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Dr. Bob
Dr. Bob, Neurologist (MD)
Category: Neurology
Satisfied Customers: 5220
Experience:  Neurology & Int Medicine (US Trained): 20 yrs experience
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I had a susceptibility weighted imaging (SWI) scan recently.

Customer Question

I had a susceptibility weighted imaging (SWI) scan recently. The doctor showed me the scan and said that there was no evidence of any damage. There were however one or perhaps two very small black dots on the scan, which he said were blood vessels and were not the result of damage. Is this possible or likely?

Submitted: 2 years ago.
Category: Neurology
Expert:  Dr. Bob replied 2 years ago.
Dr. Bob :

Yes, this is very possible and likely. These black areas are often referred to as "flow voids" because the flowing blood does not create a signal that can be captured.

Dr. Bob :

You should not worry about this, especially if the radiologist ' s report was normal.

Dr. Bob :

Are you there ?

JACUSTOMER-xweludx3- :

Yes, sorry my internet connection was playing up.

JACUSTOMER-xweludx3- :

That’s good news. The radiographers report was completely normal.

JACUSTOMER-xweludx3- :

I have read that flow voids occur because of very fast flowing blood at particular directions. The two flow voids were in line with my brain stem, which I assume is where the main blood vessels enter the cranium.

Dr. Bob :

Exactly! You've been doing your homework.

Dr. Bob :

:-)

JACUSTOMER-xweludx3- :

Thanks.

JACUSTOMER-xweludx3- :

Could I ask you one more question?

Dr. Bob :

Anytime. Nice chatting with you.

Dr. Bob :

Sure

JACUSTOMER-xweludx3- :

The neurologist whom I spoke to — who was a specialist in brain injury — claimed that one could suffer mild concussion-like symptoms after a blow to the head but without there being any damage to the brain (i.e. diffuse axonal injury); that the best indicator for damage was post-traumatic amnesia and the length of time it took for the symptoms to dissipate. He gave the example of a boxer who is stunned in the ring (i.e. feels temporarily light headed, or sees stars but is not knocked-out) but recovers his senses within seconds and later shows no signs of brain injury.

Dr. Bob :

Very true. But symptoms can be subtle, so a lot depends on one's "pre-morbid" level of functioning...if you know what I mean.

Dr. Bob :

Very high functioning individuals often notice annoying changes in cognition or memory or even personality after a concussion. ..usually, but not always, temporary.

JACUSTOMER-xweludx3- :

Right, but there is almost always going to be some type of initial sign that it has happened. Like feeling dazed or seeing stars or something. You’re not going to hit your head feel absolutely lucid and clear headed but have had some brain damage. Would that be fare to say?

Dr. Bob :

Yes, there must be, by definition, some period of altered mental status, though it does not have to be long or profound.

JACUSTOMER-xweludx3- :

What would be the mildest form of altered mental status that could potentially indicate damage, would you guess? The neurologist I spoke to said that if most people that get concussion-like symptoms (sometimes losing consciousness even) and have no damage, having no symptoms is as close as you can get to a guarantee that no damage has occurred.

Dr. Bob :

I'm a bit of a purist. In addition to the DAI that we can document pathologically (typically from a severe concussion or true TBI) there can also be dendritic injury that is microscopic in nature. This is, fortunately, the easiest to recover from.

Dr. Bob :

Symptoms are typically very mild and transient.

Dr. Bob :

But it is still wise to avoid further concussions, as effects can be cumulative.

JACUSTOMER-xweludx3- :

I see. Can you give me an idea of what mild and transient means and then I will stop asking you questions, I promise. So for example, after hitting one’s head mild and transient symptoms would be suddenly feeling a little dizzy or losing consciousness for a moment and then feeling okay later.

JACUSTOMER-xweludx3- :

by later I mean within 10 minutes or so.

JACUSTOMER-xweludx3- :

I ask because I walked into a low-hanging doorway a while ago at a slow-ish speed and have been worried about it ever since — not because I am a boxer.

Dr. Bob :

Yes, that would be mild or very mild.

Dr. Bob :

The skull is quite thick in the front and is more than adequate to protect the brain in an injury like that.

JACUSTOMER-xweludx3- :

Good news. I experienced no immediate symptoms either (or no-immediate), and what your saying is the same as the neurologist I spoke to, so that is great news. Thank you.

Dr. Bob, Neurologist (MD)
Category: Neurology
Satisfied Customers: 5220
Experience: Neurology & Int Medicine (US Trained): 20 yrs experience
Dr. Bob and other Neurology Specialists are ready to help you
Customer: replied 2 years ago.

Hi Bob,

Sorry to go over the same ground again, but I just wanted to clarify our conversation from a few days ago. Apologies if the following seems a little cold and technical.

You said that a blow to the head that produces mild or very mild concussion-like symptoms will very often not result in diffuse axonal injury, but may cause dendritic injury.

You also said that a short period of dizziness, confusion or a brief loss of consciousness immediately following head trauma would be classed as "mild or very mild" symptoms.

The question I wanted to ask is the following:

Are there always (or almost always, like 99% of the time) some noticeable symptoms very soon after a blow that is potentially injurious to the brain — even in the mildest cases? For example, if a concussion specialist had the misfortune of banging his or her head on a low-hanging doorway at a slow to normal walking speed (as I did) would their knowledge of concussions enable to rule out the possibility of dendritic injury within 10 minutes or so on the grounds that they hadn’t experienced any of the common immediate symptoms — e.g. brief loss of consciousness, seeing stars, ringing in the ears, feeling dizzy or confused, not being able to clearly remember the event? What I am saying is, are these immediate symptoms the minimum requirement to suspect any damage and would they be easily identifiable to someone who knew what they were looking for?

Also, if your answer to this question is that, yes, there can be some dendritic injury even without noticeable symptoms, is this type of dendritic injury (i.e. a near symptomless one) equivalent in severity to the type of injury caused by heading a soccer ball — i.e. so mild that you would have to do it hundreds or maybe thousands of times within a certain time-frame before there would be any impact on cognition?

Expert:  Dr. Bob replied 2 years ago.
I can only speak in generalities, of course, as each individual case can have a myriad of features that make it unique. As for dendritic injuries in mild blows to the head, I am mostly speculating...and this would apply only in cases in which there were at least some symptoms. I don't recall seeing any studies looking at neuronal changes in individuals who suffered asymptomatic blows to the head. The assumption would be that there would be none.
Customer: replied 2 years ago.

Thanks Dr Bob, I really appreciate your help!!! Sorry about the tedium.

Expert:  Dr. Bob replied 2 years ago.
You're welcome. Anytime.

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