Familial incidence of intervertebral disc herniation: An hypothesis suggesting that laminectomy and discectomy may be counterproductive

To determine (1) if familial and genetic factors play a role in the genesis of disc herniation, (2) the incidence of multiple disc herniations, (3) the incidence of disc reherniation in patients treated with standard laminectomy and discectomy, and (4) to construct a hypothesis that best explains all three. Summary Background Data: It is known that there is a substantial incidence of disc herniation in first order relatives of patients with herniated nucleus pulposa (HNP), that multiple disc herniations are not uncommon, and that disc reherniations and repeat operations after laminectomy and discectomy range from 5 to 37%. Also, there is a recent report of a genetic defect leading to defective cross-linkage of collagen strands in patients with HNP. Methods: Using the questionnaire method, a group of the author's patients with documented HNP treated with percutaneous laser disc decompression (PLDD) was surveyed as to the existence of known disc herniations among first order relatives. Analysis of the author's series of 621 patients with HNP disclosed the incidence of multiple disc herniations. A comprehensive literature search provided data on reherniations and reoperations following laminectomy and discectomy. Results: In 174 respondents, the number with first order relatives who had HNP was 74 (or 43%). This compares with the national incidence of HNP of 1.7%. The statistical significance yields a P = 0.0001. In the 621 patients with known HNP, the number who had more than one herniated disc was 235 (or 38%). In multiple reports in the literature, the incidence of reherniation after laminectomy and discectomy ranged from 5 to 37%. Conclusions: The simplest hypothesis explaining all of the above is that intervertebral disc herniation is due to an acute or subacute increase of intradiscal pressure acting against a congenitally weak anulus fibrosus and posterior longitudinal ligament, and therefore laminectomy and discectomy, by further weakening these structures, may be counterproductive.