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Cerebral Hyperperfusion Syndrome Following Intracranial Revascularization: Anatomic and Pathophysiologic ConsiderationsJin-Il CHUNG, M.D.Department of Radiology, Suncheon Pyunghwa Hospital, Suncheon, Republic of KoreaCerebral Hyperperfusion Syndrome (CHS)Rare, but not uncommonPotentially serious complication after cerebral revascularizations including carotid endarterectomy (CEA), carotid artery stenting (CAS), and intracranial angioplasty or stentingHemorrhagic complications after cerebral revascularizations; uncommon, but can be fatal and devastating when it developsPathophysiologic mechanisms of CHS; believed to occur following restoration of blood flow with impaired autoregulation (endothelial dysfunction mediated by free oxygen radicals) due to chronic hypoperfusion into brain tissuesSymptoms of CHS; headache, hypertension, focal reversible neurologic deficits or focal seizures resulting from abruptly increased cerebral perfusion

IntroductionManagement of CHS; requires immediate and aggressive blood pressure control to prevent possible intracerebral hemorrhagesImaging findings of CHS; vasogenic edema, small focal hemorrhages, and large size ICHExact mechanisms of CHS; not been clearly elucidated, although some risk factors(diminished cerebrovascular reserve) might precipitate the complications

Cerebrovascular venous structures; often revealed as less expanded appearances with chronic hypoperfusionTentative mechanisms of CHS, which related with cerebrovascular venous anatomy

IntroductionCerebral Hyperperfusion Syndrome (CHS)

Intracranial Angioplasy; Left MCA M1 segment (F/65)Case Reports

Medically refractory, intracranial atherosclerotic stenosis

Intracranial Revascularization of left MCA M1 segment with 1.5 mm PTCA (undersized) balloon with meticulous procedural cautions including 014 microguidewire (300 cm) exchange technique

3D Rotational Angiography (Innova 3100, GE Medical Systems) with 3D MPR before and after angioplasty

Before AngioplastyAfter AngioplastyIntracranial Angioplasy; Left MCA M1 segment (F/65)Case Reports

Immediate CTPost 3 Days,Follow-up MRI

Intracranial Angioplasy; Left MCA M1 segment (F/65)Case Reports

Before AngioplastyBefore AngioplastyAfter AngioplastyAfter AngioplastyIntracranial Angioplasy; Left MCA M1 segment (F/65)Case Reports

Before AngioplastyAfter AngioplastyIntracranial Stenting; Basilar artery (M/56)Case ReportsMedically refractory, symptomatic high grade intracranial atherosclerotic stenosis

Intracranial Revascularization of Basilar artery with 3.5 mm bare metallic coronary stent with meticulous procedural cautions including 014 microguidewire (300 cm) exchange technique

3D Rotational Angiography (Innova 3100, GE Medical Systems) with 3D MPR before and after stenting

After StentingBefore StentingIntracranial Stenting; Basilar artery (M/56)Case Reports

Immediate CTPost 3 Days,Follow-up MRI

Case Reports

Post 3 Days, Follow-up MRIFLAIR with DWI & ADC map imageIntracranial Stenting; Basilar artery (M/56)Intracranial Stenting; Basilar artery (M/56)Case Reports

Median, anterior pontine veinBoth Interpeduncular veins, drain upwardly and often called as pontomesencephalic veinsPosterior or Communicating veinBVR(Basal vein of Rosenthal)Lateral mesencephalic vein (LMV)Transverse pontine vein (posterior group)Veins of posterior surface of ponsPrecentral veinanteriorposteriorBefore StentingAfter Stenting

Case ReportsIntracranial Stenting; Basilar artery (M/56)Median, anterior pontine veinBoth Interpeduncular veins, drain upwardly and often called as pontomesencephalic veinsPosterior or Communicating veinThalamogeniculate veinsLateral mesencephalic vein (LMV)BVR(Basal vein of Rosenthal)Transverse pontine vein (posterior group)Veins of posterior surface of ponsPrecentral veinanteriorposteriorBefore StentingAfter Stenting

Case ReportsIntracranial Stenting; Basilar artery (M/56)

After StentingBefore Stenting

Intracranial Stenting; Basilar artery (M/56)Case Reports

Before StentingAfter StentingAfter Stenting

Case Reports

Human Brain Stem Vessels, 2005, Henri M. DuvemoyGeneral Arrangement of the Superficial Arteries and Veins of the Brain Stem, p.31Both Interpeduncular VeinBasal Vein of Rosenthal(BVR)Lateral Mesencephalic VeinSuperior Petrosal VeinPrecentral VeinBoth patients were managed with the diagnosis of acute CHSStrict BP monitoring with a plan to maintain the systolic BP between 90-140mmHgFollow-up CT scan revealed resolution of edema and patients showed no residual neurologic deficitsCerebral Hyperperfusion Syndrome (CHS)Results

Diagnosis of CHS following intracranial revascularization (angioplasty and stenting) should be confirmed by imaging studies under the impression by neurologic examinationsDuring revascularization procedures, can identify the secondary venous recruitments and redirected venous engorgements related with directly increased cerebral perfusions and blood flowsRecruited and engorged venous structures, which were not delineated before the procedures due to longstanding hypoperfused brain parenchymal changes or chronic ischemia

Probable pathophysiologic mechanisms of CHS; related with abruptly increased cerebral perfusion pressures of perfusion pressure break-through phenomenon of hypoperfused brain tissues

Cerebral Hyperperfusion Syndrome (CHS)ConclusionTherefore, secondary venous recruitments and engorgements could be explained as the potential venous reservoir preventing intracranial hypertensions, which always occurs after intracranial revascularizationsFollow-up angiography exams should be compared with the immediate post-control revascularization angiography to verify the venous adaptationsHowever, we can suggest that venous recruitments could be a one of favorable causative factors which might prevent the fatal hemorrhagic complications

Cerebral Hyperperfusion Syndrome (CHS)Conclusion