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Zorluk: ZorPhysical Examination Findings

A 34-year-old female presents to her primary care physician with progressive right shoulder discomfort and weakness. Three weeks ago, she underwent an uncomplicated excisional biopsy of an enlarged right posterior cervical lymph node, which returned benign pathology. Currently, she reports a dull ache in her right shoulder and significant difficulty performing overhead activities, such as brushing her hair. She denies neck pain, radiating pain, numbness, or tingling in her upper extremities. Vital signs are within normal limits. On physical observation, her right shoulder sits noticeably lower than her left. Which of the following specific physical examination findings is most likely to be elicited in this patient?

  1. Inability to actively abduct the right arm beyond 90∘90^\circCevap
  2. B
    Prominence of the medial border of the right scapula when pushing against a wall
  3. C
    Weakness of right shoulder abduction during the initial 15∘15^\circ of motion
  4. D
    Decreased pinprick sensation over the right lateral deltoid muscle
  5. E
    Weakness with internal rotation of the right arm against resistance

Cevap

The correct answer is the inability to actively abduct the right arm beyond 90∘90^\circ.
The patient's presentation is highly characteristic of an iatrogenic injury to the spinal accessory nerve (cranial nerve XI). This nerve courses superficially through the posterior cervical triangle, making it particularly vulnerable during surgical procedures in this area, such as a cervical lymph node biopsy. CN XI provides motor innervation to the sternocleidomastoid and the trapezius muscles. Paralysis of the trapezius muscle classically results in an ipsilateral drooping shoulder and an inability to elevate or shrug the shoulder. Furthermore, because the trapezius is biomechanically essential for the upward rotation of the scapula, its denervation severely impairs the patient's ability to actively abduct the arm beyond 90∘90^\circ (above the horizontal plane). This precise physical examination finding explains her profound difficulty with overhead activities.

Adım Adım Çözüm

1
Analyze the patient's surgical history and current presentation.
The patient had a biopsy in the right posterior cervical triangle and now has an ipsilateral shoulder droop and weakness with overhead activities.
Identifying the anatomic location of the procedure helps determine which neurological structures were at risk of iatrogenic injury.
2
Correlate the anatomic location with potential nerve injuries.
The spinal accessory nerve (cranial nerve XI) courses superficially through the posterior cervical triangle, making it highly susceptible to injury during lymph node biopsies in this region.
Recognizing the vulnerability of CN XI in this specific anatomical triangle is key to establishing the correct diagnosis.
3
Determine the physiological consequences of this specific nerve injury.
Injury to CN XI causes denervation and subsequent paralysis of the trapezius muscle.
The trapezius muscle is primarily responsible for elevating the shoulder and upwardly rotating the scapula during arm movement.
4
Translate the muscular deficit into a specific physical examination finding.
Loss of trapezius function leads to a drooping shoulder and an inability to upwardly rotate the scapula, which is a biomechanical requirement to actively abduct the arm past 90∘90^\circ.
This confirms the correct clinical sign expected on examination, directly linking the surgical complication to the physical findings.

Anahtar Kavram

Iatrogenic injury to the spinal accessory nerve (CN XI) during posterior cervical triangle procedures results in trapezius muscle denervation, presenting clinically as an asymmetric drooping shoulder and an inability to actively abduct the arm beyond 90∘90^\circ.
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Physical Examination Findings

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