• Woo Mok Byun, Sang Ho Ahn, and Myun-Whan Ahn.
• Department of Diagnostic Radiology, College of Medicine, Yeungnam University, Daemyungdong, Namku, Daegu, Korea. wmbyun@medical.yeungnam.ac.kr
• Spine. 2008 Oct 15;33(22):2440-3.

Study DesignRetrospective analysis of magnetic resonance imaging (MRI) and clinical findings about chemical radiculitis-associated anular tear in patients with radiculopathy.ObjectiveTo investigate MRI findings of the chemical radiculitis caused by anular tears and to determine whether chemical radiculitis detected by MRI is the cause of radiculopathy.Summary Of Background DataMany studies document that irritation of adjacent nerve roots by a chemical mediator of inflammation from the nucleus pulposus may result in radiculopathy. Computed tomography (CT) discography may be the best examination for diagnosing discogenic chemical radiculitis but is too invasive. A reliable imaging method for replacing invasive provocative CT discography and diagnosing chemical radiculitis is required.MethodsThe study population consisted of 12 patients with pain referred to leg(s) with or without low back pain who underwent lumbar spine MRI. All cases of our study demonstrated perianular enhancement caused by chemical radiculitis associated with anular tears. Patterns and locations of perianular enhancement adjacent to anular tears on MRI were assessed. MRI findings were compared with clinical symptoms and/or provocative transforaminal epidural injection (n = 6). For documentation of the relationship between perianular enhancement and radiculopathy, provocative CT discography was performed in 2 cases.ResultsPerianular enhancement associated with anular tears revealed thick linear patterns (2.5-7 mm thickness) along margins of anular tears on contrast enhanced axial T1-weighted images with fat suppression. Locations of perianular enhancement adjacent to anular tears were at foraminal (n = 6) and extraforaminal portions (n = 6). CT discography showed a leak of contrast from anular tear to the perianular regions. Pain reproduction at contrast leak level during discography showed concordant pain. There was an apparent correlation between perianular enhancement on MRI and clinical symptoms or provocative epidural nerve root injection in all cases.ConclusionThe perianular enhancement adjacent to anular tears on MRI may be relevant in the diagnosis of symptomatic chemical radiculitis.

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