الفهرس 
Hypoxic ischemic encephalopathyOnly 14 pages are availabe for public view
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Abstract
Neonatal encephalopathy is a heterogeneous, clinically defined syndrome
characterized by disturbed neurologic function in the earliest days of life in an
infant born at or beyond 35 weeks of gestation, manifested by a reduced level of
consciousness or seizures, often accompanied by difficulty with initiating and
maintaining respiration, and by depression of tone and reflexes (Kurinczuk et al,
2010).
Determining whether an acute hypoxic-ischemic event contributed to neonatal
encephalopathy is challenging, since there is no gold standard test for diagnosis.
The various clinical signs of HIE, including low Apgar scores, low cord pH,
neonatal seizures, and encephalopathy, are nonspecific and may occur in the
absence of global hypoxic-ischemic brain injury or long-term neurologic squeals.
However, when clinical symptoms suggest that HIE is the most likely cause of
neonatal encephalopathy, a diagnosis of "presumed HIE" is often appropriate while
awaiting additional test results, and while instituting neuroprotective therapies
designed specifically to treat HIE (Volpe, 2012).
Neonatal hypoxic ischemic insults are a significant cause of pediatric
encephalopathy, developmental delays, and spastic cerebral palsy. Although the
developing brain spasticity allows for remarkable self repair, sever disruption of
normal myelination and cortical development up on neonatal brain injury are likely
to generate life persisting sensory-motor and cognitive deficits in the growing child
(Chichi et al., 2014).
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Neonatal hypoxic ischemic encephalopathy is one of the most common causes
of cerebral palsy and other sever neurological deficits in children, it is caused by
inadequate blood flow and oxygen supply to the brain resulting in focal or diffuse
brain injury (Kurinczuk et al.,2010; Bano et al., 2017).
HIE has an incidence of 3 to 5 per 1000 live births in the developed world and
remains associated with significant mortality and neurodevelopment sequel
(Natarajan et al., 2018).
The incidence in developing countries range from 2.3-26.5 per1000 live births
(Horn et al., 2013).
Human dickkopf-1 is a member of dickkopf gene family which is composed
of dickkopf-1, dickkopf-2, dickkopf-3 and dickkopf-4 (Katoh and Katoh 2005).
Among the members of the dickkopf family, dickkopf-1 is a secreted protein
involved in embryonic development and known as potent inhibitor of the Wnt
signaling pathway, which plays a critical role in cell patterning proliferation and
fate determination during embryogenesis (Ogoshi et al., 2011).
DKK-1 binds to low density lipoprotein (LDL)-receptor related protein5
(LPR5) OR LPR6 which functions as a wnt coreceptor therapy suppressing the B-
catenin pathway (Ahn et al., 2011).
In the embryonic brain, wnt signaling induces self renewal of radial glia
progenitors and differentiation but not proliferation of intermediate progenitor
(Munji et al., 2011).
In adult neurogensis, the function and site of action of WNT signals remains
controversial (Seib et al., 2013).
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Forced expression of DKK-1 severely reduces neurogensis in the developing
hippocampus (Solberg et al., 2008).
Recent findings have pointed to an increased expression of Dkk1-1 causally
related to neurodegenerative processes associated with Alzheimer’s disease or
brain ischemia (Rosi et al., 2010).
The imaging characteristics of HIE in term neonates can be subdivided based
on the severity of injury (severe versus mild to moderate [partial] asphyxia). This
subdivision is somewhat simplistic, since HIE comprises a continuous range of
insults that vary in both severity and duration. Hence, features of both severe and
partial asphyxia may be seen in any given patient (Huang and Castillo, 2008).
Transcranial ultrasound proved to be very useful bedside screening tool for
detection of hypoxic-ischemic encephalopathy (HIE) with sensitivity of 82 %
(Herma et al., 2018).
Cranial ultrasound (US) is the initial investigation of choice in suspected
cases of neonatal HIE as it is inexpensive, portable and imparts no radiation
exposure. Cranial US is highly sensitive for detecting intracranial hemorrhage,
hydrocephalus, and cystic periventricular leukomalacia (PVL). Increased resistive
index (RI) of the middle cerebral artery (MCA) on Doppler sonography helps to
identify severe HIE. Normally, RI decreases with increasing gestational age
(Benson et al., 2002; Barkovich, 2005).
Sonography of the brain and abdominal organs can provide reliable and
comprehensive information in asphyxiated neonates with hypoxic-ischemic injury.
Dynamic color Doppler sonography is a simple bedside technique and a promising
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tool to be used in the assessment of multiorgan perfusion injury, monitoring the
response to several drugs or interventions, and helping with the prediction of long-
term outcomes in asphyxiated neonates. It also may provide the necessary
information to improve the understanding of the changes in cerebral and visceral
perfusion occurring in these infants over time. Findings include increased
echogenicity in white matter and resultant increased gray matter-white matter
differentiation (Daneman et al., 2006).
These findings, which can be focal or diffuse, are thought to reflect edema or
necrosis and correspond to abnormalities on MRI. In addition, focal
hyperechogenic regions, which can represent infarcts of hemorrhages, can often be
identified. In more severely affected neonates, the cortex may become thickened
and the distinction between gray matter and white matter less apparent.
Abnormalities at this stage typically become more diffuse, are often asymmetric
between hemispheres, and are associated with the loss of landmarks such as sulci
and major fissures (Daneman et al., 2006).