The epidemiology of the Lambert-Eaton myasthenic syndrome in the Netherlands.
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Biomedical subjects
Publications and source records attributed to J H Wokke.
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A 41-year-old woman had a 15-year history of pain in her thighs and arms, which also became weaker, and a decrease in visual acuity. Her 35-year-old brother, their 38-year-old sister and their 64-year-old mother also had myalgia, myotonia and proximal muscle weakness, and the women also had cataracts. Additional examinations and tests led to a diagnosis of proximal myotonic myopathy (PROMM) in all four cases. Neurological and ophthalmological follow-up was provided on a yearly basis, including ECG. The clinical features of PROMM display similarities to the adult form of myotonic dystrophy (MD) but differ in the proximal localisation of the muscle weakness and the frequent occurrence of pain in the affected muscles. PROMM is an autosomal dominant hereditary multisystemic disorder with a less serious course than MD and is rarely accompanied by cognitive disorders. In most cases, a genetic defect on chromosome 3q21 is the cause of the disease. A probable diagnosis can be made on the basis of the clinical symptoms and the results of simple laboratory tests, and can be confirmed via DNA analysis. As yet, the disorder can only be treated symptomatically, preferably via a multidisciplinary approach by a neurologist, an ophthalmologist, a cardiologist and a rehabilitation specialist.
Hyper-creatine-kinase(CK)-aemia in patients without neurological abnormalities may be sign of a subclinical neuromuscular disorder. Initial screening of patients with hyper-CK-aemia must include careful history taking and a neurological examination. Appropriate blood tests to exclude aeanthocytosis and glycogen storage disease type II must be done. The diagnostic value of a skeletal muscle biopsy and electromyography is small. A muscle biopsy to exclude dystrophinopathy is indicated if the CK activity exceeds 5 times the upper limit of the normal range. If the results of initial screening are normal, patients with idiopathic hyper-CK-aemia fare quite well at 7-year follow-up. Also, standardized exercise tests in these patients have provided no evidence of increased muscle vulnerability. Thus, in most of these patients, hyper-CK-aemia probably does not reflect disease.
BACKGROUND: Trophic factors, including recombinant human insulin-like growth factor I have been postulated as possible disease modifying therapies for amyotrophic lateral sclerosis. Randomised clinical trials of recombinant human insulin-like growth factor I in amyotrophic lateral sclerosis to date have yielded conflicting results. OBJECTIVES: The main objective of this review was to examine the efficacy of recombinant human insulin-like growth factor I in amyotrophic lateral sclerosis. Occurrence of adverse events has also been reviewed. SEARCH STRATEGY: A search was carried out using the Cochrane Neuromuscular Disease Group register for randomised clinical trials of recombinant human insulin-like growth factor I in amyotrophic lateral sclerosis. Enquiries were also made of authors of randomised clinical trials as well as the manufacturers of recombinant human insulin-like growth factor I regarding any other randomised clinical trials which had not yet been published. SELECTION CRITERIA: Types of studies: all randomised controlled clinical trials involving recombinant human insulin-like growth factor I treatment of amyotrophic lateral sclerosis. TYPES OF PARTICIPANTS: Adults with a clinical diagnosis of definite or probable amyotrophic lateral sclerosis according to the El Escorial Criteria. Types of interventions: Treatment with recombinant human insulin-like growth factor I or placebo. Types of outcome measures: Primary: Change in Appel Amyotrophic Lateral Sclerosis Rating Scale (AALSRS) total score with 0.1mg/kg/day of recombinant human insulin-like growth factor I after nine months treatment. Secondary: Change in AALSRS with recombinant human insulin like growth factor I 0.1mg/kg/day and 0.05mg/kg/day at 1, 2, 3, 4, 5, 6, 7, 8, 9 months, change in quality of life (Sickness Impact Profile scale), survival and adverse events. DATA COLLECTION AND ANALYSIS: We identified two randomised clinical trials. Each reviewer graded them for methodological quality. Data were extracted and entered by the lead reviewer and checked by the other two. Some missing data had to be regenerated by calculations based on ruler measurements of data presented in published graphs. MAIN RESULTS: The primary outcome measure was change in disease progression as determined by the Appel ALS Rating Scale total score with 0.1 mg/kg/day of recombinant human insulin-like growth factor I subcutaneously after nine months treatment. The level of significance was lower in the European trial which compared 59 patients on placebo with 124 on insulin-like growth factor I 0.1 mg/kg/day (weighted mean difference -3.30, 95%CI -8.68 to 2.08) than in the North American trial which compared 90 patients on placebo with 89 on recombinant human insulin-like growth factor I 0.05 mg/kg/day 89 patients and 87 patients on 0.1mg/kg/day (weighted mean difference -6.00, 95%CI -10.99 to -1.01). The combined analysis from both randomised clinical trials showed a weighted mean difference of -4.75 (95% CI -8.41 to -1.09) favouring the treated group. The secondary outcome measures showed similar trends favouring recombinant human insulin-like growth factor I but these did not reach significance at the five per cent level. Similarly the data with the 0.05mg/kg/day dose showed trends favouring recombinant human insulin-like growth factor I at all time points but did not reach significance at the five per cent level at any point. Evaluation of adverse events showed an increased risk of injection site reactions/inflammation with recombinant human insulin-like growth factor I (relative risk 2.53, 95% CI 1.40 to 4.59). The drug was otherwise safe and well tolerated. REVIEWER'S CONCLUSIONS: Recombinant human insulin-like growth factor I may be modestly effective but the evidence currently available is insufficient for a definitive assessment. Further randomised clinical trials need to be done.
