出典(authority):フリー百科事典『ウィキペディア(Wikipedia)』「2015/10/24 12:24:19」(JST)
Encephalocele | |
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Illustration of a child with encephalocele
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Classification and external resources | |
Specialty | medical genetics |
ICD-10 | Q01 |
DiseasesDB | 29394 |
eMedicine | radio/246 |
MeSH | D004677 |
Encephalocele, sometimes known by the Latin name cranium bifidum, is a neural tube defect characterized by sac-like protrusions of the brain and the membranes that cover it through openings in the skull. These defects are caused by failure of the neural tube to close completely during fetal development. Encephaloceles cause a groove down the middle of the skull, or between the forehead and nose, or on the back side of the skull. The severity of encephalocele varies, depending on its location.[1]
Encephaloceles are often accompanied by craniofacial abnormalities or other brain malformations. Symptoms may include neurologic problems, hydrocephalus (cerebrospinal fluid accumulated in the brain), spastic quadriplegia (paralysis of the limbs), microcephaly (an abnormally small head), ataxia (uncoordinated muscle movement), developmental delay, vision problems, mental and growth retardation, and seizures.
A neonate with a large encephalocele.
Encephalocele on the head of a two-year-old.
Although the exact cause is unknown, encephaloceles are caused by failure of the neural tube to close completely during fetal development. Research has indicated that teratogens (substances known to cause birth defects), trypan blue (a stain used to color dead tissues or cells blue), and arsenic may damage the developing fetus and cause encephaloceles.[citation needed]
Proper levels of folic acid have been shown to help prevent such defects when taken before pregnancy, and early in pregnancy.[citation needed]
Usually encephaloceles are noticeable deformities and are diagnosed immediately after birth, but a small encephalocele in the nasal or forehead region can go undetected. Various physical and mental developmental delays can indicate the presence of encephaloceles.
Encephaloceles of the face are generally classified as nasofrontal, nasoethmoidal, or naso-orbital, however, there can be some overlap in the type of encephalocele. They can also appear along any part of the cranial vault as they result from abnormal closure of cranial bones, the most common location for enncephaloceles is the occipital region. If the bulging portion contains only cerebrospinal fluid and the overlaying membrane, it may be called a meningocele. If brain tissue is present, it may be referred to as an meningoencephalocele.[2]
It is recommended that women who may become pregnant take 400 micrograms of folic acid daily.[citation needed]
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Currently, the only effective treatment for encephaloceles is reparative surgery, generally performed during infancy. The extent to which it can be corrected depends on the location and size of the encephaloceles; however, large protrusions can be removed without causing major disability. Surgery repositions the bulging area back into the skull, removes the protrusions, and corrects the deformities, typically relieving pressure that can delay normal brain development. Occasionally, shunts are placed to drain excess cerebrospinal fluid from the brain.[citation needed]
The goals of treatment include:
Recovery is difficult to predict prior to surgery, and depends on the type of brain tissue involved and location of the encephaloceles. If surgery is successful, and developmental delays have not occurred, a patient can develop normally. Where neurologic and developmental damage has occurred, the specialists will focus on minimizing both mental and physical disabilities.
In general, when the bulging material consists of primarily cerebrospinal fluid, a complete recovery can occur. When a large amount of brain tissue is present in the encephaloceles, there is a higher chance of perioperative complication.
Encephaloceles occur rarely, at a rate of one per 5,000 live births worldwide. Encephaloceles of the back of the head are more common in Europe and North America, while encephaloceles on the front of the head more frequently occur in Southeast Asia, Africa, Malaysia, and Russia. Ethnic, genetic, and environmental factors, as well as parental age, can all affect the likelihood of encephaloceles. The condition can occur in families with a family history of spina bifida.[4]
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リンク元 | 「神経管閉鎖障害」「脳瘤」「髄膜瘤」 |
二分脊椎 | 二分頭蓋 | ||
神経管閉鎖障害 神経管癒合不全 |
開放性 神経管閉鎖せず |
脊髄髄膜瘤 | 無脳症 |
閉鎖性 神経管は閉鎖 |
髄膜瘤 | 脳瘤 | |
潜在性二分脊椎 |
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