Presentation
Left sided sciatica. No cauda equina compromise clinically. Previous lumbar hemilaminectomy.
Patient Data
Transitional lumbosacral anatomy: the iliolumbar ligment attaches to the second last mobile segment making this vertebra L5. The S1 vertebra has a subjacent disc, but there is pseudoarthrosis of the right transverse process to the ilium.
Using this nomenclature, at L5/S1 there is left hemilaminectomy, with minor enhancing post-operative fibrosis. Residual / recurrent disc bulge at this level, with flattening and swelling of the transiting left S1 nerve root.
Case Discussion
There are a few things to trip up an unwary radiologist in this case!
Firstly, recognition of transitional lumbosacral anatomy is essential. There is hemisacralisation (right) / hemilumbarisation (left) of the S1 vertebra. However you describe it -- be explicit and consistent!
Also, this is a postoperative patient with ipsilateral symptoms and imaging features compatible with residual / recurrent disc material. The use of contrast to identify enhancing fibrotic tissue can be used in these cases to help the team plan surgery.
This patient was conservatively managed, but presented again a few months later with progressive L5/S1 disc bulge and underwent repeat surgical intervention.