Neurosonographic characteristics of peripheral nerve in transthyretin familial amyloid polyneuropathy / 中华神经科杂志

ABSTRACT

Objective:To study peripheral nerve morphology in patients with transthyretin familial amyloid polyneuropathy (TTR-FAP) using high-frequency ultrasonography (HFUS), and to evaluate the value of HFUS in diagnosis of TTR-FAP.Methods:Thirty-eight patients with TTR-FAP diagnosed by gene detection and 23 normal controls from June 2015 to June 2021 in Peking University First Hospital were enrolled in this study. Consecutive ultrasonography scanning was performed in 6 pairs of nerves of bilateral limbs with 30 sites. The cross sectional area (CSA), CSA variability and inter-nerve CSA variability data of the two groups were retrospectively calculated and compared.Results:Compared with the normal controls, TTR-FAP patients showed larger CSA values at most nerve sites of both upper and lower limbs, and there were statistically significant differences at M1(median nerve) [8.55 (6.90, 9.40) mm 2vs 10.05 (9.10, 14.10) mm 2, Z=5.58, P<0.001], M3 (median nerve) [(6.98±1.66) mm 2vs (9.29±2.30) mm 2, t=6.28, P<0.001], M5 (median nerve) [(8.91±1.81) mm 2vs (14.33±4.20) mm 2, t=9.84, P<0.001], U5 (ulnar nerve) [(6.20±1.93) mm 2vs (9.34±2.85) mm 2, t=7.31, P<0.001], Sci1 (sciatic nerve) [(53.50±17.24) mm 2vs (79.74±20.75) mm 2, t=7.57, P<0.001], Sci2 (sciatic nerve) [(53.66±14.21) mm 2vs (73.98±19.21) mm 2, t=6.82, P<0.001] and Tib (tibial nerve) [(31.05±8.43) mm 2vs (46.29±13.14) mm 2, t=7.84, P<0.001] sites. There was no statistically significant difference in CSA at each site among the different subtypes and disease severity of TTR-FAP patients ( P>0.05). There was no statistically significant difference in CSA-variability of the median and ulnar nerves between the patients with TTR-FAP and the normal controls ( P>0.05). The side-to-side difference ratio of intra-nerve CSA variability of the ulnar nerve in the patients with TTR-FAP was smaller than that of the normal controls (1.15±0.10 vs 1.46±0.43, t=3.43, P=0.002), whereas no statistically significant difference of that in the median nerve was found between the two groups ( P>0.05). Conclusions:The most pronounced peripheral nerve thickening in the proximal limb segments with no signs of asymmetric distribution or lateralization is confirmed by HFUS in TTR-FAP patients and should be regarded as a marker of TTR-FAP. HFUS has clinical value in diagnosis of peripheral neuropathy in TTR-FAP patients.