An unusual case of footdrop: anterior disc herniation mimicking a nerve sheath tumor.

OBJECTIVE

Extreme lateral disc herniations are described. Usually, the herniated disc is described as being at the lateral edge of the neural foramen. Herniated discs that lodge beyond this location need to be included in the differential of retroperitoneal lesions impinging on nerve roots.

CLINICAL PRESENTATION

A 76-year-old woman presented with left leg radicular symptoms, including footdrop and a retroperitoneal lesion. Given the location of the lesion and its distance from the edge of the neural foramen, the differential diagnosis favored a nerve sheath tumor.

INTERVENTION

An anterior retroperitoneal approach was taken. At the time of surgery, the lesion proved to be a herniated disc arising from the anterior surface of the L5-S1 disc space, medial to the psoas muscle. The disc herniation resulted in severe compression of the L5 nerve root as the root joined the lumbosacral plexus. This type of even more extreme lateral disc herniation is not widely reported. At this location, there are reports of clinicians confusing discs for tumors and occasionally tumors for discs. Given that some disc herniations are no longer visually adjacent to the foramen, perhaps extreme lateral disc herniation is not an ideal term. This individual case report is supplemented with a review of the literature on this rare condition with specific searches for disc, retroperitoneal, anterior herniation.

CONCLUSION

Using the term anterior disc herniation will aid clinicians in including herniated disc fragments in the differential diagnosis for lesions affecting nerve roots anterior to the spine in this retroperitoneal location.