Greetings, everyone. First, I would like to thank the ANS for giving us the opportunity to present our work. Today, I'm going to talk about the impact of blood pressure changes in cerebral blood perfusion of patients with ischemic myomoya disease, evaluated by SPIT. We have no disclosures. First of all, we know that myomoya disease causes chronic progressive stenosis or occlusion of the terminal internal carotid arteries, together with the development of collateral networks in order to compensate for reduced cerebral blood flow or perfusion. However, these neurovascularizations attempts often fail, causing symptoms the size of the disease. Also, we know that DSA remains as a gold standard in diagnosis of myomoya disease, and there is often disparity between angiographic findings and clinical presentation of myomoya disease patients. Therefore, quantitative dynamic studies are necessary to demonstrate cerebral perfusion and metabolism, which are important parameters when selecting further treatment modalities. Quantitative hemodynamic imaging studies such as PET, SPED, MRI, and CT perfusion are able to demonstrate cerebral blood flow, cerebral blood volume, and cerebrovascular activity under particular circumstances, such as acetacelamide challenge. However, up to now, the literature lacks in studies demonstrating the subtle changes of blood pressure modifications on CBF of pathological cohorts. Therefore, our aim was to determine the impact of targeted blood pressure modifications on CBF of myomoya disease patients as assessed by SPEC imaging. We prospective collated data from March to September 2018 and included 154 patients diagnosed with myomoya disease following the guidelines of the Japanese Society of Myomoya Disease. They were admitted to the Henan Provincial People's Hospital Neurosurgery Department. Among them, we selected 40 patients with ischemic myomoya disease and following the next inclusion criteria, age between 18 to 65 years old, symptomatic and angiographic myomoya disease, and blood pressure monitoring. We excluded 114 patients with associated cerebrovascular diseases, hemorrhagic myomoya disease, endocrine, and cardiovascular diseases. All of the patients underwent a 24-hour in-hospital blood pressure monitoring in order to identify the mean arterial pressure baseline parameter. After that, all of the patients underwent an initial SPEC imaging at admission. This group of patients was subdivided into two groups. Group one, or relative high blood pressure group, underwent a physical exercise to achieve a mean arterial pressure 10 to 20 percent above the baseline parameter. And the group two, or relative low blood pressure group, who received 10 milligrams of namphalepine sublingual to achieve a reduction of the mean arterial pressure of around 10 to 20 percent of the baseline value. After that, both groups underwent a second SPEC study under this targeted blood pressure. We collected images, and following the more than three consecutive cross-sectional radioactive spurs, the affected area were considered as systemic lesions. Regional interest or CVS measure were taken as a reference, the mean value of the cerebellar blood flow in healthy people, and it was set up by using the brain loss and correction post-processing software, which comes with the camera of the SPEC equipment. As I mentioned before, our study cohort comprised of 40 patients with a median age of diagnosis of 43 years old, and there were 22 women and 18 men, and we can see here the blood pressure median at admission, it was 96 millimeters mercury. We can say about the effects of relative high blood pressure on cerebral perfusion among the 16 unilaterally affected hemispheres. Compared from the baseline images and the relative high blood pressure group, there was an increment of around 10.5 plus minus 5% on the ratio of cerebral blood flow as compared to the baseline values. Here we can see an increment in perfusion. However, on the contrary, in the relative low blood pressure group, there was a decrease in perfusion as compared to the baseline images when the patients underwent a slight hypotension. So we can say on general aspect, and this is what we know, is Moyamoya patients are susceptible of presenting ischemic stroke and TIAs because these abnormal vessels are not enough to provide sufficient collateral flow, and it's believed that Moyamoya patients are more liable to blood pressure changes than the general population as we have seen in clinical practice. However, there is no data regarding the impact of blood pressure changes in CBF or perfusion of Moyamoya disease patients. But also, we have to talk about cerebral autoregulation. We know this plays an important role in cerebral blood flow homeostasis, and we know that CBS, by the classical description by Lassen, is maintained at the contents level across a wide range of mean arterial pressure. However, in the last decade, there's an introduction of a new concept with this called dynamic cerebral autoregulation, which consists on regulation of cerebrovascular resistance against dynamic blood pressure changes. Also, in the last decade, there has been a lot of improvement in technical and methods to quantify dynamic cerebral autoregulation and also cerebral blood flow. However, this has been difficult to incorporate into clinical practice. Therefore, our study is important because it demonstrates the dynamic changes on blood pressure and its effects on cerebral blood flow in a pathological cohort. What about exercise-induced blood pressure changes and cerebral blood flow in Moyamoya disease patients? We know healthy patients that undergo dynamic or resistant exercise, they suffer a slight increase on systolic blood pressure, followed by a slight decrease or no change in diastolic blood pressure, which translates on increase in cerebral blood flow. But however, this cerebral blood flow increase goes immediately back towards normal or below the normal baseline during the hyperventilatory-induced hypocapnia despite progressive increments of perfusion pressure, which is completely contrary to the Moyamoya disease patients. As we can see, increase of 10% of MAP causes an increase in perfusion of approximately 15% without returning to normal values only after cessation of the exercise, which causes the possibility that dynamic cerebral autoregulation is limited in Moyamoya disease patients and also the likelihood of cerebral hyperperfusion syndromes related to high blood pressure. What are the effects of hypotension and CBF on Moyamoya disease patients? We know that healthy people, short periods of hypotension do not cause brain dysfunction and compensatory cerebral autoregulation prevents hypotension from being activated. However, in our group of relatively low blood pressure patients, they experienced a decrease in perfusion of previously affected areas of around 10% to 15%, demonstrating the direct relationship between blood pressure and CBF and the susceptibility of Moyamoya disease patients. If we talk about preparative blood pressure management, it's a recommendation for the Japanese guidelines on Moyamoya disease, strict blood pressure control, normal capnia, and adequate fluid balance, which help to prevent ischemia on the non-surgical side and hyperperfusion syndrome after revascularization procedures. And this is in concordance with our findings because Moyamoya disease patients are susceptible to a small cerebral blood flow variation during dynamic blood pressure changes. Of course, our study has some limitation because it's not a direct comparison between healthy control and Moyamoya disease patients. There is no evaluation or the relationship between perfusion areas and treatment selections and also the use of physical exercise to increase the MAP may induce hyperventilatory hypocapnia, which could decrease the cerebral perfusion as a compensatory mechanism. This was not present in our series since the CBF increased even at lower PCO2 values. As a conclusion, we can say cerebral blood flow of Moyamoya disease patients is susceptible to small blood pressure changes. Cerebral autoregulation in Moyamoya disease patients might be affected due to short dynamic variation in blood pressure. And in Moyamoya disease patients, it's important to maintain a strict blood pressure monitoring during the preparative management to prevent further complications. Thank you very much.

blood pressure changes

cerebral blood perfusion

ischemic Moyamoya disease

SPEC imaging

perfusion