Increase of HCN current in SOD1-associated amyotrophic lateral sclerosis.

The clinical manifestations of sporadic amyotrophic lateral sclerosis (ALS) vary widely. However, the current classification of ALS is mainly based on clinical presentations, while the roles of electrophysiological and biomedical biomarkers remain limited. Herein, we investigated a group of patients with sporadic ALS and an ALS mouse model with superoxide dismutase 1 (SOD1)/G93A transgenes using nerve excitability tests (NET) to investigate axonal membrane properties and chemical precipitation, followed by enzyme-linked immunosorbent assay analysis to measure plasma misfolded protein levels. Six of 19 patients (31.6%) with sporadic ALS had elevated plasma misfolded SOD1 protein levels. In sporadic ALS patients, only those with elevated misfolded SOD1 protein levels showed an increased inward rectification in the current-threshold (I/V) curve and an increased threshold reduction in the hyperpolarizing threshold electrotonus (TE) in the NET study. Two familial ALS patients with SOD1 mutations also exhibited similar electrophysiological patterns of NET. For patients with sporadic ALS showing significantly increased inward rectification in the I/V curve, we noted an elevation in plasma misfolded SOD1 level, but not in total SOD1, misfolded C9orf72, or misfolded phosphorylated TDP43 levels. Computer simulations demonstrated that the aforementioned axonal excitability changes are likely associated with an increase in hyperpolarization-activated cyclic nucleotide-gated (HCN) current. In SOD1/G93A mice, NET also showed an increased inward rectification in the I/V curve, which could be reversed by a single injection of the HCN channel blocker, ZD7288. Daily treatment of SOD1/G93A mice with ZD7288 partially prevented the early motor function decline and spinal motor neuron death. In summary, sporadic ALS patients with elevated plasma misfolded SOD1 exhibited similar patterns of motor axonal excitability changes as familial ALS patients and ALS mice with mutant SOD1 genes, suggesting the existence of SOD1-associated sporadic ALS. The observed NET pattern of increased inward rectification in the I/V curve was attributable to an elevation in the HCN current in SOD1-associated ALS.

Neck triangle nerve enlargement in hereditary transthyretin amyloidosis correlates with changes in the autonomic, cardiac, and gastrointestinal systems.

BACKGROUND: Hereditary transthyretin amyloidosis (ATTRv) is a hereditary disease that affects multiple bodily systems. Although sonography generally reveals enlargement of nerves in the limbs, the brachial plexus, and vagus nerve, the clinical significance of these findings remains unclear. METHODS: We performed sonographic measurements of the median nerve, cervical spinal nerves at the C5-C7 level, and the vagus nerve in patients with ATTRv and healthy controls. Clinical profiles and cardiac and gastrointestinal examination results were also collected for linear regression analysis. RESULTS: We recruited 47 patients with ATTRv (males/females: 34/13, age: 65.6 ± 5.3 years). The sampled segments were all significantly larger than those of the controls. In the clinical profiles, the sum of the Z scores of the neck triangle nerves (cervical spinal nerves and vagus nerve) and of all nerves (cervical spinal nerves, vagus nerve, and median nerve at the wrist) significantly correlated with the familial amyloid polyneuropathy stage, onset of autonomic nervous system (ANS) symptoms, and autonomic symptom scores. On cardiac examinations, several ultrasonography and magnetic resonance imaging parameters (primarily those that reflect heart volume) were found to be significantly correlated with the sum of the Z scores of the cervical spinal nerves but not with the Z score of the vagus nerve. In gastrointestinal evaluation, the cross-sectional area of the vagus nerve was correlated with gastric emptying time parameters on scintigraphy. CONCLUSIONS: Neck triangle nerve enlargement on sonography correlated with parameters related to ANS dysfunction, indicating that nerve enlargement observed on ultrasonography may serve as a potential surrogate biomarker of ATTRv.

Limbic Connectivity Underlies Pain Treatment Response in Small-Fiber Neuropathy.

