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Compound Muscle Action Potentials (compound + muscle_action_potential)

Distribution by Scientific Domains

Medical Sciences	87%
Life Sciences	12%

Selected Abstracts

Electrical activation of the orbicularis oculi muscle does not increase the effectiveness of botulinum toxin type A in patients with blepharospasm

EUROPEAN JOURNAL OF NEUROLOGY, Issue 3 2010
A. Conte
Background:, Our primary aim in this study was to determine whether electrically induced activation of the injected muscle increases effectiveness of botulinum type A toxin (BonT-A) in patients with blepharospasm (BPS). The second aim was to assess the safety of BonT-A by investigating whether BonT-A injection alters the excitability of blink reflex circuits in the brainstem. Methods:, Twenty-three patients with BPS received BonT-A (Botox) injected bilaterally into the orbicularis oculi muscle at a standard dose. In 18 patients, electrically induced muscle activation of the orbicularis oculi muscle on one side was performed for 60 min (4 Hz frequency) in a single session, immediately after BonT-A injection and in five patients for 60 min once a day for five consecutive days. The severity of BPS was assessed clinically with the BPS score. Compound muscle action potential (cMAPs) from the orbicularis oculi muscles were measured bilaterally. The blink reflex recovery cycle was studied at interstimulus intervals of 250 and 500 ms. Participants underwent clinical and neurophysiological assessment before BonT-A injection (T0) and 2 weeks thereafter (T1). Results:, Compound muscle action potential amplitude significantly decreased at T1 but did not differ between stimulated and non-stimulated orbicularis oculi in the two groups. BonT-A injection left the blink reflex recovery cycle tested on the stimulated and non-stimulated sides unchanged. Conclusions:, In patients with BPS, the electrically induced muscle activation neither increases the effectiveness of BonT-A nor produces larger electrophysiological peripheral effects. The lack of BonT-A-induced changes in the blink reflex recovery cycle provides evidence that BonT-A therapy is safe in patients with BPS. [source]

Deficiency of electroneutral K+,Cl, cotransporter 3 causes a disruption in impulse propagation along peripheral nerves

GLIA, Issue 13 2010
Yuan-Ting Sun
Abstract Nerve conduction requires the fine tuning of ionic currents through delicate interactions between axons and Schwann cells. The K+,Cl, cotransporter (KCC) family includes four isoforms (KCC1,4) that play an important role in the maintenance of cellular osmotic homeostasis via the coupled electroneutral movement of K+ and Cl, with concurrent water flux. Mutation in SLC12A6 gene encoding KCC3 results in an autosomal recessive disease, known as agenesis of the corpus callosum associated with peripheral neuropathy. Nevertheless, the role of KCC3 in nerve function remains a puzzle. In this study, the microscopic examination of KCC isoforms expressed in peripheral nerves showed high expression of KCC2,4 in nodal segments of the axons and in the perinucleus and microvilli of Schwann cells. The KCC inhibitor [[(dihydroindenyl)oxy]alkanoic acid] but not the Na+,K+,2Cl, -cotransport inhibitor (bumetanide) dose-dependently suppressed the amplitude and area of compound muscle action potential, indicating the involvement of KCC activity in peripheral nerve conduction. Furthermore, the amplitude and area under the curve were smaller, and the nerve conduction velocity was slower in nerves from KCC3,/, mice than in nerves from wild-type mice, while the expression pattern of KCC2 and KCC4 was similar in KCC3 kockout and wild-type strains. KCC3,/, mice also manifested a prominent motor deficit in the beam-walking test. This is the first study to demonstrate that the K+,Cl, cotransporter activity of KCC3 contributes to the propagation of action potentials along peripheral nerves. © 2010 Wiley-Liss, Inc. [source]

Utility of the distal compound muscle action potential duration for diagnosis of demyelinating neuropathies

JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 3 2009
Sagiri Isose
Abstract To assess the significance of distal compound muscle action potential (CMAP) duration for diagnosis of demyelinating neuropathies, electrophysiologic data were reviewed from 471 subjects, including 145 normal controls, 60 patients with chronic inflammatory demyelinating polyneuropathy (CIDP), 205 with other neuropathy, and 61 with amyotrophic lateral sclerosis (ALS). The duration of distally evoked CMAP was measured in the median, ulnar, tibial, and peroneal nerves. Optimal cut-off values were calculated with receiver-operating characteristic (ROC) curves. In comparison of normal controls and CIDP patients, ROC analyses showed the sufficient area under the curves (82-93%). When the cut-off values in the detection of demyelination were determined as the point with 98% specificity vs. normal on the ROC curves (median, 6.6 ms; ulnar, 6.7 ms; peroneal, 7.6 ms; tibial, 8.8 ms), the sensitivity was 77% for CIDP, with a specificity of 90% vs. ALS and 95% vs. diabetic neuropathy. The distal CMAP duration is a useful index for the detection of distal demyelination. We suggest the above cut-off values for each nerve as one of the electrodiagnostic criteria for demyelinating neuropathies, preferentially affecting the distal nerve terminals, such as CIDP. [source]

