Transthyretin amyloid polyneuropathy in France: A cross-sectional study with 413 patients and real-world tafamidis meglumine use (2009-2019).

OBJECTIVE: We aimed to describe characteristics of patients with ATTR variant polyneuropathy (ATTRv-PN) and ATTRv-mixed and assess the real-world use and safety profile of tafamidis meglumine 20mg. METHODS: Thirty-eight French hospitals were invited. Patient files were reviewed to identify clinical manifestations, diagnostic methods, and treatment compliance. RESULTS: Four hundred and thirteen patients (296 ATTRv-PN, 117 ATTRv-mixed) were analyzed. Patients were predominantly male (68.0%) with a mean age of 57.2±17.2 years. Interval between first symptom(s) and diagnosis was 3.4±4.3 years. First symptoms included sensory complaints (85.9%), dysautonomia (38.5%), motor deficits (26.4%), carpal tunnel syndrome (31.5%), shortness of breath (13.3%), and unexplained weight loss (16.0%). Mini-invasive accessory salivary gland or punch skin and nerve biopsies were most common, with a performance of 78.8-100%. TTR genetic sequencing, performed in all patients, revealed 31 TTR variants. Tafamidis meglumine was initiated in 156/214 (72.9%) ATTRv-PN patients at an early disease stage. Median treatment duration was 6.00 years in ATTRv-PN and 3.42 years in ATTRv-mixed patients. Tafamidis was well tolerated, with 20 adverse events likely related to study drug among the 336 patients. CONCLUSION: In France, ATTRv patients are usually identified early thanks to the national network and the help of diagnosis combining genetic testing and mini-invasive biopsies.

Treating hereditary transthyretin amyloidosis: Present & future challenges.

Hereditary transthyretin amyloidosis (ATTRv) is a rare, lethal, autosomal dominant adult-onset genetic gain-of function (GOF) disorder provoked by mutations in the TTR gene. Until recently, therapeutic options were limited and consisted mainly in liver transplantation and TTR-stabilizers. In the last few years, ATTRv has been at the center of major therapeutic breakthroughs, including development of effective small interfering RNA (siRNA) and antisense oligonucleotide (ASO) treatments targeting liver TTR mRNA. Both siRNA (patisiran) and ASO (inotersen) treatments are now commercially available and have dramatically improved ATTRv neurological outcome. Ongoing clinical trials currently evaluate another siRNA, vutrisiran and a novel ASO formulation, eplontersen. A CRISPR-Cas9-based TTR gene editing treatment is also currently evaluated, with encouraging preliminary results. These recent therapeutic developments demonstrate the shifting paradigm of ATTRv, a previously untreatable and lethal disorder and provide a proof-of-concept for developing siRNA, ASO and CRISPR-Cas9 treatments for other GOF genetic disorders.

French recommendations for the management of adult & pediatric chronic inflammatory demyelinating polyradiculoneuropathy (CIDP).

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a rare autoimmune disorder of the peripheral nervous system, primarily affecting the myelin sheath. The pathophysiology of CIDP is complex, involving both humoral and cellular immunity. The diagnosis of CIDP should be suspected in patients with symmetrical proximal and distal motor weakness and distal sensory symptoms of progressive onset, associated with decreased/abolished tendon reflexes. Treatments include intraveinous immunoglobulins, steroids and plasma exchange, with usually an induction phase followed by a maintenance therapy with progressive weaning. Treatment should be rapidly initiated to prevent axonal degeneration, which may compromise recovery. CIDP outcome is variable, ranging from mild distal paresthesiae to complete loss of ambulation. There have been several breakthroughs in the diagnosis and management of CIDP the past ten years, e.g. discovery of antibodies against the node of Ranvier, contribution of nerve ultrasound and magnetic resonance imaging to diagnosis, and demonstration of subcutaneous immunoglobulins efficiency. This led us to elaborate French recommendations for the management of adult & pediatric CIDP patients. These recommendations include diagnosis assessment, treatment, and follow-up.

