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Biomedical subjects

A Créange

Publications and source records attributed to A Créange.

At least 19 recordsLinked to original sources
PubMed2006

[Pathophysiology and treatment of fatigue in multiple sclerosis].

Patients suffering from multiple sclerosis (MS) frequently complain of fatigue (53 to 92 percent depending on studies). Fatigue can be one of the most disabling symptoms of MS and presents as physical or mental fatigue in daily living activities. Besides this permanent feeling of exhaustion, MS patients can suffer from an abnormal tiredness and lack of energy after a given motor or mental task, which defines fatigability. A number of studies explored the origins of fatigue and fatigability by means of subjective and objective tools. The implication of central nervous system dysfunctions has been established in several studies; however the contribution of peripheral nervous system factors and systemic abnormalities associated with inflammatory and immunological parameters was also suggested. The aim of this review is to present the different types of fatigue and fatigability occurring in MS patients, their origins, the investigation tools which allow the quantification of fatigue and fatigability and characterization of their mechanisms. The currently available therapeutic strategies that have been proposed to relieve this disabling symptom are presented.

4-Aminopyridine↗
PubMed2006

[Nerve excitability studies in the assessment of dysimmune neuropathies].

INTRODUCTION: Various changes in axonal membrane excitability might explain negative symptoms in dysimmune neuropathies, e.g., acute or chronic inflammatory demyelinating neuropathies or multifocal neuropathies with persistent conduction blocks. Several electrophysiological methods have recently been designed to specifically assess such axonal membrane excitability changes. STATE OF ART: Resting and action potentials are related to ionic movements through the axonal membrane, mainly involving various types of sodium and potassium channels, as well as the ATP-dependent Na+/K+ pump. The functional status of these channels and pumps can be assessed in man, by studying the excitability recovery cycle after a single impulse, the strength-duration and stimulus-response curves, and the effects of hyperpolarization and depolarization depending on activity (voluntary contraction), ischemia or application of prolonged subthreshold currents. Various features of altered axonal membrane excitability might characterize dysimmune neuropathies, according to the course of the disease and its treatment. PERSPECTIVES: This electrophysiological approach allowed changes in axonal membrane properties to be objectively determined. In particular, some results obtained with these methods could explain the rapid action of intravenous immunoglobulins, and various pathophysiological mechanisms of conduction block or axonal degeneration. CONCLUSIONS: Nerve excitability studies appeared to be useful for the diagnosis and the follow-up of dysimmune neuropathies. New therapeutical strategies for such neuropathies will be probably developed in the future intending to improve nerve function by acting on axonal membrane excitability.

Animals↗
PubMed2005

[Polyneuropathy associated with neurofibromatosis].

INTRODUCTION: We review the literature on the spectrum of polyneuropathies associated with neurofibromatosis 1 (NF1) and 2 (NF2). BACKGROUND: Symptomatic neuropathies in NF1 are rarer than in NF2, but constitute a potentially severe complication associated with frequent morbidity related to the neuropathy itself, spinal cord compression or peripheral nerve sheath tumor malignant degeneration. Neuropathies are typically observed in young men with subcutaneous neurofibromas (NF1) or cutaneous schwannomas (NF2) and are characterized by a chronic slowly worsening sensorimotor polyneuropathy of the lower limbs. In NF1, demyelinating neuropathy may occur alone or in association with axonal features, whereas in NF2, axonal neuropathies are reported. Large multinodular roots and nerves, which can be easily detected by limb MRI, are characteristic features of NF1-associated polyneuropathies. PERSPECTIVES AND CONCLUSION: Although an associated pathogenic factor may reveal an asymptomatic neuropathy, patients should be monitored carefully because of the increased morbidity and mortality related to the significant proportion of malignant nerve-sheath tumors in these patients with NF1.

Humans↗
PubMed2005

[Convergence nystagmus and vertical gaze palsy of vascular origin].

A case of convergence-retraction nystagmus with upward vertical gaze paralysis and skew deviation (right hypotropia), without any other neurological signs, is reported. The probably vascular lesion was located at the mesodiencephalic junction, lying between the right border of the posterior commissure, the right interstitial nucleus of Cajal and the periaqueductal grey matter, accounting for the three ocular motor signs. The particular interest of this case is due to the relative smallness of the lesion.

Coiled Bodies↗
PubMed2005

[Chronic inflammatory demyelinating polyradiculoneuropathy: diagnostic strategy. Guidelines of the French CIDP study group].

