Pain as the presenting symptom of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP).

Numerous clinical forms of CIDP have been described, but pain is generally considered a rare or secondary sign. We describe here the clinical, electrophysiological and neuropathological characteristics of five patients with CIDP and pain as the main presenting symptom, and their course with treatment. Between January 2003 and December 2004, we selected five patients with prominent or isolated pain among 27 patients diagnosed with CIDP. All patients were subjected to clinical and electrophysiological examinations, and had a complete laboratory work up to exclude other causes of neuropathy. In view of the atypical clinical presentation, all five patients underwent nerve biopsy. There were two men and three women. The mean age at onset of neuropathy was 70+/-7.39 years. All patients initially presented with pain in the lower limbs associated with modest motor impairment (1 case), distal paresthesia (4 cases), cramps (1 case) and fatigue (2 cases). CSF was normal in three cases. On electrophysiological examination, three patients had nerve conduction abnormalities with subtle or clear signs of demyelination: three (case 1, 2 and 4) fulfilled the criteria of Rotta et al. and two (case 2 and 4) the criteria of both Nicolas et al and the INCAT group. Patients were all given symptomatic treatment and four patients received an immunomodulatory treatment, which was constantly effective. Pain may be a major and disabling symptom in patients with CIDP, so this diagnosis has to be considered in patients referred for a painful polyneuropathy. Moreover, immunomodulatory treatment has to be considered in such patients as symptomatic therapy may be ineffective.

Demyelinating peripheral neuropathy associated with hemophagocytic lymphohistiocytosis. An immuno-electron microscopic study.

We report the case of an 11-year-old male who developed subacute diffuse polyradiculoneuropathy, associated with digestive symptoms and Epstein-Barr virus infection. Parental consanguinity was present. The laboratory findings including bone marrow smear were consistent with hemophagocytic lymphohistiocytosis (HLH). Electrophysiological study of peripheral nerves revealed an intense and diffuse demyelinating process. The histological nerve lesions were severe and purely demyelinating. Most axons were intact. There was a diffuse infiltration of the nerve parenchyma by mononuclear cells. Immuno-electron microscopic study evidenced entry of macrophages into Schwann cell cytoplasm with dissociation of myelin sheaths. This boy died several months after the onset of the neuropathic symptoms. HLH is a rare genetic or acquired disorder in childhood characterized by abnormal immune activation, which induces an uncontrolled inflammatory response with sustained hyperactivation of T lymphocytes and macrophages. Only very rare cases of peripheral nerve involvement have been described in HLH. This is the first case showing that peripheral nerves, as other viscera, may be destroyed by the macrophagic infiltration, which characterizes HLH.

Atypical electrophysiologic findings in chronic inflammatory demyelinating polyneuropathy (CIDP)--diagnosis confirmed by nerve biopsy.

OBJECTIVES: Numerous sets of electrophysiological criteria of chronic inflammatory demyelinating polyneuropathy (CIDP) have been proposed, among which the criteria established by an ad hoc subcommittee of the American Academy of Neurology (AAN) in 1991 (Neurology 41 (1991) 617) are the most widely used. As they seemed rather restrictive, the Inflammatory Neuropathy Cause and Treatment (INCAT) group (Ann. Neurol. 50 (2001) 195) proposed modifications of these electrophysiological criteria. However, even using these criteria, some cases of CIDP may not be recognized. In such cases, nerve biopsy has proven useful for confirmation of the diagnosis by demonstrating specific abnormalities. The objective of the study was to determine the profile of electrophysiological abnormalities in patients with atypical electrophysiologic criteria of CIDP and the diagnostic value of multiple A waves and a low median to sural amplitude ratio. PATIENTS AND METHODS: Over a period of 3 years, we classified 44 patients into two categories: those presenting the strict AAN and/or INCAT criteria and those who we regarded as cases of CIDP not meeting these criteria. All patients benefited from one or more clinical and electrophysiological examination. Extensive biological workup and genetic study when appropriate excluded other causes of neuropathy. Nerve biopsies were taken from all patients and samples were included in paraffin and epon for systematic light, teasing and electron microscopic examination. RESULTS AND CONCLUSION: Out of 44 patients, 36 fulfilled the INCAT or AAN criteria. In eight other patients, the diagnosis of CIDP was suspected on clinical and EMG examinations and confirmed by nerve biopsy. In these cases, the electrophysiological exploration showed some abnormalities such as multiple A waves in four out of eight patients or an abnormal pattern of the sensory responses of the median and sural nerves in four out of eight patients that were more indicative of an initial demyelinating process. Six of our patients received immunomodulatory treatment, and five responded favorably.

