Determination of the Mean Midsagittal Lumbar Canal Diameter of Asymptomatic Adults in Enugu, Nigeria, Using Magnetic Resonance Imaging

Abstract

Background: The diagnosis of lumbar canal stenosis and ectasia is based on the dimensions of the lumbar canal. Midsagittal dimension of a lumbar canal that is <12 mm is considered canal stenosis. These dimensions vary with race. The data available for our population are osteometric studies of the anteroposterior diameter of the vertebral canal. This does not take the soft-tissue components of the lumbar canal into consideration. Magnetic resonance imaging (MRI) is the preferred imaging modality of the lumbar region. There is no large-scale MRI-based study of the lumbar MSD for the South-Eastern Nigerian population. Aim: This study aims to obtain baseline mean MSD for the South-Eastern Nigerian population. Materials and Methods: A prospective cross-sectional study was done on people aged between 21 and 50 years who do not have clinical symptoms that are referable to the spine. This was done with a 0.35 Tesla machine. The midsagittal canal diameters were taken at both mid-vertebral and intervertebral disc levels. Results: Two hundred and forty-three participants who met the criteria had T1-weighted images of their lumbar spine. The mean MSD value at the disc levels was as follows: L1/2 14.13, L2/3 13.90, L3/4 13.87, L4/5 13.95, L5/S1 14.68. The mean value at the mid-vertebral levels was L1 14.18, L2 13.56, L3 13.54, L4 13.81, L5 13.62. Conclusion: The baseline MSD is between 13.54 mm and 14.18 mm. The L3 bony canal has the smallest dimension. The values are less than previously published osteometric-based data in Nigeria.

Keywords

• adults
• asymptomatic
• canal
• diameter
• lumbar
• midsagittal