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Sudden blackout, lost sense of taste and smell. What is causing this?

Nov 2013
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Practicing since : 1994
Answered : 5293 Questions
Hello....This is about my 52 year old brother. Over the past 10 years he has approximately 5 incidents of blacking out and waking up minutes or hours later. This started while he lived in NY and had 2 lengthy hospital stays without any results despite many tests. He now live in a small town in Illinois and it has been happening yet again. No warning...nothing. He builds sets for theaters and works with power tools and on ladders. Very XXXXXXX He woke up last year covered in snow in his back yard. He has also lost his senses of taste and smell. No doctor can figure it out. He doesn't do drugs, but he does drink more than he should. None of these blackout happened while he was drinking...only when he was sober.
Posted Tue, 26 Feb 2013 in Brain and Spine
Answered by Dr. Sudhir Kumar 6 hours later
Thank you for posting your query.
There are mainly three causes for a person to lose consciousness for a short while and recover on its own:
1. Transient ischemic attack- in this case, the blood supply to brain is reduced for a while in a person with risk factors such as diabetes, high BP, high cholesterol, etc. Since your brother does not have any of the risk factors and is relatively young, this is unlikely. on
2. Syncope- in this condition, a person loses consciousness for a short while due to cardiac or vasovagal syncope. However, recovery is complete within XXXXXXX than one minute. Since your brother sometimes takes much longer, this also is unlikely.
3. Seizures (epilepsy)- this is the most likely cause in your brother's case. In this condition, a person may lose consciousness without any warning and it may last from a few minutes to hours. This can happen at any age.
Investigations helpful are MRI brain and EEG. I am sure they may have been done. If they are normal also, one can make a diagnosis of epilepsy (these tests XXXXXXX be normal in about 50% of cases).
So, I would suggest starting on empirical anti epileptic drugs such as oxcarbazepine or sodium valproate.
I hope it helps. Please get back if you have any more queries.
Best wishes,
Dr Sudhir Kumar MD DM (Neurology) XXXXXXX Consultant Neurologist
Above answer was peer-reviewed by
Follow-up: Sudden blackout, lost sense of taste and smell. What is causing this? 21 hours later
Thank you Dr. XXXXXXX A couple more can he get a diagnosis if tests are only approx. 50% accurate. Not sure if a physician will prescribe drugs without conclusive evidence of epilepsy???? Is there any chance he will ever regain his sense of smell or taste? He lost it after his first episode when he fell backwards on a sidewalk in New York and fractured his skull.
Answered by Dr. Sudhir Kumar 2 hours later

Thank you for getting back.

Just to clarify, that the tests are accurate. However, as the disease (epilepsy) is episodic, EEG is more likely to be abnormal, if it is done when the person is unconscious or having the attack, but it is not always possible to do that. MRI brain may show the abnormalities, even if it is done at any time. So, there is a good justification for doing them both.

Smell and taste may not come back, if it was due to the damage of olfactory and taste nerves, as these nerves can not regenerate. This is the most likely situation in this case, as he had fracture of skull, which has likely injured those nerves.

Regarding drugs for epilepsy, it can be (and often is) prescribed on empirical basis, as I mentioned that tests may come normal in 50% of cases.

Dr Sudhir Kumar MD DM (Neurology) XXXXXXX Consultant Neurologist
Above answer was peer-reviewed by
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