Summary

Chiari in 1891 described a constellation of anomalies at the base of the brain inherited congenitally, the characteristic of which are (1) extension of a tongue of cerebellar tissue posterior to the medulla and cord that extends into the cervical spinal canal; (2) caudal displacement of the medulla and the inferior part of the fourth ventricle into the cervical canal; and (3) a frequent but not invariable association with syringomyelia or a spinal developmental abnormality. Chiari recognized four types of abnormalities. Presently, the term has come to be restricted to Chiari’s types I and II, that is, to cerebellomedullary descent without and with a meningomyelocele, respectively. The association of Arnold–Chairi malformation and high cervical cord infarction is unusual. The most common syndrome, anterior spinal artery syndrome (ASAS), is caused by interruption of blood flow to the anterior spinal artery, producing ischaemia in the anterior two-thirds of the cord, with resulting neurologic deficits. Causes of ASAS include aortic disease, postsurgical, sepsis, hypotension and thromboembolic disorders. The authors present an interesting case of cervical cord infarction due to anterior spinal artery thrombosis in a patient of type 1 Arnold–Chiari malformation without any of the above predisposing factors.