AIM We present a MRI classification system for craniocervical anomalies that guides the selection of surgical management. METHODS One hundred and two patients with craniocervical anomalies were divided into 3 types based on the compression direction to medulla and cervical spinal cord in MRI. Type 1, ventral compression ( n =23); type 2, Dorsal compression ( n =59); type 3, mixed compression ( n =20). Ventral decompression was performed for all the patients with ventral compression and 11 patient...