Hereditary Transthyretin Amyloidosis Polyneuropathy in Patients With Carpal Tunnel Syndrome in Russia

This is a multicenter observational study consisting of retrospective and prospective phases. The retrospective phase will entail secondary data collection from electronic or paper medical records of patients who underwent surgery for CTS to assess their probability of having ATTR PN.

Inclusion Criteria: for the retrospective phase are: 1. Patients with the established diagnosis of CTS. 2. Bilateral involvement of carpal tunnel established between the 1st January 2021 and the 31st December 2024 (both patients who underwent CTS surgical intervention and without it are enrolled). 3. Age ≥ 18 years at the time of CTS diagnosis. 4. Provided written informed consent for the prospective phase of the study (including molecular genetic testing). 5. Presence of ≥1 of the following features (red flags): a. CIDP or polyneuropathy of unknown etiology in the family history; b. Spinal canal stenosis of the lumbar region; c. Autonomic dysfunction, defined by the presence of ≥1 of the following symptoms - i. Gastrointestinal complaints (constipation, chronic diarrhea, or both); ii. Erectile dysfunction; iii. Orthostatic hypotension; d. Gait disorders; e. Sweating disorders, anhidrosis. f. Paresthesia and burning of the skin of the distal extremities g. Distal symmetrical paresis h. Hypotrophy and hypotension of limb muscles, areflexia i. Biceps tendon rupture j. Aortic valve stenosis k. Diagnosis of HFpEF l. Unexplained weight loss ≥5 kilos at any timepoint since the onset of symptoms of CTS; m. Left ventricular hypertrophy (based on electro- or echocardiographic criteria documented in the patient's medical record); n. Heart rhythm disorders; o. Renal abnormalities, defined by ≥1 of the following features - i. Documented diagnosis of chronic kidney disease (CKD); ii. Decreased estimated glomerular filtration rate (eGFR \