A loss of consciousness may be related to lack of blood flow to the brain (syncope or fainting) or to abnormal electrical activity in the brain (seizure). The propensity to have recurrent seizures is called epilepsy.

It is useful to track the frequency of the episodes with a diary.

Seizures and Epilepsy

The two major types of seizures are focal or partial onset and generalised seizures.

Focal onset seizures begin in one area of the brain as synchronised electrical activity that can cause abnormal feeling (tingling, pins and needles), movement (jerking or twitching) or psychic phenomena (deja vu, hallucinations, extreme fear, warm rising feeling) or others. If these spread sufficiently, consciousness may be impaired (complex partial seizure). If these spread to affect both sides of the brain, a generalised seizure ensues. Generalised seizures involved body sitffening (tonic) and jerking (clonic). People usually fall to the ground and may lose control of their bladder and bite their tongue.

Epilepsy is the tendency to have recurrent seizures.

Epilepsy can affect driving and needs to be notified to the driver licensing authority.


Vasovagal syncope occurs when a noxious (unpleasant) stimulus triggers a response whereby blood pressure drops and there is insufficient blood flow to the brain. Usually light-headedness, nausea and a graying of vision is followed by loss of consciousness and appearing pale or ghostly white. On lying flat, the person regains consciousness quickly and is not confused (unlike a seizure). Avoiding the triggers and certain manoeuvres can help reduce the impact of fainting.

Heart problems (structural or rhythm) can also cause insufficient blood flow to the brain and a usually more abrupt and untriggered loss of consciousness. These require careful assessment and treatment.

Finally, postural hypotension is a drop in blood pressure on standing, associated with light-headedness and ocasionally fainting. Care must be taken to avoid dehydration and with blood pressure lowering medication among others. Other medications can also be of benefit.

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