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. 2021 Jun;26(2):160-166.
doi: 10.1111/jns.12444. Epub 2021 May 7.

Feasibility of assessing progression of transthyretin amyloid polyneuropathy using nerve conduction studies: Findings from the Transthyretin Amyloidosis Outcomes Survey (THAOS)

Márcia Waddington-Cruz  1 , Yukio Ando  2 , Leslie Amass  3 , Jan Kiszko  3 , Doug Chapman  3 , Yoshiki Sekijima  4 ; THAOS investigators
Affiliations

Feasibility of assessing progression of transthyretin amyloid polyneuropathy using nerve conduction studies: Findings from the Transthyretin Amyloidosis Outcomes Survey (THAOS)

Márcia Waddington-Cruz et al. J Peripher Nerv Syst. 2021 Jun.

Abstract

Patients with transthyretin amyloid polyneuropathy (ATTR-PN) show decreased motor and sensory nerve amplitudes and conduction. Electrophysiological changes over time may be sensitive indicators of progression. This analysis from the Transthyretin Amyloidosis Outcomes Survey (THAOS) assessed longitudinal changes in nerve conduction as signals of neurologic disease progression in patients with hereditary ATTR (ATTRv) amyloidosis. Patients with ATTRv in THAOS with recorded nerve conduction values were included (data cut-off: January 6, 2020); changes in nerve amplitude and velocity over time were assessed. Patients (n = 1389) were 45.0% male; 80.4% were the Val30Met (p.Val50Met) genotype. Mean (SD) age at enrollment was 43.6 (14.5) years; duration of symptoms was 9.3 (6.4) years. Median (10th, 90th percentile) sural nerve amplitude and velocity was 18.0 (4.9, 35.0) μV and 50.7 (41.0, 57.9) m/s; peroneal conduction was 13.0 (4.4, 27.0) μV and 51.0 (41.7, 59.7) m/s, respectively. Median (10th, 90th percentile) percentage change from baseline in sural nerve amplitude was variable, but generally decreased over time from -7.4 (-43.2, 52.4) at year 1 to -14.4 (-76.9, 46.7) at year 8. Percent change from baseline in sural nerve velocity declined similarly: -0.1 (-14.5, 15.3) at year 1 and - 6.4 (-21.3, 10.5) at year 8. The decline was more pronounced in patients with greater disability at baseline. Similar patterns were observed for the peroneal nerve. These data show an association between nerve amplitudes and velocities and disease severity, suggesting progressive deterioration in nerve conduction may be an indicator of ATTRv amyloidosis disease progression.

Keywords: ATTR-PN; nerve amplitude; nerve conduction; transthyretin amyloid polyneuropathy.

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Conflict of interest statement

Márcia Waddington‐Cruz received research funding, consulting fees, and travel support for advisory boards and meetings from FoldRx Pharmaceuticals and Pfizer. Yukio Ando declares receipt of consulting fee or honorarium, support for travel to meetings, and provision for writing assistance from Pfizer. Yoshiki Sekijima has received royalties from Pfizer related to tafamidis patents and has received speaker honoraria from Pfizer. Leslie Amass, Doug Chapman, and Jan Kiszko are full‐time employees of Pfizer and hold stock and/or stock options with Pfizer.

Figures

FIGURE 1
FIGURE 1
Median (10th and 90th percentile) percentage change from baseline in sural and peroneal nerve amplitude and velocity in patients with ATTRv amyloidosis and nerve conduction studies. Change from baseline (enrollment) is the baseline value subtracted from the follow‐up value, where both are non‐missing. The data presented are cross‐sectional by follow‐up time in THAOS. ATTRv, hereditary transthyretin amyloidosis; THAOS, Transthyretin Amyloidosis Outcomes Survey
FIGURE 2
FIGURE 2
Median (10th and 90th percentile) percentage change from baseline in sural and peroneal nerve conduction by latest mPND score in patients with ATTRv amyloidosis and nerve conduction studies. mPND score IIIa, IIIb, and IV values are either not available (no patients with data) or not shown due to low n (n = 1). Data from year 8 not shown due to small number of patients in certain subgroups. ATTRv, hereditary transthyretin amyloidosis; mPND, modified polyneuropathy disability; THAOS, Transthyretin Amyloidosis Outcomes Survey
See this image and copyright information in PMC

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