Empty Thecal Sac Sign

Empty Thecal Sac Sign

→ It is when the thecal sac appears empty on MRI of the lumbar spine.

→ If it is +nt , a diagnosis of adhesive arachnoiditis can be made.

→ It is best seen on T2-weighted images.

MRI findings: It can be present throughout the subarachnoid space.

Most easily seen in lumbar region where cauda equina floats in ample CSF.