Electrophysiological features in the distinction between hereditary demyelinating and chronic acquired demyelinating neuropathies

JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 2 2004
F Poglio
We carried out an electrophysiological retrospective study in 55 patients with chronic demyelinating acquired and hereditary neuropathies. Alterations of motor nerve conduction velocities (MNCV), distal motor latencies (DML), conduction blocks (CB) and compound muscle action potential (CMAP) were compared, considering the whole number of nerves for each disease. MNCV, DML, CB and CMAP were considered suggestive of demyelination when meeting the American Academy of Neurology (AAN) criteria. Abnormally slow MNCV was found respectively in the 46% of all the CMTX female nerves studied, in the 56.5% of CMTX males, 84% of CMT1A, 74% CIDP and 70% of MAG-PNP. Prolonged DML was observed in the 25% of the CMTX female nerves studied, in the 49.5% of CMTX males, 81% of CMT1A, 63% of CIDP and 71% of MAG-PNP. Moreover, CB were quite often evidenced in CIDP and MAG-PNP nerves (respectively in 48% and 29%) and rarely in hereditary neuropathies. Finally, we observed CMAP reduction in the 45% of all the CMTX female nerves studied, in the 50% of CMTX males, 63% of CMT1A, 49% of CIDP and 60% of MAG-PNP. A well-characterized pattern generally allows an electrophysiological distinction between CMT1A, CMTX males, MAG-PNP on one side and CIDP and CMTX females on the other side. A clear electrodiagnostic distinction result is often hard between CMTX males and MAG-PNP and between CIDP and CMTX females. [source]

Sensitivity of electrophysiological tests for upper and lower motor neuron dysfunction in ALS: A six-month longitudinal study

MUSCLE AND NERVE, Issue 2 2010
Mamede de Carvalho MD
Abstract By following a group of amyotrophic lateral sclerosis (ALS) patients longitudinally using lower motor neuron (LMN) and upper motor neuron (UMN) markers of dysfunction it may be possible to better understand the functional relationships between these motor systems in this disease. We used neurophysiological techniques to follow UMN and LMN dysfunction in a group of 28 patients with ALS, in comparison with the ALS functional rating scale (ALS-FRS) score and the forced vital capacity (FVC). We used motor unit number estimation (MUNE), compound muscle action potential (CMAP) amplitude, and the Neurophysiological Index (NI) to quantify the LMN disorder, and transcranial motor stimulation to study cortical motor threshold, motor-evoked response amplitude, central motor conduction time, and cortical silent period (CSP). The patients were studied shortly after diagnosis and then 6 months later, using both abductor digiti minimi muscles (ADM); ADM strength was initially >MRC 3 (Medical Research Council, UK). The NI and MUNE changed more than any other variable. CSP increased by about 30%, a change more marked than the slight increase observed in the cortical motor threshold (9%). The normal increase of CSP after acute muscle fatigue was preserved during disease progression. The CSP increase correlated with the MUNE rate of decay but not to the NI reduction, perhaps because NI includes F-wave frequency in itscalculation. There was no definite correlation between UMN and LMNdysfunction or progression, but there was a link between CSP and LMN changes in ALS. The CSP may be a useful variable in following UMN dysfunction in clinical practice and in clinical trials. Muscle Nerve, 2010 [source]

Trigeminal nerve repetitive stimulation in myasthenia gravis

MUSCLE AND NERVE, Issue 4 2004
Devon I. Rubin MD
Abstract The aim of this study was to evaluate the utility of repetitive nerve stimulation (RNS) of the trigeminal nerve in assessing patients with myasthenia gravis (MG). In 26 normal controls and 21 patients with myasthenia gravis (MG), 2-Hz repetitive stimulation of the trigeminal nerve was performed using a monopolar needle for percutaneous nerve stimulation and recording over the surface of the masseter. In the MG patients, repetitive stimulation of the ulnar, spinal accessory, and facial nerves was also performed. The mean percent decrement in the compound muscle action potential (CMAP) amplitude among the different nerves at rest were: ulnar, 4.3%; spinal accessory, 10.1%; facial, 14%; and trigeminal, 17.3%. The facial nerve demonstrated abnormal decrement in 57% of all patients, compared with the spinal accessory (48%), trigeminal (43%), and ulnar (20%) nerves. All patients tolerated trigeminal RNS better than or as well as facial RNS. The study demonstrates that trigeminal RNS is a safe, reliable, efficient, and well-tolerated technique that provides another cranial nerve,muscle combination that can be used to supplement repetitive stimulation of other limb or cranial nerves in the evaluation of patients with bulbar or generalized MG. Muscle Nerve 29: 591,596, 2004 [source]