BACKGROUND: Myasthenia gravis and the Lambert-Eaton myasthenic syndrome (LEMS) may have a similar distribution of muscle weakness. Deciding on a diagnosis of myasthenia gravis or LEMS on clinical grounds may therefore be difficult. OBJECTIVE: To compare the localisation of initial muscle weakness and the distribution of weakness at the time of maximum severity in patients with myasthenia gravis and LEMS. SUBJECTS: 101 patients with myasthenia gravis and 38 patients with LEMS. RESULTS: In myasthenia gravis, initial weakness involved extraocular muscles in 59%, bulbar muscles in 29%, and limb muscles in 12% of the patients. In LEMS no patient had ocular weakness, 5% had bulbar weakness, and 95% had weakness of the limbs as the first symptom (p < 0.001). At the point of maximum severity, weakness in myasthenia gravis was purely ocular in 25%, oculobulbar in 5%, restricted to the limbs in 2%, and present in both oculobulbar muscles and limbs in 68%. At this point, none of the LEMS patients had weakness restricted to extraocular or bulbar muscles (p = 0.002). The legs were affected in all LEMS patients, whereas in 12 patients with generalised myasthenia gravis limb weakness was restricted to the arms (p = 0.024). CONCLUSIONS: In a patient suspected to have a myasthenic syndrome whose first symptom is ocular weakness, LEMS is virtually excluded. Limb weakness confined to the arms is only found in generalised myasthenia gravis and not in LEMS. Muscle weakness in myasthenia gravis tends to develop in a craniocaudal direction, and in the opposite direction in LEMS.
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All patients with amyotrophic lateral sclerosis (ALS) are treated with the same dose of riluzole: 50 mg twice daily. Reasonably large interindividual differences in clearance of the drug have been reported. The relatively small group of patients with high blood concentrations of riluzole has probably primarily influenced the efficacy and the incidence of side-effects in the previously conducted clinical trials with riluzole. Individual dosing of the drug may, in the case of large interindividual differences in serum concentrations of the drug, be necessary in the future. Exact data concerning the plasma and serum concentrations of riluzole in patients with ALS, after standardized intake of the drug, diet and blood sampling are unknown so far. In this study, inter- and intraindividual variability of serum and plasma levels of riluzole in 21 patients with "probable" or "definite" ALS were determined. The interindividual variability of peak serum levels (coefficient of variation=74%) was significantly larger than intraindividual variability (p<0.001). Serum levels were not correlated with age or smoking status. The determination of a correlation between riluzole serum concentrations and survival of patients with ALS will be the aim of further studies.
