An autopsy case of ATTRv amyloidosis with severe amyloid deposition in the median nerve at the level of carpal tunnel

Abstract

　Patients with hereditary transthyretin amyloidosis ( ATTRv ) sometimes presents carpal tunnel syndrome ( CTS ) , the etiology of which is thought to be amyloid deposition in the transverse carpal ligament. We report an autopsy case of Val30Met mutant ATTRv amyloidosis with CTS that showed severe amyloid deposition in the median nerve carpal tunnel compared to the transverse carpal ligament.　
　The patient was a 61-year-old man. He presented with distal numbness in both lower extremities, which was diagnosed by genetic testing. Sensory disturbance was observed in the extremities, especially in the median nerve area, and was thought to be associated with CTS. He was started on tafamidis, but died after 7 years. A pathological autopsy was performed. In the median nerve, amyloid deposition was more pronounced in the carpal tunnel than in the forearm. Conversely, amyloid deposition in the transverse carpal ligament was mild.　
　In this case, the median nerve disorder was thought to result from amyloid deposition within the median nerve itself, rather than from increased intracarpal pressure due to amyloid deposition in the transverse carpal ligament. Amyloid deposition was particularly severe in the carpal tunnel. This is a valuable case for understanding the pathomechanism of CTS in amyloidosis.