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Biomedical subjects

Didier Cros

Publications and source records attributed to Didier Cros.

11 recordsLinked to original sources
PubMed2006

Multifocal motor neuropathy with conduction block: Distribution of demyelination and axonal degeneration.

OBJECTIVE: Multifocal motor neuropathy with conduction block (MMN) is an immune-mediated neuropathy, characterized by progressive muscle weakness. Although demyelination is regarded as the underlying pathophysiologic mechanism of MMN, recently, it was reported that different pathophysiologic mechanisms were responsible for disease in the upper and lower limbs. Specifically, demyelination in the upper limbs and axonal loss in the lower limbs. Consequently, the aim of the present study was to assess, through clinical neurophysiology studies, whether different pathophysiologic mechanisms were occurring in the upper and lower extremities. Furthermore, we wanted to investigate whether the presence of conduction block (CB) correlated with axonal degeneration (AD), and to determine the electrophysiological abnormalities that correlate with muscle weakness. METHODS: We reviewed medical records of 18 patients with MMN for clinical features (using the Medical Research Council score and Guys Neurology Disability Scale) and neurophysiologic abnormalities (CB, AD prolongation of distal motor and F-wave latencies, and reduction of conduction velocity in the demyelinating range). RESULTS: Electrophysiological abnormalities deemed specific of demyelination were non-significantly different in the upper and lower extremities. The presence of axonal degeneration correlated significantly with conduction block (odds ratio 10.4, 95% CI 4.2-25.6), and both parameters correlated with muscle weakness (P<0.01). CONCLUSION: Our study suggests that the same pathophysiologic process occurs in the upper and lower extremity nerves. Moreover, one pathophysiologic process may be responsible for the development of CB and AD, and therefore muscle weakness. SIGNIFICANCE: The present study has established that both AD and CB occur in MMN, irrespective of extremity, and both correlate with muscle weakness.

Action Potentials↗
PubMed2006

Acute sensory neuronopathy as the presenting symptom of Sjögren's syndrome.

Sensory neuronopathy associated with Sjögren's syndrome (SS) usually has a subacute or chronic onset. We report the case of a 37-year-old woman who presented with an unusual hyperacute form of SS ganglionopathy. She initially developed paresthesias of her fingertips and rapidly became severely ataxic. Nerve conduction studies revealed abnormal sensory but normal motor functions. Lip biopsy showed findings consistent with SS. Sural nerve biopsy showed severe axonal loss. The patient showed modest improvement with immunosuppressive therapies.

Adult↗
PubMed2006

Neuregulin 1-erbB signaling is necessary for normal myelination and sensory function.

To investigate the role of erbB signaling in the interactions between peripheral axons and myelinating Schwann cells, we generated transgenic mice expressing a dominant-negative erbB receptor in these glial cells. Mutant mice have delayed onset of myelination, thinner myelin, shorter internodal length, and smaller axonal caliber in adulthood. Consistent with the morphological defects, transgenic mice also have slower nerve conduction velocity and defects in their responses to mechanical stimulation. Molecular analysis indicates that erbB signaling may contribute to myelin formation by regulating transcription of myelin genes. Analysis of sciatic nerves showed a reduction in the levels of expression of myelin genes in mutant mice. In vitro assays revealed that neuregulin-1 (NRG1) induces expression of myelin protein zero (P0). Furthermore, we found that the effects of NRG1 on P0 expression depend on the NRG1 isoform used. When NRG1 is presented to Schwann cells in the context of cell-cell contact, type III but not type I NRG1 regulates P0 gene expression. These results suggest that disruption of the NRG1-erbB signaling pathway could contribute to the pathogenesis of peripheral neuropathies with hypomyelination and neuropathic pain.

Animals↗
PubMed2006

Cervical nerve root stimulation. Part I: technical aspects and normal data.

