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1935. MRI in Patients with Brachial Plexus Injury: Early versus Late Imaging
Authors * Denotes Presenting Author
  1. Alice Kim *; Virginia Commonwealth University
  2. Mohammad Gharavi; Virginia Commonwealth University
Objective:
The brachial plexus, formed by the union of ventral rami of C5-T1 nerve roots, is responsible for innervation of the upper extremities. Brachial plexus injury (BPI) due to trauma predominantly affects young and healthy individuals and can be debilitating. The type of BPI depends mainly on the location of nerve damage, which can be at the level of rootlets, roots, trunks, divisions and cords. Nerve root avulsion, particularly the preganglionic segment, will not repair spontaneously and requires surgical repair to regain function. Time of surgical intervention is a major prognostic factor and delays can lead to formation of nonfunctional neuromas at the injured nerve or fibrosis/degeneration of target muscles. Therefore, early identification of nerve root avulsion requiring repair is essential in managing patients with BPI. Detection of nerve root injury by CT myelography is possible after a few weeks when the hematoma resolves and the pseudo meningocele forms. However, MRI has the advantage of detecting injury even a few days after trauma. The purpose of our study was to compare the ability of early and late-performed MRI in detection of nerve root injury in patients with BPI.

Materials and Methods:
A total of 19 patients (mean age 30-years ranging between 9-63) were found from our electronic health records between 01/2009-01/2020. The included patients had positive MRI findings of traumatic BPI and subsequent completion of exploratory surgery and/or EMG/NCV studies. MRI scans were independently evaluated for radiological evidence of BPI by a board certified neuroradiologist and the results were compared with surgical and/or EMG/NCV reports. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of MRI for detection of preganglionic nerve root injury were calculated. The days elapsed between the date of trauma and acquisition of MRI were analyzed and sensitivity, specificity, PPV and NPV of early MRI (less than 15 days from trauma) and late MRI (15 or more days from trauma) were calculated separately.

Results:
The study included 19 patients with traumatic BPI and 31 separate non-contrast MRI scans of the cervical spine/brachial plexus. The most and least frequent injured nerve roots were C5(87.1%) and C7(38.7%), respectively. A total of 15 MRI scans were acquired early and 16 MRI scans were acquired later with a mean of 3 and 94 days, respectively. The sensitivity, specificity, PPV and NPV of MRI for detection of nerve root injury were 79.2%, 57.1%, 86.4%, and 44.4% respectively. The sensitivity and specificity of MRI were 76.9% and 50% in early scans and 81.8% and 60% in late scans. No significant difference between sensitivity and specificity of early vs. late MRI was identified.

Conclusion:
Our observation shows an overall high sensitivity and specificity of MRI in the detection of preganglionic brachial plexus nerve root injury even a few days after trauma. This advocates for performing an early MRI in suspected BPI patients and identification of patients who would benefit from surgical intervention rather than waiting and preforming a later scan.