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) comprises a group of dysimmune neuropathies easily diagnosed in more than half of the patients. Diagnosis is based on clinical, electrophysiological and biological clues. In some patients, diagnosis is unclear because of the debated value of the available clues. In such circumstances, dysimmune neuropathies may not be diagnosed, leading to insufficient treatment. This is an important category of patients because immunomodulatory drugs have proven efficacy. The CIDP spectrum includes a relatively wide range of diseases. Besides the easily recognized classic forms, there are many clinical variants, sometimes with a paucisymptomatic presentation leading to uncertain diagnosis. The French CIDP study group has established guidelines for diagnostic strategy in CIDP patients. The first part of this paper is devoted to the clinical aspects of the disease, classical forms and variants. In the second part, the results of electrophysiological studies are reported. In a third chapter, complementary examinations useful for diagnosis are discussed. The fourth chapter deals with the diagnostic strategy, discussed in relation to the different situations which may be encountered in clinical practice. details the technical modalities of appropriate electrophysiological studies and presents normal results together with those indicating demyelinating neuropathy. Nerve biopsy technique and results are given in appendix II.

Humans↗
PubMed2004

[Methods and clinical value of peripheral nerve refractory period measurement in man].

Immediately after action potential occurrence, owing to transient sodium channel inactivation, axon excitability is reduced for a short period of time, including the absolute refractory period, a first period of total inexcitability, followed by the relative refractory period. There are basically two different stimulation protocols to estimate axonal refractoriness, i.e. "paired-pulse" and "collision" techniques. Refractory period has been assessed in various conditions and appeared to depend on several physiological or methodological factors, featuring the type of nerve or the characteristics of the subject, but also the technique of stimulation or the method of data analysis. In addition, refractory periods can be altered by pathological conditions. Several studies showed prolonged refractory periods in patients suffering from alcoholic, diabetic or toxic neuropathies. Refractory period abnormality is a sensitive marker of axonal dysfunction as observed in Guillain-Barré syndrome, carpal tunnel syndrome or multiple sclerosis. Thus, the measurement of the refractory periods is a valuable tool to study the pathophysiology of peripheral nerves, complementary to standard nerve conduction studies. However, the application of these techniques in the routine practice of clinical neurophysiology remains limited.

Adult↗
PubMed2004

[The diagnosis of acquired sensory neuropathies].

INTRODUCTION: Peripheral neuropathies usually include a sensory component of various causes. The diagnosis approach requires careful a clinical assessment and a precise electrophysiological exploration. STATE OF ART: Axonal sensory polyneuropathies are classified according to the type of fibers involved (large or small fibers). While there is a large number of causes, current emphasis is placed on glucose intolerance as a source of small-fiber sensory neuropathies. Demyelinating polyneuropathies are often associated with a monoclonal IgM gammapathy with anti-MAG activity. Multiple sensory mononeuropathies are exceptional and suggest possible early-phase vasculities, sensorymotor neuropathy with conduction blocks or leprosy. Sensory neuronopathies can also suggest Sjögren's syndrome or a paraneoplastic syndrome. Finally chronic sensory polyradiculoneuritis constitute a rare subgroup clearly defined as demyelinating inflammatory neuropathy. CONCLUSION: The diagnostic approach to sensory neuropathies requires careful nosological electroclinical classification to reduce the number of explorations performed for etiological diagnosis.

Electrophysiology↗
PubMed2004

Neurophysiological testing correlates with clinical examination according to fibre type involvement and severity in sensory neuropathy.

OBJECTIVE: To investigate a comprehensive battery of neurophysiological tests for objective evaluation of sensory neuropathies including fibre type involvement and severity, and to determine the relation between neurophysiological data and clinical examination. METHODS: 45 patients referred for sensory neuropathy were studied using a standardised clinical evaluation of large and small fibre symptoms and an original neurophysiological battery. Clinical evaluation included: assessment of tactile, vibratory, and pin sensation; tendon reflexes; toe position sense; ataxia score; pain level; and presence of trophic, vasomotor, or sudomotor abnormalities. The neurophysiological battery included: recording of large fibre and small fibre components of the sural sensory nerve action potential; somatosensory evoked cortical potentials and soleus H reflex following tibial nerve electrical stimulation; laser evoked potentials following Nd:YAG laser stimulation of the foot; and plantar sympathetic skin response to median nerve stimulation. Neuropathy was classified according to the predominantly affected fibre type, and a severity score was established based on clinical and neurophysiological abnormalities. RESULTS: On clinical examination there were 22 patients with large fibre sensory neuropathy (LFSN), 18 with mixed sensory neuropathy (MSN), and five with small fibre sensory neuropathy (SFSN). Neurophysiological classification identified 25 patients with LFSN, 13 with MSN, and seven with SFSN. Clinical and neurophysiological classifications and severity scores were correlated, whatever the type of neuropathy. CONCLUSIONS: The correlation between clinical examination and the results of an original neurophysiological test battery offers a comprehensive clinical and neurophysiological approach to the objective assessment of peripheral neuropathies according to fibre type involvement and overall severity.

