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"low flow" TIA/orthostatic hypotension?
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"low flow" TIA/orthostatic hypotension?

I am a healthy 43-year-old woman, normal weight. My blood pressure runs on the low end of normal, usually somewhere in the neighborhood of 100/65 (give or take).  Going back to at least adolescence, I have ocassionally had very short episodes (usually only around 5 seconds or so) of dizziness/lightheadedness and total loss of vision.  This happens if I stand up too quickly, and usually does not happen again if I increase my fluid and salt intake. I have read about orthostatic hypotension, but have never been tested and/or diagnosed with that. I am so accustomed to these episodes that I can typically continue walking, maintaining my balance, and sight will return within just a few seconds.  If I feel extremely dizzy, I'll just stop in my tracks until my balance & vision returns.

This morning, however, I had an episode that was more severe.  I continued walking for a couple of steps after my vision loss, but after just a few steps, I felt very strange. In addition to the temporary blindness, I had the sudden onset of loss of coordination and impaired ability to control my arms and legs.  I went from being capable of a normal gait to barely able to shuffle my feet. I felt like I was losing my balance from my the sudden loss of momentum, but when I reached out to the counter (was in kitchen)  I had the same loss of control/coordination in my arms. This entire process only lasted maybe up to 10 seconds max, from beginning to end.

If this happens again, I will most definitely go see my doctor.  I'm wondering though if this was something along the lines of a "low-flow" TIA, or just a temporary lack of blood/oxygen to my brain (or is that what a "low-flow" TIA is?), and if so, would that result in any damage or even show up on any tests, etc.?  

Thanks in advance.
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Avatar_dr_f_tn
Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with your doctor.

Without the ability to examine you and obtain a history, I can not tell you what the exact cause of your symptoms is. However I will try to provide you with some useful information.

"Low-flow TIAs" are basically transient episodes of focal neurologic deficit that occur when the blood pressure drops and a part of the brain supplied by a narrowed artery receives less blood. The sort of criteroin for a low flow TIA is that there must be a narrowed artery in the brain (such as for example carotid stenosis or stenosis of one of the other blood vessels to the brain). Most commonly symptoms are weakness on one side of the body or the other associated with other specific neurologic symptoms. Generalized weakness and incoordination could potentially be a TIA symptoms, if localized to a specific distribution of blood flow in the brain called the vetebrobasilar system. If your symptoms were due to hypoperfusion in the vertebrobasilar system due to, for example, stenosis of the basilar artery (which supplies the brainstem) this would certainly show up on imaging of the blood vessels (such as on tests MRA, CTA, or TCD).

However, given your age and the long-standing nature of your episodes, as you mention, your symptoms could be due to generalized hypoperfusion due to a drop in blood pressure. Your symptoms of light-headedness on standing etc may be due to autonomic dysfunction.

The autonomic nervous system is the part of the nervous system that controls blood pressure, heart rate, and other functions. It is not located in one specific part of the brain or other body part but is rather made up of several different components: a region in the brainstem, certain receptors located on blood vessels and in the heart, and small nerves in our skin, among other areas. Dysfunction of the autonomic nervous system due to whatever cause can lead to a variety of symptoms including but not limited to orthostasis (which means symptoms or signs resulting from assuming an upright posture), light-headedness with drops in blood pressure when sitting up or standing up (this is an example of orthostasis), syncope (passing out), constipation, diarrhea, sweating abnormalities etc. If there is a problem in the small nerve fibers, what is medically termed a small fiber neuropathy, in addition to these symptoms, burning/tingling in the feet and hands or mild sensory loss may also occur.

Normally, there are specific blood pressure and heart rate responses that an individual mounts in response to changes in posture. Often, these include a small drop in blood pressure and an increase in heart rate when one assumes a standing posture. In individuals with a problem somewhere within the autonomic nervous system, these responses are abnormal. Diagnosis of autonomic dysfunction includes a tilt table test and tests for peripheral neuropathy.

One type of autonomic dysfunction is POTS syndrome, a condition with no known definitive cause in which the heart rate goes up inappropriately, leading to palpitations and light-headedness, and this is treated with medications that prevent these heart rate increases such as beta blockers. In addition,

Treatment of autonomic dysfunction depends again on the cause. Causes include neuropathy, including large fiber and small fiber neuropathy due to diabetes, nutritional deficiencies, monoclonal proteinemias (conditions in which certain abnormal proteins are being produced), certain types of cancers can produce a paraneoplastic autonomic neuropathy etc. Certain types of parkinson's-type diseases such as a condition called multi-system atrophy can also lead to autonomic dysfunction (this usually occurs in people older than the age of 60).

I recommend evaluation by a general practioner/internist for your symptoms. After he/she examines you and obtains vital signs in various postures (lying down, sitting up etc), he/she can help determine whether the cause of your symptoms is cardiac, vascular neurologic, due to neuropathy, or otherwise. Referral to a specialist could then be made as indicated.

Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.
2 Comments
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795786_tn?1237263458
Hi, thank you for your answer.  I found this site when searching re low flow TIA's.

Recently I began having episodes of lightheadedness that seem to come and go for no reason I can discern.  It happens nearly daily and sometimes many times a day.  Sometimes I get a strange headache with it (I do not normally get headaches) that can last for some time or sometimes just a few moments.  The pain is in the back of my neck on the right side just to the side of my spine and runs into my skull...the headache can then spread across the back, bottom, of my skull.  I don't know if these are connected.

With these episodes I also get confused and unable to process information that I know I know...like my address or how to say what is in my head.  These episodes can also cause me to become very tired.  They can last only a few minutes or very long.  I am told that I get very pale and look very sick when they are occuring.  When they get really bad I feel faint and my vision gets black around the edges.  My arms, hands, and feet also tingle or feel like they are going to sleep (but not with the usual pins and needles feeling...more like I lose sensation of them).  

The other really strange thing that happens during these is that it is like movement makes it worse, or causes me to feel semi-nausious, and my body tends to want to still to the point of not breathing...like it feels better to not breath...and I do not get that feeling like when you hold your breath and then need to breathe and so I have to make myself breathe.  

I don't know what any of this is.  I am 40 years old and in fairly good health (slightly overweight).  I have been to a doctor who ran typical blood tests and my heart, blood pressure (80/60), and nutrition looks good and is saying is chronic fatigue...but this just doesn't make sense.  These symptoms started suddenly about two months ago and comes and goes in waves...can happen anytime even when I at rest and has brought my life to a virtual standstill because I cannot predict when it will happen or how bad it will get.

If anyone has any insight to what this might be related to I'd really appreciate it.  I was thinking that maybe there is a smaller vein in the back of my neck that may be slowing or stopping flow.  

Many Thanks :)
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