A motorcyclist is involved in a high-speed collision and is found to have avulsion of C8 and T1 nerve roots. Which unique physical sign would indicate a root avulsion rather than a more distal traction lesion?
- A Loss of triceps reflex
- B Ipsilateral Horner's syndrome (ptosis, miosis, anhydrosis) ✓
- C Winging of scapula
- D Loss of small muscle function in the hand
Explanation
Ipsilateral Horner's syndrome (Claude Bernard-Horner) is a hallmark of C8–T1 root avulsion. The preganglionic sympathetic fibres to the head travel with the T1 anterior ramus before entering the sympathetic chain; avulsion at the root level severs these fibres centrally, causing ptosis, miosis, and anhidrosis. A distal traction injury (postganglionic) at the brachial plexus level may spare Horner's because the sympathetic chain itself is intact. Loss of small hand muscles and triceps reflex occur in both avulsion and distal lesions at C8–T1. Winging of scapula is a C5–C7 / long thoracic nerve sign.
Reference: BD Chaurasia's Human Anatomy, 8th ed.
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Written and medically reviewed by the StethoPrep medical team.