Palpable pseudo-tumor of the shoulder girdle: Diagnosing and managing chronic spinal accessory neuropathy – A case report

INTRODUCTION

The spinal accessory nerve, or cranial nerve XI, is a motor nerve integral to the function of the trapezius and sternocleidomastoid muscles, facilitating shoulder girdle stability and neck mobility, respectively. Its superficial course through the posterior cervical triangle predisposes it to injury, particularly during surgical interventions such as lymph node biopsies, carotid endarterectomy, and neck dissections for head-and-neck cancer.^[1-3] The spinal accessory nerve injury frequently presents as shoulder pain, winging of the scapula, trapezius atrophy, and impaired shoulder function, with profound implications for patient’s quality of life.^[3-5]

Despite the increasing recognition of iatrogenic spinal accessory nerve injuries, diagnosis is often delayed or disregarded due to their subtle clinical presentation which mimics other shoulder pathologies, including rotator cuff injuries, adhesive capsulitis, and myofascial syndromes.^[4-6] Electromyographic studies and imaging are critical diagnostic tools, yet detailed history-taking and physical examination remain the cornerstone for identifying these injuries.^[3,7]

Efficient management of spinal accessory neuropathy (SAN) varies based on the timing of diagnosis and severity of the injury. Early recognition facilitates conservative interventions, such as physiotherapy and scapular stabilization exercises, which have shown promise in reducing pain and improving functional outcomes.^[1,5,6] However, overlooked cases often necessitate surgical intervention to restore nerve integrity and optimize recovery.^[2,3]

This case report presents a rare instance of chronic SAN manifesting as a palpable pseudo-tumor in the shoulder girdle, thereby complicating the diagnostic process. To our knowledge, such a presentation has been infrequently reported in the literature. This novelty distinguishes the case from prior reports and highlights the importance of recognizing atypical physical findings that may otherwise be mistaken for musculoskeletal tumors.

Additionally, the case underscores several limitations of current clinical pathways, including the frequent misattribution of symptoms to more common shoulder pathologies, which often results in diagnostic delay and suboptimal early management. These shortcomings reinforce the need for heightened clinical awareness and the timely integration of physiotherapy-based strategies to potentially avert more invasive interventions. By detailing the clinical evaluation, diagnostic challenges, and multidisciplinary management approach, this report underscores the critical role of timely intervention and comprehensive rehabilitation in addressing the sequelae of spinal accessory nerve injuries. Furthermore, it aims to enhance awareness among clinicians about this uncommon presentation, emphasizing the need for clinical vigilance and interdisciplinary collaboration when managing shoulder girdle pathologies.^[3,4]

CASE REPORT

A 40-year-old Saudi Arabian female presented with right arm pain, weakness, easy fatigability, and neck pain. Her symptoms had progressively worsened over 5 years and were initially misdiagnosed as rotator cuff pathology. The patient had a history of neck surgery at age 10 while the procedure was not officially documented in her medical records, she reported undergoing surgical removal of a fatty lump (suspected lipoma excision) in the latero-posterior neck region on the right side, which may have contributed to her current condition.

She was a non-smoker, had no known family history of similar conditions, had no significant systemic illnesses, nor was she on any medications relevant to her condition. Her functional limitations and persistent discomfort significantly impacted her daily activities such as combing her hair, cooking, and dressing up, prompting further clinical evaluation and management. X-ray revealed misalignment of the shoulder girdle joints Figure 1.

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Figure 1:

X-ray images of the right shoulder girdle. (a) Before physical therapy: Demonstrates mild elevation of the scapula and altered scapulothoracic alignment, likely secondary to trapezius weakness and scapular instability. (b) After 10 weeks of physical therapy: Improved scapular positioning and alignment are evident, suggesting enhanced scapular control and muscular support following rehabilitation.