Phenotypic variability in autosomal recessive axonal Charcot-Marie-Tooth disease due to the R298C mutation in lamin A/C.

Autosomal recessive forms of axonal Charcot-Marie-Tooth (ARCMT2) disease are frequent in some areas, such as North Africa and the Middle East, since consanguineous marriages are still common there. Recently, a unique homozygous mutation in LMNA, which encodes lamin A/C, a component of the nuclear envelope, was identified in members of three Algerian families with ARCMT2 linked to chromosome 1q21.2-q21.3. In the present study we describe a group of 21 ARCMT2 patients from seven unrelated Algerian families with the same R298C mutation in the lamin A/C gene and marked variability of the clinical phenotype. There is a wide range of age of onset, from 6 to 27 years, with a mean of 14.4 +/- 4.6 years. The course of the disease varies considerably from one patient to another. Twelve patients with a disease duration of 10-15 years had a severe CMT phenotype with distal wasting and weakness of all four limbs and areflexia associated with involvement of the proximal lower limb muscles. In contrast, nine patients had the classical CMT phenotype with mild functional disability without proximal lower limb involvement after a disease duration of 5-18 years. Electrophysiological studies showed a median motor nerve conduction velocity (MNCV) in the normal range in almost all the patients. MNCV and compound muscle action potential (CMAP) values were inversely correlated with the disease duration and the MNCV was strictly related to the CMAP, strongly supporting a pure axonal process without a demyelinating component. Six patients had a nerve biopsy, which revealed severe rarefaction of myelinated fibres in all cases and an increased density of unmyelinated fibres in the majority of cases. In conclusion, the ARCMT2 associated with the R298C mutation differs from other types of ARCMT2. The variability among patients in the age of onset and the course of the disease strongly suggests the action of modifying genes, which remain to be identified.

The phenotypic manifestations of autosomal recessive axonal Charcot-Marie-Tooth due to a mutation in Lamin A/C gene.

Charcot-Marie-Tooth disease constitutes a genetically heterogeneous group of hereditary motor and sensory peripheral neuropathies. The axonal type of Charcot-Marie-Tooth is designated type 2. Six loci for autosomal dominant and three for recessive Charcot-Marie-Tooth type 2 have been reported so far. In this study we report the phenotype of autosomal recessive axonal Charcot-Marie-Tooth type 2 due to a recently-described mutation (c.892C>T-p.R298C) in a gene encoding Lamin A/C nuclear envelope proteins and the first gene in which a mutation leads to autosomal recessive Charcot-Marie-Tooth type 2. We have explored eight patients from four Algerian families. The onset is usually in the second decade and the course is rapid, involving upper limbs and proximal muscles, leading to a severe condition in less than 4 years. Many different mutations in Lamin A/C have been identified as causing variable phenotypes, such as limb girdle muscular dystrophy type 1B, autosomal dominant and recessive Emery-Dreyfuss muscular dystrophy, dilated cardiomyopathy with atrioventricular conduction defect, and Dunnigan-type familial partial lipodystrophy should prompt us to fully investigate the skeletal and cardiac muscles in patients affected with autosomal recessive Charcot-Marie-Tooth type 2 carrying a mutation in LMNA.

Genetic heterogeneity in giant axonal neuropathy: an Algerian family not linked to chromosome 16q24.1.