OBJECTIVE: Cervical nerve root stimulation (CRS) is a technique of assessing the proximal segments of motor axons destined to upper extremity muscles. Few studies report normal values. The objective was to determine CMAP onset-latencies and CMAP amplitude, area, and duration changes in healthy controls for the abductor pollicis brevis (APB), abductor digiti minimi (ADM), biceps, and riceps muscles. In addition, to determine the tolerability of CRS, as measured by the visual analog scale (VAS). METHODS: We studied 21 healthy volunteers prospectively with CRS using four target muscles (APB, ADM, biceps, and triceps) bilaterally. Collision studies were used in all APB recordings. VAS was obtained in all subjects. RESULTS: Mean CMAP onset-latencies were: APB 14 +/- 1.5 ms; ADM 14.2 +/- 1.5 ms; biceps 5.4 +/- 0.6 ms; triceps 5.4 +/- 1.0 ms. Onset-latency significantly correlated with height for all nerves. The mean change in CMAP amplitude and area (%) between most distal stimulation and CRS was: APB reduction of 15.1 +/- 11.6 and 4.9 +/- 3.6%; ADM reduction of 21.1 +/- 10.7 and 17.2 +/- 8.8; biceps reduction of 10 +/- 11.5 and reduction of 8.7 +/- 6.8; triceps increase of 3.3 +/- 5.2 and 11.0 +/- 9.9% respectively. Mean CMAP duration change between most distal stimulation and CRS was: APB, increase of 20.4 +/- 7.4%; ADM, increase of 14.4 +/- 8.5%; biceps, increase of 13.9 +/- 10.8%; triceps, increase of 7.7 +/- 6.7%. The mean VAS score was 3.8 +/- 1.2, and all subjects completed the study. CONCLUSIONS: The present study establishes normative data and indicates that CRS is a well-tolerated technique. SIGNIFICANCE: The normal values may be used as reference data for the needle CRS technique in the assessment of proximal conduction abnormalities.

Adult↗
PubMed2006

Cervical nerve root stimulation. Part II: findings in primary demyelinating neuropathies and motor neuron disease.

OBJECTIVE: Cervical nerve root stimulation (CRS) allows the assessment of conduction in the proximal segments of motor fibers destined to the upper extremities, which are not evaluated by routine nerve conduction studies (NCS). Since many primary demyelinating polyneuropathies (PDP) are multifocal lesions may be confined to the proximal nerve segments. CRS may therefore increase the yield of neurophysiologic studies in diagnosing PDP. METHODS: We reviewed clinical and neurophysiologic data from 38 PDP patients and compared them to 35 patients with motor neuron disease (MND), and 21 healthy controls (HC). RESULTS: Mean onset-latency was significantly prolonged in PDP patients. The optimal onset-latency cutoff necessary to distinguish PDP from MND and controls was 17.5 ms for the abductor pollicis brevis (APB) and abductor digiti minimi (ADM), and 7 ms for Biceps and Triceps. Mean reduction in proximal to distal CMAP amplitude to APB and ADM was significantly greater in PDP patients, with an optimal cutoff in proximal to distal CMAP amplitude reduction necessary to distinguish PDP from MND and HC being 45%. CONCLUSIONS: CRS is effective in distinguishing PDP from MND and HC based on prolonged onset latency and conduction block criteria. SIGNIFICANCE: CRS may increase the diagnostic yield in cases where demyelinating lesions are confined to the proximal peripheral neuraxis.

Action Potentials↗
PubMed2005

Radiculoplexopathy with conduction block caused by acute Epstein-Barr virus infection.

The authors report a case of cervicobrachial radiculoplexopathy with proximal conduction block (CB), associated with acute Epstein-Barr virus (EBV) infection. The patient presented with pain, paresthesias, and monomelic weakness in the left C7-8, and T1 myotomes. The illness was monophasic with rapid recovery. Neurophysiologic studies demonstrated CB in the proximal left median and ulnar nerve segments. The authors conclude that this syndrome resulted from a postinfectious process following acute EBV infection.

Brachial Plexus Neuritis↗
PubMed2005

IgG neuropathy: an immunoelectron microscopic study.

