If a patient has a lesion that causes loss of proprioception and vibration but preserved pain and temperature, which tract is most likely affected?

• A. Dorsal columns
• B. Spinothalamic tract
• C. Corticospinal tract
• D. Anterior spinal artery

Answer: (A)

Proprioception and vibration travel through the dorsal columns (posterior columns) of the spinal cord. A lesion in this pathway disrupts those modalities while leaving pain and temperature intact, because pain and temperature are carried by the spinothalamic tract, located in a different system. Clinically, this pattern points to damage of the dorsal column–medial lemniscus pathway. The corticospinal tract controls motor function, so a lesion there would produce weakness rather than sensory loss. Anterior spinal artery damage would typically affect the anterior two-thirds of the cord, causing loss of pain and temperature and often motor deficits, not selective loss of proprioception and vibration.