe epilepsy, characterised by neuronal loss and gliosis in the hippocampus. On MRI it appears as hippocampal atrophy with raised T2 or FLAIR signal. Its presence often predicts a good response to temporal lobe surgery.
Which drugs are used for focal seizures in temporal lobe epilepsy?
Carbamazepine, oxcarbazepine, lamotrigine, levetiracetam and lacosamide are commonly used for focal seizures, including temporal lobe epilepsy. Carbamazepine and lamotrigine are usually considered first choices, with levetiracetam often used when others fail. The choice depends on comorbidity, drug interactions and pregnancy plans.
What investigations are needed before temporal lobe epilepsy surgery?
Surgical candidacy needs video-EEG monitoring, an epilepsy-protocol MRI and often PET or SPECT, together with neuropsychological assessment. Language and memory dominance are tested with fMRI or the Wada test before resection. Concordance between these results determines whether the operation is likely to help.
Does a febrile seizure history matter in temporal lobe epilepsy?
A history of prolonged or complex febrile seizures in childhood is a recognised risk factor for hippocampal sclerosis and later mesial temporal epilepsy. It is not diagnostic on its own. Clinicians look for the typical aura and automatisms before attributing the epilepsy to childhood fever.