Dorsal thoracic arachnoid web

Case contributed by Nick Tarasov
Diagnosis almost certain


Decreased sensitivity of the lower limbs and midline paresthesia-like burning sensations of the thoracic spine.

Patient Data

Age: 55 years
Gender: Female

MRI Thoracic spine


Posterior arachnoidal space dilatation measuring 25 x 7 x 7 mm at the T5 level with spinal cord compression of about 50% and a typical scalpel sign. A turbulent CSF flow immediately below this lesion with flow voids on T2 weighted images. Myelopathy at the T3-T4 levels.

Scalpel sign


Zoomed in version of the sagittal T2 demonstrating a 'perfect' example of the scalpel sign. 

Case Discussion

This is a representative case of the scalpel sign and typical dorsal thoracic arachnoid web. This patient requires spinal cord decompression surgery.

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