1920s, German pathologist Christian Georg Schmorl studied 10,000 spines. He described protrusions of disc material, including into the vertebral body and the spinal canal, as herniations which led to the term disc herniation becoming popular in the parts of Europe
1947: Inman and Saunders discovered pain fibers in the annulus ending the concept the disc was itself a painless structure
1960's - 1st use of chemonucleolysis, the injection of the enzyme chymopapain into the disc but over the next decade or two, reports of serious complications including anaphylactic shock and neurotoxicity diminished its popularity
1967: Yasargil - first use of an operating microscope in lumbar discectomy surgery
1968: concept of disc degeneration as a cause - Francis Murphey
Studies in the 1980s and 1990s began to elucidate the mechanisms of pain generation from disc herniations and increasingly identified strong genetic susceptibility to both disc herniation and degeneration
1975: 1st endoscopic discectomy - Hijikata and Yamagishi
rates of discectomy increased rapidly from 1979 to 1990
mid 1980's more ready availability of CT scans to aid diagnosis
1988, concomitant fusion with discectomy was termed “wholly unnecessary”
in the 1990's CT guided chemonucleolysis was developed and microdiscectomy was further refined
1996, microdiscectomy pioneer John A. McCulloch wrote, “long-term results of surgery are only slightly better than conservative measures and the natural history of lumbar disc herniation”
late 1990's more ready availability of MRI scans to better aid diagnosis and guide surgery indications
MRI rapidly became sensitive enough that “absence of a clear cut abnormality on an MRI is a contraindication to surgery”
MRI also detected high rates of asymptomatic disc herniations and thus the presence of these may not be causing the patient's symptoms