Amyloid detection in the transverse carpal ligament of patients with hereditary ATTR V30M amyloidosis and carpal tunnel syndrome

Introduction: Carpal tunnel syndrome (CTS) is a nonspecific manifestation of hereditary ATTR amyloidosis (ATTRm). Amyloid deposition of wild-type TTR (WT-ATTR) has been found in transverse carpal ligament (TCL) in idiopathic CTS. We retrospectively studied a group of patients with ATTRm and CTS submitted to carpal tunnel release surgery (CTRS). Methods: From the nerve conduction studies performed in our Clinical Unit dedicated to hereditary amyloidosis between July 2009 and October 2013, we selected patients who fulfilled neurophysiological criteria for CTS, had been submitted to CTRS and whose TCL was available for pathology. Clinical registries were reviewed and amyloid detection in the ligaments was performed using Congo-red staining. Results: We included 16 patients: three males (18.8%), mean age=46.1 years old, all with V30M mutation. At the time of surgery, four patients were considered asymptomatic and 12 symptomatic carriers, five of them late-onset ATTRm (onset age >50 years old). In all but one patient, the CTS preceded the polyneuropathy. Amyloid detection in the TCL was positive in 14 patients (87.5%). Discussion/conclusions: In most patients, CTS preceded or was contemporary to the polyneuropathy and amyloid detection in TCL was positive. The detection of amyloid in TCL may add specificity to CTS as an early manifestation of the disease but more studies are needed.