Differentials
Daydreaming
SIGNS / SYMPTOMS
More likely to occur only during quiet, non-stimulating activities such as watching TV. No history of activity cessation. No unusual episodes induced by hyperventilation.
INVESTIGATIONS
EEG will be normal.
Attention deficit hyperactivity disorder (ADHD)
SIGNS / SYMPTOMS
More likely to occur only during quiet, non-stimulating activities such as watching TV. No history of activity cessation. No unusual episodes induced by hyperventilation.
INVESTIGATIONS
EEG will be normal. A variety of neuropsychological tests can help with formalising diagnosis.
Focal impaired awareness seizures of frontal or temporal lobe origin
SIGNS / SYMPTOMS
Patients are more likely to have eye deviation, facial twitching, or other localising component at onset of seizure. Seizures typically last at least 30 seconds. There may be a preceding aura and a postictal state.
INVESTIGATIONS
EEG will be normal, asymmetric, or show focal epileptiform abnormality.
Functional seizures (non-epileptic seizures)
SIGNS / SYMPTOMS
Episodes of altered movement, sensation, emotion, or experience that have the appearance of epileptic seizures but are not caused by paroxysmal, hypersynchronous electrical activity of the brain.[40]
The clinical appearance of functional seizures may mimic virtually any seizure type.
Some features more likely to suggest functional seizures include: eyes being tightly closed, tearfulness, duration more than 2 minutes, hyperventilation during a seizure, and side-to-side head shaking.[41]
Functional seizures are usually considered a functional neurological symptom disorder. Some patients will have had adverse life events, but, importantly, these are neither necessary nor sufficient for the diagnosis.[41] Psychological comorbidities - especially anxiety, panic, and depression - are common, affecting over 50% of patients.[42]
A significant minority of people with functional seizures will have co-existent epilepsy, so it is important to determine whether the patient has a number of different types of spells.
INVESTIGATIONS
The only reliable diagnostic test to differentiate functional from epileptic seizures is video-electroencephalogram (EEG; long-term monitoring). The EEG during functional seizures is either normal or obscured by movement or muscle artefact.
Correct diagnosis is usually based on the semiology of the event and the absence of epileptiform EEG correlate.
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