Syringomyelia classically produces a 'cape-like' distribution of pain and temperature loss with preserved proprioception. This pattern results from damage to which fibres in the spinal cord?
- A Descending lateral corticospinal tract fibres in the lateral funiculus
- B Ascending dorsal column fibres
- C Decussating spinothalamic fibres crossing through the anterior white commissure ✓
- D Lateral horn neurons (autonomic preganglionic cells)
Explanation
A syrinx (fluid-filled cavity) in the central spinal cord preferentially damages the decussating spinothalamic fibres as they cross through the anterior white commissure before ascending in the lateral spinothalamic tract. Since these fibres carry pain and temperature from bilateral upper limbs and upper trunk, their destruction produces bilateral loss of pain and temperature in a shawl/cape distribution over the shoulders and arms, while the dorsal columns (proprioception, vibration) are spared — hence the dissociated sensory loss. As the syrinx expands laterally it may affect the corticospinal tract (weakness) and the lateral horn (Horner's syndrome).
Reference: BD Chaurasia's Human Anatomy, 8th ed.
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Written and medically reviewed by the StethoPrep medical team.