Neuropathies périphériques associées aux syndromes lymphoprolifératifs : spectre clinique et démarche diagnostique.

Lymphoproliferative syndromes (multiple myeloma, Waldenström's disease, chronic lymphocytic leukemia, lymphomas) may be associated with peripheral neuropathies. The mechanism can be dysimmune, associated or not with monoclonal gammopathies; paraneoplastic; infiltrative; or more commonly, iatrogenic or due to vitamin deficiency. The diagnosis can be complex, especially when the neuropathy is the presenting manifestation, requiring a close cooperation between internists and neurologists. The positive diagnosis of the neuropathy is based on a systematic electro-clinical investigation, which specifies the topography and the mechanism of the nerve damage, sometimes reinforced by imaging examinations, in particular, nerve and/or plexus MRI. The imputability of the neuropathy to a lymphoproliferative syndrome is based on a set of arguments including the clinical context (B signs, tumour syndrome), first-line laboratory tests (hemogram, protein electrophoresis, viral serologies, complement), auto-antibodies discussed according to the neuropathy (anti-MAG, anti-gangliosides) and sometimes more invasive examinations (bone marrow or neuro-muscular biopsies).

Comparing ataxias with oculomotor apraxia: a multimodal study of AOA1, AOA2 and AT focusing on video-oculography and alpha-fetoprotein.

Whether the recessive ataxias, Ataxia with oculomotor apraxia type 1 (AOA1) and 2 (AOA2) and Ataxia telangiectasia (AT), can be distinguished by video-oculography and alpha-fetoprotein level remains unknown. We compared 40 patients with AOA1, AOA2 and AT, consecutively referred between 2008 and 2015 with 17 healthy subjects. Video-oculography revealed constant impairments in patients such as cerebellar signs, altered fixation, impaired pursuit, hypometric saccades and abnormal antisaccades. Horizontal saccade latencies could be highly increased reflecting oculomotor apraxia in one third of patients. Specific distinctive alpha-fetoprotein thresholds were determined for AOA1 (7-15 µg/L), AOA2 (15-65 µg/L) and AT (>65 µg/L). Early age onset, severe walking disability, movement disorders, sensori-motor neuropathy and cerebellar atrophy were all shared. In conclusion, alpha-fetoprotein level seems to permit a distinction while video-oculography does not and therefore is not mandatory, even if an appropriate oculomotor examination remains crucial. Our findings are that AOA1, AOA2 and AT form a particular group characterized by ataxia with complex oculomotor disturbances and elevated AFP for which the final diagnosis is relying on genetic analysis. These findings could guide genetic analysis, assist reverse-phenotyping and provide background for the interpretation of the numerous variants of unknown significance provided by next-generation sequencing.

Deciphering the causes of sporadic late-onset cerebellar ataxias: a prospective study with implications for diagnostic work.

The management of sporadic late-onset cerebellar ataxias represents a very heterogeneous group of patients and remains a challenge for neurologist in clinical practice. We aimed at describing the different causes of sporadic late-onset cerebellar ataxias that were diagnosed following standardized, exhaustive investigations and the population characteristics according to the aetiologies as well as at evaluating the relevance of these investigations. All patients consecutively referred to our centre due to sporadic, progressive cerebellar ataxia occurring after 40 years of age were included in the prospective, observational study. 80 patients were included over a 2 year period. A diagnosis was established for 52 patients (65%) corresponding to 18 distinct causes, the most frequent being cerebellar variant of multiple system atrophy (n = 29). The second most frequent cause was inherited diseases (including spinocerebellar ataxias, late-onset Friedreich's disease, SLC20A2 mutations, FXTAS, MELAS, and other mitochondrial diseases) (n = 9), followed by immune-mediated or other acquired causes. The group of patient without diagnosis showed a slower worsening of ataxia (p < 0.05) than patients with multiple system atrophy. Patients with later age at onset experienced faster progression of ataxia (p = 0.001) and more frequently parkinsonism (p < 0.05) than patients with earlier onset. Brain MRI, DaT scan, genetic analysis and to some extent muscle biopsy, thoracic-abdominal-pelvic tomodensitometry, and cerebrospinal fluid analysis were the most relevant investigations to explore sporadic late-onset cerebellar ataxia. Sporadic late-onset cerebellar ataxias should be exhaustively investigated to identify the underlying causes that are numerous, including inherited causes, but dominated by multiple system atrophy.

