Jean Pouget

Intravenous immunoglobulin treatment in patients with motor neuron syndromes associated with anti‐GM1 antibodies A double‐blind, placebo‐controlled study

We studied the effects of intravenous immunoglobulin (IVIg) in 12 patients with motor neuron syndromes associated with high titers of anti-GM1 antibodies. Five of the patients had conduction blocks. The study design was a double-blind, placebo-controlled, crossover trial with IVIg (0.4 g/kg body weight per day injected for 5 consecutive days). We evaluated the patients before and 5, 28, and 56 days after drug administration using a computerized analyzer for muscle strength, the Norris scale for disability, motor nerve conduction velocities for patients with conduction blocks, and measurements of immunologic markers. Compared with placebo, IVIg induced a significant increase in muscle strength only in the patients with conduction blocks.

A mitochondrial origin for frontotemporal dementia and amyotrophic lateral sclerosis through CHCHD10 involvement

Mitochondrial DNA instability disorders are responsible for a large clinical spectrum, among which amyotrophic lateral sclerosis-like symptoms and frontotemporal dementia are extremely rare. We report a large family with a late-onset phenotype including motor neuron disease, cognitive decline resembling frontotemporal dementia, cerebellar ataxia and myopathy. In all patients, muscle biopsy showed ragged-red and cytochrome c oxidase-negative fibres with combined respiratory chain deficiency and abnormal assembly of complex V. The multiple mitochondrial DNA deletions found in skeletal muscle revealed a mitochondrial DNA instability disorder. Patient fibroblasts present with respiratory chain deficiency, mitochondrial ultrastructural alterations and fragmentation of the mitochondrial network. Interestingly, expression of matrix-targeted photoactivatable GFP showed that mitochondrial fusion was not inhibited in patient fibroblasts. Using whole-exome sequencing we identified a missense mutation (c.176C>T; p.Ser59Leu) in the CHCHD10 gene that encodes a coiled-coil helix coiled-coil helix protein, whose function is unknown. We show that CHCHD10 is a mitochondrial protein located in the intermembrane space and enriched at cristae junctions. Overexpression of a CHCHD10 mutant allele in HeLa cells led to fragmentation of the mitochondrial network and ultrastructural major abnormalities including loss, disorganization and dilatation of cristae. The observation of a frontotemporal dementia-amyotrophic lateral sclerosis phenotype in a mitochondrial disease led us to analyse CHCHD10 in a cohort of 21 families with pathologically proven frontotemporal dementia-amyotrophic lateral sclerosis. We identified the same missense p.Ser59Leu mutation in one of these families. This work opens a novel field to explore the pathogenesis of the frontotemporal dementia-amyotrophic lateral sclerosis clinical spectrum by showing that mitochondrial disease may be at the origin of some of these phenotypes.

Ataxia with oculomotor apraxia type 2: clinical, biological and genotype/phenotype correlation study of a cohort of 90 patients