OBJECTIVE: Small-fiber neuropathy (SFN) is characterized by neuropathic pain due to degeneration of small-diameter nerves in the skin. Given that brain reorganization occurs following chronic neuropathic pain, this study investigated the structural and functional basis of pain-related brain changes after skin nerve degeneration. METHODS: Diffusion-weighted and resting-state functional MRI data were acquired from 53 pathologically confirmed SFN patients, and the structural and functional connectivity of the pain-related network was assessed using network-based statistic (NBS) analysis. RESULTS: Compared with age- and sex-matched controls, the SFN patients exhibited a robust and global reduction of functional connectivity, mainly across the limbic and somatosensory systems. Furthermore, lower functional connectivity was associated with skin nerve degeneration measured by reduced intraepidermal nerve fiber density and better therapeutic response to anti-neuralgia medications, particularly for the connectivity between the insula and the limbic areas including the anterior and middle cingulate cortices. Similar to the patterns of functional connectivity changes, the structural connectivity was robustly reduced among the limbic and somatosensory areas, and the cognition-integration areas including the inferior parietal lobule. There was shared reduction of structural and functional connectivity among the limbic, somatosensory, striatal, and cognition-integration systems: (1) between the middle cingulate cortex and inferior parietal lobule and (2) between the thalamus and putamen. These observations indicate the structural basis underlying altered functional connectivity in SFN. INTERPRETATION: Our findings provide imaging evidence linking structural and functional brain dysconnectivity to sensory deafferentation caused by peripheral nerve degeneration and therapeutic responses for neuropathic pain in SFN. ANN NEUROL 2023;93:655-667.

Electrodiagnostic subtyping in Guillain-Barré syndrome patients in the International Guillain-Barré Outcome Study.

BACKGROUND AND PURPOSE: Various electrodiagnostic criteria have been developed in Guillain-Barré syndrome (GBS). Their performance in a broad representation of GBS patients has not been evaluated. Motor conduction data from the International GBS Outcome Study (IGOS) cohort were used to compare two widely used criterion sets and relate these to diagnostic amyotrophic lateral sclerosis criteria. METHODS: From the first 1500 patients in IGOS, nerve conduction studies from 1137 (75.8%) were available for the current study. These patients were classified according to nerve conduction studies criteria proposed by Hadden and Rajabally. RESULTS: Of the 1137 studies, 68.3% (N = 777) were classified identically according to criteria by Hadden and Rajabally: 111 (9.8%) axonal, 366 (32.2%) demyelinating, 195 (17.2%) equivocal, 35 (3.1%) inexcitable and 70 (6.2%) normal. Thus, 360 studies (31.7%) were classified differently. The areas of differences were as follows: 155 studies (13.6%) classified as demyelinating by Hadden and axonal by Rajabally; 122 studies (10.7%) classified as demyelinating by Hadden and equivocal by Rajabally; and 75 studies (6.6%) classified as equivocal by Hadden and axonal by Rajabally. Due to more strictly defined cutoffs fewer patients fulfilled demyelinating criteria by Rajabally than by Hadden, making more patients eligible for axonal or equivocal classification by Rajabally. In 234 (68.6%) axonal studies by Rajabally the revised El Escorial (amyotrophic lateral sclerosis) criteria were fulfilled; in axonal cases by Hadden this was 1.8%. CONCLUSIONS AND DISCUSSION: This study shows that electrodiagnosis in GBS is dependent on the criterion set utilized, both of which are based on expert opinion. Reappraisal of electrodiagnostic subtyping in GBS is warranted.

The effects of double-filtration plasmapheresis on coagulation profiles and the risk of bleeding.

BACKGROUND/PURPOSE: Double-filtration plasmapheresis (DFPP) can be used to remove circulating pathogenic molecules. By reclaiming filtered albumin, DFPP reduces the need for albumin and plasma replacement. Large proteins, such as fibrinogen, are removed. Our institution adopts a DFPP treatment protocol consisting of active surveillance of coagulation profiles and prophylactic supplementation of blood products containing fibrinogen. This study aims to investigate the effects of consecutive DFPP treatments on serial coagulation profiles and the risk of bleeding under this protocol. METHODS: Serial laboratory data and bleeding events at a single tertiary medical center were prospectively collected. Prophylactic transfusion of cryoprecipitate or fresh frozen plasma (FFP) was instituted if significant coagulopathy or a clinically evident bleeding event was observed. RESULTS: After the first treatment session, plasma fibrinogen levels decreased from 332 ± 106 mg/dL to 96 ± 44 mg/dL in the 37 study patients. In the following sessions, plasma fibrinogen levels were maintained at around 100 mg/dL under prophylactic transfusion. No major bleeding events were recorded, but five (14%) patients experienced minor bleeding. CONCLUSION: DFPP treatment might be performed safely along with active monitoring of coagulation profiles and prophylactic transfusion of cryoprecipitate or FFP.

