Abstract: Far-out syndrome (FOS) is a rare spinal disorder primarily caused by the compression of the L5 nerve root between the L5 transverse process and the sacral ala, leading to severe lower back pain, leg pain, and functional impairment. The underlying causes include osteophyte formation, pseudarthrosis, thickened lumbosacral ligaments, ligamentum flavum hypertrophy, intervertebral disc degeneration, and anatomical variations such as transitional vertebrae. Diagnosing FOS is challenging and requires a combination of imaging techniques (such as MRI and CT) and neurophysiological testing. For patients with mild to moderate symptoms, non-surgical treatments, including medications and physical therapy, may be effective. However, for those with severe symptoms or cases unresponsive to conservative treatment, minimally invasive surgery, such as unilateral biportal endoscopic decompression (UBE), is the preferred option. This article reviews the etiology, pathogenesis, diagnosis, and treatment of FOS and presents a case report of a 67-year-old female patient who successfully underwent UBE surgery, demonstrating the efficacy and potential of this technique.

Key words: Far-out syndrome,  ,  , UBE,  ,  ,  , Anatomical variation