Ataxia with oculomotor apraxia type 2 (AOA2) is an autosomal recessive disease due to mutations in the senataxin gene, causing progressive cerebellar ataxia with peripheral neuropathy, cerebellar atrophy, occasional oculomotor apraxia and elevated alpha-feto-protein (AFP) serum level. We compiled a series of 67 previously reported and 58 novel ataxic patients who underwent senataxin gene sequencing because of suspected AOA2. An AOA2 diagnosis was established for 90 patients, originating from 15 countries worldwide, and 25 new senataxin gene mutations were found. In patients with AOA2, median AFP serum level was 31.0 microg/l at diagnosis, which was higher than the median AFP level of AOA2 negative patients: 13.8 microg/l, P = 0.0004; itself higher than the normal level (3.4 microg/l, range from 0.5 to 17.2 microg/l) because elevated AFP was one of the possible selection criteria. Polyneuropathy was found in 97.5% of AOA2 patients, cerebellar atrophy in 96%, occasional oculomotor apraxia in 51%, pyramidal signs in 20.5%, head tremor in 14%, dystonia in 13.5%, strabismus in 12.3% and chorea in 9.5%. No patient was lacking both peripheral neuropathy and cerebellar atrophy. The age at onset and presence of occasional oculomotor apraxia were negatively correlated to the progression rate of the disease (P = 0.03 and P = 0.009, respectively), whereas strabismus was positively correlated to the progression rate (P = 0.03). An increased AFP level as well as cerebellar atrophy seem to be stable in the course of the disease and to occur mostly at or before the onset of the disease. One of the two patients with a normal AFP level at diagnosis had high AFP levels 4 years later, while the other had borderline levels. The probability of missing AOA2 diagnosis, in case of sequencing senataxin gene only in non-Friedreich ataxia non-ataxia-telangiectasia ataxic patients with AFP level > or =7 microg/l, is 0.23% and the probability for a non-Friedreich ataxia non-ataxia-telangiectasia ataxic patient to be affected with AOA2 with AFP levels > or =7 microg/l is 46%. Therefore, selection of patients with an AFP level above 7 microg/l for senataxin gene sequencing is a good strategy for AOA2 diagnosis. Pyramidal signs and dystonia were more frequent and disease was less severe with missense mutations in the helicase domain of senataxin gene than with missense mutations out of helicase domain and deletion and nonsense mutations (P = 0.001, P = 0.008 and P = 0.01, respectively). The lack of pyramidal signs in most patients may be explained by masking due to severe motor neuropathy.

Effect of ascorbic acid in patients with Charcot–Marie–Tooth disease type 1A: a multicentre, randomised, double-blind, placebo-controlled trial

BACKGROUND Charcot-Marie-Tooth disease type 1A (CMT1A) is a hereditary peripheral neuropathy that affects roughly one in 5000 births. No specific therapy currently exists for this degenerative disorder, which is characterised by distal progressive muscle atrophy and sensory loss, although ascorbic acid has been shown to reduce demyelination and improve muscle function in a transgenic mouse model of CMT1A. We tested the safety and efficacy of ascorbic acid in adults with CMT1A. METHODS This 12-month, randomised, double-blind, placebo-controlled study was undertaken between September, 2005, and October, 2008. Patients diagnosed with CMT1A according to clinical examination and confirmation by genotyping were randomly assigned in a 1:1:1 ratio to receive 1 g ascorbic acid per day, 3 g ascorbic acid per day, or placebo. Treatment allocation was based on a computer-generated list of random numbers in blocks of 12, with stratification according to study site and sex; all investigators and participants were unaware of treatment allocation. The primary outcome was the Charcot-Marie-Tooth disease neuropathy score (CMTNS) at 12 months. Analysis was by intention to treat. This study is registered with the Orphanet Database, number ORPHA60779. FINDINGS The median change in CMTNS from baseline to 12 months was 0.5 points (95% CI -0.3 to 1.4) for the placebo group (n=62), 0.7 points (0.0 to 1.4) for the 1 g ascorbic acid group (n=56), and -0.4 points (-1.2 to 0.4) for the 3 g ascorbic acid group (n=61). We did not find any significant difference in these changes between the groups (p=0.14). The occurrence of adverse events did not differ between the groups (p=0.74). INTERPRETATION Ascorbic acid at both doses was safe and well tolerated in adults with CMT1A over 12 months. However, there were no significant differences between the groups and the efficacy of ascorbic acid was not shown.

31P NMR spectroscopy and ergometer exercise test as evidence for muscle oxidative performance improvement with coenzyme Q in mitochondrial myopathies