Pulmonary function tests and diaphragmatic compound muscle action potential in patients with sporadic amyotrophic lateral sclerosis

ACTA NEUROLOGICA SCANDINAVICA, Issue 6 2010
T. N. Sathyaprabha
Sathyaprabha TN, Pradhan C, Nalini A, Thennarasu K, Raju TR. Pulmonary function tests and diaphragmatic compound muscle action potential in patients with sporadic amyotrophic lateral sclerosis. Acta Neurol Scand: 2010: 121: 400,405. © 2010 The Authors Journal compilation © 2010 Blackwell Munksgaard. Background,,, Respiratory failure is the primary cause of death in patients with amyotrophic lateral sclerosis (ALS). Diaphragmatic compound muscle action potentials (DCMAP) are valid parameters to assess the respiratory muscle innervation. Aim,,, In this study we propose to establish evidence of pulmonary dysfunction in patients with ALS and its relation to DCMAP parameters among patients with sporadic ALS. Materials and methods,,, Twenty nine patients (M-20, F-9) diagnosed to have sporadic ALS by El. Escorial criteria, without symptoms of pulmonary dysfunction, and able to perform the PFT satisfactorily, were studied. Thirty controls (M-20, F-10) were selected from patient's relatives. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), peak expiratory flow rate (PEFR) and maximum voluntary ventilation (MVV) were measured by spirometry. Maximum expiratory pressure (MEP) was measured by digital peak pressure monitor. Right phrenic nerve conductions (DCMAP) were performed and the latencies and amplitude of diaphragmatic com-pound action potential (DCMAP) was recorded in controls and ALS patients. Results,,, The mean age of patients was 51.41 ± 10.72 years (37,82) and control was 53.57 ± 8.85 years (30,68). None of the patients had symptoms or clinical evidence of respiratory dysfunction. The FVC, FEV1, PEFR, MVV, MIP and MEP were significantly (P < 0.001) reduced in ALS. The mean DCMAP amplitude was reduced among patients (610 ± 506.231 ,v) as compared to controls (1303.33 ± 584.56, P < 0.001) and mean latency was increased in patients (9.73 ± 2.57 ms) compared to controls (7.69 ± 0.87, P = 0.001). There was significant negative correlation between PFTs and latencies of DCMAP. Amplitude of DCMAP did not correlate with PFTs. Conclusion,,, There is significant negative correlation between DCMAP latencies and PFTs suggesting early loss of myelinated fibres and diaphragmatic dysfunction. DCMAP latencies may be a good indicator of early respiratory muscle involvement and also of disease progression in ALS. [source]

Assessment of corticodiaphragmatic pathway and pulmonary function in acute ischemic stroke patients

EUROPEAN JOURNAL OF NEUROLOGY, Issue 3 2000
E. M. Khedr
This study investigates the effect of stroke on the corticodiaphragmatic pathway and attempts to clarify the relationship between neurophysiological data and degree of motor disability, site of infarction in computerized tomography (CT) scan, diaphragmatic excursion, blood gases and pulmonary function in stroke patients. Using magnetic stimulation of the scalp sites and cervical roots, an assessment of corticodiaphragmatic pathway was made. The study included 34 sequentially selected patients from a total of 250 patients with acute ischemic stroke. Twenty-five (age- and sex-matched) volunteers served as controls. Sixteen patients had cortical infarction, 13 had subcortical infarction and five had both cortical and subcortical infarction. The mean according to the Scandinavian Stroke Scale was 32.2. Decreased diaphragmatic excursion was observed in 41% of the patients. Twenty-four patients (70.5%) had abnormal magnetic evoked potentials (MEPs) in the affected hemisphere. In five patients MEPs could not be elicited from the affected hemisphere; the remaining 19 patients had abnormal values of both cortical latency and central conduction time (CCT). Cortical latency, CCT, amplitude of compound muscle action potentials (CMAPs) and excitability threshold of the affected hemisphere were significantly altered compared with both the unaffected hemisphere and the control group. Those patients with hemiplegia had a greater degree of hypoxia, hypocapnia and decreased serum bicarbonate level compared with the control group. Also, hemiplegic patients had different degree of respiratory dysfunction. A statistically significant association was found between neurophysiological data and disability score, diaphragmatic excursion, site of infarction in CT scan and degree of respiratory dysfunction. Central diaphragmatic impairment may occur in acute stroke and could contribute to the occurence of hypoxia in those patients. [source]