Is deltoid muscle biopsy useful in isolated camptocormia? A prospective study.

BACKGROUND AND PURPOSE: Camptocormia is a marked anterior curvature of the thoracolumbar spine that may be caused by parkinsonism, amyotrophic lateral sclerosis (ALS), myasthenia gravis (MG) and muscle disease. The interest of a systematic muscle biopsy has not been evaluated until now. In our study, the aim was to prospectively evaluate the proportion of patients with isolated camptocormia without ALS, MG and parkinsonism who have an underlying myopathy. METHODS: Twenty consecutive patients (75% female, mean age 70 years) with isolated camptocormia were enrolled in a single centre in this 5-year prospective study. ALS, MG and parkinsonism had been excluded in all cases. A left deltoid muscle biopsy was performed in all patients and processed with standard techniques for histology and immunohistochemistry. Additional biochemical and genetic studies were performed when pathological analysis was consistent with myopathy. RESULTS: A myopathy was identified in seven patients (35%). Three patients presented with mitochondrial myopathy, including two patients harbouring a heterozygous POLG gene pathogenic variant and one patient with a heterozygous RRM2B gene pathogenic variant. Two patients presented with an inflammatory myopathy, including one with anti-PM/Scl antibodies. One patient presented with facioscapulohumeral muscular dystrophy and one patient with an MYH7 gene-related myofibrillar myopathy. No obvious myopathy was found in the 13 remaining cases. DISCUSSION: In this prospective study, an underlying myopathy was found in 35% of patients with isolated camptocormia. These results suggest that a muscle biopsy should be systematically performed in patients with isolated camptocormia when ALS, MG and parkinsonism have been excluded.

The shifting paradigm of Charcot-Marie-Tooth disease.

Molecular studies have created a paradigm shift in our perception of Charcot-Marie-Tooth disease (CMT). Indeed, CMT has evolved from the concept of a rather homogeneous hereditary disease exclusively involving peripheral nerves to the concept of a highly heterogeneous clinical and genetic syndrome mainly - but sometimes not exclusively - involving the peripheral nervous system. The phenotypic spectrum of CMT overlaps with other inherited neuropathies such as distal hereditary motor neuropathy (dHMN), hereditary sensory and autonomic neuropathy (HSAN), spinal muscular atrophy (SMA) subtypes, and the neuropathies of mitochondrial disorders. At a molecular level, mutations in one given gene may alternatively provoke CMT, HSAN, dHMN or SMA variants. Over the last years, there have been dramatic advances in deciphering the molecular basis for many CMT subtypes and more than 900 different mutations in more than 60 causative genes are now described. However, as 75% of CMT causative genes apparently remain unknown and as disease-specific therapies are not available, major advances are yet to come in the field of CMT.

[Investigating peripheral nerve injuries: what's new in 2013?]. / Explorations dans les neuropathies périphériques: revue de la littérature 2013.

Magnetic resonance imaging (MRI) and ultrasonographic (US) investigations have recently became prominent tools for the investigation of peripheral nerve injuries. MRI is the most valuable for the study of proximal nervous structures, i.e. roots and plexi, whereas US is better suited for the investigation of distal nerves, including entrapment syndromes. However, as nerve conduction studies and electromyographic studies still have a better sensitivity and specificity than MRI and US, they remain the gold standard for the evaluation of the peripheral nervous system.

Adult centronuclear myopathies: A hospital-based study.

