title: Clinical Significance of High-intensity Zone for Discogenic Low Back Pain: A Review.
abstract: High-intensity zone (HIZ) was originally described as a high-intensity signal on T2-weighted magnetic resonance (MR) images, located in the posterior annulus fibrosus, clearly separated from the nucleus pulposus. Among symptomatic patients with low back pain, HIZ is present in 28-59% of cases. In morphologically abnormal discs, high sensitivity and specificity of 81% and 79%, respectively, were reported for HIZs and concordant pain during discography. In contrast, another report indicated low rates. Although most papers reported high sensitivity and specificity for this relationship, it remains controversial. Regarding the pathology of HIZs, inflammatory granulation tissues are found at sites showing HIZs. Such inflammatory tissues produce pro-inflammatory cytokines and mediators, which sensitize the nociceptors within the disc and cause pain. An effective treatment for this condition is yet to be established. Recently, minimally invasive surgery using percutaneous endoscopic discectomy (PED) under local anesthesia was introduced. After removal of the degenerated disc material, the HIZ is identified with the endoscope and then coagulated and modulated with a bipolar radio pulse. This technique is called thermal annuloplasty. In conclusion, HIZs is an important sign of painful intervertebral disc disruption, if identified precisely based on factors such as location and intensity.
authors.affiliation: Department of Orthopedics, Tokushima University.
authors.forename: Subash C
authors.initials: SC
authors.lastname: Jha
authors.forename: Kosaku
authors.initials: K
authors.lastname: Higashino
authors.forename: Toshinori
authors.initials: T
authors.lastname: Sakai
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Takata
authors.forename: Mitsunobu
authors.initials: M
authors.lastname: Abe
authors.forename: Kazuta
authors.initials: K
authors.lastname: Yamashita
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Morimoto
authors.forename: Shoji
authors.initials: S
authors.lastname: Fukuta
authors.forename: Akihiro
authors.initials: A
authors.lastname: Nagamachi
authors.forename: Koichi
authors.initials: K
authors.lastname: Sairyo
mesh_terms: D006801:Humans; D007405:Intervertebral Disc Displacement / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy; D017116:Low Back Pain / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000628:therapy; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging / Q000379:methods