Clinical Significance of Nerve Root Enhancement in Contrast-Enhanced MR Imaging of the Postoperative Lumbar Spine

PURPOSE: To determine the significance of nerve root contrast enhancement in patients with residual or recurrent symptomatic postoperative lumbar spine. MATERIALS AND METHODS: Eighty-eight patients with 116 postoperative lumbar disc lesions causing radiating back pain underwent enhanced MR imaging. Intradural nerve root enhancement was quantified by pixel measurement, and affected nerve roots were compared before and after contrast administration. Extradural nerve root enhancement was assessed visually, and nerve root enhancement and clinical symptoms were correlated. Associated lesions such as recurrent disc herniation, scar tissue, nerve root thickening and nerve root displacement were also evaluated. RESULTS: Of 26 cases(22.4%) involving intradural nerve root enhancement, 22 (84.6%) showed significant clinical symptoms (p=0.002). and of 59 (50.9%) demonstrating extradural enhancement, clinical symptoms showed significant correlation in 47 (79.7%) (p=0.001). Nerve root enhancement, including eleven cases where this was both intra-and extradural, showed highly significant association with clinical symptoms in 74 of the 116 cases (63.8%) (p=0.000). Among 33 cases (28.4%) of recurrent disc herniation, nerve root enhancement was observed in 28 (84.8%) and in 24 of these 28 (85.7%), significant correlation with clinical symptoms was observed (p=0.000). Where epidural fibrosis was present, correlation between nerve root enhancement and clinical symptoms was not significant (p>0.05). Nerve root thickening and displaced nerve root were, however, significantly associated with symptoms(87.2% and 88.6%, respectively). CONCLUSION: In patients with postoperative lumbar spine, the association between nerve root enhancement revealed by MRI and clinical symptoms was highly significant.

MR Imaging of Traumatic Brachial Plexus Injury

PURPOSE: The aim of our study was to evaluate the usefulness of MR imaging in cases of traumatic brachial plexus injury. MATERIALS AND METHODS: We evaluated 25 patients with traumatic brachial plexus injury as seen on MR images prior to surgical exploration and repair. MR images were retrospectively evaluated for nerve root avulsion and pseudomeningocele, and postganglionic lesions. Results were correlated with final diagnosis after surgical exploration . RESULTS: One hundred and four of 125 root levels (83%) were adequately imaged. Neve root avulsion was shown at 28 levels(54%). Avulsion with or without pseudomeningocele was seen at 37 levels(71%)(80% sensitivity, 91% specificity). The presence of ten of 12 postganglionic lesions (83%) was revealed by MR imaging. CONCLUSION: MR imaging is valuable for revealing preganglionic nerve root avulsion in patients with traumatic brachial plexus injury or postganglionic lesions.

MR Imaging of Traumatic Brachial Plexus Injury

PURPOSE: The aim of our study was to evaluate the usefulness of MR imaging in cases of traumatic brachial plexus injury. MATERIALS AND METHODS: We evaluated 25 patients with traumatic brachial plexus injury as seen on MR images prior to surgical exploration and repair. MR images were retrospectively evaluated for nerve root avulsion and pseudomeningocele, and postganglionic lesions. Results were correlated with final diagnosis after surgical exploration . RESULTS: One hundred and four of 125 root levels (83%) were adequately imaged. Neve root avulsion was shown at 28 levels(54%). Avulsion with or without pseudomeningocele was seen at 37 levels(71%)(80% sensitivity, 91% specificity). The presence of ten of 12 postganglionic lesions (83%) was revealed by MR imaging. CONCLUSION: MR imaging is valuable for revealing preganglionic nerve root avulsion in patients with traumatic brachial plexus injury or postganglionic lesions.

Redundant Nerve Roots of the Cauda Equina: MR Findings

PURPOSE: To evaluate MR findings of redundant nerve roots (RNR) of the cauda equina. MATERIALS AND METHODS: 17 patients with RNR were studied; eight were men and nine were women, and their ages ranged from 46 to 82 (mean63) years. Diagnoses were established on the basis of T2-weighted sagittal and coronal MRI, which showed a tortuous or coiled configuration of the nerve roots of the cauda equina. MR findings were reviewed for location, magnitude, and signal intensity of redundant nerve roots, and the relationship between magnitude of redundancy and severity of lumbar spinal canal stenosis (LSCS) was evaluated. RESULTS: In all 17 patients, MR showed moderate or severe LSCS caused by herniation or bulging of an intervertebral disc, osteophyte from the vertebral body or facet joint, thickening of the ligamentum flavum, degenerative spondylolisthesis, or a combination of these. T2-weighted sagittal and coronal MR images well clearly showed the location of RNR of the cauda equina; in 16 patients (94%), these were seen above the level of constriction of the spinal canal, and in one case, they were observed below the level of constriction. T2-weighted axial images showed the thecal sac filled with numerous nerve roots. The magnitude of RNR was mild in six cases (35%), moderate in five cases (30%), and severe in six cases (35%). Compared with normal nerve roots, the RNR signal on T2-weighted images was iso-intense. All patients with severe redundancy showed severe LSCS, but not all cases with severe LSCS showed severe redundancy. CONCLUSION: Redundant nerve roots of cauda equina were seen in relatively older patients with moderate or severe LSCS and T2-weighted MR images were accurate in identifying redundancy of nerve roots and evaluating their magnitude and location.