Patisiran, an RNAi therapeutic for hereditary transthyretin-mediated amyloidosis: Sub-analysis in Taiwanese patients from the APOLLO study.

BACKGROUND: To examine the efficacy and safety of patisiran, an RNA interference therapeutic, in patients from Taiwan with hereditary transthyretin-mediated (hATTR) amyloidosis with polyneuropathy. METHODS: The APOLLO phase 3 trial included patients from Taiwan who received patisiran 0.3 mg/kg intravenously or placebo once every 3 weeks (q3w) for 18 months (18 M), followed by patisiran 0.3 mg/kg q3w in an ongoing global open-label extension (OLE) study. The primary endpoint was change from baseline in modified Neuropathy Impairment Score +7 (mNIS+7) at 18 M. RESULTS: Eighteen Taiwanese patients were enrolled in APOLLO (patisiran, n = 8; placebo, n = 10; all A97S gene variant) and 14 continued in the global OLE. In this Taiwanese sub-population, beneficial treatment effects at 18 M were observed in mNIS+7 (least squares mean difference in change from baseline [patisiran-placebo], -26.5 points; 95% confidence interval: -45.5, -7.5). Patients who switched from placebo to patisiran demonstrated slowing of polyneuropathy progression at month 12 in the global OLE, while those who received patisiran in APOLLO maintained the beneficial treatment effects. Patisiran had an acceptable safety profile in the Taiwanese sub-population. CONCLUSION: This analysis suggests that patisiran is well tolerated and may provide a substantial clinical benefit for Taiwanese patients with hATTR amyloidosis with polyneuropathy. TRIAL REGISTRATION INFORMATION: The studies were registered on the ClinicalTrials.gov. The APOLLO study ClinicalTrials.gov identifier is NCT01960348 (https://clinicaltrials.gov/ct2/show/NCT01960348), with the registration date of October 10, 2013, and the first patient was enrolled on December 13, 2013. For the global OLE, the ClinicalTrials.gov identifier is NCT02510261 (https://clinicaltrials.gov/ct2/show/NCT02510261) with the registration date of July 29, 2015, and the first patient was enrolled on July 13, 2015. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that treatment with patisiran is safe and efficacious in Taiwanese patients with hereditary transthyretin-mediated amyloidosis with polyneuropathy.

Use of technetium-99m-pyrophosphate single-photon emission computed tomography/computed tomography in monitoring therapeutic changes of RNA interference therapeutics in patients with hereditary transthyretin amyloid cardiomyopathy.

BACKGROUND: RNA interference therapeutics reduce transthyretin production; however, their effect on hereditary transthyretin amyloid cardiomyopathy (ATTR-CA) remains unclear. We aimed to investigate alterations in technetium-99 m (99mTc)-pyrophosphate (PYP) single-photon emission computed tomography/computed tomography (SPECT/CT) outcomes in patients receiving patisiran or vutrisiran. METHODS: We retrospectively identified individuals with hereditary ATTR-CA who received patisiran or vutrisiran. First and second 99mTc-PYP SPECT/CT data, including visual grading, planar heart to contralateral lung (H/CL) ratio, and volumetric heart to lung (H/L) ratio were assessed. RESULTS: Eight patients with hereditary ATTR-CA were enrolled. Cohort A included four patients who underwent their first 99mTc-PYP SPECT/CT imaging at the initiation of small interfering RNA (siRNA) treatment, while cohort B comprised four patients who had been receiving siRNA treatment before their first 99mTc-PYP SPECT/CT imaging (median duration 1281 days). Overall, there were numerical reductions in planar H/CL ratio (1.7 ± 0.2 to 1.6 ± 0.1, p = 0.050) and a significant improvement in volumetric H/L ratio (4.0 ± 0.9 to 3.5 ± 0.4, p = 0.035). Although without significance, subgroup analysis showed more pronounced changes in cohort A for both planar H/CL ratio and volumetric H/L ratio (-20.1 ± 12.6% and -17.1 ± 11.4%) compared to cohort B (-3.3 ± 11.2% and -4.3 ± 12.7%). CONCLUSION: Our results demonstrated a significant decrease in volumetric H/L ratio in hereditary ATTR-CA patients receiving RNA interference therapeutics.