Thyroid hormone enhances transected axonal regeneration and muscle reinnervation following rat sciatic nerve injury

JOURNAL OF NEUROSCIENCE RESEARCH, Issue 8 2010
Petrica-Adrian Panaite
Abstract Improvement of nerve regeneration and functional recovery following nerve injury is a challenging problem in clinical research. We have already shown that following rat sciatic nerve transection, the local administration of triiodothyronine (T3) significantly increased the number and the myelination of regenerated axons. Functional recovery is a sum of the number of regenerated axons and reinnervation of denervated peripheral targets. In the present study, we investigated whether the increased number of regenerated axons by T3-treatment is linked to improved reinnervation of hind limb muscles. After transection of rat sciatic nerves, silicone or biodegradable nerve guides were implanted and filled with either T3 or phosphate buffer solution (PBS). Neuromuscular junctions (NMJs) were analyzed on gastrocnemius and plantar muscle sections stained with rhodamine ,-bungarotoxin and neurofilament antibody. Four weeks after surgery, most end-plates (EPs) of operated limbs were still denervated and no effect of T3 on muscle reinnervation was detected at this stage of nerve repair. In contrast, after 14 weeks of nerve regeneration, T3 clearly enhanced the reinnervation of gastrocnemius and plantar EPs, demonstrated by significantly higher recovery of size and shape complexity of reinnervated EPs and also by increased acetylcholine receptor (AChRs) density on post synaptic membranes compared to PBS-treated EPs. The stimulating effect of T3 on EP reinnervation is confirmed by a higher index of compound muscle action potentials recorded in gastrocnemius muscles. In conclusion, our results provide for the first time strong evidence that T3 enhances the restoration of NMJ structure and improves synaptic transmission. © 2010 Wiley-Liss, Inc. [source]

Diabetes mellitus exacerbates motor and sensory impairment in CMT1A

JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 4 2008
Soham Sheth
Abstract Charcot-Marie-Tooth disease type 1A (CMT1A) is caused by a duplication of PMP22 on chromosome 17 and is the most commonly inherited demyelinating neuropathy. Diabetes frequently causes predominantly sensory neuropathy. Whether diabetes exacerbates CMT1A is unknown. We identified 10 patients with CMT1A and diabetes and compared their impairment with 48 age-matched control patients with CMT1A alone. Comparisons were made with the Charcot-Marie-Tooth disease (CMT) neuropathy score (CMTNS) and by electrophysiology. The CMTNS was significantly higher in patients with diabetes (20.25 ± 2.35) compared with controls (15.19 ± 0.69; p = 0.01). Values were particularly higher for motor signs and symptoms. Seven of the 10 diabetic patients had CMTNS >20 (severe CMT), while only 7 of the 48 age-matched controls had scores >20. There was a trend for CMT1A patients with diabetes to have low compound muscle action potentials and sensory nerve action potentials, although nerve conduction velocities were not slower in diabetic patients compared with controls. Diabetes was associated with more severe motor and sensory impairment in patients with CMT1A. [source]

CMT1A Associated With The 17p11.2 Duplication: Differential Features And Correlation

JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 1 2001
D Pareyson
A duplication on chromosome 17p11.2 encompassing the gene coding for the peripheral myelin protein-22 (PMP22) is the most common genetic abnormality underlying Charcot-Marie-Tooth disease (CMT). We report clinical and electrophysiologic features of our series of CMT1A patients harboring the duplication. There were 92 patients from 53 families representing 42% of all CMT index cases (n = 125) and 64% of CMT1 probands (n = 83). In CMT1A patients, mean age at onset was 9.7 ± 11.4 and was significantly lower than in non-duplicated CMT1 cases (12.6 ± 9.7, p < 0.01) and CMT2 cases (21.5 ± 17, p < 0.001). Clinical severity was similar to that of CMT2 patients, but significantly milder than in non-duplicated CMT1 cases. Pes cavus, upper limb involvement, deep tendon reflexes abnormalities, and sensory loss were more frequent compared to CMT2. Electrophysiologic examination revealed motor and sensory conduction velocity (MCV, SCV) slowing below 32 m/s in upper limbs. MCV and SCV were significantly lower than in non-duplicated CMT1 patients. Amplitudes of upper limb compound muscle action potentials (CMAPs) and of upper and lower limb sensory action potentials (SAPs) were significantly lower than in CMT2, paralleling clinical differences. Clinical severity correlated with CMAP amplitudes and with disease duration. On the other hand, MCV slowing was not correlated with either severity or duration of the disease. We found a direct correlation between age at onset and upper limb MCV slowing. Conclusions: CMT1A is an early-onset but slowly progressive disorder, on average milder than other CMT1. Axonal loss rather than demyelination per se underlies disease progression. [source]