BACKGROUND: Spinal muscular atrophy (SMA) results from mutations of the survival motor neuron (SMN) gene on chromosome 5. The SMN gene exists in two highly homologous copies, telomeric (SMN1) and centromeric (SMN2). SMA is caused by mutations in SMN1 but not SMN2. The clinical phenotype of SMA appears to be related to the expression of SMN2. Patients suffering from the milder forms of SMA carry more copies of the SMN2 gene compared with patients with more severe SMA. It is suggested that the SMN2 gene is translated into an at least partially functional protein that protects against loss of motor neurons. OBJECTIVE: To investigate whether genetic mechanisms implicated in motor neuron death in SMA have a role in ALS. METHODS: The presence of deletions of exons 7 and 8 of SMN1 and SMN2 was determined in 110 patients with sporadic ALS and compared with 100 unaffected controls. RESULTS: The presence of a homozygous SMN2 deletion was overrepresented in patients with ALS compared with controls (16% versus 4%; OR, 4.4; 95% CI, 1.4 to 13.5). Patients with a homozygous SMN2 deletion had a shorter median time of survival (p < 0.009). Furthermore, multivariate regression analysis showed that the presence of an SMN2 deletion was independently associated with survival time (p < 0.02). No homozygous deletions in SMN1 were found. Carrier status of SMA appeared to be equally present in patients and controls (1 in 20). CONCLUSION: These results indicate that, similar to SMA, the SMN2 gene can act as a prognostic factor and may therefore be a phenotypic modifier in sporadic ALS. Increasing the expression of the SMN2 gene may provide a strategy for treatment of motor neuron disease.
BACKGROUND: In polyneuropathy associated with immunoglobulin M (IgM) monoclonal gammopathy, antibodies to myelin-associated glycoprotein (MAG), sulfoglucuronyl paragloboside (SGPG), and sulfatide have been associated with specific clinical and electrophysiologic features. However, it is not known whether the results of antibody tests provide additional information for the individual patient (and the neurologist) in terms of future neurologic deficit or outcome. OBJECTIVE: To study the independent contribution of potential prognostic factors to the prediction of outcome of neuropathy associated with IgM monoclonal gammopathy. METHODS: In accordance with the chronology in which prognostic factors are available in clinical practice, the association between prognostic factors and outcome was evaluated by univariate and multivariate logistic regression analysis in 65 patients with polyneuropathy and IgM monoclonal gammopathy. RESULTS: In univariate analysis, the initial symptoms, the IgM light chain type, electrophysiologic and pathologic studies, the presence of sural nerve IgM deposition, and anti-MAG or anti-SGPG antibodies were significantly associated with outcome. However, multivariate analysis showed that only initial symptoms and electrophysiologic studies are independent prognostic factors: initial sensory symptoms of the feet are prognostic for a slowly progressive disease course and less disability at 4 years, and evidence for demyelination on electrophysiologic examination is prognostic for development of weakness and symptoms of the upper extremities at 4 years. Addition of anti-MAG or anti-SGPG antibody tests did not yield any additional prediction of outcome. CONCLUSION: These results indicate that in clinical practice, antibody tests in polyneuropathy associated with IgM monoclonal gammopathy do not have a prognostic value in terms of future neurologic deficit or outcome.
OBJECTIVE: To investigate the utilization of T-cell receptor (TCR) variable (V) regions in infiltrates of sural nerve biopsies of patients with chronic inflammatory demyelinating polyneuropathy (CIDP) and vasculitic neuropathy. BACKGROUND: The presence of infiltrating T lymphocytes in sural nerve biopsies may suggest a T cell-mediated immune mechanism in the pathogenesis of CIDP and vasculitic neuropathy. PATIENTS AND METHODS: The utilization of TCR Vbeta regions in sural nerves of 13 patients with CIDP and five patients with vasculitic neuropathy was determined by immunohistochemistry, reverse-transcription PCR, and nucleotide sequence analysis. These techniques were also applied in four patients with chronic idiopathic axonal polyneuropathy (CIAP) who acted as noninflammatory controls, and in five autopsy controls. RESULTS: The TCR Vbeta utilization of infiltrating T cells in sural nerves of patients with CIDP, vasculitic neuropathy, and noninflammatory controls is heterogeneous. A dominant TCR Vbeta utilization was not found in any of the patients or controls. CONCLUSION: There is no evidence for the presence of clonally expanded T cells in sural nerves of patients with CIDP and vasculitic neuropathy.