There are many potential mechanisms of peripheral nerve impairment by a monoclonal IgG dysglobulinemia. In this study, using electron microscopy, we observed widening of the myelin lamellae comparable to that commonly described in IgM neuropathies with antimyelin-associated glycoprotein activity. Such features have yet to be described in IgG neuropathies. In addition, we observed deposits of a granular material in the interstitial tissue of the nerve. By immunoelectron microscopy, we demonstrated the presence of the IgG in the lesions of myelin and the endoneurial space. A direct link between monoclonal dysglobulinemia (regardless of type) and polyneuropathy should be confirmed by nerve biopsy, because the result may influence treatment.

Antibodies, Anti-Idiotypic↗
PubMed2004

Multifocal motor neuropathy: decrease in conduction blocks and reinnervation with long-term IVIg.

BACKGROUND: Multifocal motor neuropathy with conduction blocks (MMNCB) is an immune-mediated motor neuropathy. Previous long-term IV immunoglobulin (IVIg) treatment studies have documented improvement in muscle strength and functional disability but revealed a concomitant increase in acute axonal degeneration (AD) and conduction block (CB). OBJECTIVE: To determine the long-term effects of IVIg therapy on clinical and neurophysiologic outcome measures in MMNCB patients responsive to IVIg. METHODS: The authors reviewed medical records of 10 patients with MMNCB for outcomes in muscle strength (Medical Research Council score), functional disability (Modified Rankin Disability score), CB, and AD. All patients had received IVIg (2g/kg in 5 days for 3 consecutive months), followed by monthly maintenance therapy. RESULTS: Patients were followed for an average of 7.25 years (range, 3.5 to 12 years). There was significant and sustained improvement in muscle strength and functional disability while on IVIg therapy. Furthermore, the authors found significant improvement in CB, decrease in AD, and evidence of reinnervation by the end of the follow-up period. CONCLUSION: Long-term IV immunoglobulin therapy improves muscle strength and functional disability, decreases the number of conduction blocks and the extent of axonal degeneration, and promotes reinnervation. These findings differ from previous reports of deterioration in neurophysiologic outcome measures. Comparison of the IV immunoglobulin regimen in those reports and this study shows that the authors' patients were treated with significantly higher IV immunoglobulin maintenance doses. These findings have implications for the long-term treatment of patients with multifocal motor neuropathy with conduction blocks.

Action Potentials↗
PubMed2004

Neurophysiologic findings in early acute inflammatory demyelinating polyradiculoneuropathy.

BACKGROUND: Patients with early acute inflammatory demyelinating polyradiculoneuropathy (AIDP) may not meet the current neurophysiologic criteria. OBJECTIVE: To document neurophysiologic findings in early AIDP. METHODS: Clinical and neurophysiologic data from 38 AIDP patients, assessed within 10 days of symptom onset were reviewed. RESULTS: In addition to absent H reflexes and abnormal F-wave responses in the acute stage of AIDP, abnormalities of blink reflexes, upper limb sensory responses abnormalities with spared sural responses, presence of distal CMAP dispersion, and A-waves were frequently observed. Established demyelinating neurophysiologic parameters were infrequently seen. CONCLUSIONS: Abnormalities of H reflexes and F responses were most frequently noted in early AIDP. Additionally, distal temporal dispersion, prolonged or absent blink reflexes, and A-waves were often present in the acute stage of AIDP when classic diagnostic criteria of AIDP were not satisfied. SIGNIFICANCE: Neurophysiologic studies in early AIDP frequently reveal abnormalities that are not specific of primary demyelinating neuropathy.

Adolescent↗
PubMed2003

Atypical presentations of primary amyloid neuropathy.

Primary amyloidosis (AL) may be complicated by peripheral neuropathy in 15-35% of cases. We report on four patients with atypical neurological presentations of AL neuropathy, whose diagnoses were delayed due to varied clinical presentations. The clinical presentation included painful sensory neuropathy (two patients), mononeuropathy multiplex (one patient), and primary demyelinating polyneuropathy (one patient). The latter two types of presentation have not been reported previously. The diagnosis was established by fat pad biopsy in two patients, lymph node biopsy in one, and sural nerve biopsy in one. Two patients were treated with high-dose melphalan followed by stem cell rescue, and one was treated with oral melphalan and prednisone. All three cases experienced stabilization of neuropathic symptoms. We report these cases in order to raise awareness of the varied clinical presentation of AL neuropathy.

Action Potentials↗