Dissociated small hand muscle atrophy in amyotrophic lateral sclerosis: Frequency, extent, and specificity

MUSCLE AND NERVE, Issue 4 2008
Satoshi Kuwabara MD
Abstract Previous studies suggest that in amyotrophic lateral sclerosis (ALS) the abductor pollicis brevis (APB) and first dorsal interosseous (FDI) are more severely involved than abductor digiti minimi (ADM). To elucidate the pattern, frequency, extent, and specificity of such dissociated muscle atrophy in ALS, compound muscle action potentials recorded from APB, FDI, and ADM were analyzed in 77 ALS patients, 171 normal controls, and 196 disease controls. Compared with normal controls, ALS patients had a reduced APB/ADM amplitude ratio (P < 0.001) and FDI/ADM ratio (P < 0.001), whereas patients with other anterior horn diseases showed similar APB/ADM and FDI/ADM ratios to normal values. Decreased APB/ADM ratio was found in 41% of ALS patients, 5% of normal controls, and 4% of disease controls. Prominent muscle atrophy in APB and FDI, with relatively preserved ADM, appears to be specific to ALS. Dissociated hand muscle atrophy presumably reflects part of the pathophysiology and supports the diagnosis of ALS. Muscle Nerve, 2008 [source]

Morvan's syndrome: Clinical, laboratory, and in vitro electrophysiological studies

MUSCLE AND NERVE, Issue 2 2004
Wolfgang N. Löscher MD
Abstract Morvan's syndrome is a rare disorder characterized by neuromyotonia, hyperhidrosis, and central nervous system dysfunction. We report a patient with features of this syndrome, but who initially presented with breathing difficulties. Concentric needle electromyography showed an abundance of myokymic and neuromyotonic discharges. Exercise tests and repetitive nerve stimulation showed a decrement,increment response of compound muscle action potentials. Antibodies against voltage-gated potassium channels were not detected on repeated testing, but the presence of oligoclonal bands in the cerebrospinal fluid (CSF) suggested an autoimmune etiology. At follow-up over 3 years, no cancer was found. Electrophysiological in vitro studies of effects of patient serum and CSF on rat nerves provided no evidence of altered voltage-gated sodium or potassium conductances. We conclude that putative humoral factors do not block ion channels acutely but may cause channel dysfunction with chronic exposure. Muscle Nerve 30: 157,163, 2004 [source]

Lower motor neuron loss in multiple sclerosis and experimental autoimmune encephalomyelitis,

ANNALS OF NEUROLOGY, Issue 3 2009
Johannes Vogt MD
Objective Multiple sclerosis (MS) is considered a chronic inflammatory and demyelinating disease of the central nervous system. Evidence that axonal and neuronal pathology contributes to the disease is accumulating, however, the distribution of neuronal injury as well as the underlying mechanisms have not yet been fully clarified. Here, we investigated the role of neuronal cell loss in MS and its animal model, experimental autoimmune encephalomyelitis (EAE). Methods We performed electrophysiological investigations in MS patients, including assessment of compound muscle action potentials and motor unit numbers and quantified neuronal cell loss in human MS samples and different EAE models by high-precision stereology. Results Both electrophysiological and morphological analyses indicated a massive loss of lower motor neurons in MS patients. We regularly found dying spinal motor neurons surrounded by CD3+ (CD4+ as well as CD8+) T cells expressing tumor necrosis factor,related apoptosis-inducing ligand (TRAIL). We observed a similar degree of damage and immune attack in different variants of EAE; the lower motor neurons were preserved in adoptive transfer EAE induced with TRAIL-deficient T lymphocytes. Interpretation Our study indicates that damage to lower motor neurons and TRAIL-mediated inflammatory neurodegeneration in the spinal cord contribute to MS pathology. Ann Neurol 2009;66:310,332 [source]