【体外膜肺ECMO精品课件】 Central Nervous System Physiology,

Brain Injury at Birth
Intracerebral Hemorrhage
– Uncommon occurrence – Blood can be found within the germinal matrix, ventricles or
parenchyma – Thalamus is a common site of hemorrhage – Predisposing factors include prior hypoxic–ischemic cerebral
– Axons are projected to neurons over long distances to reach their final targets
– CNS myelin proteins might also help preserve an appropriate CNS neuronal network
Subarachnoid hemorrhage
– Primary
Hemorrhage in the subarachnoid space Most common form of intracranial bleeding in term neonates Rupture of small veins bridging the leptomeninges is most
downward eye deviation
Brain Injury at Birth
Cerebral infarction (perinatal stroke)
– Occurs 1 in 4,000 births – Causes:
May occur from both embolic and thrombotic phenomena Intrapartum asphyxia , deficiency of one of the systemic
– Tears in the falx and tentorium or bridging cortical veins secondary to stretching can cause significant hemorrhage
– Most likely to occur during difficult vaginal deliveries – Symptoms include: increased intracranial pressure, seizures,
injury, sepsis, and coagulopathy – Can be observed in association with subarachnoid or subdural
hemorrhage – Symptoms:
Sudden onset of marked neurologic abnormalities, Signs of seizures, evidence of increased intracranial pressure and
15 mL per week – Week 28: Brain is 13% of term brain volume – Week 34: Brain is 64% of term brain – Weeks 35-41: Five fold increase of white matter volume
accumulation, lipid peroxidation and nitric oxide neurotoxicity serve to disrupt essential components of the cell with its ultimate death
– Hemorrhage – Focal cerebral infal injury
Other causes:
– Metabolic disturbances related to inborn errors of metabolism – Hypoglycemia – Hyperbilirubinemia – Infection/meningitis
【体外膜肺ECMO精品课件】 Central Nervous System Physiology, Behavior & Stress
Timing of the Development of the Brain and CNS
Last half of gestation
– “Critical period”
coagulation inhibitors (ie, protein C or protein S), primary hemorrhage with vasospasm, meningitis, polycythemia, or ECMO
– Etiology is unclear – Symptoms:
common occurrence
– Secondary
Extension of subdural, intraventricular, or intraparenchymal hemorrhages
Occur less often Trauma, coagulation disorders and rupture of intracranial
Brain Injury at Birth
Epidural hemorrhage
– Rare lesion in the neonate (~2% of all cases) – Hemorrhage occurs from branches of the middle
meningeal artery or from major veins or venous sinuses – Progressive neurological dysfunction and death are common results unless epidural hemorrhage is evacuated and further bleeding stopped
– Developmental changes occur largely in the last half of gestation
– Growth and development continue to occur beyond the neonatal period
Timing of the Development of the Brain and CNS
focal neurological deficits, herniation of the temporal lobe over the tentorial edge causing ipsilateral third nerve paralysis, large movements, decreased responsiveness, metabolic acidosis, hypoglycemia, anemia and hypotension
Seizures or apnea, usually on the 2nd postnatal day
Brain Injury at Birth
Hypoxia–ischemia cerebral injury
– The brain injury that develops is an evolving process beginning at the insult and extends into the recovery period (reperfusion phase)
Brain Injury at Birth
Clinical expression:
– Subtle
Mild hypotonia or hyperalert state
– Severe
Stupor or coma
Severity and extent of damage dictate short and long-term consequences
aneurysm or arteriovenous malformation can be responsible
Brain Injury at Birth
Subdural hemorrhage
– Categorized by origin and direction of spread (supratentorial and infratentorial)
Brain size during gestation
– The growth of the brain is not a linear process – Development of different parameters may peak at different
times – Weeks 29-41 of gestation: Brain size increases at a rate of
Increasing neuronal connectivity, dendritic arborizatoin and connectivity, increasing synaptic junctions, and the maturation of neurochemical and enzymatic processes
Prevents an overly exuberant axonal sprouting with misconnections
Brain Injury at Birth
Very rare in the term infant (1 in 1,000 live births) Most often secondary to:
Brain Injury at Birth
Intracranial hemorrhage
– Subarachnoid hemorrhage – Subdural hemorrhage – Epidural hemorrhage
Intracerebral hemorrhage
Brain Injury at Birth
– Causes severe, long term neurological deficits in children (i.e. cerebral palsy)
– Impaired cerebral blood flow (CBF) in principle pathogenetic mechanism
Time sensitive, irreversible decision point in the development of the neural structure or system
Rapid and/or dramatic changes in one or more of the structural, neurochemical, or molecular parameters
Interruption of placental blood flow and gas exchange (asphyxia) Fetal acidemia Cellular energy failure, acidosis, glutamate release, intracellular Ca+2
Mediating the Development of the Brain and CNS
Prenatal development
– Neurotrophic factors and guidance factors mediate the successful targeting and steering of axons