Giant axonal neuropathy is a rare severe autosomal recessive childhood disorder affecting both the peripheral nerves and the central nervous system. Peripheral nerves characteristically show giant axonal swellings filled with neurofilaments. The giant axonal neuropathy gene was localised by homozygosity mapping to chromosome 16q24.1 and identified as encoding a novel, ubiquitously expressed cytoskeletal protein named gigaxonin.We describe a consanguineous Algerian family with three affected sibs aged 16, 14 and 12 years who present a mild demyelinating sensory motor neuropathy, hypoacousia and kyphoscoliosis which was moderate in the two elder patients, severe in the third one, with no sign of central nervous system involvement and normal cerebral magnetic resonance imaging. This clinical picture is different from the classical severe form, with kinky hairs and early onset of central nervous system involvement and from the less severe form, with protracted course and late involvement of central nervous system. Nerve biopsy showed a moderate loss of myelinated fibers and several giant axons with thin or absent myelin, filled with neurofilaments. This neuropathological aspect is similar to the previously described families linked to the gigaxonin gene. Genetic study in this family showed absence of linkage to chromosome 16q24.1, indicating for the first time, a genetic heterogeneity in giant axonal neuropathy. We propose to call this form of giant axonal neuropathy giant axonal neuropathy 2, and to use the name of giant axonal neuropathy 1 for the form linked to 16q24.1.

Myelin widenings and MGUS-IgA: an immunoelectron microscopic study.

A few studies have reported a variety of nonspecific histological lesions in patients with IgA monoclonal gammopathies and polyneuropathy. In our case, using electron microscopy, we observed widenings of the myelin lamellae identical to those commonly described in IgM neuropathies with anti-myelin-associated glycoprotein activity. Using immunoelectron microscopy, we demonstrated a direct involvement of IgA in myelin lesions. The search for a direct link between monoclonal dysglobulinemia, regardless of type, and polyneuropathy is important and may influence treatment.

Ultrastructural immunocytochemical abnormalities of peripheral myelin proteins in hereditary sensory-motor neuropathies: 12 cases.

Hereditary sensorimotor neuropathies form a heterogeneous group of genetically determined diseases, of which Charcot-Marie-Tooth (CMT) disease is the most common. In order to establish relations between genotype and the expression of peripheral myelin proteins, we carried out a quantitative study by ultrastructural immunocytochemistry of several myelin proteins (PMP22, P0, MBP) on sural nerve biopsy samples from 12 unrelated CMT patients. The diagnosis of CMT was based on the clinical, electrophysiological, and histological findings along with those of molecular biological studies. CMT X diagnoses were not included in this study. The expression of myelin proteins was well correlated with the molecular biological findings in these patients. The results also provided evidence for interference between different myelin proteins. Our findings are in line with the results from animal studies (trembler and knock-out mice), which may provide insights into the pathogenesis of these human conditions.

Expression of myelin proteins in the adult heterozygous Trembler mouse.

The Trembler mouse (Tr) suffers from a dominantly inherited autosomal mutation (glycine to aspartic acid. G150D) affecting the PMP22 gene, which results in an abnormal myelination of the peripheral nervous system. The Tr mouse represents an animal model for the human hereditary neuropathy, Charcot-Marie-Tooth disease. We compared the expression of PMP22, P0, myelin basic protein (MBP) and myelin-associated glycoprotein (MAG) in nerve biopsies from a 1-year-old heterozygous Tr mouse (Tr/+) with that of a control mouse of the same age. Quantitative and qualitative ultrastructural immunocytochemical analysis showed a significant decrease in PMP22, P0 and MBP and an abnormal location of the MAG in the sciatic nerve of the Tr/+ mouse. We also noted a marked reduction in number of myelinated fibers associated with the presence of two types of myelinated axons: a population of abnormally thin myelin sheaths with lower PMP22 labeling than that observed in myelinated fibers from the control mouse, and some others fibers with normal sheaths for axons of comparable diameter to those of normal mouse with no difference in the PMP22 immunolabeling. This pointed to an involvement of PMP22 in the structure of myelin sheaths.

Demyelinating X-linked Charcot-Marie-Tooth disease: unusual electrophysiological findings.

X-linked Charcot-Marie-Tooth disease (CMT-X) is caused by mutations of connexin-32 (Cx-32), which encodes a gap-junction protein. Whether the neuropathy is primarily demyelinative or axonal remains to be established. We report findings of prominent demyelination in a 71-year-old woman with late-onset disease. Electrophysiological studies revealed a nonuniform slowing of motor conduction velocities and dispersion of compound action potentials indicative of a demyelinating process which was confirmed by nerve biopsy. Such electrophysiological features are unusual in hereditary neuropathies and are more commonly found with acquired chronic demyelinating neuropathies. A systematic search confirmed the molecular genomic diagnosis of CMT-X, illustrating the value of such tests in sporadic cases. Severity of clinical symptoms and signs may vary with age and sex of the patient. The pathology of CMT-X in other reported cases has been variably interpreted as axonal, demyelinating, or showing both features. Our observations emphasize the demyelinative nature.

