脑动静脉畸形件

CEREBRAL ARTERIOVENOUS MALFORMATIONS AVM: a TLA for the CNS Incidence 0.52% at autopsy Slight male preponderance (1.09 to 1.94) Congenital lesions (although rarely familial) Embryology First half of third week of gestation epiblastic cells migrate to form mesoderm mesodermal cells differentiate to arterial and venous vessels on the surface of the embryonic nervous system Embryology First half of third week of gestation epiblastic cells migrate to form mesoderm mesodermal cells differentaite to arterial and venous vessels on the surface of the embryonic nervous system Seventh gestational week vessels sprout branches & penetrate developing brain reach the gray-white interface, either loop back to pial surface or traverse entire neural tube, thus epicerebral & transcerebral circn eventually connect arterial and venous systems by around the twelfth week Pathology & Pathophysiology absence of normal capillary system Pathology & Pathophysiology absence of normal capillary system usual function displaced Pathology & Pathophysiology absence of normal capillary system usual function displaced asymptomatic at birth Pathology & Pathophysiology absence of normal capillary system usual function displaced asymptomatic at birth vessels change with time may develop aneurysms parenchymal changes within and around the lesion Pathology & Pathophysiology absence of normal capillary system usual function displaced asymptomatic at birth vessels change with time may develop aneurysms parenchymal changes within and around the lesion site frequency is proportional to brain volume Pathology & Pathophysiology absence of normal capillary system usual function displaced asymptomatic at birth vessels change with time may develop aneurysms Clinical presentation 95% have symptoms by age of 70 years Clinical presentation 95% have symptoms by age of 70 years peak presentation second to fourth decade Clinical presentation 95% have symptoms by age of 70 years peak presentation second to fourth decade high output failure, neonate, vein of Galen hydrocephalus, first decade headache, hemorrhage, seizures, 2nd & 3rd Clinical presentation factors contributing to symptoms vessel walls, flow and pressures Clinical presentation factors contributing to symptoms vessel walls, flow and pressures enlargement and encroachment Clinical presentation factors contributing to symptoms vessel walls, flow and pressures enlargement and encroachment dural sinuses Clinical presentation factors contributing to symptoms vessel walls, flow and pressures enlargement and encroachment dural sinuses ischaemia Clinical presentation factors contributing to symptoms vessel walls, flow and pressures enlargement and encroachment dural sinuses ischaemia cardiac output Clinical presentation D e f ic it s10%He ad ac h e s10%S e iz u r e s30%He m or r h age50%Hemorrhage AVM rupture not a function of size Aneurysm rupture related to aneurysm size Hemorrhage AVM rupture not a function of size no marked increase with exercise, pregnancy, trauma Aneurysm rupture related to aneurysm size increase with trauma exercise, end pregnancy Hemorrhage AVM rupture not a function of size no marked increase with exercise, pregnancy, trauma arteriovenous, therefore less severe Aneurysm rupture related to aneurysm size increase with trauma exercise, end pregnancy arterial, therefore more severe Hemorrhage AVM rupture not a function of size no marked increase with exercise, pregnancy, trauma arteriovenous, therefore less severe mortality 6 to 13.6% Aneurysm rupture related to aneurysm size increase with trauma exercise, end pregnancy arterial, therefore more severe mortality 30-50% Hemorrhage AVM rupture not a function of size no marked increase with exercise, pregnancy, trauma arteriovenous, therefore less severe mortality 6 to 13.6% lower rebleed mortality rate (1%) Aneurysm rupture related to aneurysm size increase with trauma exercise, end pregnancy arterial, therefore more severe mortality 30-50% higher rebleed mortality rate (13%) Hemorrhage AVM rupture not a function of size no marked increase with exercise, pregnancy, trauma arteriovenous, therefore less severe mortality 6 to 13.6% lower rebleed mortality rate (1%) vasospasm rare Aneurysm rupture related to aneurysm size increase with trauma exercise, end pregnancy arterial, therefore more severe mortality 30-50% higher rebleed mortality rate (13%) vasospasm common Hemorrhage - AVM Nonetheless, risk of major, incapacitating, or fatal hemorrhage in untreated lesion is 40 to 50% Hemorrhage - AVM Nonetheless, risk of major, incapacitating, or fatal hemorrhage in untreated lesion is 40 to 50% Yearly risk of initial hemorrhage 3% Rebleed in first subsequent year 6-18%, reducing to 3% again thereafter Pediatric prognosis worse than adult Spetzler & Martin Grading System Criteria Score Size of Nidus Small (6cm) 3 Eloquence of Adjacent Brain No 0 Yes 1 Deep Vascular Component No 0 Yes 1 Treatment Options Surgical Resection Treatment Options Surgical Resection Endovascular Embolisation Treatment Options Surgical Resection Endovascular Embolisation Stereotatic Radiosurgery Treatment Options Surgical Resection Endovascular Embolisation Stereotatic Radiosurgery Multimodal Therapy Treatment Options Surgical Resection Endovascular Embolisation Stereotatic Radiosurgery Multimodal Therapy Conservative Management Normal Perfusion Pressure Breakthrough Theory R.F. Spetzler et al Normal perfusion pressure breakthrough theory Loss of autoregulation and carbon dioxide reactivity in presence of large arteriovenous malformation. Normal perfusion pressure breakthrough theory Loss of autoregulation and carbon dioxide reactivity in presence of large arteriovenous malformation. Normal hemispheric vessels are chronically maximally dilated to attempt to divert flow from the AVM Normal perfusion pressure breakthrough theory Loss of autoregulation and carbon dioxide reactivity in presence of large arteriovenous malformation. Normal hemispheric vessels are chronically maximally dilated to attempt to divert flow from the AVM Obliteration of the AVM diverts all flow to these