Significance of High-Intensity Zones in Lumbar Discs: A Correlation with Endoscopic Findings

Background and Study Aims: The high-intensity zone (HIZ) in a lumbar intervertebral disc on T2-weighted magnetic resonance images has been associated with discogenic low back pain. However, its clinical significance remains uncertain. Histological studies reveal inflammatory changes surrounding the HIZ, suggesting a potential link to disc degeneration. Recent advancements in full-endoscopic spine surgery (FESS) have enabled more detailed intradiscal observations. The purpose of this study is to examine the characteristics of endoscopic findings in the HIZ. Material and Methods: Eighty-six patients who underwent FESS between January 2020 and August 2022 were investigated. We defined intradiscal bleeding and/or inflammation as “red annulus fibrosus” (RAF) and compared its occurrence between patients with HIZ and without HIZ. In 45 patients with HIZ, the ratio of the signal intensity of the HIZ to that of cerebrospinal fluid (the HIZ/CSF ratio) was compared according to RAF status. Results: RAF was observed in 54.7% of all patients, with a higher prevalence in those with an HIZ (73.3% vs. 34.1%, p0.48 on preoperative magnetic resonance images may predict intradiscal bleeding.