Nonpermissive Skin Environment Impairs Nerve Regeneration in Diabetes via Sec31a.

OBJECTIVE: Although the microenvironment for peripheral nerve regeneration is permissive, such a mechanism is defective in diabetes, and the molecular mediators remain elusive. [Correction added on May 11, 2022, after first online publication: In the preceding sentence, "is ok" was changed to "is defective".] This study aimed to (1) investigate the relationship between skin innervation and collagen pathology in diabetic neuropathy and to (2) clarify the molecular alterations that occur in response to hyperglycemia and their effects on axon regeneration. METHODS: We addressed this issue using two complementary systems: (1) human skin from patients with diabetic neuropathy and to (2) a coculture model of human dermal fibroblasts (HDFs) with rat dorsal root ganglia neurons in the context of intrinsic neuronal factor and extrinsic microenvironmental collagen and its biosynthetic pathways. RESULTS: In diabetic neuropathy, the skin innervation of intraepidermal nerve fiber density (IENFd), a measure of sensory nerve degeneration, was reduced with similar expression of a growth associated protein 43, a marker of nerve regeneration. In contrast, the content and packing of collagen in the diabetic skin became more rigid than the control skin. Sec31a, a protein that regulates the collagen biosynthetic pathway, was upregulated and inversely correlated with IENFd. In the cell model, activated HDFs exposed to high-glucose medium enhanced the expression of Sec31a and collagen I through the activation of transforming growth factor ß, a profibrotic molecule. Sec31a upregulation impaired neurite outgrowth. This effect was reversed by silencing Sec31a expression and neurite outgrowth was resumed. INTERPRETATION: The current study provides evidence that Sec31a plays a key role in inhibiting nerve regeneration in diabetic neuropathy. ANN NEUROL 2022;91:821-833.

Eplontersen for Hereditary Transthyretin Amyloidosis With Polyneuropathy.

Importance: Transthyretin gene silencing is an emerging treatment strategy for hereditary transthyretin (ATTRv) amyloidosis. Objective: To evaluate eplontersen, an investigational ligand-conjugated antisense oligonucleotide, in ATTRv polyneuropathy. Design, Setting, and Participants: NEURO-TTRansform was an open-label, single-group, phase 3 trial conducted at 40 sites across 15 countries (December 2019-April 2023) in 168 adults with Coutinho stage 1 or 2 ATTRv polyneuropathy, Neuropathy Impairment Score 10-130, and a documented TTR variant. Patients treated with placebo from NEURO-TTR (NCT01737398; March 2013-November 2017), an inotersen trial with similar eligibility criteria and end points, served as a historical placebo ("placebo") group. Interventions: Subcutaneous eplontersen (45 mg every 4 weeks; n = 144); a small reference group received subcutaneous inotersen (300 mg weekly; n = 24); subcutaneous placebo weekly (in NEURO-TTR; n = 60). Main Outcomes and Measures: Primary efficacy end points at week 65/66 were changes from baseline in serum transthyretin concentration, modified Neuropathy Impairment Score +7 (mNIS+7) composite score (scoring range, -22.3 to 346.3; higher scores indicate poorer function), and Norfolk Quality of Life Questionnaire-Diabetic Neuropathy (Norfolk QoL-DN) total score (scoring range, -4 to 136; higher scores indicate poorer quality of life). Analyses of efficacy end points were based on a mixed-effects model with repeated measures adjusted by propensity score weights. Results: Among 144 eplontersen-treated patients (mean age, 53.0 years; 69% male), 136 (94.4%) completed week-66 follow-up; among 60 placebo patients (mean age, 59.5 years; 68% male), 52 (86.7%) completed week-66 follow-up. At week 65, adjusted mean percentage reduction in serum transthyretin was -81.7% with eplontersen and -11.2% with placebo (difference, -70.4% [95% CI, -75.2% to -65.7%]; P < .001). Adjusted mean change from baseline to week 66 was lower (better) with eplontersen vs placebo for mNIS+7 composite score (0.3 vs 25.1; difference, -24.8 [95% CI, -31.0 to -18.6; P < .001) and for Norfolk QoL-DN (-5.5 vs 14.2; difference, -19.7 [95% CI, -25.6 to -13.8]; P < .001). Adverse events by week 66 that led to study drug discontinuation occurred in 6 patients (4%) in the eplontersen group vs 2 (3%) in the placebo group. Through week 66, there were 2 deaths in the eplontersen group consistent with known disease-related sequelae (cardiac arrhythmia; intracerebral hemorrhage); there were no deaths in the placebo group. Conclusions and Relevance: In patients with ATTRv polyneuropathy, the eplontersen treatment group demonstrated changes consistent with significantly lowered serum transthyretin concentration, less neuropathy impairment, and better quality of life compared with a historical placebo. Trial Registration: ClinicalTrials.gov Identifier: NCT04136184; EU Clinical Trials Register: EudraCT 2019-001698-10.

