[Repeat interventions after decompression of the carpal tunnel]

If after carpal tunnel release, symptoms continue or progress, or if new ones appear, they must be examined thoroughly and differentiated. Such symptoms may hint at incomplete splitting of the retinaculum flexorum, a more proximally located nerve compression (faulty diagnosis or double-crush syndrome), a general or a new disease, a previously unrecognized or a new hypertrophic synovialitis, a hypertrophically contracted scar, or a neuroma. Iatrogenic lesions have frequently been reported. A second follow-up operation is indicated only after all findings, including the neurophysiological assessment, have been taken into consideration: scar, neuroma resection, revision and neurolysis of the median nerve at all levels. The most difficult question is the coverage of the nerve in the scar tissue with thin and well-vascularised tissue. Various types of flaps using muscle or subcutaneous or synovial tissue have been suggested.