Unilateral to Bilateral Lumbosacral Plexopathy After Radiation Therapy: A Case Report

Radiation therapy (RT) has been one of the standard treatments for prostate cancer; however, its potential impact on nearby neural structures, such as the lumbosacral plexus (LSP), is often overlooked. The lack of contouring in treatment plans has led to unintended consequences. Radiation-induced lumbosacral plexopathy (RILSP) is a rare but serious complication that presents with progressive lower extremity sensory changes and weakness, mimicking radiculopathy. We report the case of a 66-year-old male who developed bilateral lower extremity neurological deficits post-pelvic radiation for prostate cancer. Radiographically, no compressive lesions were found, and the Electromyography (EMG) revealed involvement of nerves inconsistent with radiculopathy. This led to the diagnosis of RILSP. This case highlights the importance of recognition of RILSP in contrast to radiculopathy in patients with unexplained neurological symptoms after pelvic RT. This highlights the importance of incorporating the LSP as an organ at risk while planning for RT and reviewing retrospectively the dosimetry. It also emphasizes the need for improved contouring of LSP in radiation planning to minimize adverse effects. This sentiment is reflected in the literature, along with the consensus that more research is needed to address the true rate of RILSP.