Development of symptoms in arachnoid cysts

フォーマット:

図書

責任表示:

Hayashi, Yasuhiko

言語:

英語

出版情報:

Nova Science Publishers, Inc., 2016-01-01

著者名:

Hayashi, Yasuhiko  

掲載情報:

Arachnoid Cysts: Epidemiology, Treatment and Clinical Outcomes

開始ページ:

1

終了ページ:

33

バージョン:

author

概要:

Arachnoid cysts are benign developmental anomalies of the central nervous system and arise in virtually all locations where arachnoid membrane exists. It is reported that they account for approximately 1% of all intracranial lesions and are caused by the splitting of the arachnoid membrane. Many authors have indicated that arachnoid cysts typically remain constant in size or grow very slowly. Therefore, most opportunities to detect arachnoid cysts are incidental. … However, recent advent of more advanced imaging techniques has increased the frequencies to find them. The enlargement of arachnoid cysts are reported to occur most frequently in patients under 5 years of age, and the symptoms and signs derived from arachnoid cysts include elevated intracranial hypertension and focal signs due to the effects of compression to the surrounding cerebral parenchyma. Even in cases in which neurological symptoms are present, it is often difficult to properly correlate nonspecific signs and symptoms with the findings of arachnoid cysts. This is especially true in the cases common symptoms, such as headache, that arise frequently in the general population. In most of the cases, arachnoid cysts usually bring with a thin and bulging inner table of the skull. These bone deformities suggest a long process accompanying a gradual increase in intracystic pressure that probably begins in early infancy. Three mechanisms of the cyst expansion in arachnoid cysts have been described by many authors as follows: First, osmotic gradient between the cyst and the surrounding subarachnoid space induced fluid influx into the cyst cavity; second, fluid is secreted from ependymal cells on the cyst wall; third, a one-way ball-valve mechanism develops on the cyst wall. Almost symptomatic arachnoid cysts belong in children, the progressive growth of the skull and plasticity of the brain in children can buffer the mass effect caused by the cysts. Therefore, the arachnoid cysts in children and adolescence are usually asymptomatic or minimally symptomatic. The patient’s symptoms develop once the breakdown of compensatory mechanism in the brain surrounding the arachnoid cyst happens. Even in elderly patients with or without cyst expansion, the breakdown of compensatory mechanisms can lead to relatively rapid progression of symptoms. However, the factors that induce the breakdown of compensatory capacity remain unknown. In addition to those mechanisms, the symptomatic arachnoid cyst infrequently associates with intracranial hematoma, such as chronic subdural hematoma, acute subdural hematoma, acute epidural hematoma, and intra-cyst wall hematoma. Especially, it is well known that arachnoid cysts located in the middle cranial fossa can present with chronic subdural hematoma. The hematomas are frequently induced by minor trauma. The symptoms in arachnoid cysts are presented according to the various locations arachnoid cysts arise, and the developmental mechanisms are also discussed with the aspects of accompanying hydrocephalus or intracranial hematomas, and patients’ ages. © 2016 by Nova Science Publishers, Inc. All rights reserved.<br />Embargo Period 12 months<br />[Book Chapter] 続きを見る

URL:

http://hdl.handle.net/2297/48556