Histological composition of lumbar disc herniations related to the type of herniation and to the age.

OBJECTIVES To compare the data for histologic composition of the herniated disc material between different types of disc herniations and between patients of different age. BACKGROUND Lots of studies have investigated the histologic composition of disc herniations. Few studies have examined the presence of granulation tissue related to the type of herniations and age of the subjects. METHODS 120 patients divided in to two age groups underwent MR imaging before microsurgical removal of the herniations. Disc herniations were divided in to two groups, non migrated and large migrated disc herniations. The histologic assessment of the herniated material is done by dividing the intercellular matrix into four types. The existence of areas of granulation tissue and hyaline cartilage is evaluated too. RESULTS The tissue composition showed significant differences between patients of different age. Areas of granulation tissue and neovascularisation are found in 12% of 64 protrusions and contained extrusions, and in 29% of 56 large migrated disc extrusions (p=0.029 ). In elderly patients the tissue composition changed with a significant decrease of prevailing nucleus pulposus composition in 7% of 60 (p=0.000) and a significant increase of prevailing fibrous tissue composition in 40% of 60 patients (p=0.000). Areas of granulation tissue and neovascularisation were found in 27% of 60 patients aged ≤ 50 and in 13% of 60 patients aged >50. CONCLUSIONS The tissue composition of the herniated material showed more expressed differences between subjects of different age. Granulation tissue and neovascularisation were more frequent findings in large migrated disc herniations and in patients aged 35 to 50 years (Fig. 8, Ref. 22).