Age / Sex : 67 / F

Chief complaint : Back pain and radiating pain in both lower leg(L>R)

 P/Hx: laminectomy at T12-L3, 35 years ago/posterior fixation at L5-S1, 5 years ago

What is your impression?

Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer).

Courtesy : Jeongmi Park, Yeouido St. Mary’s Hospital

Discussion

Answer:  Arachnoiditis ossificans

Findings:

Saccular distention & septation of thecal sac at multiple laminectomy level at T12-L3, especially at L1-L3 body .
 - partly calcified peripheral wall of distended thecal sac.
 - distortion of the cauda equina

 - posterior bony erosions of L 1 & 2  body
 

Differential Diagnosis:

 Adhesive arachonoidits, arachnoid hemorrhage

Discussion:

• Unusual chronic meningeal inflammatory process: Sequale of end-state adhesive arachnoiditis


• Cause: trauma, surgery, arachnoid hemorrhage, myelography (particularly oil based contrast agents), and spinal anesthesia


• Etiology: uncertain, osseous metaplasia associated with chronic inflammation


• CT: ossified intraspinal lesion & nerve roots, specific & diagnostic


• MR: central clumping of nerve roots, peripheral adhesion of the nerve roots and intradural cysts due to loculation of subarachnoid space

References:

A rare cause of progressive myelopathy Open Neuroimag J 2015; 9:13-20.

Arachnoiditis Ossificans: MR imaging features in five patients AJR 2001;177:461-464