Pseudocyst of Ligamentum Flavum

Today I operated a very unique case. Patient presented with left sided radicular pain. Pain was intense so much so that patient was tossing in the bed. When MRI was done after due physical examinations, it was found that patient had a fluid filled cyst compressing the left L5 root. At first i thought its a synovial cyst arising from L4-L5 facet.

I posted the patient for Microscopic ( Matrix ) fenestration decompression. When i reached the ligamentum flavum. I found it unusually thickened and hypertrophied. facet capsule were looking relatively in order to the routine degneration.

I performed a laminotomy and could found that ligamentum flavum was getting fused with the L4 lamina. With Neurodrill ( Midas Rex ) , we opened the upper border of the ligamentum flavum. I could not dissect the flavum from dura. there were dense adhesion. I tried to open the flavum from it's lateral attachment. I could feel a cystic lession compressing the root. I punctured it and mucoid fluid drained out. Cyst base was again adhered to the dura. I had to find the cleavage plane from the inferior margin of the dura. Gradually, i could take off the cyst en block from the dura.

I have sent it for histopathological report. But i feel that its Mucoid Degeneration of Ligamentum flavum that has formed the cyst.

That's a relatively rare pathology i feel. Lets see i am waiting for the results and than will plan to upload the snaps.