Epilepsy & seizures

Epilepsy is a neurological condition characterised by a predisposition to recurrent, unprovoked seizures. A seizure is a transient episode of signs or symptoms caused by abnormal, excessive, or synchronous neuronal activity in the brain. Epilepsy is defined by two or more unprovoked seizures occurring more than 24 hours apart, or one unprovoked seizure with a high risk of recurrence.

Approximately 1–3% of the population has epilepsy. Around 10% of people will have at least one seizure during their lifetime — but a single provoked seizure (caused by fever, drugs, or metabolic disturbance) does not constitute epilepsy.

**Causes:** - Structural: head injury, stroke, brain tumour, vascular malformation, cortical dysplasia - Metabolic: electrolyte abnormalities, glucose disorders, toxic exposures - Infectious: encephalitis, meningitis, brain abscess - Genetic: several epilepsy syndromes have identified genetic causes (e.g., Dravet syndrome) - In many cases (particularly primary generalised epilepsies), no specific cause is found

**Types of seizures** — the major classification divides seizures by onset:

*Generalised-onset seizures* (both hemispheres involved simultaneously): - **Absence (petit mal):** brief lapse in awareness, staring, eyelid flickering; no post-ictal confusion; may occur hundreds of times a day - **Tonic-clonic (grand mal):** loss of consciousness, bilateral stiffening (tonic phase), then rhythmic jerking (clonic phase); post-ictal confusion and fatigue - **Tonic:** bilateral stiffening without a clonic phase - **Myoclonic:** brief, lightning-like jerks of the limbs or whole body; no loss of consciousness - **Atonic (drop attacks):** sudden loss of muscle tone causing collapse

*Focal-onset seizures* (arising from one region of the brain): - **Simple focal (aware):** no loss of consciousness; motor, sensory, autonomic, or psychic symptoms depending on the brain region involved - **Complex focal (impaired awareness):** typically begins with an aura (fear, smell, déjà vu), followed by altered consciousness, automatisms (repetitive movements such as chewing or hand fumbling) - Focal seizures can secondarily generalise

**Diagnosis** relies on a detailed clinical history, electroencephalography (EEG), and brain imaging (MRI). Video-EEG telemetry — recording both EEG and clinical behaviour simultaneously — is the gold standard for characterising seizure type and identifying a surgical target in drug-resistant cases. Functional MRI and PET scanning provide additional localising information.

**Treatment:** - *First-line:* Anticonvulsant medications (carbamazepine, valproate, levetiracetam, lamotrigine, and others) achieve seizure control in approximately 70% of patients - *Drug-resistant epilepsy:* When two appropriately chosen anticonvulsants fail, surgical evaluation is indicated. Options include focal resection (curative in suitable temporal lobe epilepsy), vagal nerve stimulation, corpus callosotomy, deep brain stimulation, and ketogenic diet - *Neuromodulation:* rTMS has an emerging evidence base in reducing seizure frequency in selected patients with focal epilepsy