A case-control study using magnetic resonance imaging and plain radiography to evaluate whether a family history of lumbar disc herniation is a risk factor for disc degeneration.
To evaluate the significance of a family history of operated lumbar disc herniation in the development of lumbar disc degeneration and lumbar disc herniation.
There are only a few epidemiologic studies indicating that a family history of intervertebral disc herniation is a risk factor for juvenile disc herniation. Recently, similarities in degenerative findings of the lumbar spine between identical twins have been reported.
In the case group, 24 patients who were the immediate relatives of patients who had undergone surgery for disc herniation and who presented or had a history of low back pain and/or unilateral leg pain were included. Control individuals included 72 age- and gender-matched outpatients who reported low back pain and/or leg pain without a family history of operated disc herniation. The incidence, level, and topographic location of disc herniation/diffuse bulge; the incidence and grade of disc degeneration observed on magnetic resonance images; and degenerative changes suggesting disc degeneration observed on plain radiographs were compared between the relatives of patients with disc herniation (cases) and the controls.
The incidence of disc degeneration at L4-L5 and L5-S1 in cases (L4-L5, 18/24; L5-S1, 18/24) and controls (L4-L5, 45/72; L5-S1, 43/72) was similarly high. However, the grade of disc degeneration according to magnetic resonance imaging signal intensity on the T2-weighted sagittal image using Schneiderman's four-grade classification was significantly more severe in cases (L4-L5: Grade 1, 6/24; Grade 2, 4/24; Grade 3, 13/ 24; Grade 4, 1/24; L5-S1: Grade 1, 6/24; Grade 2: 3/24, Grade 3: 12/24, Grade 4: 3/24) than in controls (L4-L5: Grade 1, 27/72; Grade 2, 24/72; Grade 3, 20/72; Grade 4, 1/72; P = 0.034; L5-S1: Grade 1, 29/72; Grade 2, 23/72; Grade 3, 13/72; Grade 4, 7/72; P = 0.023; Mann-Whitney U test). The incidence of disc herniation/diffuse bulge at L4-L5 (16/24) and L5-S1 (11/24) in cases was higher than that in controls (L4-L5, 33/72; P = 0.07; L5-S1, 17/ 72; P = 0.04; chi-square test).
The current study provided evidence that a family history of operated lumbar disc herniation has a significant implication in lumbar degenerative disc disease. There may be a genetic factor in the development of lumbar disc herniation as an expression of disc degeneration.