Exploring the Intersection of Thoracic Outlet Syndrome, Dysferlinopathy, and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

By SWA

 Introduction

Thoracic outlet syndrome (TOS), dysferlinopathy, and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) are distinct conditions that share some overlapping clinical features. These features, including fatigue, arm heaviness, and difficulties with overhead activities, may lead to diagnostic challenges. While each condition has unique pathophysiologic mechanisms, understanding their interplay is critical for proper diagnosis and treatment, particularly when symptoms mimic or exacerbate one another.

This article explores the connections between these conditions, focusing on TOS-like symptoms in dysferlinopathy and systemic fatigue provoked during diagnostic maneuvers in ME/CFS.

Thoracic Outlet Syndrome (TOS)

TOS is caused by compression of the brachial plexus, subclavian artery, or subclavian vein as they pass through the thoracic outlet. It presents with a variety of symptoms depending on the structures involved, including:

  • Neurologic symptoms (e.g., paresthesias, weakness, or pain radiating into the arm).
  • Vascular symptoms (e.g., arm swelling, cyanosis, or vascular insufficiency).
  • Functional limitations, such as arm fatigue or heaviness during overhead activities.

Diagnostic maneuvers such as Adson’s test, Wright’s hyperabduction test, and the elevated arm stress test (EAST) are designed to provoke symptoms by compressing the thoracic outlet structures.

Dysferlinopathy and TOS-Like Symptoms

Dysferlinopathy is a group of genetic muscle disorders caused by mutations in the DYSF gene, leading to deficits in dysferlin protein and progressive muscle weakness. This condition primarily affects proximal muscles, such as the shoulder girdle and hips. Although dysferlinopathy does not directly involve the thoracic outlet, TOS-like symptoms may emerge as secondary effects due to:

  1. Postural Changes: Weakness in the shoulder girdle muscles can lead to scapular winging or abnormal shoulder biomechanics, placing strain on the brachial plexus and vascular structures.
  2. Muscle Atrophy: Atrophy in stabilizing muscles of the upper body can alter the thoracic outlet anatomy, increasing the likelihood of neurovascular compression.
  3. Overhead Activity Challenges: Patients with dysferlinopathy often report arm fatigue, heaviness, or pain during overhead tasks. These symptoms mimic TOS but are primarily due to muscle weakness rather than neurovascular compression.

Key Differences:

  • In TOS, symptoms result from vascular or neurologic compression, with effects localized to the affected limb.
  • In dysferlinopathy, systemic fatigue and exercise intolerance dominate due to the muscle disorder itself.

ME/CFS and Systemic Symptom Provocation During TOS Testing

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating condition characterized by profound fatigue, post-exertional malaise (PEM), and widespread pain. While ME/CFS is primarily systemic, certain diagnostic maneuvers for TOS, such as the elevated arm stress test (EAST), can provoke systemic symptoms.

Common Symptoms in ME/CFS:

  • Fatigue and heaviness in the arms, even with minimal activity.
  • Generalized pain, including in the shoulders, neck, and upper back.
  • Postural adaptations and deconditioning that may resemble TOS-like postural dysfunction.

Overlap Between TOS and ME/CFS:

Diagnostic maneuvers like the EAST test, which involve prolonged elevation of the arms, can exacerbate ME/CFS symptoms. In ME/CFS patients, this is not due to mechanical compression but rather an exaggerated systemic response, likely related to:

  • Autonomic nervous system dysregulation.
  • Impaired energy metabolism and oxygen utilization.
  • Heightened central pain sensitization.

Clinical Considerations

When evaluating a patient with arm fatigue, heaviness, or systemic symptoms during overhead activities, it is crucial to differentiate between TOS, dysferlinopathy, and ME/CFS. A thorough history, physical examination, and appropriate diagnostic testing are essential.

For Dysferlinopathy Patients:

  • Assess for postural and biomechanical abnormalities that may predispose to TOS-like symptoms.
  • Perform strength testing to evaluate shoulder girdle and proximal muscle weakness.
  • Imaging or nerve conduction studies may help rule out true thoracic outlet involvement.

For ME/CFS Patients:

  • Consider the systemic nature of their symptoms, including PEM, which may be triggered by TOS diagnostic maneuvers.
  • Avoid overinterpreting positive TOS tests in the absence of localized neurovascular compression.
  • Focus on management strategies for autonomic dysfunction and fatigue rather than structural interventions.

For TOS Diagnosis:

  • Differentiate primary neurovascular compression from secondary causes, such as postural changes due to muscle weakness or deconditioning.
  • Use imaging (e.g., MRI, Doppler ultrasound) to confirm structural causes of TOS when clinical suspicion is high.

Conclusion

While thoracic outlet syndrome, dysferlinopathy, and ME/CFS are distinct entities, their overlapping symptoms—particularly difficulties with overhead activities and fatigue—can complicate diagnosis. Dysferlinopathy may mimic TOS due to postural changes and muscle weakness, while ME/CFS can provoke systemic symptoms during TOS diagnostic maneuvers, potentially leading to misdiagnosis. A multidisciplinary approach that incorporates clinical, imaging, and electrophysiologic evaluations is essential to differentiate these conditions and tailor treatment to the patient’s underlying pathology.

By recognizing the subtle interplay between these conditions, clinicians can avoid diagnostic pitfalls and provide more effective, patient-centered care.

Provocation of brachial plexus and systemic symptoms during the elevated arm stress test in individuals with myalgic encephalomyelitis/chronic fatigue syndrome or idiopathic chronic fatigue

© 2000-2025 Sieglinde W. Alexander. All writings by Sieglinde W. Alexander have a fife year copy right. Library of Congress Card Number: LCN 00-192742 ISBN: 0-9703195-0-9

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