[The involvement of myelin proteins in hereditary neuropathies]. / Implications des protéines myéliniques dans les neuropathies héréditaires.

Hereditary sensoro-motor neuropathies such as Charcot-Marie-Tooth disease (CMT) form a heterogeneous group including some genetic conditions whose clinical manifestations differ in severity within a group or even within a sub-group. Diagnosis is based on the clinical, electrophysiological and pathological findings along with a genetic analysis. The current classification of CMT encompasses the clinical signs, mode of transmission, genomic localization and identification of the proteins actually involved. Several authors have identified the mutations on genes coding for proteins of peripheral myelin in CMT patients. Recent advances in molecular genetics have thrown more light on the differences between phenotypes within a sub-group, and have established genotype-phenotype relationships. It has been shown recently that the severity of the clinical signs depends on the nature and site of various mutations affecting the genes coding for certain myelin proteins. These mutations give rise to "dominant negative effects" or "mutations with loss of function of the allele". These observations may be extended to other proteins as many of them belong to the super family of immunoglobulins and have similar structures. In this study, we present a review of the literature focussing on the principal myelin proteins and the genomic modifications observed in patients with CMT.

Ultrastructural protein zero expression in Charcot-Marie-Tooth type 1B disease.

Charcot-Marie-Tooth type 1B (CMT 1B) disease, an inherited demyelinating peripheral neuropathy, results from different point mutations located in the P0 gene on chromosome 1 q21-23. We have quantified, at the ultrastructural level, the immunocytochemical expression of the P0 protein in two unrelated CMT 1B patients with mutations (Ser 78 to Leu and Asn 122 to Ser) located in two different exons in the extracellular domain of the protein. A twofold decrease in P0 expression was observed in compact myelin in each case, compared with age-matched controls. The severity of the phenotypes showed no direct relationship to the levels of P0 protein expression in these 2 patients.

Serum autoantibodies to neurofilament proteins in sporadic amyotrophic lateral sclerosis.

Anti-neurofilament (NF) autoantibodies were searched for by enzyme-linked immunosorbent assays (ELISA) in the serum from 85 sporadic amyotrophic lateral sclerosis (ALS) patients, 98 healthy controls and 79 patients with unrelated immunological diseases (Guillain-Barré syndrome, myasthenia gravis and multiple sclerosis). ELISA cutoff value was determined as mean control levels +2 SD and it corresponded to a specificity of 94%. Such high level antibodies were detected in 24.7% of ALS patients contrasting with 12.6% of neurological controls (P<0.05) and only 6.1% of healthy subjects (P<5.10[-4]). In ALS, anti-NF antibodies were significantly associated with a slow evolution, as measured by the mean time spent in the initial functional states. They did not relate with age, sex and clinical form. The predominant isotype of the anti-NF antibodies was IgM lambda by ELISA. In contrast to negative sera, indirect immunohistochemical studies demonstrated that most sera positive for anti-NF antibodies reacted with axons with predominant isotypes restricted to IgM lambda. By using Western blotting, small amounts of serum monoclonal IgM were found with a high frequency in anti-NF antibody-positive patients. These results suggest the possible involvement of anti-NF antibodies in an autoimmune process in a subgroup of ALS patients.

Ultrastructural PMP22 expression in inherited demyelinating neuropathies.

Charcot-Marie-Tooth type 1A (CMT-1A) disease results from a duplication of the PMP22 gene on chromosome 17p11.2. A deletion of the same region causes hereditary neuropathy with liability to pressure palsies (HNPP). We examined the expression of PMP22 in sural nerve biopsies from 2 unrelated patients with CMT-1A, 2 unrelated patients with HNPP, and control patients. The ultrastructural immunocytochemical quantitative analysis of cases of CMT-1A and HNPP showed, respectively, an elevated and reduced expression of PMP22 level compared with controls.