INTRODUCTION: Centronuclear myopathies (CNM) are rare inherited disorders characterized by nuclei placed in rows in the central part of the muscle fibres. Three CNM-causing genes have been identified, with MTM1 mutations provoking X-linked myotubular myopathy, DNM2 mutations provoking autosomal dominant (AD) CNM, and BIN1 mutations provoking autosomal recessive (AR) CNM. METHODS: In this retrospective monocentric study, we describe 14 adult patients (age>18 years) diagnosed with CNM in our hospital in the 2000-2012 interval. Twelve patients originated from four families, and two patients presented with sporadic CNM. All patients underwent standardized clinical examinations, biological tests, electrophysiological studies, muscle biopsy, and molecular testing. RESULTS: Seven patients developed CNM before age 15, and seven after age 25. All patients presented with distal upper and lower limbs weakness, and normal CK levels. Disease severity remained mild, with all patients being able to walk without assistance even after decades-long disease duration. Cognitive impairment was found in seven cases, axonal polyneuropathy in six cases and ophthalmoparesis and ptosis in five cases. DNM2 gene mutations were found in eight patients, whereas BIN1 and MTM1 mutations were not observed. Overall, no molecular diagnosis was available for six patients. CONCLUSION: Adult CNM is a slowly progressive distal myopathy with normal CK levels sometimes associated with cognitive impairment, axonal polyneuropathy, and ophthalmoparesis and ptosis. DNM2 mutations were found in eight patients, including AD and sporadic cases, and represent the major cause of CNM in this adult cohort. In contrast, no MTM1 and BIN1 mutations were observed in our series, leaving six patients with no molecular diagnosis. As these six patients presented with AD (3 cases), AR (2 cases), and sporadic (1 case) CNM, it is likely that several CNM-causing genes remain to be discovered.

Novel SPG10 mutation associated with dysautonomia, spinal cord atrophy, and skin biopsy abnormality.

BACKGROUND: SPG10 is a rare form of autosomic dominant hereditary spastic paraplegia (HSP) caused by mutations in the KIF5A gene, which may be involved in axonal transport. METHODS: We report the characteristics of a French family with a novel missense mutation c.580 G>C in exon 7 of the KIF5A gene. RESULTS: The proband and his sister presented with an adult onset HSP, a sensory spinal cord-like syndrome, dysautonomia, and severe axonal polyneuropathy. Contrary to the proband, his sister presented a secondary improvement in spasticity and walking. In the proband, MRI findings consisted in spinal cord atrophy and symmetric cerebral demyelination, whereas the skin biopsy suggested a defect in the number of vesicles and synaptophysin density at the pre-synaptic membrane. CONCLUSION: This study extends the phenotype of SPG10 and argues for abnormalities in the axonal vesicular transport.

Muscle phosphorylase kinase deficiency: a neutral metabolic variant or a disease?

OBJECTIVE: To examine metabolism during exercise in 2 patients with muscle phosphorylase kinase (PHK) deficiency and to further define the phenotype of this rare glycogen storage disease (GSD). METHODS: Patient 1 (39 years old) had mild exercise-induced forearm pain, and EMG showed a myopathic pattern. Patient 2 (69 years old) had raised levels of creatine kinase (CK) for more than 6 months after statin treatment. Both patients had increased glycogen levels in muscle and PHK activity <11% of normal. Two novel pathogenic nonsense mutations were found in the PHKA1 gene. The metabolic response to anaerobic forearm exercise and aerobic cycle exercise was studied in the patients and 5 healthy subjects. RESULTS: Ischemic exercise showed a normal 5-fold increase in plasma lactate (peak 5.7 and 6.9 mmol/L) but an exaggerated 5-fold increase in ammonia (peak 197 and 171 µmol/L; control peak range 60-113 µmol/L). An incremental exercise test to exhaustion revealed a blunted lactate response (5.4 and 4.8 mmol/L) vs that for control subjects (9.6 mmol/L; range 7.1-14.3 mmol/L). Fat and carbohydrate oxidation rates at 70% of peak oxygen consumption were normal. None of the patients developed a second wind phenomenon or improved their work capacity with an IV glucose infusion. CONCLUSION: Our findings demonstrate that muscle PHK deficiency may present as an almost asymptomatic condition, despite a mild impairment of muscle glycogenolysis, raised CK levels, and glycogen accumulation in muscle. The relative preservation of glycogenolysis is probably explained by an alternative activation of myophosphorylase by AMP and P(i) at high exercise intensities.

