A patient with a spinal cord lesion at T10 has loss of pain and temperature sensation on the contralateral side beginning 2 segments below the lesion, with preserved ipsilateral proprioception. Which tract is damaged?

• A Contralateral lateral spinothalamic tract ✓
• B Ipsilateral posterior column (dorsal column — medial lemniscus pathway)
• C Contralateral anterior corticospinal tract
• D Ipsilateral lateral spinothalamic tract (anterolateral system)

Explanation

Pain and temperature fibres (first-order neurons) enter the spinal cord ipsilaterally, ascend 1–2 segments in Lissauer's tract, then synapse in the dorsal horn (Rexed laminae I, II, V). Second-order neurons immediately decussate via the anterior commissure and ascend in the contralateral anterolateral (lateral spinothalamic) tract. Therefore, a unilateral lesion of the lateral spinothalamic tract causes contralateral pain/temperature loss beginning 2 segments below the level of the lesion (accounting for the ascent in Lissauer's tract before decussation). The preserved ipsilateral proprioception confirms the posterior column is intact on that side.

Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.