The Treatment of Far-Out Foraminal Stenosis Below a Lumbosacral Transitional Vertebra

Abstract

Far-out foraminal stenosis with radiculopathy caused by bony spur formation secondary to anomalous articulation between the transverse process and the sacral ala is rarely reported. We report two cases of unilateral far-out foraminal entrapment of the L5 spinal nerve below a transitional vertebra, with a review of the literature. The objective of this work was to describe the management of a rare far-out foraminal stenosis below a transitional vertebra and to evaluate the surgical and conservative procedures and results. In a previous article, decompression was performed through an anterior approach. However, we report no difficulty with decompression using a posterior approach for one patient. The diagnosis was confirmed with computed tomography, magnetic resonance imaging, and selective radiculography. First, selective nerve root blocks were performed in two cases for the purpose of nonoperative treatment. After failure of conservative treatment with selective nerve root block, one patient underwent posterior decompression by resection of the bony spur using a posterior approach. One patient obtained good relief of radicular pain with only selective nerve root block. The other patient obtained good relief of radicular pain after posterior decompression was performed. Posterior decompression through the posterior approach is an easy, safe, and useful treatment for radicular pain caused by an L5 nerve far-out foraminal stenosis below a transitional vertebra when conservative treatments have failed to obtain good relief of radicular pain.

Posterior Decompression of Far-Out Foraminal Stenosis Caused by a Lumbosacral Transitional Vertebra -Case Report-

“…1,6,8,9,11,12,15,20,21) Selective radiculography is the most reliable modality to diagnose far-out entrapment of the L5 nerve root, 1,6,8,11,12,15,17) which was also true in our case. Selective radiculography demonstrates the entrapment point of the L5 nerve root, and simultaneous nerve block relieves the symptoms.…”

“…1,8) A summary of the 4 cases including ours is shown in Table 1. The median age was 33 years (range 29-37 years).…”

“…1,8,12,14) Furthermore, CT in combination with radiculography clearly demonstrates not only the degree and the point of L5 nerve impingement, but also the etiology of the L5 nerve compression. 1,8,12,14) Surgical options for the treatment of far-out foraminal stenosis below a TV include an anterior approach used in one case, 1) and a posterior approach used in two cases, including ours, 8) as shown in Table 1. An anterior approach, especially Fraser's wide muscle-splitting extraperitoneal approach, 5) may be easier and less invasive to the spine and the trunk muscles than the conventional posterior procedure.…”

The Role of Computed Tomography in the Presurgical Diagnosis of Foraminal Entrapment of Lumbosacral Junction

“…Spine surgeons often miss the entrapments, which can cause failed back surgery syndrome 3) . Therefore, foraminal or extraforaminal entrapment of the L5 spinal nerve on the lumbosacral junction is a very important disease entity in patients presenting with L5 radiculopathy 9,[14][15][16] . However, a confirmative diagnosis of these conditions is not easy and the pathology may not be often detected even by conventional magnetic resonance image (MRI) 9) .…”

“…Therefore, foraminal or extraforaminal entrapment of the L5 spinal nerve on the lumbosacral junction is a very important disease entity in patients presenting with L5 radiculopathy 9,[14][15][16] . However, a confirmative diagnosis of these conditions is not easy and the pathology may not be often detected even by conventional magnetic resonance image (MRI) 9) . The purpose of this study was to demonstrate that comparison between symptom-sided anterior primary division (APD) size and opposite-sided APD size of the L5 spinal root along the ventral surface of the sacral ala on conventional computed tomography (CT) scans ( Fig.…”