On-Table Catheter-Based Neurosalvage Performed by Cardiologists for Embolic Complication during an Endovascular Procedure.

Objectives: To report our experience and clinical results of neurosalvage techniques, performed by interventional cardiologists without moving the patient, to manage cerebral thromboembolic complications. Background: Iatrogenic emboli may be released during an endovascular procedure, causing permanent neurological complications and catastrophic outcomes. Methods: Between July 2013 and December 2017, a total of eight patients suffered from embolic complications during endovascular procedures (two radiofrequency catheter ablation, five coronary angiogram/angioplasty, and one subclavian artery angioplasty). Catheter-based neurosalvage was attempted by experienced interventional cardiologists promptly in the same catheterization room. Results: The embolized locations were the M1 segment of the middle cerebral artery in four patients, the M2/M3 segments in three, and the basilar artery in one. Access to the supra-aortic vessels was achieved. Local intra-arterial thrombolysis was given in five patients (63%) and balloon angioplasty in three (38%). Intra-arterial thrombectomy with a stent retriever was attempted in three patients but failed in one. A combination of different techniques was used in three patients (38%). Final thrombolysis in cerebral infarction grade 3 flow was achieved in seven patients (88%). Favorable clinical outcomes at 1-month follow-up (modified Rankin scale of 0-2) were observed in seven patients (88%), and none of the patients had died at 12 months. Conclusions: Our experience demonstrated that acute embolic complications during an endovascular procedure can be salvaged by interventional cardiologists with acceptable angiographic and clinical results.

Efficacy of Tafamidis in Patients with Ala97Ser Hereditary Transthyretin Cardiac Amyloidosis: A Six-Month Follow-Up Study.

Background: Hereditary transthyretin amyloid cardiomyopathy (ATTR-CM) is a progressive and fatal disease. A97S (p.Ala117Ser) is the most common transthyretin genetic mutation in Taiwan. Tafamidis is a transthyretin stabilizer, and it has been shown to improve outcomes. However, its effect on A97S ATTR-CM subtypes remains unknown. Objectives: This study aimed to investigate the efficacy of tafamidis in patients with hereditary A97S ATTR-CM after 6 months of treatment. Methods: We retrospectively analyzed ATTR-CM patients who received tafamidis (61 mg/day) treatment at National Taiwan University Hospital. Functional status, biochemistry and echocardiography were measured at baseline and after 6 months of tafamidis treatment. The outcome measure was to compare the N-terminal pro-brain natriuretic peptide (NT-proBNP) level at baseline and after 6 months of tafamidis treatment. Results: Twenty patients were enrolled in this study. Their mean age was 63.0 ± 5.8 years and 75% were men. The baseline left ventricular (LV) mass index was 200.9 ± 63.9 g/m2, and the baseline LV ejection fraction was 58.9 ± 13.5%. After 6 months of treatment, the log NT-proBNP level significantly improved from 2.9 ± 0.6 to 2.7 ± 0.5 (p = 0.036). Subgroup analysis showed that the LV posterior wall thickness and left atrial diameter were significantly higher in the patients with improved NT-proBNP, suggesting the benefits of tafamidis for ATTR-CM patients with severe cardiac involvement. Conclusions: The patients with hereditary A97S ATTR-CM in this study had decreased levels of NT-proBNP after 6 months of tafamidis treatment, and this reduction was especially pronounced in those with more severe cardiac involvement.

Maladaptive motor cortical excitability and connectivity in polyneuropathy with neuropathic pain.

