Inclusion Criteria:  bilateral carpal tunnel with indication of surgery and judged suspect: age of 50 years old and more non-traumatic or undetermined neuropathic etiology or cardiac history (atrial arrhythmia or Heart Failure or cardiac stimulation) or family history of hereditary amyloidosis or monoclonal gammopathy  Exclusion Criteria:  patient with diagnosis of amyloidosis traumatic bilateral carpal tunnel or linked to rheumatoid arthritis