Tsuchida R, Sumitani M, Azuma K, et al. - As it is difficult to diagnose lumbar adhesive arachnoiditis, a debilitating neuropathic condition, owing to lack of definitive diagnostic criteria, researchers examined if valuable diagnostic criteria could be established using MRI by focusing on the intrathecal mobility of nerve roots. In this study, participants comprising 17 patients with a high risk for lumbar adhesive arachnoiditis and 18 no-risk patients with chronic low back pain and/or leg pain underwent MRI in both the supine and prone positions. Patients with a high risk for lumbar adhesive arachnoiditis vs the no-risk patients exhibited relatively larger low-intensity area in the dorsal half of the dural sac. In the no-risk group, they identified significantly higher proportion of the low-intensity area in the dorsal half in the supine position than that observed in the prone position at all lumbar levels. However, in the high-risk group, no significant differences in the proportions in the dorsal half of the dural sac between the supine and prone positions were evident at some levels. These findings suggest that nerve roots lose their potential to migrate in the dural sac in the gravitational force direction on MRI among patients with a known risk for lumbar adhesive arachnoiditis.