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Medical Q & A: Dysautonomia News June 2019


We welcome your letters to DINET's Medical Advisors.  Please be aware that the information provided is not meant to be a diagnosis or medical advice.  It is provided to give you background information to discuss with your medical team and general information to keep you well informed about dysautonomia disorders. If you have a question for our advisors, please send to webmaster@dinet.org 

Related Questions from Two Members: 

Question #1 from Member Bxxx:
Hello,  Please can you explain how someone can feel extremely lightheaded and faint when they are sitting with a completely normal heart rate and blood pressure?

1479918797_MedicalQA.jpg.e35e5b223319b8999dd42eeb2e13f43f.jpgI understand you can still have low stroke volume and hence cardiac output, which is not measurable without invasive tests.

I have heard other patients say they also feel presyncopal with normal observations, but medical professionals often do not seem to understand this.

Many thanks

Question #2 from Christina
Hello,  I’m a Dinet volunteer, username clb75. I have a question for the medical advisory board.

Many people with Pots experience dizziness when upright even though their BP and heart rate are normal. What causes this and what are the best ways to treat this type of dizziness?

- Christina

Answer from Dr. Satish Raj

I think that there are a couple of issues here – one of nomenclature and one of physiology.

The nomenclature problem is with the word “dizzy”. It is not a medical term and could refer to two different medical problems: vertigo or light-headedness. Vertigo is where either the room spins around you or you spin within the room. This is usually not a blood pressure (or heart rate) issues but can be due to problems with the inner ear or brainstem. Light-headedness is the feeling that one is going to faint, although to a lesser degree than when actually fainting. In some languages, the term for light-headedness directly translates to “head spinning”, making it difficult at times to sort these out.

The second issue, assuming that it is light-headedness that is being discussed, is physiology. Low blood pressure or a low or high heart rate DO NOT, in and of themselves, cause light-headedness. They do this presumably by altering blood flow in the brain, and perhaps the delivery of nutrients (such as oxygen or glucose) to the brain. This disruption could occur on a more local scale (within the brain) as well. Many things alter blood flow in the brain…many more than I can name. Something as simple as breathing can do so. Hyperventilation, for example, can do this.

The challenge is that light-headedness is a common symptom that can be caused by many/most medical disorders. That is why, in many cases, more specific presentations (e.g. association with tachycardia or with fainting) are needed to help to narrow down the list of possibilities.

Edited by edriscoll

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Thanks for the answer! For me personally the described situation is definitely presyncope rather than vertigo. 

I still believe low stroke volume and cardiac output to be implicated, as I would assume other problems such as local alterations in cerebral blood flow or hyperventilation to not necessarily be posture related & would therefore persist in the supine position. 

My symptoms were also greatly improved by volume expansion.

How I would love to be able to have my supine and upright cardiac output and cerebral blood flow measured!

B xxx

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