Seizure versus faint: tongue biting and prolonged recovery
A faint (syncope, falling blood flow to the brain) and a seizure both cause collapse, but biting the side of the tongue and slow recovery with confusion favour a seizure.
Remember
Biting the side of the tongue and confusion lasting minutes favour a seizure, while a quick, clear recovery favours a faint, but each clue suggests rather than proves the cause.
Memory aid
side of the tongue points to a seizure, tip of the tongue points to a faint
Use it to place a tongue bite: the side of the tongue suggests a seizure and the tip suggests a faint, though a clue suggests rather than proves the cause.
A faint, also called syncope, happens when blood flow to the brain falls briefly. A seizure comes from abnormal, excessive electrical activity in the brain instead. To a witness the two can look alike, because both involve a person suddenly collapsing, so the history has to separate them.
In a generalised tonic-clonic seizure the body first stiffens (the tonic phase) and then jerks (the clonic phase). While the person stiffens, the jaw clenches and the tongue is caught between the teeth, so the injury is classically on the side of the tongue. A bite to the tip of the tongue is more often seen with a vasovagal faint (a faint set off, for example, by prolonged standing, when blood pools in the leg veins). Other clues are incontinence (loss of bladder or bowel control), an aura (a warning sensation before a seizure) and confusion lasting minutes afterwards.
A vasovagal faint usually comes with a recognisable build-up, such as prolonged standing, light-headedness (a warning that blood flow to the brain is falling) and sweating. Recovery is quick and clear once the person lies flat. After a seizure there is usually a spell of confusion lasting minutes, and patients with a generalised tonic-clonic seizure often take hours to recover fully. This recovery period is the post-ictal phase (the period of confusion and drowsiness after a seizure).
Limb jerking can be a trap. Brief jerks (myoclonus, short sudden muscle jerks) can occur in an uncomplicated vasovagal faint, so they do not prove a seizure, whereas prolonged limb jerking suggests epilepsy. Each clue suggests rather than proves the cause, and seizures can be subtle and easy to miss, including a first seizure in older adults.
Key facts
- Biting the side of the tongue
- suggests a seizure, because in a generalised tonic-clonic seizure the jaw clenches and the tongue is caught between the teeth during the stiffening phase.
- Biting the tip of the tongue
- suggests a vasovagal faint.
- Recovery after a seizure
- there is usually a spell of confusion lasting minutes.
- Recovery after a faint
- quick and clear once the person lies flat.
- Other seizure clues
- incontinence and an aura.
- Brief limb jerking
- can occur in an uncomplicated vasovagal faint, whereas prolonged limb jerking suggests epilepsy.
- Caution
- these features suggest rather than prove the cause.
Exam traps
- Light-headedness before a collapse does not point to a seizure, because it is a warning that blood flow to the brain is falling, which supports a faint.
- Rapid recovery to full awareness does not point to a seizure, because it is the pattern of a faint, whereas a seizure is usually followed by confusion lasting minutes.
- Wrist pain after the fall does not help to separate a seizure from a mechanical fall (a fall with an external trigger such as a trip), because it is an injury that follows a fall of any cause.
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