There is no known definitive single mechanism that causes<unk> . However, researchers believe there are many possible causes of<unk> . It is a common symptom of other neurological disorders in newborns, can be caused as a result of shunt treatment of hydrocephalus, developmental disorders in premature infants, due to intrauterine disturbances during pregnancy, genetic disorders, underdevelopment or lack of white matter in the cerebrum, and exposure of the mother and the developing fetus to medications, infections, radiation, or toxic substances. Also, it is usually more common in premature infants than in full-term infants, especially in babies born with hypoxia or lung immaturity. Some of the central nervous system disorders which are associated with<unk>  are as follows: * polymicrogyria * Periventricular leukomalacia (PVL) * intraventricular hemorrhage * Hydrocephalus * schizencephaly * microgyria * microcephaly * Pierre-Robin syndrome * Neurofibromatosis Often<unk>  occurs as a result of hydrocephalus. Hydrocephalus is the accumulation of cerebrospinal fluid (CSF) in the ventricles or in the subarachnoid space over the brain. The increased pressure due to this condition dilates occipital horns causing<unk> . The most generally accepted theory is that of neuronal migration disorders occurring during the second to fifth months of fetal life. Neuronal migration disorders are caused by abnormal migration, proliferation, and organization of neurons during early brain development. During the seventh week of gestation, neurons start proliferating in the germinal matrix which is located in the subependymal layer of the walls of the lateral ventricles. During the eighth week of gestation, the neurons then start migrating from the germinal zone to cortex along specialized radial glial fibers. Next, neurons organize themselves into layers and form synaptic contacts with other neurons present in the cortex. Under normal conditions, the neurons forming a germinal layer around ventricles migrate to the surface of the brain and form the cerebral cortex and basal ganglia. If this process is abnormal or disturbed it could result in the enlargement of the occipital horns of the lateral ventricles. Common prenatal disturbances that have been shown to disturb the neuronal migration process include the following: * continuation of oral contraceptives * exposure to alcohol * intrauterine malnutrition * intrauterine infections such as toxoplasmosis * maternal drug ingestion during early pregnancy such as corticosteroids, salbutamol, and theophylline Researchers also believe that these factors can cause destruction of neural elements that have previously been normally formed. It is suggested that the underdevelopment or lack of white matter in the developing fetus could be a cause of<unk> . The partial or complete absence of white matter, also known as agenesis of the corpus callosum results in anatomic malformations that can lead to<unk> . This starts to occur around the middle of the second month to the fifth month of pregnancy. The lateral ventricles are formed as large cavities of the telencephalic vesicle. The size of the ventricles are decreased in normal development after the formation of the Foramen of Magendie, which decompresses the ventricular cavities. Myelination of the ventricular walls and association fibers of the corpus callosum and the calcarine fissure helps shape the occipital horns. In cases where this developmental process is interrupted, occipital horns are disproportionately enlarged.<unk>  has been associated with chromosomal abnormalities such as trisomy 8 mosaic and trisomy 9 mosaic. A few reports of genetically transmitted<unk>  are also found in literature. Some of these are of two siblings, monozygotic twins, and non-identical twins. The authors suggest a genetic origin with an autosomal or X-linked recessive inheritance rather than resulting from early prenatal disturbances.
Colpocephaly
Cebocephaly
Plagiocephaly
Ethmocephaly
Otocephaly
Scaphocephaly
Trigonocephaly
Dolichocephaly