Sagittal post-contrast T1-weighted MRI shows a large T1 hypointense intramedullary spinal cord cavity characteristic of a syrinx (yellow arrow). It extends from the C2-C3 cervical level inferiorly in a child with a known Chiari I malformation (pink arrow). This finding is defined as syringohydromyelia because syringomyelia (an eccentric spinal cord cavity) cannot be differentiated from hydromyelia (a central spinal cord cavity) by imaging.