oh, wow - I've been interested in this connection for awhile now ... let me try to throw out a quick overview before I hear out the door ...
MS and yawning are connected in some people:
Pathological yawning as a symptom of multiple sclerosis
More personally, when I was having my major relapse, I was yawning constantly. Over and over again, it was bizarre.
I found some papers indicating that this can be symptomatic of pontine (brainstem) lesions - and I did have one of those active at the time. I would feel better for a few seconds after every yawn.
ABNORMAL YAWNING. Abnormal repetitive yawning may be the consequence of opiate withdrawal; intoxication with CNS depressants; drug side effects (tricyclic antidepressants, reserpine); lesions to the CNS such as postencephalific conditions, CNS tumors. apallic syndrome, cerebral malformations, transtentorial herniation. Yawning is associated with diminished brain oxidative metabol ism. Such is the case of anemia or cerebral anemia (occlusion of the carotid arteries), hypoglycemie states. In these situations, yawning through its action on the cerebral blood flow, is a protective homeostatic reflex to increase brain oxygen levels in situations of decreased brain oxidative metabolism.
I do think there is a connection to CCSVI - I think yawning was my body trying to get oxygen to my brain and get old blood out of it, when I had a stenosis form (note: however, I have not had an MRV and don't know for sure that I have a blockage), before the colalteral veins could form and take some of the pressure off.
Hypoxia response - yawning is the response of the brain being starved of oxygen when it cannot get the old deoxygenated blood out successfully.
Yawning opens the eustachian tube and lets air up into the middle ear, where the bloodstream flows through, absorbing oxygen directly into the blood. (Pilots who have used all their cabin oxygen up in flight are trained to use the 'valsalva procedure' several times to ventilate the middle ear, in a practical example - to avoid painful problems later.)
Yawning responses induced by local hypoxia in the paraventricular nucleus of the rathttp://baillement.com/suzuki-hypoxia.html
... yawning may be an arousal behavior caused by higher brain ischemia.
Also, yawning triggers the omohyoid muscle - which briefly compresses the internal jugular veins, ... possibly increasing blood drainage afterward? Or is it causing the very constrictions we are looking to stent?
evidence of a significant increase in the venous surface was found above the omohyoid muscle. These data confirm the role of compression of the vein by the omohyoid muscle, leading to modifications in intracerebral venous hemodynamics, which can be affected in yawning.
... it is quite possible that compression of the jugular vein by the omohyoid muscle leads to an anti-reflux phenomenon, equivalent to venous valvules, which plays an important role in cerebral protection ...
Actually, that whole website is an amazing research resource about yawning (with full papers available that can only be acquired as abstracts elsewhere) - see some of these links too - and note that there are usually good English translations lower down the pages:
Yawning is a multifarious reflex possibly subserving the purposes of: ... b) reversing mild brain hypoxia or hypoxemia ...
- this page has the Navigation bar in English, yay!
I don't pretend to really know how yawning ties in exactly, but I think it can - and I know that if I have a relapse or start feeling fatigued and MS-y, I'm likely gonna be trying to pump oxygen to my brain by yawning as much as possible ...