Rt or Left damage?

[kd re: longstanding MR]

A couple of years ago I had a mild stroke in the watershed area of my brain.  Last Fall, I had a mild stroke (left parietal lobe) and resulting seizures (left focal temporal lobe).  This spring, I had another mild stroke (left parietal lobe).  They were all slightly different.  The last one had a pure expressive aphasia as part of it.
I recently saw a neuropsychologist.  He said my left side function is diminished but very good - vocabulary, reading, spelling, etc.  The bigger problem was with the right side - spatial, executive functions, etc. and pointed to problems with the frontal, temporal and possibly occipital lobes on the right.
There are no lesions noted in my last MRI/MRA on the right.  There was mention of something that had to do with the middle cerebral artery, however.
I am right handed.
I am confused because the lesions are on the left side of my brain but the functions that are damaged are on the right side.  Shouldn't they be on the same side?
Also, what is a watershed area?
And, what does the middle cerebral artery have to do with anything?

Thanks.

[CCF Neuro[P] MD, RPS]

Dear Louise:

MELAS is a mitochondrial disease that can produce strokes.  CADSIL is a genetic disorder that can also produce strokes.

CCF Neuro MD

[kd re: longstanding MR]

What are MELAS and CADSIL?

[pacca1000]

I have been trying to get thru forever.  Do you know what the best time is to post?  I am central time.  It is 3:00 am.  Can you help me out please.  Thanks.

[CCF Neuro[P] MD, RPS]

Dear Louise:

I am glad that I could help.  Usually an etiology will surface, but I would check into MELAS or CADSIL.  Since I do not know your history or the look of the MRI these may be things you neurologist hasn't thought about that depending on your history and the lab findings.

CCF Neuro MD

[PATTY]

The best time is at 9 AM eastern standard time.

[kd re: longstanding MR]

Thank you very much.  I've been looking for something about the watershed area for a long time and you explained it well.
There's no consensus on why the strokes are happening.  Since they don't appear to be clot related and are not hemorrhages, the last two times I went to the ER I was just sent home.  They said they couldn't do anything if it wasn't a clot or a hemorrhage.
Thanks also for the other explanation.  I've always wondered how bilateral things were and when the neurologist said the damage was left-sided and the neuropsychologist said all of the indications pointed to the right side, I was confused.
Have a good day,
louise

[CCF Neuro[P] MD, RPS]

Dear Louise:

Sorry to hear about your multiple strokes.  I hope that the cause of your strokes has been addressed and corrected.  A watershed stoke is where the brain tissue between major arteries has been compromised due to lack of blood flow.  This is usually bilateral when it occurs but can also be unilateral.  This is like when your watering your lawn with two long hoses.  When the water pressure goes down, the lawn inbetween the two hoses doesn't get as much water.  So, like the lawn between the two hoses, your brain matter between the two arteries doesn't get much blood and hence you have a watershed stroke.  The distribution of function in the brain can be bilateral.  So, although one side of the brain is dominant, the other side can have some, albeit lesser function.  So, although all of your strokes are on the left side, there might be some function of the right side on the left side of your brain.  Expression of language is usually left side dominant, so I am not quite sure why you were told that this should be right sided.  

The middle cerebral artery is the main artery of the anterior circulation (coming off the internal carotid).  Many strokes, including watershed strokes occur because of damage occuring in the middle cerebral artery.

I hope I have helped you.

CCF Neuro MD