Diagnosis and staging of carpal tunnel syndrome: Comparison of magnetic resonance imaging and intra-operative findings

Purpose: In order to determine the reliability of magnetic resonance imaging (MRI) in the diagnosis and staging of carpal tunnel syndrome (CTS), the most common entrapment neuropathy, the following prospective study has been performed. Methods: We compared clinical and electrophysiological studies in 58 cases of CTS with MRI investigations and confirmed the reliability by exact correspondence with intra-operative findings. Results: Typical MRI characteristics of the median nerve in CTS have been established. There is a significant difference in flattening (p < 0.05), swelling (p < 0.01) and signal intensity (p < 0.05) of the median nerve between early and advanced CTS. Comparison of MRI and intra-operative findings revealed that median nerve compression was diagnosed correctly in 91% of cases. Additional lesions in the carpal tunnel, which are a primary cause of nerve compression, were established by MRI in 25 cases and confirmed by surgery. Conclusion: MRI is a reliable diagnostic tool for assessing as well as staging of CTS. Morphological changes following chronic nerve compression can be visualized. It is particularly useful in cases of suspected lesions within the carpal tunnel as a cause of CTS. The information provided may support the choice of adequate treatment modality.