- LA05.0 Microcephaly - failure of the head to correctly develop during the antenatal period. This condition is characterized by a head size that is significantly smaller than normal for their age and sex. This condition may also present with developmental delays, difficulties with balance and coordination, short stature, hyperactivity, mental retardation, seizures, or other neurological abnormalities.
- LA05.1 Megalencephaly - failure of the brain to correctly develop during the antenatal period. This condition is characterized by increased size or weight of an otherwise correctly formed brain. This condition may also present with seizures, motor deficits, mental retardation and mild cognitive impairment.
- LA05.2 Holoprosencephaly - brain malformation resulting from incomplete cleavage of the prosencephalon, occurring between the 18th and the 28th day of gestation and affecting both the forebrain and the face. In most of the cases, facial anomalies are observed: cyclopia, proboscis and median or bilateral cleft lip/palate in severe forms, and ocular hypotelorism or solitary median maxillary central incisor in minor forms. These latter midline defects can occur without the cerebral malformations (microforms). Children with HPE have many medical problems: developmental delay and feeding difficulties, epilepsy, and instability of temperature, heart rate and respiration. Endocrine disorders like diabetes insipidus, adrenal hypoplasia, hypogonadism, thyroid hypoplasia and growth hormone deficiency are frequent.
- LA05.3 Corpus callosum agenesis - the most common brain malformation and is characterized by total or partial absence of the main interhemispheric commissure, the corpus callosum.
- LA05.4 Arhinencephaly - failure of the olfactory organs to correctly develop during the antenatal period. This condition is characterized by absence of the olfactory bulbs and tracts.
- LA05.5 Abnormal neuronal migration - any condition caused by abnormal migration of neuronal cells during the antenatal period. These conditions may present with poor muscle tone and motor function, seizures, developmental delays, mental retardation, failure to grow and thrive, difficulties with feeding, swelling in the extremities or microcephaly.
- LA05.6 Encephaloclastic disorders
- LA05.7 Brain cystic malformations - A disease caused by expansion of the roof plate of the brain vesicle, or by extraaxial structures such as an arachnoid membrane or migrating ependymal cells. This disease is characterized by the presence of fluid filled cysts in the brain. This disease may present with asymmetry of the skull, brain compression, raised intracranial pressure, hydrocephalus, bleeding or seizures. This disease may also be asymptomatic. Confirmation is through observation of intracerebral cysts by imaging.