The active elevation lag sign and the triangle sign: New clinical signs of trapezius palsy
Background: Spinal accessory nerve palsy causing trapezius dysfunction can lead to significant disability. Diagnosis is frequently delayed or inaccurate leading to inappropriate treatment. Methods: We describe new clinical signs for trapezius muscle dysfunction and palsy, and accessory nerve palsy, viz. The Active Elevation Lag sign and the Triangle sign. These signs help to differentiate between scapular winging due to trapezius dysfunction and that due to serratus anterior dysfunction. The signs are based on the principle that the deficiency of trapezius function causes an 'active forward elevation lag' with compensatory spinal hyperextension, and lead to the Triangle sign in the prone position, whereas no such lag is found in patients with pure serratus anterior dysfunction. Video recordings of clinical examination of 10 patients, 5 with isolated spinal accessory nerve palsy and 5 with long thoracic nerve palsy (confirmed by neurophysiology studies) were blinded and reviewed by 8 assessors.
Results: Of the total of 80 readings, 100% sensitivity and 95% specificity were found, in correlation with the diagnosis confirmed by neurophysiology studies, with positive predictive value of 95% and negative predictive value of 100%. Conclusion: These are simple clinical signs, easy to perform which are useful in diagnosing trapezius weakness in clinical practice.
Level of evidence: Level 2-1; Evidence obtained from well-designed controlled trials without randomization.
Keywords: Accessory nerve palsy; scapular winging; triangle sign; elevation-lag sign; trapezius dysfunction; serratus anterior dysfunction