Lumbar arachnoiditis with empty thecal sac sign

Case contributed by Krzysztof Nocoń
Diagnosis almost certain


Chronic symmetrical pain of lumbar region with radiation towards legs.

Patient Data

Age: 60 years
Gender: Female

At the level of L4 vertebra the nerve roots begin to clump together and adhere to the thickened thecal sac walls - empty thecal sac sign. Below that they appear to be thickened and disorganized.

Degenerative changes of lumbar intervertebral discs. Fatty transformation of paraspinal muscles.

Case Discussion

The MRI appearance is characteristic for adhesive arachnoiditis, which may be iatrogenic in nature. Unfortunately, for this patient there was no known history of surgery or previous spinal anesthesia and the cause is unknown. 

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