High-resolution ultrasound of peripheral nerves in late-onset hereditary transthyretin amyloidosis with polyneuropathy: similarities and differences with CIDP.

INTRODUCTION: Hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN) remains a diagnostic challenge due to clinical, neurophysiological, and laboratory findings suggestive of other diagnoses, particularly chronic inflammatory demyelinating polyneuropathy (CIDP). In this cross-sectional prospective study, we aimed to investigate the utility of high-resolution ultrasonography of peripheral nerves as a diagnostic tool to differentiate ATTRv-PN from CIDP. METHODS: In 11 treatment-naive patients with genetically confirmed late-onset ATTRv-PN and 25 patients with CIDP, we collected clinical, electrodiagnostic, and high-resolution ultrasonography data of the peripheral nerves. In each patient, we used high-resolution ultrasonography to assess 26 nerve sites. RESULTS: Of the 11 patients with ATTRv-PN, two had electrodiagnostic study data compatible with a CIDP diagnosis. High-resolution ultrasonography showed that the cross-sectional area of the brachial plexus, median nerve at the axilla, arm, and forearm, ulnar nerve at the forearm, and peroneal nerve at the popliteal fossa were significantly smaller in the 11 ATTRv-PN patients than in CIDP patients. However, in the two patients with electrodiagnostic study data compatible with a CIDP diagnosis, high-resolution nerve ultrasonography data were comparable to those in patients with CIDP. CONCLUSION: Although high-resolution ultrasonography of peripheral nerves provides reliable information in patients with ATTRv-PN, its usefulness as a standalone diagnostic tool to differentiate ATTRv-PN from CIDP might be limited.

Rate of neuropathic progression in hereditary transthyretin amyloidosis with polyneuropathy and other peripheral neuropathies: a systematic review and meta-analysis.

BACKGROUND: We aimed to compare neuropathic progression rate between hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN) and other peripheral neuropathies, including diabetic peripheral neuropathy (DPN) and Charcot-Marie-Tooth disease (CMT). METHODS: Literature searches identified studies reporting neuropathic progression, measured by Neuropathy Impairment Score (NIS) or NIS-Lower Limbs (NIS-LL). Our study also included unpublished data from a clinical registry of patients who were diagnosed with different peripheral neuropathies and seen at the Oregon Health & Science University (OHSU) during 2016-2020. Meta-analysis and meta-regression models examined and compared annual progression rates, calculated from extracted data, between studies of ATTRv-PN and other peripheral neuropathies. RESULTS: Data were synthesized from 15 studies in which NIS and/or NIS-LL total scores were assessed at least twice, with ≥12 weeks between assessments, among untreated patients with ATTRv-PN or other peripheral neuropathies. Meta-analysis models yielded that the annual progression rate in NIS total scores was significantly different from zero for studies in ATTRv-PN and CMT (11.77 and 1.41; both P < 0.001), but not DPN (- 1.96; P = 0.147). Meta-regression models showed significantly faster annual progression in studies in ATTRv-PN, which statistically exceeded that in other peripheral neuropathies by 12.45 points/year for NIS, and 6.96 for NIS-LL (both P < 0.001). CONCLUSIONS: Peripheral nervous function deteriorates more rapidly in patients with ATTRv-PN than for other peripheral neuropathies. These findings may improve understanding of the natural history of neuropathy in ATTRv-PN, facilitate early diagnosis, and guide the development of assessment tools and therapies specifically targeting neuropathic progression in this debilitating disease.

Efficacy and safety of patisiran for ATTRv-PN: a systematic review and meta-analysis.

