Search results for "Neural Conduction"
showing 10 items of 54 documents
Increased risk of sensory neuropathy in workers with chloracne after exposure to 2,3,7,8-polychlorinated dioxins and furans
1999
Objective - The existence of a peripheral neuropathy after exposure to polychlorinated dioxins (PCDD) is still discussed, as studies concerning dioxin effects on the peripheral nervous system are rare and contradictory. Material and methods - Clinical and neurophysiological examinations (motor conduction velocity of the peroneal nerve, sensory conduction velocities of the sural and ulnar nerves) were made in 156 dioxin exposed workers (42 with, 114 without cloracne) from one pesticide producing plant. Because of known risk factors for peripheral neuropathy, 7 workers with and 28 without cloracne were excluded from further analysis. Results - Workers with chloracne had a significantly higher…
Central motor conduction time by magnetic stimulation of the cortex and peripheral nerve conduction follow-up studies in Friedreich's ataxia.
1998
A follow-up clinical study, peripheral motor and sensory nerve conduction velocities and central motor conduction by magnetic stimulation of the cortex were performed in 13 patients with classical Friedreich's ataxia (FA) phenotype, for a period of 9-12 years. Clinical worsening was unrelated to peripheral nerve abnormalities. The amplitude of the nerve action potentials and delayed conduction velocity remained unchanged for several years. Central motor conduction times were abnormal in all patients. Clinical conditions worsened significantly between successive examinations with significant increments in threshold and significant decrement of the amplitude of motor evoked potentials. The re…
Progressive cerebellar ataxia, proximal neurogenic weakness and ocular motor disturbances: hexosaminidase A deficiency with late clinical onset in fo…
1997
Tay-Sachs disease is a genetically determined neurodegenerative disorder, resulting from mutations of the hexosaminidase (Hex) A gene coding for the alpha-subunit of beta-D-N-acetyl-hexosaminidase. Clinically, there is severe encephalomyelopathy leading to death within the first few years of life. Hex A activity is usually absent in tissue and body fluids of these patients. Juvenile and adult Hex A deficiencies are less severe but rare variants with some residual Hex A activity. All these variants are most prevalent among Ashkenazi Jews. We describe a non-Jewish family in which four adult brothers and sisters had markedly reduced Hex A activities and onset of symptoms in the second decade o…
Impaired action potential conduction at high force levels after eccentric exercise
2010
High-density surface electromyography was used to examine whether gross sarcolemmal function is impaired in m. biceps brachii after intensive eccentric elbow flexor exercise, when measured at wide range of isometric contraction levels. Root mean square (RMS), mean power frequency (MNF) and mean muscle fibre conduction velocity (CV) were calculated before and up to four days post-exercise. Maximal isometric voluntary (MVC) force decreased by 21.3+/-5.6% two hours after exercise, and by 12.6+/-11.1% two days post-exercise. CV and MNF decreased both during MVC (CV from 4.1+/-0.3m/s to 3.8+/-0.4m/s and MNF from 92.6+/-10 Hz to 85.2+/-11 Hz) and during electrically evoked maximal M-wave (CV from…
Electrically stimulated axon reflexes are diminished in diabetic small fiber neuropathies.
2004
Axon reflex mediated flare depends on the density and the function of cutaneous C-fibers and may be impaired in diabetic neuropathy. We induced neurogenic axon reflex flare by intracutaneous electrical stimulation and analyzed size and intensity of the flare on the dorsum of the foot and ventral thigh with laser Doppler imaging (LDI). We investigated 12 diabetic subjects with small fiber neuropathies (SFNs), 5 diabetic subjects without neuropathy (NO-Ns), and 14 healthy control subjects. Five of the normal subjects were reassessed after 12 months. In comparing patients with SFN to control subjects, we found that SFN flare size but not the intensity of vasodilation (flux) was reduced on the …
Analysis of F-wave in metabolic neuropathies: a comparative study in uremic and diabetic patients.
1987
Motor nerve conduction study along the entire length of the ulnar and tibialis posterior nerves was carried out in 30 diabetics compared with 30 uremic patients and 30 control subjects. The conduction in the proximal and the distal nerve segments was evaluated by the determination of the M and F latencies, MNCV (between the stimulus sites), FWCV (between the spinal cord and the stimulus sites), and F-ratio (conduction time ratio of proximal to distal segment). In both groups of patients the lower limbs appear much more involved than the upper, where the ulnar nerve is more commonly affected in uremic than in diabetic patients. In diabetic neuropathy the motor conduction abnormalities are di…
EDSS correlated analysis of median nerve somatosensory evoked potentials in multiple sclerosis
2001
Median nerve somatosensory evoked potentials (SEP) were recorded in 30 patients with multiple sclerosis. The examined patients had an expanded disability status scale (EDSS) between 0 and 6. The primary cortical potential N20, the subcortical potentials P14, N13b, N13a and the peripheral potential P9 were recorded simultaneously. In 5 patients normal SEP were observed (group 1), and in 6 patients there were consecutive disturbances of the somatosensory pathway (group 3). In 19 patients subcortical potentials were abnormal or absent while the following potentials were normal or identified which pattern corresponds to amplification within CNS structures (group 2). The EDSS of groups 1 and 2 w…
Neuromuscular fatigue during dynamic maximal strength and hypertrophic resistance loadings
2011
The purpose of this study was to compare the acute neuromuscular fatigue during dynamic maximal strength and hypertrophic loadings, known to cause different adaptations underlying strength gain during training. Thirteen healthy, untrained males performed two leg press loadings, one week apart, consisting of 15 sets of 1 repetition maximum (MAX) and 5 sets of 10 repetition maximums (HYP). Concentric load and muscle activity, electromyography (EMG) amplitude and median frequency, was assessed throughout each set. Additionally, maximal bilateral isometric force and muscle activity was assessed pre-, mid-, and up to 30 min post-loading. Concentric load during MAX was decreased after set 10 (P<0…
Evoked potential study in facio-scapulo-humeral muscular dystrophy.
1997
Nerve conduction velocities (NCVs), somatosensory (SEPs) and auditory evoked potentials (BAEPs) were recorded in 9 patients with facio-scapulo-humeral dystrophy (FSHD) and in 20 age-matched controls. In FSHD patients a significant increase of the nerve distal sensory latencies and of the absolute SEP latencies revealed a subclinical involvement of the afferent sensory pathways, as well as the abnormal slowing of the later components of the BAEPs, pointed to a central auditory dysfunction. Moreover all patients underwent brain MRI that showed the presence of white matter hyperintense lesions in 4 of them (44%). No correlations were found between individual or total number of SEP and BAEP abn…
Modulation of spinal cord excitability by subthreshold repetitive transcranial magnetic stimulation of the primary motor cortex in humans.
2001
Repetitive transcranial magnetic stimulation (rTMS) allows the modulation of intra-cortical excitability and may therefore affect the descending control of spinal excitability. We applied rTMS at subthreshold intensity and 1 Hz frequency for 10 min to the left primary motor cortex representation of the flexor carpi radialis muscle (FCR) in 10 subjects and assessed the H and M responses to median nerve stimulation before and after the rTMS. Following rTMS, H wave thresholds significantly reduced by ∼20%. Maximal H but not M wave amplitude significantly increased over the baseline, so that H/M amplitude ratio was increased by 41%. Sham stimulation did not induce any noticeable change in M or …