Is Intervertebral Disc Degeneration a Compensatory Mechanism in Adult Tethered Cord Syndrome?

The purpose of the present study was to evaluate the influence of high nerve tension on lumbar disc degeneration and sagittal morphologies.

A total of 50 young and middle-aged patients (mean age 32.1 ± 7.4 years, 22 men and 28 women) who suffered from tethered cord syndrome (TCS) were retrospectively assessed by two observers. Demographic and radiological data were recorded, including lumbar disc degeneration, disc height index and lumbar spine angle, and were compared with 50 patients (mean age 29.7 ± 5.4 years, 22 men and 28 women) without spinal cord abnormalities. Statistical associations were assessed by student's t-test and chi-square test.

Our results showed patients with TCS had a significantly higher rate of lumbar disc degeneration in L1/2, L2/3, L4/5 and L5/S1 than in those without TCS (P < 0.05). Moreover, the rates of multilevel disc degeneration and severe disc degeneration in TCS group were significantly higher than those in control group (P < 0.01). The mean disc height index of L3/4 and L4/5 in TCS group was significantly lower than that in control group (P < 0.05). The mean lumbosacral angle of TCS patients was significantly higher than that of patients without TCS (38.4 ± 3.5°vs. 33.7 ± 5.9°, P < 0.01).

We found a certain correlation between TCS and lumbar disc degeneration and lumbosacral angle enlargement, suggesting that the spine reduces the high tension of the spinal cord through disc degeneration. Therefore, it is speculated that there is a "compromised regulation" mechanism in the body under the condition of neurological abnormalities.