Syringomyelia preferentially damages fibres crossing in the anterior white commissure of the spinal cord. Which specific tracts are affected earliest?
- A Crossing spinothalamic fibres (pain and temperature) ✓
- B Dorsal column-medial lemniscal fibres
- C Lateral corticospinal tract fibres
- D Anterior corticospinal tract fibres
Correct answer: A. Crossing spinothalamic fibres (pain and temperature)
Explanation
In syringomyelia, the expanding central canal cavity first compresses the decussating spinothalamic fibres in the anterior white commissure, producing the classic 'cape' or 'suspended' dissociated sensory loss — loss of pain and temperature in a shawl distribution with preserved touch and proprioception (dorsal columns). Dorsal column fibres ascend ipsilaterally and are not in the anterior commissure. Corticospinal fibres are in the lateral white matter and affected only late.
Reference: BD Chaurasia's Human Anatomy, 8th ed.
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Written and medically reviewed by the StethoPrep medical team.