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Differentiation of aging and degenerative changes in the spine. 2008

General Spine

Victor Haughton, MD,

Scientific Paper

Purpose

Imaging findings in the lumbar intervertebral disks of older individuals may represent either aging changes or degeneration. Aging and degenerative changes are often not discriminated and referred to as "normal age-related degenerative changes. The purpose of this review is to attempt to classify imaging changes in the disk due solely to aging or to degeneration.

Methods & Materials

Cryomicrotome sections and MR images in cadaver spine material were reviewed and the disks classified as aging or degenerative. If a disk had features found in the majority disks of individuals with a similar age, the disk was classified as "aging". If the disk had obviously reduced height or reduced signal intensity compared to the normal for that age, it was classified as degenerative.

Results

With aging, the disk cartilage appears progressively less homogeneous. The small decreases in water content in the disk with aging result in a gradual decrease in signal intensity in T2 weighted images but without the loss of a high signal intensity region in the disk. Concentric and transverse tears were identified in a majority of these disks.

Degenerative disks, that is disks with reduced height or signal had a feature not found in aging disks: a radial tear of the annulus fibrosus. MR shows a variety of findings in intervertebral disks with a radial tear. Some had a "high intensity zone" ("HIZ") correlating with the presence of a radial tear. Thirty percent of radial tears. Lacking mucoid material, are not shown on T2 weighted images. Generally diminished signal intensity in a disk or a "dark disk" on T2 weighted images indicates the presence of a radial tear of the annulus fibrosus, whether or not it is demonstrated by MR.

Conclusion

By the criteria employed, aging intervertebral disks are characterized by little or no loss of height or signal intensity. Transverse and concentric tears may be present. Degeneration is characterized by a radial tear of the annulus fibrosus, loss of a high signal intenisty region, loss of height and deformity of the peripheral annulus fibrosus, not found in aging disks.