Systemic transthyretin amyloidosis: carpal tunnel syndrome in a Portuguese population (CarPoS)

Carpal tunnel syndrome (CTS) is the most common type of entrapment neuropathy and affects approximately 1% to 5% of the general population, mostly patients older than 50 years. CTS is present in various conditions and diseases and could also be an early sign of systemic transthyretin amyloidosis (ATTR), associated with amyloid cardiomyopathy and subsequent heart failure. With advances in the treatment of cardiac amyloidosis, patient prognosis could be significantly improved with an early diagnosis. Amyloidosis represents a group of disorders characterized by the extracellular deposition of destabilized protein fragments, aggregating as amyloid fibrils, thereby leading to organ dysfunction. Among these, ATTR is a significant subgroup. This study protocol aims to explore the potential association between CTS and systemic and cardiac ATTR. The study design involves a case-control approach, with assessments including physical examination, laboratory tests, electromyography, electrocardiogram, wrist ultrasound, and scintigraphy with 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid (99mTc-DPD). Histopathological analysis and genetic testing will be performed when appropriate. Statistical analysis will be conducted to evaluate the relationship between CTS and ATTR. The study seeks to contribute to a better understanding of the diagnostic and therapeutic implications of identifying ATTR in patients with idiopathic CTS (ClinicalTrials.gov identifier: NCT05409833).