Radiologic imaging of the carpal tunnel

Compression neuropathy of the median nerve (carpal tunnel syndrome) is the most common nerve compression syndrome of the extremities. Although the disease is usually diagnosed on the basis of clinical examination and nerve conduction studies, radiologic imaging plays an important role in equivocal cases and especially in the assessment of recurrent or unrelieved symptoms after surgical carpal tunnel release. While plain radiographs and computed tomography are of limited diagnostic value except for the evaluation of osseous carpal stenosis and soft tissue calcifications, high-resolution sonography and magnetic resonance imaging allow for direct visualization of the compressed median nerve and the other soft tissue structures of the carpal tunnel. Due to its excellent contrast resolution, magnetic resonance imaging is superior in detecting mild degrees of median nerve compression and in identifying potential causes of carpal tunnel syndrome, such as tenovaginitis of the flexor tendons or space-occupying lesions. However, the low cost and time requirement favor the use of sonography as the initial imaging study in evaluating the carpal tunnel.