Electrodiagnostic characteristics of upper lumbar stenosis: Discrepancy between neurological and structural levels

Background Radiculopathies caused by spinal stenosis in the upper lumbar spinal canal (L1/2, L2/3, L3/4) have not been comprehensively investigated. Methods This retrospective study reviewed 14 patients from a tertiary hospital outpatient clinic. The inclusion criteria were upper lumbar stenosis seen on MRI and radiculopathies with active denervation confirmed on electromyography. Patients with any other conditions that could explain the clinical or electrophysiological manifestations were excluded. Results Neurogenic findings were predominantly observed in L5 or S1 myotomes on electromyography. Abnormal spontaneous activity was observed in distal muscles in all patients and in proximal muscles in eight patients. Axonal involvement was bilateral in 10 patients and unilaterally in 4 patients. MRI showed redundant nerve roots in 13 patients with chronic reinnervation on electromyography. Conclusions Upper lumbar spinal stenosis usually causes L5 or S1 radiculopathies with diverse patterns. This discrepancy may cause diagnostic confusion.