Мидың шағылысқан құрылысы және сусымалдау синдромы

Congenital malformation of the cerebellar vermis

The most frequent and prominent symptoms of DWM are those associated with hydrocephalus in the postnatal period. Hydrocephalus occurs in an estimated 80% of patients with classic DWM. This usually presents within the first year of life (85% of the time), most often within the first three months. In contrast to classic DWM, only around 30% of those with Dandy–Walker variant (DWV), in which the posterior fossa is not enlarged, have hydrocephalus. However, many of the genetic conditions associated with DWM can present with developmental delay and other brain anomalies. This does not seem to result in intellectual disability on its own, however. In Dandy–Walker variant (DWV) and mega cisterna magna specifically, which are less severe malformations, there appears to be an increased rate of psychotic spectrum disorders such as schizophrenia, bipolar disorder, mania or catatonia.

A 2017 review found the following associations in patients with DWS (usually from an associated genetic condition or abnormality): One review reported an occurrence of 4.3% in a sample. This may be due to herniation of the bottom of the cyst through the foramen magnum (a similar mechanism to Chiari malformation). Alternatively, it may be a result of hydrocephalus, in which it forms as a "fifth ventricle" due to an enlarged central canal.

DWM is caused by any disruption to embryonic development that affects the formation of the cerebellar vermis. This is usually a genetic mutation that results in impaired cell migration and division. A large number of genetic conditions can result in the anomaly. In a large portion of DWM cases, the condition is identified in the person affected, however in most cases the cause is not identified. At least 21% of those with DWM have a sibling with the malformation, and at least 16% have a parent with the malformation. Other comorbid genetic conditions that were found included oculocerebrocutaneous syndrome, oral facial digital syndrome, Coffin–Siris syndrome, Meckel–Gruber syndrome type 7 and Kallmann syndrome, among many others. Walker–Warburg syndrome, Fukuyama congenital muscular dystrophy, Ellis–Van Creveld syndrome, Fraser syndrome, Aicardi syndrome, Cornelia de Lange syndrome, and acrocallosal syndrome, among others. Craniosynostosis Dandy Walker malformation hydrocephalus syndrome has also been described in a handful of cases. Many of these disorders are classified as ciliopathies, genetic disorders that affect the cellular primary cilia, thin cell projections made from microtubules that are believed to be crucial in signalling embryonic cell division and migration. DWM is one of the single largest predictors of a ciliopathic genetic disease. Other genes that have been linked to DWM include ZIC1, ZIC4, FOXC1, FGF17, LAMC1 and NID1.

The prognosis is first and foremost dependent on the early and successful treatment of hydrocephalus, if present. The other significant factor affecting prognosis is the presence of a comorbid genetic condition or brain anomaly. Shunts in the fourth ventricle (cystoperitoneal shunts, or CP shunts) have a generally high rate of successful cyst and ventricle size reduction, especially in the cyst (at least 80%). With a shunt in the lateral ventricles (ventriculoperitoneal shunt, or VP shunt), studies have generally found a roughly 50% successful cyst size reduction rate, with successful ventricle size reduction roughly two thirds of the time. In 1914, American neurosurgeon Walter Dandy and American paediatrician Kenneth Blackfan described the malformation as partial or complete absence of the cerebellar vermis, an enlarged fourth ventricle and hydrocephalus. In 1976, Harwood Nash and Fitz proposed the term Dandy–Walker variant (DWV) for a malformation in which the posterior fossa is not enlarged but the cerebellar vermis is hypoplastic. In 1989, Barkovich et al. proposed the term Dandy–Walker complex (DWC) to include classic DWM and DWV (under type A) plus a third malformation (under type B) in which the cerebellar vermis remains large enough to sit between the fourth ventricle and the cisterna magna, and instead it is mostly the cisterna magna that is enlarged (sometimes diagnosed as "mega cisterna magna"). In 1999, Calabró et al. first used the phrase Dandy–Walker continuum when referring to proposals that a condition known as Blake's pouch cyst falls under the umbrella of the Dandy–Walker complex proposed by Barkovich. These additional terms are mostly discouraged by modern authors due to additional confusion and complexity to the diagnosis of DWM.