How can Brown-Séquard syndrome be differentiated from anterior cord syndrome?

• A. Brown-Séquard: ipsilateral motor weakness and vibration/position loss with contralateral pain/temperature loss; anterior cord: bilateral motor weakness and pain/temperature loss with preserved vibration/position sense.
• B. Brown-Séquard: bilateral motor weakness; anterior cord: bilateral sensory loss only.
• C. Brown-Séquard: only dorsal column loss; anterior cord: only lateral corticospinal loss.
• D. Brown-Séquard: contralateral motor weakness; anterior cord: ipsilateral motor weakness with loss of vibration.

Answer: (A)

Pattern of tract involvement in spinal cord syndromes shows Brown-Séquard causes ipsilateral motor and dorsal-column loss with contralateral pain and temperature loss; anterior cord causes bilateral motor and bilateral pain/temperature loss with preserved vibration and position sense.

Brown-Séquard comes from a hemicord lesion. On the side of the lesion, the corticospinal tract is damaged, producing weakness or UMN-type signs that affect the same side below the level of the injury. The dorsal columns, which carry vibration and proprioception, are also damaged on that same side, so vibration/position sense is lost ipsilaterally. The spinothalamic tract, which carries pain and temperature, has already crossed early in the cord, so it transmits sensory information from the opposite side of the body; thus, pain and temperature loss appears on the opposite side beginning a couple of levels below the lesion.

Anterior cord syndrome results from loss of the anterior two-thirds of the cord, typically due to anterior spinal artery compromise. It damages the motor pathways and the spinothalamic tract bilaterally, causing bilateral weakness and bilateral pain/temperature loss below the lesion. The dorsal columns are spared, so vibration and proprioception are preserved.

That combination of ipsilateral motor and dorsal-column loss with contralateral pain/temperature loss is what makes this distinction the best match.