Significance of perianular enhancement associated with anular tears on magnetic resonance imagings in diagnosis of radiculopathy.

STUDY

DESIGN

Retrospective analysis of magnetic resonance imaging (MRI) and clinical findings about chemical radiculitis-associated anular tear in patients with radiculopathy.

OBJECTIVE

To 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 DATA: Many 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.

METHODS

The 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.

RESULTS

Perianular 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.

CONCLUSION

The perianular enhancement adjacent to anular tears on MRI may be relevant in the diagnosis of symptomatic chemical radiculitis.