Authors: Ahilraj Siva, Marc Price-Morris, Shayan Khimji.
Background: We present a case of an atypical fluoroscopic neurogram pattern for complex chronic axial low back pain during a lumbar dorsal root ganglia (DRG) pulsed radiofrequency stimulation.
Case Report: A 70 year old female with a history of complex chronic axial low back pain with radicular leg pain. Initially her pain was described as intermittent, burning, and sharp with an intensity of 9/10 on the Numeric Rating Scale (NRS). This pain worsens with ambulation, lumbar extension, turning, weight bearing and spinal loading activities. MRI imaging noted lumbar anterolisthesis, moderate to severe central spinal stenosis, and mild bilateral neural foraminal space narrowing. From these findings, her pain is likely secondary to components of sacroiliac (SI) joint dysfunction, lumbar facetogenic pain, lumbar radiculitis, and spinal stenosis with neurogenic claudication. A multimodal and multidisciplinary rehabilitation approach involving minimally invasive interventional procedures and medication management was implemented with varying pain relief. She responded to L5 transforaminal epidural nerve root injections, SI joint prolotherapy, and sacral lateral branch radiofrequency ablation. She completed bilateral L5 DRG pulsed radiofrequency stimulation, which did not provide radicular pain relief. We performed a unilateral L4 DRG pulsed radiofrequency stimulation, which revealed an atypical L4 fluoroscopic neurogram pattern. At the 3 month follow up she reported the pain severity to have a NRS between 7-8/10. At 4 months, the pain severity was reported to have a NRS between 4-6/10 with subjective improvements with her daily activities.
Conclusion: In a normal transforaminal epidural fluoroscopic neurogram, the anteroposterior view should demonstrate contrast spread medially around the pedicle and laterally following the exiting nerve root. In the case of this patient the combined anatomical presentation of anterolisthesis, central spinal canal stenosis, and circumferential disc bulging are all potential reasons for insufficient contrast passage resulting in the atypical neurogram.