FAMILIAL PREDISPOSITION FOR LUMBAR DEGENERATIVE DISC DISEASE - A CASE-CONTROL STUDY

Study Design. A case-control study using magnetic resonance imaging an d plain radiography to evaluate whether a family history of lumbar dis c herniation is a risk factor for disc degeneration. Objectives. To ev aluate the significance of a family history of operated lumbar disc he rniation in the development of lumbar disc degeneration and lumbar dis c herniation. Summary of Background Data. There are only a few epidemi ologic studies indicating that a family history of intervertebral disc herniation is a risk factor for juvenile disc herniation. Recently, s imilarities in degenerative findings of the lumbar spine between ident ical twins have been reported. Methods. In the case group, 24 patients who were the immediate relatives of patients who had undergone surger y for disc herniation acid who presented or had a history of low back pain and/or unilateral leg pain were included. Control individuals inc luded 72 age- and gender-matched outpatients who reported low back pai n and/or leg pain without a family history of operated disc herniation . The incidence, level, and topographic location of disc herniation/di ffuse bulge; the incidence and grade of disc degeneration observed on magnetic resonance images; and degenerative changes Suggesting disc de generation observed on plain radiographs were compared between the rel atives of patients with disc herniation (cases) and the controls. Resu lts. The incidence of disc degeneration at L4-L5 and L5-S1 in cases (L 4-L5, 18/24; L5-S1, 18/24) and controls (L4-L5, 45/72; L5-S1,43/72) wa s similarly high. However, the grade of disc degeneration according to magnetic resonance imaging signal intensity on the T2-weighted sagitt al image using Schneiderman's four-grade classification was significan tly 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-Whi tney U test). The incidence of disc herniation/difuse 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 tests). Concl usion. The current study provided evidence that a family history of op erated lumbar disc herniation has a significant implication in lumber degenerative disc disease. There may be a genetic factor in the develo pment of lumbar disc herniation as an expression of disc degeneration.