Magnetic Resonance Imaging Classification Using the Three-Dimensional T2-weighted SPACE Method for Brachial Plexus Injury.

Abstract

Three-dimensional T2-weighted SPACE (3D-T2-SPACE) magnetic resonance imaging (MRI) has demonstrated diagnostic validity for detecting intravertebral injuries in traumatic brachial plexus injury (BPI). This study aimed to classify preganglionic injuries based on 3D-T2-SPACE findings. A total of 206 BPI patients underwent 3D-T2-SPACE MRI. Intravertebral structures, including the spinal cord, rootlets, nerve roots, dorsal root ganglions, and meningeal cysts, were evaluated using synchronized T2-coronal, transverse, and coronal-oblique images. Extravertebral lesions were assessed on T2-STIR images, evaluating root continuity, signal changes, edema, hypertrophy, and displacement. Intravertebral lesions were classified into five types: Type M (meningeal cyst), Type A (injury at the cord-rootlet junction), Type B (rootlet avulsion), Type C (partial rootlet injury), and Type N/D (no intravertebral injury or distal injury only). Meningeal cysts strongly indicated preganglionic injuries, whereas spinal edema and partial or total rootlet absence also were important indicators. Type C was subdivided into anterior rootlet-only injury and combined anterior-posterior partial injury. In 106 patients with total palsy, Type A was most frequent at C7, Type M at C8-T1, and Type N/D at C5. In particular, Type N/D, which allows nerve repair, was observed more frequently in the C5 root, and this classification was useful for selecting surgical methods. Extravertebral signs included root rupture, signal changes, edema, hypertrophy, and distal displacement. The 3D-T2-SPACE MRI allows detailed, noninvasive classification of preganglionic injuries in BPI, supporting accurate diagnosis and guiding selection of reconstructive procedures, such as nerve transfers without surgical diagnostic exploration of the brachial plexus. Diagnosis IIb.