Peripheral Neuroanatomy, Human Anatomy, USMLE Step 1 - Full Vignette with Extended Explanations

A 48-year-old woman develops sudden shoulder droop, difficulty abducting her right arm, and scapular asymmetry following an open excisional biopsy of a posterior cervical lymph node. How do these specific symptoms and exam findings guide your approach to postoperative complications affecting shoulder movement? What anatomical considerations and clinical clues are most important in evaluating new deficits after neck surgery?

VIDEO INFO
Category: Peripheral Neuroanatomy, Human Anatomy, USMLE Step 1
Difficulty: Expert - Expert level - For those seeking deep understanding
Question Type: Treatment - Evaluate therapeutic interventions and management
Case Type: Tricky Findings

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QUESTION
A 48-year-old woman presents 48 hours after an open excisional biopsy of a right posterior cervical lymph node performed for persistent, painless lymphadenopathy that had been nondiagnostic on an ultrasound-guided core needle biopsy 1 week earlier. She reports new shoulder girdle pain, difficulty abducting the right arm above shoulder level, a sensation that her shoulder is drooping, and worsening scapular asymmetry when she tries to reach forward. She denies dysphonia or dysphagia....

OPTIONS
A. Arrange early surgical exploration of the spinal accessory nerve within weeks using intraoperative nerve action potential-guided strategy (neurolysis if in continuity with recordable NAP; end-to-end repair or interposition graft if discontinuity), combined with immediate scapular-stabilization ph...
B. Pursue nonoperative management alone for 6-12 months with scapular-stabilization physiotherapy and external bracing, reserving surgical exploration only if no improvement after a full year given possible delayed spontaneous recovery.
C. Inject botulinum toxin into the pectoralis minor and rhomboids with scapular taping to rebalance scapulothoracic rhythm, deferring any nerve exploration because accessory neuropathies typically recover without intervention.
D. Schedule arthroscopic subacromial decompression with acromioplasty and corticosteroid injections for presumed rotator cuff impingement, while avoiding exploration of the posterior cervical triangle to reduce iatrogenic risk.

CORRECT ANSWER
A. Arrange early surgical exploration of the spinal accessory nerve within weeks using intraoperative nerve action potential-guided strategy (neurolysis if in continuity with recordable NAP; end-to-end repair or interposition graft if discontinuity), combined with immediate scapular-stabilization physical therapy; perform as outpatient day surgery under general anesthesia with postoperative PT protocol.

EXPLANATION
Arrange early surgical exploration of the spinal accessory nerve within weeks using intraoperative nerve action potential-guided strategy (neurolysis if in continuity with recordable NAP; end-to-end repair or interposition graft if discontinuity), combined with immediate scapular-stabilization physical therapy; perform as outpatient day surgery under general anesthesia with postoperative PT protocol. This is correct because the presentation localizes to an iatrogenic spinal accessory nerve (SAN, CN XI) lesion in the posterior cervical triangle after open nodal excision, with classic findings of trapezius weakness, shoulder droop, and scapular dyskinesis while preserving deltoid and rotator cuff innervation....


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