Two patients with mitochondrial encephalomyopathy due to complexes I and IV deficiencies received 150 mg/d of coenzyme Q10 (CoQ). We studied them with a bicycle ergometer exercise test and 31P NMR spectroscopy before and after 10 months of treatment. Before treatment, we observed a low phosphocreatine/inorganic phosphate (PCr/Pi) resting value along with abnormally high resting lactate concentration. During exercise, there was a pronounced acidosis with delayed kinetics of postexercise recovery for blood lactate, pH, PCr, and PCr/Pi ratio. Oxygen uptake during exercise was reduced while the lowering of the ventilatory threshold indicated an early activation of glycolysis. After treatment, the bicycle ergometer exercise test indicated a significant improvement with a decrease in resting blood lactate level, an increase in oxygen consumption during exercise, and an increase in the kinetics of lactate disappearance during the recovery period. A shift of the ventilatory threshold to higher workload was present. 31P NMR spectroscopy confirmed the improvement, showing a significant increase in the PCr/Pi ratio at rest and in the kinetics of recovery for pH, PCr, and PCr/Pi ratio following exercise in patient 1. For patient 2, we observed a less pronounced acidosis correlated with a lesser amount of Pi produced during exercise. These observations indicate an improvement of mitochondrial function and a shift from high to low glycolytic activity in both patients consequent to CoQ treatment.

Long term follow up of multifocal motor neuropathy with conduction block under treatment.

Eighteen patients (15 men, three women; age range 30 to 71 years, mean 45.8 years) with multifocal motor neuropathy treated with high dose intravenous immunoglobulin (IVIg) were evaluated for nine to 48 months (mean follow up 25.3 months). The median time between onset of multifocal motor neuropathy and treatment was 5.8 years. The dose of IVIg was 0.4 g/day for three to five days. The interval between each treatment was determined for each patient by the evaluation of the effect of the first course. Muscle strength was evaluated by a computerised analyser. Clinical improvement was seen in 12 patients treated with IVIg (67%). Isometric strength increased from 32% to 97% (mean 54.5%) of the initial value. Functional scales corroborated these findings. No clear predictive factors of response to IVIg was found except the presence of high titres of IgM anti-GM1 antibodies. Often, patients needed repeated courses of IVIg to maintain the improvement. In two patients, IVIg infusions were stopped without signs of relapse after one year. Four patients were initially treated with prednisone (1 mg/kg/day), without any clear improvement. Five patients with no response to IVIg or who were IVIg dependent were treated with cyclophosphamide, but only one showed improvement. These results show the long term benefits and safety of IVIg in multifocal motor neuropathy but also the transient effect of this expensive treatment in most patients.

Placebo-controlled trial of rituximab in IgM anti-myelin–associated glycoprotein neuropathy

Objective: To determine whether rituximab 375 mg/m2 was efficacious in patients with immunoglobulin M (IgM) anti-myelin–associated glycoprotein antibody demyelinating neuropathy (IgM anti-MAG demyelinating neuropathy). Methods: Fifty-four patients with IgM anti-MAG demyelinating neuropathy were enrolled in this randomized, double-blind, placebo-controlled trial. The inclusion criteria were inflammatory neuropathy cause and treatment (INCAT) sensory score (ISS) ≥4 and visual analog pain scale >4 or ataxia score ≥2. The primary outcome was mean change in ISS at 12 months. Results: Twenty-six patients were randomized to a group receiving 4 weekly infusions of 375 mg/m2 rituximab, and 28 patients to placebo. Intention-to-treat analysis, with imputation of missing ISS values by the last observation carried forward method, showed a lack of mean change in ISS at 12 months, 1.0 ± 2.7 in the rituximab group, and 1.0 ± 2.8 in the placebo group. However, changes were observed, in per protocol analysis at 12 months, for the number of patients with an improvement of at least 2 points in the INCAT disability scale (p = 0.027), the self-evaluation scale (p = 0.016), and 2 subscores of the Short Form–36 questionnaire. Conclusions: Although primary outcome measures provide no evidence to support the use of rituximab in IgM anti-MAG demyelinating neuropathy, there were improvements in several secondary outcomes in per protocol analysis. Level of evidence: This study provides Class I evidence that rituximab is ineffective in improving ISS in patients with IgM anti-MAG demyelinating neuropathy.

