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 an event diary downloadable from here.

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.

Testing for epilepsy starts with an MRI scan of the brain and EEGs – eectroencepahlograms (tests that look at the brain waves and can diagnose epilepsy). Here’s what the EEG involves and how to prepare.


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.

So, before your consultation…

Therefore, before your consultation, it is useful to think about:

  1. What you felt before the episode. Were you feeling light-headed, confused, dissociated, sweaty? Was there any particular trigger, such as pain, a hot room?
  2. What happened during the episode. This is really useful to ask eyewitnesses about. Were you motionless, pale? Were your arms or legs jerking? Were you blue?
  3. What you felt afterwards. Were you sweaty, light-headed? Confused or sleepy? Had you bitten your tongue or lost control of your bladder?

And finally, think about other occasions something like this has happened, and think about answering those three questions for those as well.

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