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Upon physical examination the patient showed subclavicular/pectoral asymmetry and shoulders level asymmetry [Figure 2], with a palpable mass-like prominence in the shoulder girdle during 90° of shoulder elevation, noticeable only through palpation and not clearly visible to the eye. There was evident sternocleidomastoid and trapezius muscle atrophy [Figure 3], along with lateral scapular winging, accompanied by weakness in shoulder elevation and abduction.. There was evident sternocleidomastoid with lateral scapular winging, accompanied by weakness in shoulder elevation and abduction. Table 1 summarizes the patient’s baseline assessment and then after 10 weeks of physical therapy (PT). Although we suspected SAN based on clinical manifestation, testing of the upper trapezius (shoulder shrug)^[8] was negative, although we performed the triangle sign which was positive. The active elevation lag sign and the triangle sign are newer clinical metrics used to identify trapezius dysfunction.^[7] These signs are reported to have high specificity for identifying trapezius weakness, and purport an excellent ability to distinguish between scapular winging and spinal accessory nerve injury, and the more common cause of winging, long thoracic nerve injury.^[9] To confirm our diagnosis, a nerve conductive study was performed which revealed SAN.

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Figure 2:

Shoulder girdle level assessment. (a) Before physical therapy: Note the asymmetry in shoulder height, with visible elevation of the left shoulder and drooping of the right side, indicating muscle imbalance and scapular dyskinesis. (b) After 10 weeks of physical therapy: The shoulder levels appear more symmetrical, reflecting improved muscular control and scapular stabilization following rehabilitation.

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Figure 3:

Clinical images showing evidence of sternocleidomastoid and upper trapezius atrophy. (a) Prior to physical therapy, marked atrophy of the upper trapezius and flattening of the supraclavicular fossa are visible, along with reduced bulk of the sternocleidomastoid muscle. (b) After 10 weeks of physical therapy, there is noticeable improvement in muscle definition and volume, particularly in the upper trapezius area, indicating functional recovery and hypertrophy in response to rehabilitation.

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DISCUSSION

This case underscores the importance of early recognition and accurate diagnosis of SAN, particularly in patients with a history of neck surgery. The patient’s clinical presentation, including shoulder girdle asymmetry, trapezius and sternocleidomastoid atrophy, and lateral scapular winging, aligns with previous case studies that have highlighted the diagnostic challenges of spinal accessory nerve injuries.^[2-4,7,11]

The presence of a palpable mass-like prominence in the shoulder girdle of this patient was a significant finding, raising initial concerns about a possible tumor or abnormal tissue growth. However, as described in a similar case by Lin et al.,^[2] musculoskeletal sonography confirmed that the mass was not an actual tumor but the superior angle of the scapula. In patients with SAN, loss of trapezius muscle function leads to altered scapular biomechanics, specifically downward rotation of the scapula, which causes the superior angle of the scapula to protrude and become palpable beneath the skin. This phenomenon can be misinterpreted as a pseudo-tumor, delaying the correct diagnosis. The findings in this case are consistent with previous reports that emphasize the importance of detailed physical examination and imaging to differentiate true pathological masses from biomechanical adaptations due to muscle denervation.^[12,13]

Several published studies have reported similar cases of delayed SAN diagnosis due to symptom overlap with rotator cuff pathology and adhesive capsulitis. For example, Macaluso et al.^[7] discussed a case where a patient with chronic shoulder pain and weakness was initially treated for a rotator cuff injury before EMG confirmed spinal accessory nerve involvement. Similarly, Ozen et al.^[4] emphasized the role of nerve conduction studies in differentiating SAN from other shoulder pathologies.

In this case, traditional clinical tests such as the shoulder shrug test were negative; alterations in shrugging are suspect because the levator scapula and rhomboid can adequately perform this activity.^[14,15] Yet, the triangle sign was valuable in confirming trapezius dysfunction. This aligns with recent literature^[7] suggesting that the use of newer clinical tests, such as the active elevation lag sign and triangle sign, improves diagnostic accuracy. In addition, while conservative management remains the primary approach for SAN,^[6] other studies have suggested surgical interventions for cases with persistent dysfunction or nerve discontinuity.^[16-20]

Following a structured rehabilitation program, this patient demonstrated significant pain reduction, improved shoulder function, and enhanced scapular stability. These outcomes are consistent with findings by McGarvey et al.,^[5] who reported favorable functional recovery with targeted PT in patients with SAN. The present case further supports the effectiveness of PT in optimizing scapular biomechanics and restoring shoulder function.

CONCLUSION

This case underscores the need for increased clinical awareness of chronic SAN, particularly in patients with a history of neck surgeries. Early diagnosis and tailored rehabilitation strategies can optimize patient outcomes and prevent unnecessary surgical interventions. Future studies should explore the long-term outcomes of conservative rehabilitation in patients with spinal accessory nerve injuries.