Constitutive Activation of the Calcium Sensor STIM1 Causes Tubular-Aggregate Myopathy

Tubular aggregates are regular arrays of membrane tubules accumulating in muscle with age. They are found as secondary features in several muscle disorders, including alcohol- and drug-induced myopathies, exercise-induced cramps, and inherited myasthenia, but also exist as a pure genetic form characterized by slowly progressive muscle weakness. We identified dominant STIM1 mutations as a genetic cause of tubular-aggregate myopathy (TAM). Stromal interaction molecule 1 (STIM1) is the main Ca(2+) sensor in the endoplasmic reticulum, and all mutations were found in the highly conserved intraluminal Ca(2+)-binding EF hands. Ca(2+) stores are refilled through a process called store-operated Ca(2+) entry (SOCE). Upon Ca(2+)-store depletion, wild-type STIM1 oligomerizes and thereby triggers extracellular Ca(2+) entry. In contrast, the missense mutations found in our four TAM-affected families induced constitutive STIM1 clustering, indicating that Ca(2+) sensing was impaired. By monitoring the calcium response of TAM myoblasts to SOCE, we found a significantly higher basal Ca(2+) level in TAM cells and a dysregulation of intracellular Ca(2+) homeostasis. Because recessive STIM1 loss-of-function mutations were associated with immunodeficiency, we conclude that the tissue-specific impact of STIM1 loss or constitutive activation is different and that a tight regulation of STIM1-dependent SOCE is fundamental for normal skeletal-muscle structure and function.

Strategies of segmental stabilization during gait in Parkinson's disease

Abstract This study compared the postural strategies adopted by patients with Parkinson’s disease (PD; n=16) during locomotion to those of elderly controls (n=16). We focused mainly on the head and trunk stabilization modes in sagittal and frontal planes. Subjects were asked to walk at their natural speed on an uniformly gray, flat ground. Gait data were recorded before and 1 h after l-dopa intake and were analyzed by an automatic motion analyser (Elite system). The modes of segmental stabilization adopted by each group were determined by means of the anchoring index, associated with cross-correlation functions between angular movements of pairs of segments. The major findings were: (a) PD patients generally had shorter step length, greater step width, and slower gait velocity than the healthy elderly. (b) No difference in angular dispersion of any anatomical segment studied was observed between the two groups. (c) PD patients had adopted a strategy of head stabilization on the shoulder (”en bloc” functioning of the head-shoulder unit) about the roll axis only. (d) PD patients displayed head and shoulder angular movements around the roll axis that were more correlated than those of controls, confirming their more en bloc functioning. (e) Shoulder and hip were equally stabilized in space in the two groups around the roll axis. (f) There was no difference between the two groups about the pitch axis where an en bloc functioning of the whole trunk was shown. These results are discussed with respect to the similarities observed between the visuo-locomotor PD performances and those of children.

Lewis-Sumner syndrome and multifocal motor neuropathy.

We compared the clinical, electrophysiological, laboratory, and pathological features of 13 patients with Lewis–Sumner syndrome (LSS) with those of 20 patients with multifocal motor neuropathy (MMN). LSS and MMN patients have several common clinical features: age at onset, weakness in the distribution of individual peripheral nerves, mild wasting, cramps and fasciculations, partial areflexia, and frequent stepwise disease course. Cerebrospinal fluid protein level was normal or slightly elevated, but always less than 100 mg/dl. Conduction blocks are the electrophysiological hallmarks of these two neuropathies, and no differences in distribution and number of blocks were found. Contrary to MMN, lower‐limb involvement at onset was frequent in LSS but extension to the upper limbs was a frequent later feature of the disease. Cranial nerve involvement was noted in 4 LSS patients during relapses and absent in all MMN patients. The major distinguishing features were the clinical and electrophysiological sensory involvement in LSS, and the lack of anti‐GM1 antibodies in LSS, whereas IgM anti‐GM1 were found in 40% of MMN patients. Some LSS patients responded to steroid therapy, whereas this was ineffective in MMN. From these features, LSS can be considered an entity distinct from MMN, with its own clinical, laboratory, and electrophysiological characteristics, and as an intermediate link between chronic inflammatory demyelinating polyneuropathy and MMN. Muscle Nerve, 2005