新生儿缺氧缺血性脑病HIE课件PPT

发病机制
脑血流改变
缺氧缺血加重→脑血流重新分布
脑血管自主调节功能障碍
脑组织代谢改变
能量衰竭 细胞膜上钠钾泵功能不足 Ca2+通道开启异常 氧自由基损伤 兴奋性氨基酸的神经毒性
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发病机制1 脑血流改变
缺氧缺血加重→脑血流重新分布 第 6 版 缺氧缺血为部分性或慢性
大脑半球血流↓
代谢最旺盛部位血流↑
developing fibrillary processes
Calcification钙化
Deposition of calcium in damaged neurons is commonly seen after hypoxic-ischemic insult and, if extensive enough, may be apparent on brain imaging..
Insults other than those due to hypoxia-ischemia may also cause extensive calcification, including viral infection and certain metabolic disorders.
If the hypoxemia is severe enough, initially peripheral tissues (muscle and heart) and ultimately brain tissue develop an
oxygen debt, leading to anaerobic glycolysis and production of a lactic acidosis. The lactic acid diffuses into the bloodstream, causing metabolic acidemia. This can be measured by blood gas analysis.
大脑前、中、后动脉 的边缘带（矢状旁区 及其下白质）受损
基底神经节、丘脑、 脑干、小脑血流↑
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选择性易损区（selective vulnerability)
脑组织内在特性不同而具有对损害特有的高危性
足月儿
早产儿
大脑矢状旁区脑组织 脑室周围的白质区
ቤተ መጻሕፍቲ ባይዱ11
Selective Vulnerability 选择性易损性
Asphyxia
This is the state in which placental or pulmonary gas exchange is compromised or ceases altogether, typically producing a combination of progressive hypoxemia and hypercapnia.
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大脑前动脉 大脑中动脉 大脑后动脉
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Types of Hypoxic-Ischemic Insult
Acute total asphyxia This produced injury to the thalamus（丘 脑）, brainstem,and spinal cord structures. The longer the duration of the acute insult, the more extensive was the damage in these regions. Little damage was reported in higher structures
Cerebral Edema（脑水肿） Cellular Responses Calcification Chronic Lesions No consistent neuropathologic features The type and duration of the insult and the gestational age of the
Others
Other types of hypoxic-ischemic insults include maternal fever during labor, which may accelerate fetal brain injury, fetal starvation with reduction in intracerebral glucose availability, sepsis,and twinning.
child at the time of the insult The interval between the insult and death
Cerebral Edema
Cellular edema develops within an hour of the insult and resolves by 7 days after its onset
Neuroprotective therapy with hypothermia has been shown to be effective in reducing the risk for disability and death in affected term babies and as such will offer an important therapeutic strategy to reduce brain damage in surviving babies.
Edema particularly affects white matter and probably accounts for the abnormal signal on MRI
In the most severe cases, herniation（疝） of the cerebellar tonsils （小脑扁桃）and vermis （蚯蚓）
Periventricular leukomalacia（脑室周围白质软化 ） has been described as being a watershed lesion as the major factor in its pathogenesis.
Regional Susceptibility
A partial asphyxial insult----in the cerebral hemispheres and particularly in the watershed distribution,brainstem, hippocampus（海马）, and temporal （颞叶）and occipital lobes.（枕叶 ）。
Hypoxic-Ischemic Encephalopathy
This term describes abnormal neurologic behavior in the neonatal period arising as a result of a hypoxic-ischemic event.
The effects of these factors may act through one or a number of the variables discussed previously.
Etiology
缺氧是核心
围生期窒息是最主要的病因 其他 出生后肺部疾患
心脏病变 严重失血或贫血
Neuropathology
The neuron is the most sensitive cellular element to hypoxic-ischemic insult, followed by glia cells comprising cerebral vasculature
Maturity
Gestational age plays an important role in the changing susceptibility of cerebral structures to hypoxic-ischemic insult for a number of reasons
新生儿缺氧缺血性脑病
Hypoxic-ischemic Encephalopathy
重点
新生儿缺氧缺血性脑病的临床表现 新生儿缺氧缺血性脑病的诊断、治疗
HIE
Severe enough to cause irreversible damage in the mature fetal brain, has an incidence of 1 to 2 per 1000 live births, but is 2 to 3 times more common in developing countries. Up to 25% of surviving infants may be irreversibly damaged by this condition.
Cellular Responses
Neurons may undergo either necrosis or apoptosis Microglial cells (brain macrophages) --ingesting and
lysing dead tissue Glial cells ---enlarging,proliferating, and later
the vascular factors high metabolic rates of individual nuclei the distribution of glutamate excitotoxic receptors Regional cerebral glucose use
大脑大动脉分布
Vascular Territories
Watershed injury（分水岭损伤）refers to tissue damage that occurs in regions that are most vulnerable to reduction in cerebral perfusion
rapid changes in neuronal development, changing vascular watersheds, and biochemical variables within cells, such as relative proportions of excitotoxic and inhibitory expression.
The severity of hypoxic-ischemic encephalopathy (HIE) can be defined as mild, moderate, or severe depending on symptoms and signs;
Hypoxia or Anoxia
This denotes a partial (hypoxia) or complete (anoxia) lack of oxygen in the brain or blood.
Definitions
HIE是指各种围生期 （perinatal period）窒息引起的 部分或完全缺氧、脑血流减少或暂停而导致胎儿或新生 儿脑损伤。
HIE是引起新生儿急性死亡和慢性神经系统损伤的主要原 因之一。
Definitions
Hypoxic-Ischemic Encephalopathy（缺氧缺血性脑病） Hypoxia or Anoxia（缺氧） Asphyxia（窒息） Ischemia（缺血）
Cellular susceptibility(易感性) Maturity Vascular territories Regional susceptibility Type of hypoxic-ischemic insult Others
Cellular Susceptibility