BACKGROUND AND PURPOSE: Sensory symptoms, especially neuropathic pain, are common in polyneuropathy. Conventional diagnostic tools can evaluate structural or functional impairment of nerves but cannot reveal mechanisms of neuropathic pain. Changes in the brain after polyneuropathy may play roles in the genesis of neuropathic pain. METHODS: This cross-sectional study investigated changes of cortical excitability within left primary motor cortex (M1) by measuring resting motor thresholds, short-interval intracortical inhibition (SICI), intracortical facilitation (ICF), and afferent inhibition between polyneuropathy patients and controls, and investigated the correlates of these parameters with neuropathic pain and M1 structural and functional connectivity assessed by diffusion tractography imaging and functional magnetic resonance imaging. RESULTS: Thirty-three painful and 15 nonpainful neuropathic patients and 21 controls were enrolled. There were no differences in intraepidermal nerve fiber density, nerve conduction studies, thermal thresholds, or autonomic functional tests between patients with and without neuropathic pain. Compared to controls, neuropathic patients exhibited similar resting motor thresholds or afferent inhibition, but attenuated SICI and augmented ICF, especially in painful patients. Changes of intracortical excitability in neuropathic patients were correlated with intensities of neuropathic pain, and different presentations of SICI and ICF were noted between patients with and without thermal paresthesia. Additionally, short-latency afferent inhibition at an interstimulus interval of 20 ms was associated with structural connectivity of left M1 with brain areas associated with pain perception. CONCLUSIONS: Maladaptive cortical excitability with altered structural connectivity in left M1 developed after peripheral nerve degeneration and was associated with neuropathic pain and sensory symptoms in polyneuropathy.

Diabetic visceral neuropathy of gastroparesis: Gastric mucosal innervation and clinical significance.

BACKGROUND AND PURPOSE: The pathogenesis of diabetic gastroparesis due to visceral neuropathy involves multidimensional mechanisms with limited exploration of gastric mucosal innervation. This study aimed to examine quantitatively this topic and its relationship with gastroparesis symptoms and gastric emptying in diabetes. METHODS: We prospectively enrolled 22 patients with type 2 diabetes and gastroparesis symptoms and 25 age- and gender-matched healthy controls for comparison. The assessments included: (i) neuropathology with quantification of gastric mucosal innervation density (MID) on endoscopic biopsy; (ii) clinical manifestations based on the Gastroparesis Cardinal Symptom Index (GCSI) questionnaire; and (iii) functional tests of gastric emptying scintigraphy (GES). RESULTS: In patients with diabetes, stomach fullness, bloating and feeling excessively full after meals constituted the most common GCSI symptoms. Seven patients with diabetes (32%) had prolonged gastric emptying patterns. In diabetes, gastric MID was significantly lower in all the regions examined compared with the controls: antrum (294.8 ± 237.0 vs. 644.0 ± 222.0 mm/mm3 ; p < 0.001), body (292.2 ± 239.0 vs. 652.6 ± 260.9 mm/mm3 ; p < 0.001), and fundus (238.0 ± 109.1 vs. 657.2 ± 332.8 mm/mm3 ; p < 0.001). Gastric MID was negatively correlated with gastroparesis symptoms and total scores on the GCSI (p < 0.001). Furthermore, gastric MID in the fundus was negatively correlated with fasting glucose and glycated hemoglobin levels. Gastric emptying variables, including half emptying time and gastric retention, were prolonged in patients with diabetes, and gastric retention at 3 h was correlated with fasting glucose level. CONCLUSION: In diabetes, gastric MID was reduced and GES parameters were prolonged. Both were correlated with gastroparesis symptoms and glycemic control. These findings provide pathology and functional biomarkers for diabetic visceral neuropathy of gastroparesis and underlying pathophysiology.

Early changes of nerve integrity in preclinical carriers of hereditary transthyretin Ala117Ser amyloidosis with polyneuropathy.

BACKGROUND AND PURPOSE: 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, were the most frequent neurophysiological abnormality in carriers, could differentiate carriers from controls and diabetic patients, were correlated with IENF densities in carriers but not in controls and diabetic patients, and were correlated with nerve excitability parameters in carriers but not in controls. Fifteen carriers (34.9%) with electrophysiological evidence of median nerve entrapment at the 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.

Mitochondrial UQCRC1 mutations cause autosomal dominant parkinsonism with polyneuropathy.

