Normal neuronal migration
Normal neuronal migration involves the development of six cortical layers, each one performing distinct functions.Normal cerebral development occurs in three dynamic and overlapping stages:
first stage: stem cells proliferate and differentiate into neurons or glial cells within the forebrain and the ventricular and subventricular zones lining the cerebral cavity;
in humans this stage lasts from gestational weeks 5-6 to 16-20;
second stage: migration away from the origin in a radial fashion along the glial fibers from the periventricular region of the ganglionic eminences towards the pial surface;
the generations settle into a pattern within the cortical plate during this stage;
in humans this stage lasts from gestational weeks 6-7 to 20-24;
third stage: apoptosis and synaptogenesis within the six cortical layers to develop correct cortical organization;
in humans this stage lasts from gestational week 16 until long after birth.Most types of incomplete neuronal migration to the cortex occur during the third and fourth gestational months. The abnormal migration of the neurons causes them to not reach their proper final destinations, which results in failure of the sulci and gyri to form.The stage of cortical development at which migration is arrested is directly related to the level of structural malposition.One of the most critical stages in brain development is when the post-mitotic neurons migrate from the ventricular zone to form the cortical plate. Migration arrested toward the latter part of development usually restricts the abnormal cell position to the cortex level. Neuronal migration disorder caused by genetic mutations
Several genetic mutations have been isolated and linked to specific malformations of the cerebral cortex.
Aortopulmonary window (APW) refers to a congenital heart defect similar in some ways to persistent truncus arteriosus. Persistent truncus arteriosus involves a single valve; aortopulmonary window is a septal defect.A large number of patients with a large APW usually die within 1 year of age. It is extremely rare to find cases of APW surviving till adult age and it is still rare to surgically treat such patients who are incidentally detected in adult age because such subsets of patients invariably have associated pulmonary vascular obstructive disease in advanced stage and thus there is therapeutic dilemma to surgically correct these patients.Although cases of uncorrected APW presenting in adulthood have been reported but literature on surgically treated AP window in adult populations is limited. A rare case of successful surgical management of an incidentally detected large APW with reversible pulmonary arterial hypertension has been reported as isolated case reports. See also
Aortic window
Major aortopulmonary collateral artery, developes when native pulmonary circulation is underdeveloped

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