Anosmia or Loss of Smell from Brain Injury

Question: 

My friend had a brain hemorrhage from a blow to the head 10 years ago and has completely lost his sense of smell. Apparently, the part of his brain that controls his sense of smell was permanently damaged.

Is it possible that even though the brain does not recognize or register any kind of smell, the effects of that smell still be experienced? For example, even though he can’t smell coffee or lavender, could he still get stimulating effects of the coffee aroma or the relaxation effects of the scent of lavender?

Answer: 

Smell loss following traumatic brain injury is often overlooked as doctors tend not bother to ask about or test for loss or change in smell — or taste for that matter. Many times, people with brain injury first report changes in taste when they lose or notice a change in their ability to smell. Typically, complete loss of smell — or what is called anosmia — will be quite noticeable to a person following a traumatic brain injury and may affect numerous aspects of their life. Unfortunately, there is no good treatment cure for post-traumatic anosmia. Typically, if a person doesn’t regain his ability to smell six months after the injury, the loss will likely be permanent.

Because of the complex mechanisms involved in olfaction — a person’s sense of smell — it’s difficult to determine the reason for the loss. Problems with smell loss can result from craniofacial trauma, specifically damage to nasal passage ways, shearing injury of the olfactory nerve, or injury to primary or secondary smell centers in the frontotemporal regions of the brain. There are also other non-traumatic causes for smell impairment including Alzheimer’s disease and smoking, to name just two. This is why it’s important for people with this type of problem to seek out appropriate evaluation by a doctor familiar with post-traumatic smell loss.

If your friend is truly anosmic, that is, he has totally lost his sense of smell, then he would probably not recognize or register any kind of smell since the olfactory nerve is responsible for scent recognition. Therefore, your friend would not benefit from smelling any substance. That said, we don’t have a lot of research on this. Some people have anecdotally described “blind smell” similar to blind sight (a phenomenon in which people who are perceptually blind in a certain area of their visual field demonstrate some response to visual stimuli), and it wouldn’t hurt for your friend to try and experiment with smells.

 

Posted on BrainLine September 20, 2010. Reviewed July 25, 2018.

Comments (253)

My main issue 4 years later is the zero function in my smell and my taste is awkward at best. Basically my taste buds are effective but nothing else concerned with smell so too many flavours in one pallete cause me to to taste nothing, so with spicy foods all i get is "Hot" unless it is mild. Main issue though is my complete loss of people skills. I used to be a people person who could naturally chat to anyone anywhere anytime but now i get all nervous when i'm chatting to people i don't know or havent seen in ages or am talking to for purposes etc. It really is an understated condition that hospitals/doctors should prioritise better.
thanks for your information, I am from Halabja-Iraq, and my small brother suffered from head injury because of motor accident about 4 months ago,and he have not smell sense now,I wish and I ask God to regive him the grace of smell, Thanks
Having Anosmia seems to be related to sense of taste also. I am 14 years post injury and my sense of smell is not totally gone, but it is picky. For example, I can smell vanilla, and most other smells, but they have to be very strong. My sense of taste is also dulled.

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