Sciatica Caused by Nerve Root Entrapment Due to a Prominent Lumbosacral Ligament

A 61-year-old female patient presented at our hospital with worsening sciatica of the right leg. Examination revealed involvement of the fifth lumbar nerve root. Pain was the leading complaint. A computed tomographic scan of the lumbar spine was performed. At the disc level L5-S1 osteochondrosis and spondylarthrosis could be seen. There was no disc prolapse or formainal stenosis affecting the L5 root. A prominent lumbosacral ligament was present on both sides on computed tomography as well as on MRI (Fig. A, arrows). Coronal reformations revealed direct contact of the lumbosacral ligament and the nerve root (Figs. B, C). In contrast, there is no obvious contact on the left (Fig. C). The right nerve root appeared slightly edematous compared to the left side and the surrounding fat tissue seemed minimally infiltrated (Fig. A). A possible entrapment of the fifth nerve root on the right side was suggested. To test this hypothesis, a CT guided selective nerve root infiltration (local anesthetic and corticoid) was performed on the next day resulting in improvement of the patient’s pain (Fig. D). With further infiltrations the patient experienced a significant and lasting pain reduction.