Parkinson's disease is a neurodegenerative disorder with a multifactorial aetiology. Nevertheless, the genetic predisposition in many families with multi-incidence disease remains unknown. This study aimed to identify novel genes that cause familial Parkinson's disease. Whole exome sequencing was performed in three affected members of the index family with a late-onset autosomal-dominant parkinsonism and polyneuropathy. We identified a novel heterozygous substitution c.941A>C (p.Tyr314Ser) in the mitochondrial ubiquinol-cytochrome c reductase core protein 1 (UQCRC1) gene, which co-segregates with disease within the family. Additional analysis of 699 unrelated Parkinson's disease probands with autosomal-dominant Parkinson's disease and 1934 patients with sporadic Parkinson's disease revealed another two variants in UQCRC1 in the probands with familial Parkinson's disease, c.931A>C (p.Ile311Leu) and an allele with concomitant splicing mutation (c.70-1G>A) and a frameshift insertion (c.73_74insG, p.Ala25Glyfs*27). All substitutions were absent in 1077 controls and the Taiwan Biobank exome database from healthy participants (n = 1517 exomes). We then assayed the pathogenicity of the identified rare variants using CRISPR/Cas9-based knock-in human dopaminergic SH-SY5Y cell lines, Drosophila and mouse models. Mutant UQCRC1 expression leads to neurite degeneration and mitochondrial respiratory chain dysfunction in SH-SY5Y cells. UQCRC1 p.Tyr314Ser knock-in Drosophila and mouse models exhibit age-dependent locomotor defects, dopaminergic neuronal loss, peripheral neuropathy, impaired respiratory chain complex III activity and aberrant mitochondrial ultrastructures in nigral neurons. Furthermore, intraperitoneal injection of levodopa could significantly improve the motor dysfunction in UQCRC1 p.Tyr314Ser mutant knock-in mice. Taken together, our in vitro and in vivo studies support the functional pathogenicity of rare UQCRC1 variants in familial parkinsonism. Our findings expand an additional link of mitochondrial complex III dysfunction in Parkinson's disease.

Skin nerve pathology: Biomarkers of premanifest and manifest amyloid neuropathy.

OBJECTIVE: Small-fiber sensory and autonomic symptoms are early presentations of familial amyloid polyneuropathy (FAP) with transthyretin (TTR) mutations. This study aimed to explore the potential of skin nerve pathologies as early and disease-progression biomarkers and their relationship with skin amyloid deposits. METHODS: Skin biopsies were performed in patients and carriers to measure intraepidermal nerve fiber (IENF) density, sweat gland innervation index of structural protein gene product 9.5 (SGII[PGP9.5]) and peptidergic vasoactive intestinal peptide (SGII[VIP]), and cutaneous amyloid index. These skin pathologies were analyzed with clinical disability assessed by FAP stage score (stage 0-4) and compared to neurophysiological and psychophysical tests. RESULTS: There were 70 TTR-mutant subjects (22 carriers and 48 patients), and 66 cases were TTR-A97S. Skin nerve pathologies were distinct according to stage. In carriers, both skin denervation and peptidergic sudomotor denervation were evident: (1) IENF density was gradually reduced from stage 0 through 4, and (2) SGII(VIP) was markedly reduced from stage 1 to 2. In contrast, SGII(PGP9.5) was similar between carriers and controls, but it declined in patients from stage 2. Skin amyloids were absent in carriers and became detectable from stage 1. Cutaneous amyloid index was correlated with SGII(PGP9.5) and stage in a multivariate mixed-effect model. When all tests were compared, only IENF density, SGII(PGP9.5), and cutaneous amyloid index were correlated with stage, and IENF density had the highest abnormal rate in carriers. INTERPRETATION: Biomarkers of sensory and sudomotor innervation exhibited a stage-dependent progression pattern, with sensory nerve degeneration as the early skin nerve pathology. Ann Neurol 2019;85:560-573.

Cardiac manifestations and prognostic implications of hereditary transthyretin amyloidosis associated with transthyretin Ala97Ser.

