Uneven cerebral hemodynamic change as a cause of neurological deterioration in the acute stage after direct revascularization for moyamoya disease: cerebral hyperperfusion and remote ischemia caused by the ‘watershed shift’

Abstract

Superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis is the standard surgical treatment for moyamoya disease (MMD). The main potential complications of this treatment are cerebral hyperperfusion (CHP) syndrome and ischemia, and their managements are contradictory to each other. We retrospectively investigated the incidence of the simultaneous manifestation of CHP and infarction after surgery for MMD. Of the 162 consecutive direct revascularization surgeries performed for MMD, we encountered two adult cases (1.2%) manifesting the simultaneous occurrence of symptomatic CHP and remote infarction in the acute stage. A 47-year-old man initially presenting with infarction developed CHP syndrome (aphasia) 2 days after left STA-MCA anastomosis, as assessed by quantitative single-photon emission computed tomography (SPECT). Although lowering blood pressure ameliorated his symptoms, he developed cerebral infarction at a remote area in the acute stage. Another 63-year-old man, who initially had progressing stroke, presented with aphasia due to focal CHP in the left temporal lobe associated with acute infarction at the tip of the left frontal lobe 1 day after left STA-MCA anastomosis, when SPECT showed a paradoxical decrease in cerebral blood flow (CBF) in the left frontal lobe despite a marked increase in CBF at the site of anastomosis. Symptoms were ameliorated in both patients with the normalization of CBF, and there were no further cerebrovascular events during the follow-up period. CHP and cerebral infarction may occur simultaneously not only due to blood pressure lowering against CHP, but also to the 'watershed shift' phenomenon, which needs to be elucidated in future studies.

Incidence and Risk Factors of the Watershed Shift Phenomenon after Superficial Temporal Artery-Middle Cerebral Artery Anastomosis for Adult Moyamoya Disease

“…Based on our study, the incidence of the WS phenomenon was as high as 10.9% after STA-MCA anastomosis for adult MMD. The clinical outcome of the WS phenomenon was generally favorable in the present series, but there is a potential risk for perioperative cerebral infarction [17,19,20]. Taken together with a variety of postoperative pathophysiologies, such as local CHP [7,8,10,11,13], intrinsic hypoperfusion [12], cerebral infarction at the remote/ contralateral cortex [15], cerebral ischemia due to the compression of the brain surface by a swollen muscle pedicle of the indirect bypass flap [9], we recommend routine CBF measurement in the acute stage after revascularization surgery for adult MMD to avoid surgical complications.…”

“…MR imaging included diffusion-weighted imaging, fluid-attenuated inversion recovery, T2-wighted imaging, and T2*-weighted imaging. In light of the heterogeneous hemodynamic distribution in the acute stage after revascularization surgery for adult MMD [16,17], we quantitatively measured CBF, and a small region of interest (ROI) with a diameter of 1 cm was defined manually exactly at the site of anastomosis, adjacent to the cortex near the site of anastomosis and the ipsilateral cerebellar hemisphere [23]. Sites of anastomosis were confirmed by the original axial slice on MR angiography.…”

“…Accurate diagnosis of the WS phenomenon with concomitant local CHP is clinically important because standard blood pressure reduction to counteract local CHP may be contraindicated in the presence of the WS phenomenon. Indeed, previous pediatric case series and an adult case report demonstrated that MMD patients develop perioperative cerebral infarction due to the WS phenomenon, although the exact incidence of this phenomenon in adult cases is unknown [17,19,20]. Thus, we sought to clarify the incidence, clinical presentation, and risk factors of the WS phenomenon after direct revascularization surgery for adult MMD patients who were managed by the modern perioperative management protocol.…”

“…To counteract the damaging effects of local CHP, we have introduced prophylactic blood pressure reduction and the use of minocycline chloride administration in the acute stage after direct revascularization surgery for MMD, which improved the outcome of surgery [14][15][16]. However, the perioperative management of adult MMD patients is still challenging because the management methods of local CHP and cerebral ischemia at the remote area are contradictory [15,17].…”

“…Recent hemodynamic analysis on the acute stage after revascularization surgery for MMD revealed a more complex and unique pathophysiological condition, the so-called "watershed shift (WS) phenomenon," which is defined as a paradoxical decrease of cerebral blood flow (CBF) at the adjacent cortex near the site of local CHP [17,19,20]. Accurate diagnosis of the WS phenomenon with concomitant local CHP is clinically important because standard blood pressure reduction to counteract local CHP may be contraindicated in the presence of the WS phenomenon.…”