ARNOLD-CHIARI malformation19 denotes a congenital anomaly consisting of (1) caudal displacement of the inferior cerebellar vermis or tonsils, and (2) "hunch-back" or nodular reduplication of the medulla oblongata accompanied by descent of the lower pons, medulla, and fourth ventricle into the spinal canal. A malformation comprised of only cerebellar displacement without medullary deformity is known as Chiari type 1 or Arnold malformation, and the reverse is called Chiari type 2 or Chiari deformity.2,5,6
Schwalbe and Gredig19 claimed that the Arnold-Chiari malformation was invariably associated with a severe degree of spina bifida, and often other anomalies of the spinal column and cranium. During the last three decades, there have been several recorded cases with normal spine, but recently in a critical review, Peach17 considered none of these as Arnold-Chiari malformation but designated all of them type 1 deformity,1,3,9,11,14,16,21 and he reported a well-documented case, a