Utility of Ultrasound-Based Dynamic Assessment in Physical Therapy for Far-Lateral Lumbar Disc Herniation: A Case Report.

Far-lateral lumbar disc herniation is a relatively uncommon condition for which conservative treatment is generally prioritized; however, patients often present with severe radicular pain or motor deficits. This report describes the case of a woman in her 50s with a left L4/5 far-lateral disc herniation, who presented with persistent anterior thigh pain. Although magnetic resonance imaging (MRI) clearly demonstrated the herniated fragment, dynamic ultrasonography revealed reduced flexibility and impaired gliding among the herniated fragment, the psoas major muscle, and the L4 spinal nerve. Based on these findings, manual and targeted therapeutic exercises were performed on the affected regions. Following these interventions, the patient's anterior thigh pain during walking resolved, and neurological findings associated with L4 radiculopathy, including muscle weakness, sensory disturbance, and abnormal deep tendon reflexes, improved. A follow-up MRI at six months showed no reduction in the size of the herniation; however, no symptom recurrence was observed for up to one year. This case suggests that clinical improvement may occur even without morphological changes in the herniated disc, potentially through functional restoration of the nerve and surrounding tissues. Dynamic ultrasonography appears useful for identifying functional impairments and guiding treatment.