Patterns of lumbar disc degeneration are different in degenerative disc disease and disc prolapse magnetic resonance imaging analysis of 224 patients

Rishi M Kanna, MS MRCS FNB
The Spine Journal: Available online 16 November 2013: In Press

Abstract
Background Context
Existing research works on lumbar disc degeneration have remained inconclusive regarding its etiology, pathogenesis, symptomatology, prevention and management. Degenerative disc disease (DDD) and disc prolapse (DP) are common diseases affecting the lumbar discs. Though they manifest clinically differently, existing studies on disc degeneration have included patients with both these features leading to wide variations in observations. The possible relationship or disaffect between DDD and DP is not fully evaluated.

Purpose
To analyse the patterns of lumbar disc degeneration in patients with chronic back pain and DDD, and those with acute disc prolapse (DP).

Study Design
prospective, MRI based radiological study.

Methods
Two groups of patients (age: 20-50 years) were prospectively studied. Group 1 included patients requiring a single level microdiscectomy for acute DP. Group 2 included patients with chronic low back pain and DDD. Discs were assessed by MRI through Pfirmann’s grading, Schmorl’s nodes, Modic changes and the Total end plate damage score for all the five lumbar discs.

Results
Group 1 (DP) had 91 patients and Group 2 (DD) had 133 patients. DP and DDD patients differed significantly in the number, extent and severity of degeneration. DDD patients had a significantly higher number of degenerated discs than DP patients (p < .000). The incidence of multilevel and Pan lumbar degeneration was also significantly higher in DDD group. The pattern of degeneration also differed in both the groups. DDD patients had predominant upper lumbar involvement whereas DP patients had mainly lower lumbar degeneration. Modic changes were more common in DP patients, especially at the prolapsed level. Modic changes were present in 37% of prolapsed levels compared to 9.9% of normal discs (p < .00). TEPS had a positive correlation with disc degeneration in both the groups. Further the mean TEPS score at prolapsed level was also significantly higher.

Conclusion
The results suggest that patients with disc prolapse, and back pain with DDD are clinically and radiologically different groups of patients with varying patterns, severity and extent of disc degeneration. This is the first study in literature to compare and identify significant differences in these two commonly encountered patient groups. In patients with single level DP, majority of the other discs are non-degenerate, the lower lumbar spine is predominantly involved and the end plate damage is higher. Patients with back pain and DDD have larger number of degenerate discs, early multi-level degeneration and predominant upper lumbar degeneration. The knowledge that these two groups of patients are different clinically and radiologically, is critical for our improved understanding of the disease and for future studies on disc degeneration and disc prolapse.

Journal Abstract:  http://www.sciencedirect.com/science/article/pii/S1529943013016471