Explorative and Descriptive Analysis of Differential Diagnosis with Nerve Magnetic Resonance Imaging (MRI) in Patients with Neuromuscular Diseases: Subgroup Study of Patients with Parsonage Turner Syndrome (PTS)

Background Parsonage-Turner Syndrome (PTS) is a rare, immune-mediated brachial plexopathy characterized by acute shoulder pain followed by muscle weakness and atrophy. Due to its heterogeneous clinical presentation and overlap with other neuropathies, diagnosis is often delayed. Magnetic Resonance Imaging (MRI) has emerged as a promising tool for early detection and differential diagnosis, yet its role in clinical practice remains underexplored. This study aims to evaluate the diagnostic value of advanced MRI techniques in PTS by integrating clinical, neurophysiological, and imaging data. Methods A retrospective cohort of 51 patients with confirmed PTS and 25 healthy controls underwent standardized high-resolution MRI of the brachial plexus using 3D Cube Nerve sequences. Qualitative assessments included muscle edema, fat infiltration, and atrophy, while quantitative measurements focused on cross-sectional area (CSA), and T2 signal intensity, using two measurements: the area of the region of interest (AR) and the median value (MED) of the C5-C8 nerve roots. Electromyography (EMG) and clinical data were collected and correlated with imaging findings. Statistical analysis was performed using hierarchical linear models and subgroup comparisons. Results PTS predominantly affected middle-aged males (mean age 51.9 years), with unilateral symptoms in over 80% of cases. Pain was the most common presenting symptom (70.6%), followed by functional impairment. MRI revealed significant structural alterations, particularly at the C6-C8 nerve roots. Quantitative analysis showed a marked increase in CSA and T2 signal intensity in PTS patients compared to controls (p < 0.001), with pathological roots exhibiting significantly larger diameters and areas. Muscle edema was most prevalent in the infraspinatus and trapezius muscles and was significantly associated with pain (p = 0.018), while fat infiltration and atrophy in the supraspinatus correlated with chronicity and functional decline (p = 0.001 and p = 0.028, respectively). Despite these findings, no direct correlation was observed between the degree of nerve root involvement and symptom severity, highlighting the multifactorial nature of PTS. Conclusion MRI, particularly when combining qualitative and quantitative analyses, proves to be a powerful tool for diagnosis and monitoring of PTS. Its integration with EMG and clinical evaluation enhances diagnostic accuracy and supports a personalized, multimodal approach to patient care. These findings advocate for the routine use of advanced MRI protocols in the diagnostic workflow of suspected PTS and suggest potential for future applications in longitudinal monitoring and AI-assisted diagnostics.