Adult↗
PubMed2003

Low levels of ventricular CSF orexin/hypocretin in advanced PD.

The origins of excessive daytime sleepiness in Parkinson disease (PD) are unclear. The authors hypothesize that orexin neurons, a recently identified wake promoting system, could contribute to its pathophysiology. They measured orexin-A/hypocretin-1 concentration in ventricular CSF in 19 parkinsonian patients and compared it with neurologic controls. Orexin levels were lower in patients and decreased with the severity of the disease. The authors suggest that orexin neurons contribute to daytime sleepiness in late stage PD.

Antiparkinson Agents↗
PubMed2003

Monocyte chemoattractant protein 1 and chemokine receptor CCR2 productions in Guillain-Barré syndrome and experimental autoimmune neuritis.

Infiltration of activated lymphocytes and monocytes is a key phenomenon in the pathogenesis of Guillain-Barré syndrome (GBS) and experimental autoimmune neuritis (EAN). To investigate the role of chemokines, we determined the blood and nerve tissue expression of monocyte chemoattractant protein 1 (MCP-1), a major chemoattractant of monocytes and activated lymphocytes, and its receptor CCR2 in GBS and EAN. MCP-1 circulating levels (ng/ml) in GBS were increased at the time of progression, peaked at the time of plateau and normalized with recovery. MCP-1 circulating levels were the highest in the most disabled patients. The number of circulating CCR2 positive cells was lower in patients with GBS than in healthy subjects (p<0.004). In GBS, MCP-1 expression was observed in epineurial and endoneurial vessels, on infiltrating cells, Schwann cells and in the endoneurial extracellular matrix. Some CCR2 positive cells were observed in nerve biopsies of GBS patients. In EAN, a slight positivity for MCP-1 was observed in the sciatic nerve. There was no circulating CCR2 positive cells. However, at the time of plateau, a conspicuous infiltration of CCR2 positive cells was observed in the sciatic nerve that was no longer observed at the time of recovery. These results suggest that MCP-1 and CCR2 may participate to the recruitment of circulating mononuclear cells in nerve tissue in EAN and GBS.

Animals↗
PubMed2003

Intravenous immunoglobulin modulates lymphocyte CD54 and monocyte FcgammaRII expression in patients with chronic inflammatory neuropathies.

We studied the expression of different lymphocyte and monocyte cellular determinants involved in leukodiapedesis and antigen presentation in 10 patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and multifocal motor neuropathy (MMN) with persistent conduction blocks before intravenous immunoglobulin (IVIg), immediately after infusion of IVIg and 1 week after infusion. We observed a decrease of T lymphocytes expressing ICAM-1 (CD54) immediately after infusion in 8 out of 10 patients (p<0.04) with a return to pretreatment values after 1 week. The monocytes showed an increase in CD14(+) cells and CD14(+) FcgammaRII inhibitory receptor positive cells, no change in the number of CD14(+) FcgammaRIII activation receptor cells, and an increase in the FcgammaRII/FcgammaRIII ratio on monocytes 1 week after IVIg. Thus, the mechanism of action of IVIg in both CIDP and MMN may involve inhibition of T cell transmigration and modulation of antigen presentation capacities through FcgammaR expression.

Adult↗
PubMed2003

A variant of multifocal motor neuropathy with acute, generalised presentation and persistent conduction blocks.

OBJECTIVE: Multifocal motor neuropathy with persistent conduction blocks is classically described as a chronic neuropathy with progressive onset, and acute forms have not previously been characterised. We report four cases of severe motor impairment with acute and generalised onset and with persistent motor conduction blocks. PATIENTS AND RESULTS: An acute tetraparesis with diffuse areflexia but little or no sensory disturbance was the clinical picture. Serial electrophysiological tests showed persistent multifocal motor conduction blocks with absent F waves in most tested motor nerves. No or minor abnormalities of the sensory nerve action potentials were observed. Cerebrospinal fluid contained normal or mildly increased protein levels (<1 g/l) without cells. Campylobacter jejuni serology was negative in three patients and consistent with past infection in one patient. Anti-ganglioside antibodies were positive in three patients. A five day course of intravenous immunoglobulins produced nearly complete symptom resolution in three patients and was ineffective in one patient. CONCLUSION: Because of the persistence of multifocal motor conduction blocks for several weeks or months as the isolated electrophysiological feature, these cases could not be consistent with Guillain-Barré syndrome or chronic inflammatory demyelinating polyneuropathy. They suggest an original variant of multifocal motor neuropathy with an acute and generalised initial presentation and persistent motor conduction blocks affecting all four limbs.

