You might want to take a look at this article regarding "Steal Effect"; http://www.nature.com/jcbfm/journal/v21/n2/full/9591052a.html

Here's an except:

Intracerebral steal, a term popularized by Symon (Symon, 1968), refers to the paradoxical decrease of flow in the ischemic areas in response to vasodilator stimuli (Brawley et al., 1967; Hoedt et al., 1967). This behavior is attributed to shunting of blood flow away from nonautoregulating ischemic areas by the action of normally reactive vessels. The term "steal" has been suggested to be misleading because the underlying mechanism is rooted in a decrease in perfusion pressure (Wade and Hachinski, 1987). The concept of steal has been questioned and attributed to other sources such as a decrease in arterial pressure (Gogolak et al., 1985). Clinical studies have shown that the phenomenon has an ephemeral nature and can be documented only in a small proportion of patients and only in limited areas (Nariai et al., 1998; Olesen and Paulson, 1971). Furthermore, the demonstration of the effectiveness of the "inverse steal," by attempting to increase the flow in ischemic areas by vasoconstriction on normally autoregulating brain regions, has not been straightforward in head-injured patients (Darby et al., 1988; Roberts et al., 1998).

I had a neurlogist take me off of Aggrenox (Dipyridamole) because he thought it might cause this steal effect in a Moyamoya brain.
Kim

ntrlpwr wrote on Nov 4^th, 2010 at 5:08am:


This has also been happening to me for a little over a month. My neuro had my opthamologist perform a vision field test and I had a VEP...I've also had numerous EEG, MRI and CT...everything appears normal, but I have really bad headaches everyday and I have been getting very dizzy.  I'm not on aggrenox. I take Keppra, Plavix, aspirin, lipitor, and metoprolol.

KTiller wrote on Nov 7^th, 2010 at 1:35pm:



Hi Kim,
so you have moyamoya and also this "steal" affect? what others types of symptoms did you have?

Hi
my son temporarily lost his eyesight last year and he had trouble with his leg which prompted the visit to the neurologist and the subsequent diagnosis of moyamoya. No one was able to give us a reason for the loss of eyesight, they weren't able to relate it to the moyamoya, and it hasn't happened again fortunately...

ntrlpwr wrote on Nov 29^th, 2010 at 12:12am:


After figuring out that she had moyamoya, they figured that she was and is still having TIA's.  Since her surgery in March, they are not as often or as intense but are still occuring.  She just had her check up at Stanford and they told us that her blood flow is adequate, but she had two events while we were in CA.  They don't last long and she does regain all that is lost during the TIA.  Still scary but much better since surgery.