NZer1 wrote:
Dr is there any indication as yet about the percentages of external or compression causes for stenosis versus internal?
I am aware that the most common discussed issue is currently valves, it is of interest to me about the 'other' causes that could be from for example the development of muscle bulk because of postural issues or spine and skull alignment compensation issues.
That is very difficult to determine the incidence of compression because it is episodic, dynamic and positional. Whether one sees it depends upon circumstances. For example, we do not see it in some patients without turning the head into a particular position, something that we do not do during venography.
I question whether this is abnormal, actually. In the legs we expect the muscular contractions to propel the blood toward the heart. Is this also happening in the jugular veins??
I commonly see compression of the internal jugular vein by the carotid artery. IVUS shows me that this is phasic and that there is ample room for the jugular vein to distend "away" from the carotid, essentially ignoring the compression. I have noted compression at the second cervical vertebrae. whether one sees it depends upon performing a lateral view and whether the neck is flexed or extended.
i have noted the candy wrapper "stenosis" butonly see it when patients take a deep expiration, never in full inspiration.
episodic compression seems very common.
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There are a few people who are listing injury to spine for example from whiplash around the first attack of RRMS.
This in my humble opinion would be similar to a person re-stenosising.
It of course does not explain a progressive disease form and that is in my opinion is where we will find the that the disease and cause is quite different between the two.
it is my guess is that this is coincidental
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Flow issues and aging may explain the progression over time seen in PPMS and SPMS, but it does not really explain the episodic nature of RRMS for instance where there is known underlying progression happening with all RRMS people, which in my opinion is misleading when the episodic nature is the focus and the progression seen on MRI (grey matter) is not talked about.
People do not go from PPMS and have episodic periods, so this in my opinion is another clue that there is differing causes that will be explained in the future why there are some who respond well to PTA and others who one would expect a good response do not.
I guess you worked this out ages ago and are waiting to find the it factor, sorry to steal your thunder .

Regards Nigel
geez, nigel
i am only a plumber.