BACKGROUND: Autosomal dominant cerebellar ataxias (ADCAs), or spinocerebellar ataxias (SCAs), are a heterogeneous group of neurodegenerative disorders. Mild CAG repeat expansions in the alpha(1A) voltage-dependent calcium channel gene are associated with SCA type 6 (SCA6). OBJECTIVE: To obtain further insight into the contribution of SCA6 mutations to the phenotypic variability in Dutch patients with ataxia. DESIGN: Survey and case series. SETTING: Hospitalized care, referral center. PATIENTS AND METHODS: The SCA6 locus was analyzed for CAG repeat expansions in a referred sample of 220 Dutch families with progressive cerebellar ataxia. Clinical characteristics of patients with SCA6 were investigated and correlated with molecular findings. RESULTS: The diagnosis SCA6 was confirmed in 24 families comprising 30 familial and 4 sporadic cases. Mean +/- SD age at onset was 50.1 +/- 11.1 years. Expanded CAG repeats with sizes 22, 23, and 25 were found. These sizes correlated inversely with age at onset. No intergenerational changes in CAG repeat size were detected. Despite this, 2 families showed clinical anticipation. CONCLUSIONS: This study provides the first detailed description of Dutch patients with SCA6. Clinical analysis identifies SCA6 as a late-onset ataxia in which eye movement abnormalities are prominent and consistent early manifestations. No single clinical sign can be considered specific for SCA6. Some patients have ataxia combined with episodic headaches or nausea, suggesting an overlap among SCA6, eposidic ataxia type 2, and familial hemiplegic migraine. Spinocerebellar ataxia type 6 accounts for approximately 11% of all Dutch families with ADCA. Analysis of SCA6 contributes further to the genetic classification of patients with ADCA, including patients without a clear family history of the disease.
On magnetic resonance (MR) imaging of the brachial plexus increased signal intensity and swelling of the brachial plexus has been found in chronic inflammatory demyelinating polyneuropathy (CIDP). Whether these proximal abnormalities are also present in the distal polyneuropathy associated with monoclonal gammopathy is unknown. Therefore, we performed MR imaging of the brachial plexus in 21 patients with polyneuropathy associated with IgM monoclonal gammopathy (11 IgM with anti-MAG antibodies, 10 IgM without anti-MAG antibodies). For comparison we studied 9 patients with polyneuropathy associated with IgG monoclonal gammopathy and 8 patients with CIDP. Among the 30 patients with monoclonal gammopathy, 24 patients had demyelinating polyneuropathy. Among these 24 patients, there was increased signal intensity of the brachial plexus on the T2-weighted images regardless of whether clinical deficits were generalized or purely distal in location. No association was found with the isotype of the monoclonal gammopathy. Of the 8 patients with CIDP, 5 had brachial plexus abnormalities. None of the 6 patients with axonal polyneuropathy associated with monoclonal gammopathy had such abnormalities. Thus, MR imaging of the brachial plexus shows that the distal demyelinating polyneuropathy associated with monoclonal gammopathy is more generalized than presumed.
We describe three members each of two families presenting with a hereditary form of lower motor neuron disease with adult onset and rapid progression and compare their pathological and clinical features with hereditary lower motor neuron disease with adult onset, as described in the literature. No involvement of upper motor neurons was found either clinically or pathologically. Disease progression was rapid, and the majority of patients died from respiratory failure within 1-5 years after onset of disease. On pathological examination of the spinal cord we found ballooned neurons, neuronophagia and gliosis in family A, which have been regarded as characteristic pathological features of infantile-onset spinal muscular atrophy (SMA). In family B specific neuronal changes were observed that also occur in patients with amyotrophic lateral sclerosis (ALS). An autosomal dominant mode of inheritance would seem likely in both families. In family A the pathological findings and the clinical presentation with symmetrical proximal limb weakness show similarities with autosomal dominant SMA. Based on the finding of pathological features in family B that also occur in ALS, together with the distal asymmetrical muscle weakness and bulbar signs and a high age at onset we hypothesize that the members of family B suffered from familial ALS. The disease forms in both families in our opinion further broaden the spectrum of motor neuron disease.
Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disorder, in which antibodies against voltage-gated calcium channels located at nerve terminals cause muscle weakness and autonomic dysfunction. In approximately half of the patients the autoimmune process is initiated by a tumor. In the other half of patients no tumor is found and the etiology is unknown. The aims of this study were to investigate the strength of HLA-associations with nontumor LEMS (NT-LEMS) and to study the relation of HLA-haplotypes with age at onset of LEMS and other clinical features. Therefore, typing of HLA class I and II was performed in 19 patients with NT-LEMS, who were clinically evaluated. NT-LEMS was significantly associated with alleles of both HLA-class I (i.e. HLA-B8) as well as -class II (i.e. HLA-DR3 and -DQ2). HLA-B8+ patients had significantly younger age at onset of LEMS and tended to be female. This study shows that HLA-class I haplotype is associated with a distinct phenotype in NT-LEMS.
