Adjacent Double–Nerve Root Contributions in Unilateral Lumbar Radiculopathy

BACKGROUND AND PURPOSE: Image-guided selective nerve root block/steroid injection is commonly performed for lumbar radiculopathy. The purpose of this study was to evaluate the clinical/imaging characteristics and injection response of adjacent double-root contributions to unilateral lumbar radiculopathy in a typical interventional spine practice.

MATERIALS AND METHODS: In 132 of 350 patients (37.7%) with unilateral radiculopathy, adjacent double–nerve root block/steroid injection was performed on the basis of preprocedural clinical/imaging characteristics. Clinical presentation (pain pattern, VAS), response to injection, and imaging features of potential root compression/irritation (disk protrusion, subarticular/foraminal stenosis) were tabulated.

RESULTS: Clinically, a subset of patients with both L4+L5 and L5+S1 radiculopathy presented with proximal sciatica only in addition to those with typical L4, L5 or S1 radicular patterns. Preprocedural imaging demonstrated evidence of adjacent double-root abnormality in 56 of 79 (71%) patients without prior surgery (single-level disease, 32; 2-level disease, 24) and in all 53 patients with prior lumbar surgery (scar, 42; separate-level root abnormality, 13). Adjacent double-level replication of the patient's familiar pain was present in 82 of 132 (62%) patients, with single-root replication in 37 (28%) and no response in 13 (10%). Typical sciatica was encountered by injection at L4 (15%–33%), likely reflecting furcal nerve lumbar plexus contribution from L5. Sensations from each injected root usually replicated separate recognizable portions of the patient's radiculopathy, with marked or complete pain improvement reported in most patients.

CONCLUSIONS: Adjacent double-level contributions to lumbar radiculopathy are common, and clinical/imaging clues should be assessed to ensure optimum nerve root block/steroid injection treatment response.