hiari dị tật là một rối loạn của neurulation tiểu học, các khuyết tật ống đóng cửa chủ yếu là thần kinh và hệ thần kinh trung ương đầu bất thường, thường xảy ra xung quanh tuổi thai 3-4 tuần. Quang phổ của các dị tật bẩm sinh có nhãn dị tật Chiari kéo dài một phạm vi rộng. Bệnh nhân có triệu chứng với Chiari | 434 Chapter 13 3 Sacral chordoma Common locations of chordoma include sacrococcygeal region 50 clivus and C1-2. Accounts for 40 of all sacral tumors. The tumor is destructive lytic and is often associated with calcification. Differential diagnosis includes chondrosarcoma. 4 Multiple myeloma The rate of sacral involvement by plasmacytoma or multiple myeloma is 2-4 . Solitary osseous plasmacytomas usually have longer survival periods following radiation therapy. 5 Others Giant cell tumor most common benign sacral tumor Osteomyelitis Neurofibroma Aneurysmal bone cyst Specific diseases differentials Chiari malformations Chiari malformation is a disorder of primary neurulation mostly neural tube closure defects and early CNS anomalies typically occurring around 3-4 weeks gestation. The spectrum of congenital anomalies labeled the Chiari malformations spans a wide range. Symptomatic patients with Chiari malformations are seen with ataxia vertical nystagmus headache cranial nerve VI through XII abnormalities and signs of syringomyelia. The different features of Chiari I and II are discussed in the table below. Chiari III malformations are associated with herniation of posterior fossa contents into an occipital or high cervical encephalocele with other features of Chiari II malformations. Chiari IV malformations are very rare and are associated with severe hypoplastic cerebellum small brainstem and large posterior fossa CSF spaces. Features Chiari I malformations Chiari II malformations Major abnormalities Peg-like pointed tonsils displaced into Cerebellar tonsils vermis fourth upper cervical canal 5 mm below ventricle and brainstem are foramen magnum herniated through the foramen magnum and the egress fourth ventricle is obstructed Neuroradiology 435 Features Chiari I malformations Chiari II malformations Associated anomalies Skull dura Normal Calvarial defects Small posterior fossa Fenestrated falx Gaping foramen magnum Brain Normal Inferiorly displaced vermis Medullary
