Correlation between clinical features and magnetic resonance imaging findings in lumbar disc prolapse

BACKGROUND: Lumbar disc prolapse is one of the common causes of low back pain seen in the working population. There are contradictorty reports regarding the clinical significance of various magnetic resonance imaging (MRI) findings observed in these patients. The study was conducted to correlate the abnormalities observed on MRI and clinical features of lumbar disc prolapse. MATERIALS AND METHODS: 119 clinically diagnosed patients with lumbar disc prolapse were included in the study. Clinical evaluation included pain distribution, neurological symptoms and signs. MR evaluation included grades of disc degeneration, type of herniation, neural foramen compromise, nerve root compression, and miscellaneous findings. These MRI findings were tested for inter- and intraobserver variability. The MRI findings were then correlated with clinical symptoms and the level of disc prolapse as well as neurological signs and symptoms. Statistical analysis included the Kappa coefficient, Odd’s ratio, and logistic regression analysis. RESULTS: There were no significant inter- or intraobserver variations for most of MRI findings (Kappa value more than 0.5) except for type of disc herniation which showed a interobserver variation of 0.46 (Kappa value). The clinical level of pain distribution correlated well with the MRI level (Kappa 0.8), but not all disc bulges produced symptoms. Central bulges and disc protrusions with thecal sac compression were mostly asymptomatic, while centrolateral protrusions and extrusions with neural foramen compromise correlated well with the dermatomal distribution of pain. Root compression observed in MRI did not produce neurological symptoms or deficits in all patients but when deficits were present, they correlated well with the presence of root compression in MRI. Multiple level disc herniations with foramen compromise were strongly associated with the presence of neurological signs. CONCLUSIONS: The presence of centrolateral protrusion or extrusion with gross foramen compromise correlates with clinical signs and symptoms very well, while central bulges and disc protrusions correlate poorly with clinical signs and symptoms. The presence of neural foramen compromise is more important in determining the clinical signs and symptoms while type of disc herniation (bulge, protrusion, or extrusion) correlates poorly with clinical signs and symptoms.