Which syndrome results from a hemisection of the spinal cord, causing motor and light touch loss on the same side and pain loss on the opposite side?

• A. Anterior cord syndrome
• B. Brown-Sequard syndrome
• C. Central cord syndrome
• D. Spinal shock

Answer: (B)

Brown-Sequard syndrome arises from a hemisection of the spinal cord. On the injured side, the corticospinal tract is disrupted, producing ipsilateral motor weakness or paralysis below the lesion. The dorsal columns are also affected on that same side, causing ipsilateral loss of fine touch, vibration, and proprioception. The spinothalamic tract, which carries pain and temperature, crosses to the opposite side within a couple of levels after entry; once the cord is hemisected, this tract is interrupted on the opposite side, leading to contralateral loss of pain and temperature below the level of injury. This combination—ipsilateral motor and light touch loss with contralateral pain loss—is characteristic of Brown-Sequard syndrome.