Synopsis
Apply the 2025 ILAE seizure classes and supported consciousness and manifestation descriptors, avoid inferring a Generalized seizure from bilateral convulsions alone, and use classification to select safe investigations and syndrome-appropriate treatment.
- Use the 2025 ILAE main classes—Focal, Generalized, Unknown whether focal or generalized, and Unclassified—then apply supported classifiers and descriptors: consciousness where assessable, observable or non-observable manifestations, and the chronological evolution of the event.
- A Focal seizure begins in a network limited to one hemisphere. When assessable, classify consciousness as preserved or impaired—using both awareness and responsiveness—then describe observable and non-observable manifestations in the order they occurred.
- A focal to bilateral tonic-clonic seizure may look fully generalised once convulsions spread, so the aura, first head or eye deviation and initial unilateral movement are disproportionately informative.
- The Generalized class involves rapidly engaging bilateral networks and includes absence, myoclonic, tonic, atonic and generalized tonic-clonic seizures, often within a recognisable age-related epilepsy syndrome.
- Unknown whether focal or generalized is a legitimate provisional class when available evidence cannot distinguish the two; use Unclassified when the event is accepted as epileptic but available information does not permit a more specific class.
- Seizure type, epilepsy type and epilepsy syndrome are different levels: one person can have several seizure types within one defined syndrome.
- An EEG pattern can support and refine classification but should be reconciled with semiology; a focal discharge, generalised spike-wave or normal recording is not interpreted in isolation.
- Classification is safety-critical because narrow-spectrum sodium-channel medicines can aggravate absence or myoclonic seizures, while reproductive and interaction risks also shape the final choice.
Investigation priorities
Identify the earliest manifestation, consciousness and sequence needed to assign a seizure class and supported descriptors.
Management branches
A suspected epileptic event is being classified after immediate safety needs are met.
- 1. Ask what the person experienced first, including sensory, emotional, cognitive, autonomic or motor symptoms before awareness changed.
- 2. Ask witnesses about responsiveness, eye and head direction, first moving body part, symmetry, sequence, duration and post-event behaviour without offering diagnostic labels.
- 3. Assign Focal, Generalized, Unknown whether focal or generalized, or Unclassified, then add consciousness and observable or non-observable descriptors only where supported and record manifestations in chronological order.
- 4. Preserve the raw description in the record so a later EEG or video can refine the category without being constrained by an early label.
Key medicines
Lamotrigine or levetiracetam for focal seizuresNICE advises either as first-line monotherapy; dosing is titrated from the current BNF and product guidance, with lamotrigine increased particularly slowly and according to interacting medicines.Lamotrigine can cause serious rash and has major titration interactions with valproate; levetiracetam may worsen irritability or mood. Pregnancy, renal function, adherence and psychiatric history influence selection.
Ethosuximide for isolated absence seizuresNICE recommends ethosuximide first line for absence seizures without other seizure types; start and titrate using age, weight, current formulary and specialist instructions.It does not cover generalised tonic-clonic seizures. Ask specifically about myoclonus and convulsions, and monitor gastrointestinal, neuropsychiatric, haematological or hepatic adverse effects as clinically indicated.