Percutaneous Radiofrequency Ablation of Spinal Osteoid Osteomas Using a Targeted Navigational Bipolar Electrode System

An 18-year-old woman with lumbar spine hypomobility and low back pain. This case highlights the advantages of articulating the distal electrode tip for challenging-to-access nidus location as well as real-time monitoring of ablation zone volume, considering the proximity to neural elements. Sagittal unenhanced CT (A) and sagittal T1-weighted fat-saturated gadolinium-enhanced MR imaging (B) show a partly mineralized nidus in the posterior L2 vertebral body abutting the posterior wall cortex and resulting in cortical thinning and slight convexity toward the central canal. Note surrounding reactive medullary sclerosis and reactive osteitis (A and B, small arrows) as well as partial obliteration of the anterior epidural space (B, large arrow). Prone maximum-intensity-projection axial CT (C) and sagittal CT (D) during radiofrequency ablation show articulation of the distal tip of the navigational RF electrode placed via a lateral transpedicular approach for optimal access to the nidus in the central posterior vertebral body, which would be challenging to reach with traditional straight RF electrodes. Note the epidural injection of carbon dioxide and 5% dextrose in water (diluted in iodinated contrast) for active thermal protection (C and D, arrows). An 18-ga spinal needle is placed in the neuroforamen (C) for passive thermal protection (temperature monitoring). Somatosensory and motor-evoked potential monitoring was performed during the procedure.