Acute Cauda Equina Syndrome With Clinicoradiological Discordance Treated via Unilateral Biportal Endoscopy: A Case Report.

Cauda equina syndrome (CES) is a severe neurosurgical emergency typically caused by lumbar disc herniation. Its diverse clinical manifestations include radiating lower limb pain, numbness, decreased muscle strength, saddle anesthesia or reduced perineal sensation, bladder and bowel dysfunction (such as urinary retention and constipation), and sexual dysfunction. Early diagnosis and timely decompression surgery are crucial for improving prognosis. Currently, literature reporting the use of unilateral biportal endoscopy (UBE) for treating radiologically atypical CES remains scarce. We report a 21-year-old male patient who presented with the sudden onset of left lower extremity pain and numbness resulting in an antalgic posture, accompanied by acute urinary retention and constipation. Physical examination confirmed cauda equina syndrome with retention (CES-R). Although lumbar magnetic resonance imaging (MRI) revealed a paracentral recess lesion with less central canal compromise than expected for the severity of the symptoms (Schizas Grade A), the patient underwent urgent UBE surgery due to the acute clinical presentation. Postoperatively, the antalgic posture resolved immediately, and the urinary retention and constipation completely resolved within 24 h. Six months postoperatively, the patient demonstrated complete neurological recovery and significantly improved quality of life. Ultimately, this case demonstrates that UBE represents a safe, feasible, and effective alternative option for emergency decompression in acute CES characterized by clinicoradiological discordance, allowing for thorough lateral recess exploration and motion preservation that leads to a favorable neurological recovery.