Nerve ultrasonography findings as possible pitfall in differential diagnosis between hereditary transthyretin amyloidosis with polyneuropathy and chronic inflammatory demyelinating polyneuropathy

Quantitative muscle ultrasound as a disease biomarker in hereditary transthyretin amyloidosis with polyneuropathy

INTRODUCTION

There is an increasing need for a reproducible and sensitive outcome measure in patients with hereditary transthyretin amyloidosis (ATTRv) with polyneuropathy (PN) due to the emergence of disease modifying therapies. In the current study, we aimed to investigate the role of quantitative muscle ultrasound (QMUS) as a disease biomarker in ATTRv-PN.

METHODS

Twenty genetically confirmed ATTRv amyloidosis patients (nine symptomatic, 11 pre-symptomatic) were enrolled prospectively between January to March 2023. Muscle ultrasound was performed on six muscles at standardized locations. QMUS parameters included muscle thickness (MT) and muscle echo intensity (EI). Twenty-five age- and sex-matched healthy controls were recruited for comparison. Significant QMUS parameters were correlated with clinical outcome measures.

RESULTS

Muscle volume of first dorsal interosseus (FDI) muscle [measured as cross-sectional area (CSA)] was significantly lower in symptomatic patients compared to healthy controls and pre-symptomatic carriers (98.3 ± 58.0 vs. 184.4 ± 42.5 vs. 198.3 ± 56.8, p < 0.001). EI of biceps and FDI for symptomatic ATTRv-PN patients were significantly higher compared to the other two groups (biceps: 76.4 ± 10.8 vs. 63.2 ± 11.5 vs. 59.2 ± 9.0, p = 0.002; FDI: 48.2 ± 7.5 vs. 38.8 ± 7.5 vs. 33.0 ± 5.3, p < 0.001). CSA of FDI and EI of biceps and FDI correlated with previous validated outcome measures [polyneuropathy disability score, neuropathy impairment score, Karnofsky performance scale, Rasch-built overall disability scale, European quality of life (QoL)-5 dimensions and Norfolk QoL questionnaire-diabetic neuropathy].

CONCLUSION

QMUS revealed significant difference between ATTRv amyloidosis patients and healthy controls and showed strong correlation with clinical outcome measures. QMUS serves as a sensitive and reliable biomarker of disease severity in ATTRv-PN.

Focused Neuromuscular Ultrasound Approach for the Diagnosis of Chronic Inflammatory Demyelinating Polyneuropathy

PURPOSE

Previous ultrasonographic studies of individuals with chronic inflammatory demyelinating polyneuropathy (CIDP) have shown nerve enlargement at several sites. This prospective study compares only the bilateral median and ulnar nerves of individuals with CIDP with reference values to determine the clinical usefulness of this focused approach as a diagnostic tool.

METHODS

The cross-sectional area, echogenicity, and vascularity of the bilateral median and ulnar nerves of 25 subjects with CIDP were measured using ultrasound. Nineteen had typical CIDP based on the European Federation of Neurological Societies and the Peripheral Nerve Society guidelines, whereas six had atypical CIDP and were diagnosed based on clinical impression.

RESULTS

Focal nerve enlargement was found in at least one segment in all subjects. Subjects with typical CIDP had larger cross-sectional areas compared with subjects with atypical CIDP.

CONCLUSION

A focused ultrasound study, involving only the median and ulnar nerves, is sensitive for the detection of nerve enlargement in CIDP. Measuring the cross-sectional area of the median and ulnar nerves is clinically feasible and may help establish the diagnosis of CIDP.

Ultrasonographic nerve enlargement in post-transplanted patient with hereditary transthyretin amyloidosis

A 43-year-old male patient with a 7-year history of liver transplantation due to p.Val50Met hereditary transthyretin amyloidosis (ATTRv) persisted with refractory neuropathic pain, distal weakness, and progressive worsening of dysautonomia. Nerve ultrasound was performed showing increased nerve cross-sectional area and enlarged fascicles in proximal sites in both arms, suggestive of amyloidosis. Nerve enlargement is commonly reported in inflammatory and hereditary demyelinating hypertrophic neuropathies but can also be present in deposition diseases. Neuromuscular ultrasound is a tool for the bed-side assessment of peripheral neuropathies and it is useful for early diagnosis of ATTRv.

Enlarged cross-sectional area in peripheral nerves in Swedish patients with hereditary V30M transthyretin amyloidosis

INTRODUCTION

In hereditary transthyretin amyloidosis (ATTRv), two different fibrillar forms causing the amyloid deposition, have been identified, displaying substantially cardiac or neuropathic symptoms. Neuropathic symptoms are more frequent in early-onset patients, whereas late-onset patients, besides cardiac symptoms, seem to develop carpal tunnel syndrome, more often. With ultrasonography (US) of peripheral nerves, it is possible to distinguish structural changes, and enlarged cross-sectional area (CSA). The main purpose of this study was, for the first time, to elucidate US of peripheral nerves in Swedish ATTRv patients at an early stage of the disease, and to evaluate possible early enlarged CSA.

