Brown-Séquard syndrome caused by cervical disc herniation with associated Horner's syndrome: a case report.

Brown-Séquard Syndrome (BSS) is a rare incomplete spinal cord injury. Its association with Horner syndrome (HS) secondary to cervical disc herniation is exceptionally rare, presenting a significant diagnostic and therapeutic challenge. A 37-year-old man presented with neck pain, right shoulder pain, and progressive right upper limb motor weakness. The patient also exhibited gait disturbances and ipsilateral facial signs of HS, including ptosis, miosis, and anhidrosis. Cervical magnetic resonance imaging revealed a large right-sided disc extrusion at the C3-4 level, which resulted in severe spinal cord compression. The patient underwent anterior cervical discectomy and fusion. The extruded disc fragment was completely removed. After surgery, his right upper limb motor strength fully recovered and the gait disturbance resolved. Signs of HS also resolved completely. This case highlights that cervical disc herniation, although uncommon, should be considered in the differential diagnosis of BSS, particularly when associated with HS.