BACKGROUND: The cardiac manifestations of late-onset hereditary transthyretin amyloidosis with p.A97S variant have not been extensively studied, and the prognostic factors remain unclear. METHODS: The clinical profile, echocardiography, and ECG of patients diagnosed with ATTR p.A97S polyneuropathy between 2000 and 2016 were retrospectively collected. 67 patients with ATTR p.A97S were collected. RESULTS: A total of 82% of patients met the criteria for left ventricular (LV) hypertrophy. Reduced global longitudinal strain (GLS) was noted in 42.1% of patients, and 14% of patients had a relative apical sparing pattern. A low voltage pattern in the ECG was observed in 31.3% of patients, while 64.2% presented with a pseudoinfarction pattern. End-systolic LV inner dimension (HR: 2.25 (95% CI: 1.01-5.01), p = 0.048), reduced GLS (HR: 5.26 (1.08-25.0), p = 0.039), relative apical longitudinal strain (RALS>1, HR: 8.57 (1.69-43.3), p = 0.009), increased E/A ratio (HR: 6.51 (1.17-36.4), p = 0.033), and increased QRS duration (HR: 1.02 (1.00-1.04), p = 0.05) were correlated with reduced survival in univariate analysis. Multivariate analysis revealed reduced RALS was significantly correlated with reduced survival (HR: 13.00 (1.81-93.45), p = 0.011). CONCLUSION: Our findings reveal that ATTR p.A97S is a cardiomyopathy as well as a polyneuropathic syndrome. Routine use of more contemporary echocardiographic techniques are recommended to identify cardiac amyloidosis and provide prognostic information.

Pathophysiology of Central Poststroke Pain: Motor Cortex Disinhibition and Its Clinical and Sensory Correlates.

Background and Purpose- Central poststroke pain (CPSP) is a disabling condition in stroke patients, and evidence suggests that altered corticospinal and motor intracortical excitability occurs in neuropathic pain. The objective of this study was to investigate changes in motor cortex excitability and sensorimotor interaction and their correlates with clinical manifestations and alterations in somatosensory systems in CPSP patients. Methods- Fourteen patients with CPSP but no motor weakness were compared with age- and sex-matched healthy controls for motor cortex excitability and sensorimotor interaction assessed by transcranial magnetic stimulation to measure resting motor thresholds, short-interval intracortical inhibition, intracortical facilitation, and afferent inhibitions. The sensory pathway was evaluated by quantitative sensory testing, contact heat evoked potential, and somatosensory evoked potentials. Clinical pain and quality of life were assessed with validated tools. Results- The duration of CPSP was 3.3±3.0 years (ranging 0.5-10 years), and pain significantly impaired quality of life. Compared with the unaffected hemisphere, the stroke hemisphere had higher thermal thresholds, lower contact heat evoked potential amplitudes, and prolonged cortical somatosensory evoked potential latencies. There was no difference in resting motor thresholds between the stroke and unaffected hemisphere or between patients and controls. CPSP patients had a reduction in short-interval intracortical inhibition in the stroke hemisphere compared with that in the unaffected hemispheres of patients and controls. No changes were noted in afferent inhibitions between the stroke and unaffected hemispheres. The short-interval intracortical inhibition of the stroke hemisphere was negatively correlated with self-rated health on a visual analog scale and positively correlated with cortical somatosensory evoked potential latencies. Conclusions- CPSP patients with intact corticospinal tracts showed reduced motor intracortical inhibition in the stroke hemisphere, suggesting defective gamma-aminobutyric acid-ergic inhibition. This disinhibition was associated with impaired quality of life and was related to dorsal column-medial lemniscus pathway dysfunction.

Neural activity and CaMKII protect mitochondria from fragmentation in aging Caenorhabditis elegans neurons.

Decline in mitochondrial morphology and function is a hallmark of neuronal aging. Here we report that progressive mitochondrial fragmentation is a common manifestation of aging Caenorhabditis elegans neurons and body wall muscles. We show that sensory-evoked activity was essential for maintaining neuronal mitochondrial morphology, and this activity-dependent mechanism required the Degenerin/ENaC sodium channel MEC-4, the L-type voltage-gated calcium channel EGL-19, and the Ca/calmodulin-dependent kinase II (CaMKII) UNC-43. Importantly, UNC-43 phosphorylated and inhibited the dynamin-related protein (DRP)-1, which was responsible for excessive mitochondrial fragmentation in neurons that lacked sensory-evoked activity. Moreover, enhanced activity in the aged neurons ameliorated mitochondrial fragmentation. These findings provide a detailed description of mitochondrial behavior in aging neurons and identify activity-dependent DRP-1 phosphorylation by CaMKII as a key mechanism in neuronal mitochondrial maintenance.