Background: Hereditary transthyretin amyloidosis (ATTRv; v for variant) with polyneuropathy is a rare, progressive, and fatal autosomal dominant disorder. Therapies such as liver transplantation and TTR stabilizations have limitations. Patisiran is a small interfering RNA (siRNA), offering potential as a genetic-level therapy for hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN). However, evidence on patisiran's efficacy and safety for ATTRv-PN remains limited. Objectives: This study aimed to further clarify patisiran's efficacy and safety for ATTRv-PN by meta-analysis. Design: Systematic review and meta-analysis. Methods: After literature searches in PubMed, Ovid MEDLINE, Embase, JBI EBP, Cochrane, and ClinicalTrials.gov databases on 7 June 2024, 11 studies with 503 patients were included and clinical data were extracted. Results: Results showed an 88% (95% confidence interval (CI): 81%-94%) pooled responsiveness rate. The standardized mean difference of modified Neuropathy Impairment Score plus 7 nerve tests (mNIS + 7) scores was -0.18 (95% CI: -0.32 to -0.03, p-value 0.018) and Norfolk Quality of Life-Diabetic Neuropathy was -0.21 (95% CI: -0.35 to -0.08, p-value 0.002). In total, 413 adverse events (AEs) (84.8%), 158 serious AEs (32.4%), and 37 deaths (7.6%) were recorded. Most of AEs were mild to moderate. No deaths were attributed to patisiran. However, there is no statistically significant improvement in Neuropathy Impairment Scores. Conclusion: In conclusion, patisiran was effective and safe for patients with ATTRv-PN. More large-scale clinical trials and long-term studies are necessary to further validate patisiran's efficacy and safety. Trial registration: PROSPERO registration ID: CRD42023428838.

Altered connectivity of central autonomic network: effects of dysautonomia in hereditary transthyretin amyloidosis with polyneuropathy.

BACKGROUND: Hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN) is a progressive fatal disorder caused by deposition of mutant transthyretin (TTR) amyloids mainly in the nerves and heart. Autonomic dysfunction is a major disabling manifestation, affecting 90% of patients with late-onset ATTRv-PN. The current study aimed to investigate brain functional alterations associated with dysautonomia due to peripheral autonomic nerve degeneration in ATTRv-PN. METHODS: Resting-state functional MRI data were acquired from 43 ATTRv-PN patients predominantly of A97S (p.A117S) genotype, and the functional connectivity of central autonomic regions was assessed. RESULTS: Compared with age-matched healthy controls, the ATTRv-PN patients exhibited (1) reduced functional connectivity of the central autonomic regions such as hypothalamus, amygdala, anterior insula, and middle cingulate cortex with brain areas of the limbic, frontal, and somatosensory systems, and (2) correlations of reduced functional autonomic connectivity with the severity of autonomic dysfunction especially orthostatic intolerance, decreased heart rate variability, and greater clinical disability. CONCLUSIONS: Our findings provide evidence linking peripheral autonomic dysfunction with altered connectivity in the central autonomic network in ATTRv-PN.

Responder analysis for neuropathic impairment and quality-of-life assessment in patients with hereditary transthyretin amyloidosis with polyneuropathy in the NEURO-TTR study.

OBJECTIVE: Hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN) is a rare disease characterized by rapid neuropathic progression. In pivotal studies of gene-silencing treatments, the modified Neuropathy Impairment Score + 7 tests (mNIS + 7) and Norfolk-Quality of Life (QOL)-Diabetic Neuropathy (DN) questionnaire assessed treatment impact on neuropathic progression. Establishing responder definition (RD) thresholds for these measures would enable evaluation of clinically meaningful treatment benefit. METHODS: mNIS + 7 and Norfolk-QOL-DN were administered at baseline and week 65 to 165 adults with ATTRv-PN receiving inotersen (n = 106) or placebo (n = 59) in the NEURO-TTR study. Anchor-based approaches for estimating RD thresholds were used for Norfolk QOL-DN, while distribution-based approaches were used for both measures. Responders were patients with a score change < RD, indicating improvement or stabilization (i.e., no clinically meaningful progression). Odds ratios (ORs) and Fisher's exact tests compared proportions of responders by treatment. RESULTS: The mean RD estimates were 12.2 points and 8.8 points for mNIS + 7 and Norfolk QOL-DN, respectively. The proportions of patients whose change in score indicated improvement or stabilization were statistically significantly larger for inotersen than placebo for all estimated RD thresholds for mNIS + 7 (64-86% responders for inotersen vs. 27-46% for placebo, ORs = 3.8-7.2, ps < 0.001) and Norfolk QOL-DN (66-81% vs. 35-56%, ORs = 2.4-3.6, ps < 0.05). DISCUSSION: Establishing RD thresholds for these instruments enables evaluation of clinically relevant and individual-level treatment benefit on neuropathic progression. Across RDs estimated using multiple methods, a higher proportion of patients receiving inotersen than placebo showed improved or stabilized neuropathic progression at week 65. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01737398; Date of registration: November 29, 2012.