Quantifying nerve Compression: A Methodical approach to Calculating nerve occupancy within the foramen for diagnostic precision in lumbar foraminal stenosis

• 3D MRI quantified nerve occupancy in 800 patients with lumbar foraminal stenosis. • Nerve occupancy and symptom severity increase progressively from L1/L2 to L5/S1. • Higher occupancy scores correlate strongly with increased pain and disability. • L4/L5 and L5/S1 are identified as the most critical sites for clinical diagnosis. Foraminal neuropathy involves stenosis at the level of the foramen leading to nerve compression causing pain, sensory disturbances, and muscle weakness. It results from the narrowing of the neural foramen due to degenerative, traumatic, or congenital factors. Quantifying nerve occupancy within the foramen can illuminate potential compression issues and guide clinical decisions, particularly in lumbar foraminal stenosis (LFS). This six-year retrospective cohort study on 800 patients at NCC No. 2, Moscow, focused on quantifying nerve occupancy in the foramen using high-resolution MRI. Inclusion criteria included symptoms of nerve compression and prior spinal imaging. Advanced imaging software provided precise volumetric measurements of the foraminal spaces and nerves. The percentage of foramen occupied by the nerve was calculated to assess compression. The study found a progressive increase in nerve occupancy and symptom severity from L1/L2 to L5/S1 levels. High nerve occupancy percentages correlated with higher pain (VAS scores) and disability (ODI scores). L4/L5 and L5/S1 showed the most significant nerve compression and symptom severity, indicating critical sites for LFS diagnosis and treatment. This study advances understanding of lumbar foraminal stenosis by quantifying nerve occupancy. The findings highlight the importance of targeting lower lumbar levels in diagnosis and treatment, emphasizing the correlation between high nerve occupancy and symptom severity. This methodological approach enhances clinical precision and outcomes in managing foraminal stenosis.