L-2-hydroxyglutaric aciduria diagnosed in a young adult with progressive cerebellar ataxia and facial dyskinesia.

INTRODUCTION: L-2-hydroxyglutaric aciduria is a rare metabolic disorder with quite typical radiological abnormalities and various clinical symptoms. OBSERVATION: A 19-year-old girl presented with ataxia, facial dyskinesia, and mild cognitive impairment. Cerebral magnetic resonance imaging demonstrated subcortical white matter T2 abnormalities and a suggestive rim hyperintensity around the caudate nuclei and the putamen. Diagnosis was confirmed by increased 2-hydroxyglutaric acid in urine and a genetic study (Gly260Ala mutation in the L-2-hydroxyglutarate dehydrogenase (L2HGDH) gene). DISCUSSION: This case highlights the movement disorder onset and radiological aspects that should indicate the L-2-hydroxyglutaric aciduria diagnosis.

[Peripheral neuropathies after bariatric surgery]. / Polyneuropathies après chirurgie bariatrique.

INTRODUCTION: Peripheral neuropathies sometimes complicate bariatric surgery. PATIENTS AND METHODS: We report the detailed clinical, electrophysiological, biological and histological characteristics of five patients who developed peripheral neuropathy after bariatric surgery. RESULTS: Three patients presented with small fiber neuropathy, one presented with axonal polyneuropathy, and one with demyelinating polyradiculoneuropathy. All patients had in common prominent neuropathic pain, massive weight loss, and multiple nutritional deficiencies. The pathophysiology of postbariatric surgery polyneuropathies is complex and involves nutritional, infectious and dysimmune mechanisms. CONCLUSION: The spectrum of peripheral neuropathies complicating bariatric surgery is wide, and includes pure small fiber neuropathy, axonal polyneuropathy, and demyelinating polyradiculoneuropathy. Treatment is mainly preventive, but sometimes surgical revision is needed.

[Research in amyotrophic lateral sclerosis: what is new in 2009?]. / La recherche sur la SLA en 2009 : compte rendu du groupe bibliographique de la coordination des centres SLA.

This paper, written by French amyotrophic lateral sclerosis (ALS) center experts, presents an update of recent advances in fundamental, epidemiological and clinical research in ALS based on a review of the literature between September 2008 and November 2009. Among other pathophysiological mechanisms, the role of stress of the endoplasmic reticulum and the importance of energetic metabolic disturbances have been underscored. In the field of genetics, research has been advanced through the identification of mutations of the gene FUsed in Sarcoma/Translated in LipoSarcoma (FUS/TLS) in individuals with familial and sporadic ALS. This gene is involved in the regulation of transcription, splicing and RNA transport, and has functional homology to another ALS gene, TARDBP, which suggests that a common mechanism may underlie motor neuron degeneration. A report showed that mice expressing a mutant form of human TDP-43 develop a progressive and fatal neurodegenerative disease reminiscent of both ALS and frontotemporal lobar degeneration with ubiquitin aggregates (FTLD-U), providing a new animal model that may help to better understand the pathophysiology and test new therapeutics. Beside genetic studies, several epidemiologic studies have investigated the role of environmental factors. A recent study suggests that smoking is a risk factor for developing ALS and it is hypothesized that this could occur through lipid peroxidation via formaldehyde exposure. From a neuroprotective perspective, trials with IGF-1, sodium valproate, coenzyme Q or glatiramer acetate have failed to demonstrate any beneficial effect. A study published in 2008 argued that lithium may have a neuroprotective effect in ALS mice and also in patients. However, two preclinical studies failed to replicate the neuroprotective effect of lithium in ALS mice. Therapeutic trials have been performed or are currently ongoing in Europe and North America. Their results have not yet been published.