1. Early changes of nerve integrity in preclinical carriers of hereditary transthyretin Ala117Ser amyloidosis with polyneuropathy
- Author
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Sung Ju Hsueh, Sung-Tsang Hsieh, Fang Ping Feng, Kai Chieh Chang, Chi-Chao Chao, Yea Huey Lin, Yi Hui Kao, Ming-Chang Chiang, Ti Yen Yeh, Hsueh-Wen Hsueh, and Jia Ying Sung
- Subjects
medicine.medical_specialty ,Neural Conduction ,Nerve fiber ,Wrist ,Gastroenterology ,Asymptomatic ,Polyneuropathies ,03 medical and health sciences ,0302 clinical medicine ,Internal medicine ,medicine ,Humans ,Prealbumin ,030212 general & internal medicine ,Amyloid Neuropathies, Familial ,biology ,business.industry ,Amyloidosis ,medicine.disease ,Median nerve ,Transthyretin ,medicine.anatomical_structure ,Neurology ,biology.protein ,Neurology (clinical) ,Abnormality ,medicine.symptom ,business ,Polyneuropathy ,030217 neurology & neurosurgery - Abstract
Background Disease-modifying therapies provide new horizons for hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN) to slow neuropathic progression. Initiating treatment at the earliest time requires biomarkers reflecting both small- and large-fiber degeneration in carriers. Methods This study included examinations of pathology [intraepidermal nerve fiber (IENF) density], physiology (nerve conduction studies, autonomic function test and nerve excitability), and psychophysics (thermal thresholds) in carriers to compare to healthy controls and asymptomatic diabetic patients. Results There were 43 carriers (44.2±11.4 years, p.Ala117Ser in 42 carriers), 43 controls (43.4±12.7 years) including 26 noncarrier families, and 50 asymptomatic diabetic patients (58.1±9.5 years). Carriers had lower IENF densities than controls and similar densities as diabetic patients. Median nerve conduction parameters, especially distal motor latency, (1) were the most frequent neurophysiological abnormality in carriers, (2) could differentiate carriers from controls and diabetic patients, (3) were correlated with IENF densities in carriers but not in controls and diabetic patients, and (4) were correlated with nerve excitability parameters in carriers but not in controls. Fifteen carriers (34.9%) with electrophysiological evidence of median nerve entrapment at wrist had lower IENF densities and more abnormal conduction parameters than carriers without. We defined nerve dysfunction index (the ratio of median distal motor latency to IENF density) which differentiated carriers from controls. Conclusions In late-onset ATTRv-PN carriers with predominant p.Ala117Ser, median conduction parameters were the most common neurophysiological abnormalities, and served as surrogate signatures of small- and large-fiber impairment. Combination of median distal motor latency and IENF density can reflect early neuropathy in carriers.
- Published
- 2021