GPAtlas🧭 When to suspect
Epilepsy is a clinical diagnosis, and the single most valuable piece of information is a clear eyewitness account of the event. A patient typically presents after an episode of altered awareness or abnormal movements that someone else has witnessed. The diagnosis rests on the description, not on a test – EEG and imaging support classification and aetiology, but neither confirms nor excludes epilepsy.
Suspect an epileptic seizure where there is a preceding aura (a rising epigastric sensation, an unusual smell or taste, or déjà vu), loss of awareness, characteristic motor features such as rhythmic jerking or stiffening, lateral tongue biting, or incontinence, followed by a distinct period of post-ictal confusion or drowsiness. Be alert too to subtle focal seizures – brief, stereotyped, repetitive episodes of tingling, specific smells or tastes, or staring spells – which are easily missed but equally warrant urgent assessment.
A crucial task in primary care is separating epilepsy from its mimics. The commonest pitfall is misdiagnosing syncope as a seizure; brief myoclonic jerks are common in convulsive syncope and do not make it epileptic. Dissociative (non-epileptic) seizures are also frequently mistaken for epilepsy.
| Feature | Epileptic seizure | Syncope |
|---|---|---|
| Onset | Often abrupt; may have an aura | Prodrome of light-headedness, nausea, greying vision, sweating |
| Posture / trigger | Any posture; can occur in sleep | Usually upright; prolonged standing, pain, heat |
| Motor features | Prolonged rhythmic jerking or stiffening | Brief, irregular myoclonic jerks (convulsive syncope) |
| Tongue biting | Lateral – fairly specific | Tip of tongue, or none |
| Recovery | Prolonged post-ictal confusion, drowsiness, Todd's paresis | Rapid (seconds to minutes) |
For clarity, epilepsy means two or more unprovoked seizures occurring more than 24 hours apart, or a single unprovoked seizure where the risk of recurrence is high (for example a structural brain lesion or unequivocal epileptiform EEG). A single seizure is therefore not in itself a diagnosis of epilepsy – but every first suspected seizure still needs urgent specialist assessment.
Seizures are classified by where they begin (the ILAE 2017 framework). The label matters because it drives drug choice and counselling – but the underlying diagnosis still rests on the clinical description.
| Category | What to recognise |
|---|---|
| Focal onset | Arise in one area of one hemisphere. Classified as aware or with impaired awareness, and as motor (jerking, automatisms such as lip-smacking) or non-motor (sensory, autonomic, or psychic features like déjà vu). May evolve to a bilateral tonic-clonic seizure. |
| Generalised onset | Engage both hemispheres from the start. Motor: tonic-clonic, tonic, atonic, myoclonic, clonic, epileptic spasms. Non-motor: absence seizures (brief loss of awareness with staring). |
| Unknown onset | Used when the onset was not witnessed or cannot be determined; reclassify once more information is available. |
| Epilepsy type | A separate level: focal, generalised, combined focal and generalised, or unknown. |
| Common syndromes | Juvenile myoclonic epilepsy, childhood absence epilepsy, infantile spasms (West syndrome), Lennox-Gastaut syndrome, and Dravet syndrome. |
Source: NICE NG217
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