MATERIAL AND METHODS

This prospective study included first visit data of 13 patients, aged 30-88 years, of which 11 with late-onset age. All had a positive V30M mutation. Eight men and six women (aged 28-74 years) served as controls.

RESULTS

Significantly enlarged CSA was seen in ATTRv patients for the tibial nerve at the ankle (p = .001), the sural nerve (p < .001), the peroneal nerve at the popliteal fossa (p = .003), and the ulnar nerve at the middle upper arm (p = .007).

CONCLUSION

US of peripheral nerves could be a valuable tool in disease evaluation and could facilitate monitoring of disease progression.

3-T MR neurography of lumbo-sacral plexus in hereditary transthyretin-related amyloidosis with polyneuropathy

OBJECTIVES

Our aim was to evaluate the ability of magnetic resonance neurography (MRN) of the lumbo-sacral plexus (LSP) to distinguish patients with hereditary transthyretin-related amyloidosis with polyneuropathy (ATTRv-PN) from asymptomatic variant carriers (AVC) and healthy controls and to assess its prognostic value.

METHODS

Three-Tesla MRN was performed in 25 consecutive ATTRv-PN patients, 18 AVC, and 10 controls including T2-w DIXON and DWI MR sequences. Two blinded readers independently assessed LSP root diameter and intraneural signal on the MRN images of each subject. MRN findings were compared between groups and correlated with clinical impairment scored on the Neuropathy Impairment Score (NIS) and the modified Polyneuropathy Disability score (mPND).

RESULTS

The agreement between readers on MRN images was excellent (Cohen's kappa = 0.82). LSP root enlargement was significantly more frequent in ATTRv-PN patients compared to AVC (ratio = 4.38, p = 0.038). Increased LSP root intraneural signal on T2-w images was significantly more frequent in ATTRv-PN patients compared to AVC (ratio = 3.4, p = 0.016). In contrast, there were no MRN abnormalities in controls. In ATTRv-PN patients, LSP root enlargement was associated with higher mPND scores (p = 0.03) and increased intraneural signal on T2-w images was associated with significantly higher NIS and mPND scores (p = 0.004 and 0.02, respectively).

CONCLUSIONS

MRN of the LSP can help differentiate ATTRv-PN patients from AVC. LSP root enlargement and increased intraneural signal are significantly associated with clinical impairment, suggesting potential implications for patient care.

KEY POINTS

• ATTRv-PN patients showed abnormal LSP changes on MRN. • MRN of the LSP can help to differentiate ATTRv-PN patients from AVC and healthy controls. • LSP root enlargement and increased intraneural signal were significantly associated with clinical impairment in ATTRv-PN patients.

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.

Nerve Ultrasound Comparison Between Transthyretin Familial Amyloid Polyneuropathy and Chronic Inflammatory Demyelinating Polyneuropathy

Backgrounds: Transthyretin familial amyloid polyneuropathy (TTR-FAP) is frequently misdiagnosed as chronic inflammatory demyelinating polyneuropathy (CIDP) because of similar phenotypes in the two diseases. This study was intended to identify the role of nerve ultrasonography in evaluating TTR-FAP and CIDP.

Methods: Eighteen patients with TTR-FAP, 13 patients with CIDP, and 14 healthy controls (HC) were enrolled in this study. Consecutive ultrasonography scanning was performed in six pairs of nerves of bilateral limbs with 30 sites. The cross-sectional areas (CSAs) and CSA variability data of different groups were calculated and compared.

Results: Both TTR-FAP and CIDP showed larger CSAs at most sites of both upper and lower limbs than in HC groups. CIDP patients had larger CSAs than TTR-FAP patients at 8/15 of these sites, especially at U1-3, Sci2 sites (p < 0.01). However, the CSAs at above sites were not a credible index to differentiate TTR-FAP from CIDP with a low area under the curve (<0.8). The CSA variability of median nerves was significantly higher in CIDP than in TTR-FAP and HC groups, with high sensitivity (0.692) and specificity (0.833) to differentiate CIDP from TTR-FAP. The CSA variability of ulnar nerves was not significantly different between the three groups. For the TTR-FAP group, mean CSAs at each site were not correlated with different Coutinho stages, modified polyneuropathy disability, course of sensory motor peripheral neuropathy, Neuropathy Impairment Score, or Norfolk Quality of life-diabetic neuropathy score. The mean compound muscle action potential of ulnar nerves was negatively correlated with the mean CSAs of ulnar nerves.

Interpretation: TTR-FAP patients had milder nerve enlargement with less variability in CSAs of median nerves than those with CIDP, suggesting that nerve ultrasound can be a potential useful auxiliary tool to help differentiate the two neuropathies.