Modifications of neuronal phosphorylated tau immunoreactivity induced by NMDA toxicity.

Glutamate toxicity has been involved in the pathophysiology of a large variety of neurodegenerative disorders. Tau Protein is a micro-tubule-associated protein that promotes microtubule polymerization and stabilization. Phosphorylated tau protein accumulates in paired helical neurofilaments, the major constituent of neurofibrillary tangles observed in the brain of patients suffering from Alzheimer disease (AD). In this study, using confocal laser microscopy and immunoblot analysis, we report that acute (500 mu M for 15 min) or chronic (20 mu M for 16 h) N-methyl-D-aspartate (NMDA) neuronal toxicities modify the immunoreactivity of phosphorylated tau. Neuronal degeneration produced by N-methyl-D-aspartate is associated with an augmented immunolabeling of phosphorylated tau proteins at serine 202 (AT8 antibody) as observed in paired helical neurofilaments. This finding could help to determine the cellular mechanisms at the origin of neuronal degeneration associated with modifications of phosphorylated tau immunoreactivity produced by receptor-mediated extracellular signals.

Nerve biopsy.

For many years, nerve biopsy has been very useful for clarifying the mechanism and aetiology of human peripheral neuropathies. Recently, this morphological examination has greatly benefited from the contribution of new immunocytochemical, ultrastructural and molecular biological techniques, which can often be used together in studies on inflammatory, paraproteinaemic and genetic neuropathies.

Modulation of tau neuronal expression induced by NMDA, non-NMDA and metabotropic glutamate receptor agonists.

We have analysed changes in tau protein immunoreactivity in rat embryonic neurons degenerating in response to treatment with N-methyl-D-aspartate (NMDA), non-NMDA and metabotropic agonists. Glutamate agonists were applied in Mg(++)-free and glycine-supplemented medium 8 days after initial plating. Cell viability was assessed by fluorescein diacetate staining and neuronal survival was evaluated by cell counting. Immunocytochemical and confocal laser microscopic studies used a tau2 monoclonal antibody. Acute and chronic NMDA treatment induced a concentration-dependent increase in intraneuronal tau immunoreactivity. Increased tau immunolabelling during chronic NMDA toxicity was dramatically attenuated by tetrodotoxin and also by 6-cyano-7-nitroquinoxaline-2,3-dione. Non-NMDA and metabotropic receptor agonist treatment produced a weaker augmentation in tau2 immunoreactivity. These findings suggest that, in this model, glutamate-receptor and sodium-channel coactivation are together needed to produce changes in tau immunoreactivity.

Prevention of HIV coat protein (gp120) toxicity in cortical cell cultures by riluzole.

Neurological complications observed in HIV-infected patients are very frequent. Neocortical lesions include reduced neuronal density due to neuronal degeneration. The HIV envelope protein gp120 has potent neurotoxic properties in cell cultures blocked either by NMDA antagonists or calcium channel antagonists. Moreover, human monocytoid cell lines infected by HIV release endogenous toxic factors with comparable cellular actions. We have analysed the effects of riluzole, a compound reducing the excitatory amino acid release on gp120-induced neurotoxicity in primary neuronal cultures. Riluzole, which blocks the release of glutamate and aspartate from nerve terminals, prevents (10(-7) M) the neuronal degeneration produced by 20 pM of gp120 in cortical cell cultures. This result could suggest that toxic factors produced by activated macrophages might increase glutamate release, and that this may be prevented by riluzole.

Synaptophysin expression during in vitro neuronal differentiation. An immunocytochemical and a confocal laser microscopic study.

Primary neuronal cultures from mammalian fetal brains are widely used for morphological, biochemical and pharmacotoxicological studies. The usefulness of relatively pure neuronal cultures are now demonstrated for such studies. We have compared the neuronal survival and differentiation, the synaptophysin expression and the glial cell percentage in primary neuronal cultures using two different media: a M1 medium containing 10 % fetal calf serum and a M2 medium supplemented with hormones, ions and chemicals. Our study demonstrates that the M2 medium (a serum-free defined medium) is associated with an increased survival at 14 days of culture, an earlier neuronal differentiation and synaptophysin expression in cell bodies and neurites as it was confirmed by immunocytochemical and confocal laser microscopic studies.