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Problems in diagnosing sporadic inclusion body myositis may arise if all clinical features fit a diagnosis of polymyositis, but the muscle biopsy shows some rimmed vacuoles. Recently, immunohistochemistry with an antibody directed against phosphorylated neurofilament (SMI-31) has been advocated as a diagnostic test for sporadic inclusion body myositis. The aims of the present study were to define a quantitative criterion to differentiate sporadic inclusion body myositis from polymyositis based on the detection of rimmed vacuoles in the haematoxylin-eosin staining and to evaluate the additional diagnostic value of the SMI-31 staining. Based on clinical criteria and creatine kinase levels in patients with endomysial infiltrates, 18 patients complied with the diagnosis of sporadic inclusion body myositis, and 17 with the diagnosis of polymyositis. A blinded observer counted the abnormal fibres in haematoxylin-eosin-stained sections and in SMI-31-stained sections. The optimal cut-off in the haematoxylin-eosin test was 0.3% vacuolated fibres. Adding the SMI-31 staining significantly increased the positive predictive value from 87 to 100%, but increased the negative predictive value only to small extent. We conclude that (1) patients with clinical and laboratory features of polymyositis, including response to treatment, may show rimmed vacuoles in their muscle biopsy and that (2) adding the SMI-31 stain can be helpful in differentiating patients who respond to treatment from patients who do not.
The objective of the study was to determine the diagnostic value of features of demyelination and inflammation in sural nerve biopsy specimens of patients with chronic inflammatory demyelinating polyneuropathy (CIDP). The features of (i) demyelination, (ii) axonal de- and regeneration and (iii) inflammation were investigated by measuring the number of onion bulbs, g ratio (axon diameter/total nerve fibre diameter), myelinated nerve fibre density, number of clusters and endoneurial area in 21 patients with CIDP, as well as in 13 patients with chronic idiopathic axonal polyneuropathy (CIAP) and six autopsy controls. In addition, teased fibres were classified and lengths of internodes measured. We found no difference in demyelinating features between patients with CIDP and CIAP, as the percentage of fibres with segmental de- and remyelination and the number of onion bulbs were similar in both polyneuropathy groups. The g ratio, expected to be higher in a demyelinating disease due to thinner myelin sheaths, was significantly lower in CIDP than CIAP. Evidence for axonal degeneration was found in both CIDP and CIAP, as both showed a decrease in myelinated nerve fibre density. There was no evidence of endoneurial oedema in CIDP, as the endoneurial area did not differ between CIDP, CIAP and the autopsy controls. Although significant differences of features of demyelination, axonal degeneration and inflammation were found in sural nerve biopsy specimens, there was a considerable overlap between abnormalities in CIDP and CIAP patients. In the majority of patients, quantitative analysis of light microscopical abnormalities in sural nerves was similar in CIDP and CIAP. Therefore, a sural nerve biopsy is of limited diagnostic value in CIDP.
OBJECTIVE: Guillain-Barré syndrome (GBS) is characterized by nerve infiltration of leukocytes and autoantibodies of the immunoglobulin G (IgG) isotype directed against nerve constituents. Leukocyte receptors for IgG (FcgammaR) constitute an important link between the humoral and cellular parts of the immune system and confer potent cellular effector functions to myelin-directed antibodies. Three FcgammaR subclasses exhibit genetically determined biallelic functional polymorphisms (FcgammaRIIa: R131 versus H131; FcgammaRIIIa: 158V versus 158F; FcgammaRIIIb: NA1 versus NA2) that determine efficacy of the cellular immune response. To study the relevance of these polymorphisms for susceptibility and severity of GBS, we compared FcgammaR genotype distributions in GBS patients with those in controls. METHODS: Genomic DNA was isolated from whole blood of 31 randomly selected patients with GBS and 187 healthy blood donors. Genotypes of the three polymorphic FcgammaR genes were determined by PCR. RESULTS: FcgammaRIIa-H131 homozygosity was significantly increased in patients as compared with healthy controls (OR 2.45; 95% CI 1.12 to 5.36; p = 0.037). Furthermore, FcgammaRIIa-H131 homozygous GBS patients had a higher risk for severe disease than did patients with other genotypes (OR 18.57; 95% CI 1.95 to 176.49; p = 0.007). CONCLUSION: FcgammaRIIa allotypes capable of initiating efficient cellular effector functions are associated with increased risk for GBS and a more severe disease course. FcgammaR alleles may constitute novel genetic risk markers for GBS.