Presentation
Right sciatica.
Patient Data
The right-sided roots of L5 and S1 are conjoined resulting in asymmetry of the subarticular recess dural sac.
The nerve roots exit the theca in a single dural sheath which then splits into separate nerve sheaths in the subarticular recess.
There is also a complete bilateral sacralization of L5 vertebra: lumbosacral transitional vertebra (Castellvi IIIb).
The image illustates the asymmetry of the dural sac at the level of L5-S1 subarticular recess.
Case Discussion
A conjoined nerve root is defined as two adjacent nerve roots that share a common dural envelope at some point during their course from the thecal sac.
The L5 and S1 segments are most frequently involved and it is most commonly found to be unilateral; however, bilateral cases have been noted.
They can cause sciatica even without the presence of an additional compressive impingement (such as disc herniation, spondylolisthesis or lateral recess stenosis).
They are frequently undiagnosed until the operating room and can be one of the origins of failed back syndrome.