Kuhn James, Weisbrod Luke J., Emmady Prabhu D.
Aventura Hospital and Medical Center
UNMC
At the end of the nineteenth century, the pathologists Julius Arnold (1835-1915) and Hans Chiari (1851-1916) described a complex clinical and pathological condition involving deformity of the cerebellum and brainstem in children. Chiari malformations are now defined as a spectrum of hindbrain abnormalities involving the cerebellum, brainstem, skull base, and cervical cord. According to the type of herniation of the brain tissue displaced in the spinal canal and the characteristics of the anomalies of the brain or spine development, 4 types of Chiari malformations have been classified. Together with basilar invaginations, Chiari malformations represent the most common craniocervical junction malformations seen in adults. Chiari malformation type 2 or Chiari 2 malformation, commonly referred to as Arnold-Chiari malformation, is usually associated with spina bifida and is characterized by caudal displacement of the cerebellar vermis, brainstem, and fourth ventricle. Despite its name, rather than a continuation of a spectrum with Chiari 2 malformation representing a severe version of Chiari 1 malformation, these malformations represent distinct disease processes with overlapping radiographic findings. (see Chiari Malformation Types 1 and 2). Chiari 2 malformation can be associated with numerous additional findings, most commonly hydrocephalus and syringomyelia. Clinically, Chiari 1 malformation can be an asymptomatic hindbrain hernia, while Chiari types 2, 3, and 4 are congenital and clinically significant. Chiari 2 malformation may present a variety of clinical manifestations, which can include spinal symptoms secondary to myelomeningocele, tethered cord syndrome or syringomyelia, symptoms of secondary hydrocephalus, brainstem symptoms, or those due to lower cranial nerve dysfunction. The nosographic collocation of type 0 or 0.5 Chiari malformation or Chiari-like symptoms without tonsillar herniation, type 1.5 Chiari malformation between types 1 and 2, and complex Chiari is controversial and not universally accepted.
19世纪末，病理学家朱利叶斯·阿诺德（1835 - 1915）和汉斯· Chiari（1851 - 1916）描述了一种涉及儿童小脑和脑干畸形的复杂临床和病理状况。Chiari畸形现在被定义为一系列涉及小脑、脑干、颅底和颈髓的后脑异常。根据椎管内移位脑组织的疝出类型以及脑或脊柱发育异常的特征，Chiari畸形已被分为4种类型。与基底凹陷一起，Chiari畸形是成人中最常见的颅颈交界畸形。Chiari 2型畸形或Chiari 2畸形，通常称为阿诺德 - Chiari畸形，通常与脊柱裂相关，其特征是小脑蚓部、脑干和第四脑室尾侧移位。尽管其名称如此，但这些畸形并非Chiari 2畸形代表Chiari 1畸形的严重形式这一连续谱系的延续，而是代表具有重叠影像学表现的不同疾病过程。（见Chiari畸形1型和2型）。Chiari 2畸形可伴有许多其他表现，最常见的是脑积水和脊髓空洞症。临床上，Chiari 1畸形可以是无症状的后脑疝，而Chiari 2、3和4型是先天性的且具有临床意义。Chiari 2畸形可能表现出多种临床表现，包括继发于脊髓脊膜膨出、脊髓栓系综合征或脊髓空洞症的脊柱症状、继发脑积水的症状、脑干症状或因低位颅神经功能障碍引起的症状。0型或0.5型Chiari畸形或无扁桃体疝的Chiari样症状、1型和2型之间的1.5型Chiari畸形以及复杂Chiari畸形的疾病分类搭配存在争议且未被普遍接受。