Acute Disease↗
PubMed2002

MMP-9 correlates with electrophysiologic abnormalities in Guillain-Barré syndrome.

To investigate the role of MMP-9 in Guillain-Barré syndrome, the authors correlated electrophysiologic abnormalities and MMP-9 plasma levels in a series of 21 patients. MMP-9 plasma levels were higher in the demyelinating group than in the nondemyelinating group, and in patients with high CSF protein level. Increase of MMP-9 circulating levels correlated with the increase of F waves latencies, reduction of CMAP amplitude, and decrease of nerve conduction velocities. Circulating MMP-9 may contribute to the peripheral nerve dysfunction of demyelinating Guillain-Barré syndrome.

Action Potentials↗
PubMed2002

Oligoclonal T-cells in blood and target tissues of patients with anti-Hu syndrome.

T-cell clones of unknown significance (TCUS), assessed by monoclonal or oligoclonal T-cell patterns in PCR-DGGE, were detected in blood of 7/9 patients with anti-Hu syndrome. Clonal patterns were also detected in 2/2 neoplastic lymph nodes, and in 2/2 inflamed dorsal root ganglia from three patients. Only some T-cell clones found in target tissues were also detected in blood or non-target tissues, and likely corresponded to TCUS. In one patient, an identical T-cell clone was found in both neoplastic lymph node tissue and dorsal root ganglia, but not in blood. Dorsal root-infiltrating lymphocytes were cytotoxic CD8(+) TIA-1(+) T-cells. They were often found in close contact to sensory neurons, most of which expressed MHC-1. Taken together, these data support a direct effector role of cytotoxic CD8(+) T-cells, the same clones being likely operative in sensory neuron damage and immune-mediated tumor growth control.

Adult↗
PubMed2002

[Neurofibromatosis 1: recommendations for management].

Twenty experts, members of a French medical network devoted to neurofibromatosis 1 have elaborated recommendations for the management of the disease. Bibliography was obtained through a Medline of articles from 1966 to 1999 for the terms neurofibromatosis, NF1, neurofibroma and from textbooks. A consensual document was written taking into account extracted data. An annual careful clinical examination is recommended except in cases with complications. Screening investigations are not recommended due to the rarity of complications, generally symptomatic and easily detected during the clinical follow-up. The only controversial exception might be magnetic resonance imaging for early detection of optic pathway gliomas in young children. A co-ordinated follow-up in specialised multidisciplinary centres, providing patients with a rational management, is recommended.

Adolescent↗
PubMed2002

[Cellular aspect of neuroinflammation in Guillain-Barré syndrome: a key to a new therapeutic option?].

Guillain-Barré syndrome (GBS) is an acute inflammatory demyelinating neuropathy associated with long-lasting morbidity and substantial risk of mortality. The two reference treatments (plasma exchange-PE and intravenous immunoglobulins-IVIGs) do not change the functional prognosis in patients with very severe disease. Pathogenesis of GBS associates recently characterized humoral and cellular immune dysfunctions. Antibodies against nerve antigens may participate in complement activation, antibody-dependent macrophage cytotoxicity, and reversible conduction failure. Cellular immune reaction is associated with an increase of proinflammatory cytokines (for exemple TNF-alpha), a decrease of anti-inflammatory cytokines (such as TGF-B1), an increase of matrix metalloproteinases (MMP-9-gelatinase B), all abnomalities favoring adhesion to and transmigration across endothelium of immune cells, a key phenomenon in GBS. Recovery of GBS is characterized by the normalization of these abnormalities. Experimental allergic neuritis (EAN), the experimental model of GBS has strikingly similar immunological abnormalities. The treatments of GBS, PE and IVIGs, mainly target the humoral component of the immune response. IFN-B is a cellular immunomodulator that inhibits antigen presentation, TNF-alpha production and binding, modulates macrophages properties. IFN-B increases anti-inflammatory T cell functions and cytokines, such as TGF-B1. IFN-B has important properties on leukodiapedesis by modulating expression of cell adhesion molecules and the MMP-9 proteinase. IFN-B has been used with success in EAN, in some patients with acute exacerbation of chronic inflammatory demyelinating polyneuropathy, and in one patient with GBS. Pathophysiology of GBS, IFN-B properties, and experimental studies support the initiation of a trial of IFN-B in GBS.

Guillain-Barre Syndrome↗