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PubMedDate not supplied

ERP evidence of a dichotic left-ear deficit in some dyslexic children.

Children with and without behavioral dichotic left-ear deficits participated in an event-related potential study with quasidichotic presentations of familiar fairy tale segments. Electrical activity was recorded from the scalp while the children listened for semantically and/or syntactically anomalous words from either the right side or the left side while competing segments of the fairy tale were simultaneously presented from the opposite side. Latencies and amplitudes were averaged for each target condition within the group with dichotic left-ear deficits (LED) and the group with normal dichotic listening performance (WNL). Individual global field power waveforms and topographic brain maps were generated for the average response in each of the two listening conditions, target right and target left. Cross-correlations were performed on the grand averaged global field power waveforms to measure the degree of synchrony between target right and target left responses in both groups. Integration functions were performed to compare the accumulated sum of voltages during target (right and left) and control (right and left) conditions. WNL children produced typical ERP responses to the target words in both target right and target left conditions. Responses from LED children were at delayed latencies in the target left condition and were at reduced amplitudes in both target conditions. Topographic brain maps revealed more lateralized scalp distributions and greater activation of frontal regions in LED children in the target left condition. Cross-correlational and integration function results demonstrated interaural asymmetries in responses from the LED children. Overall results suggest that slowed neural conduction times, poor interhemispheric transfer of neural activity, and a failure to suppress competing information arriving at the right ear may be involved in poor left-sided processing in children with behavioral left-ear dichotic deficits.

Analysis of Variance↗
PubMed2000

[Electrophysiological study of the lateral dorsal cutaneous nerve: technical applicability and normal values].

The distal nerve conduction study of the long nerve in the leg is more efficient to work with so that it can establish the early diagnosis of the majority of polyneuropathies. The main purpose of this study is the technical applicability of the orthodromic neural conduction examination of the dorsal cutaneous branch of the sural nerve (lateral dorsal cutaneous nerve) on healthy people, and define the normal values used as references to compare with the proximal segment. Forty five persons mean age 41.56 years old (range 19-75) were examined, and the sensory nerve action potentials were registered from ninety feet. The active recording superficial electrode was placed below and behind the lateral malleolus and the stimulating electrode was placed 10 cm distal to the recording superficial electrode at the dorsal lateral aspect of the feet. The mean value for the lateral dorsal cutaneous nerve conduction velocity was 47.35 +/- 4.8 m/s and for amplitudes 4.19 +/- 1.9 microV. The sensory conduction velocity in the distal segment was 14% lower than the proximal one. The sensory nerve action potential amplitude of the distal segment was 73% lower than the proximal one. The lower normal limit recommended for conduction velocity of this nerve plus correction for skin temperature of 34 degrees C is 38 m/s. Some differences in amplitude and conduction velocity among group ages are to be considered.

Adult↗
PubMed2002

Nerve conduction study on patients with severe liver syndrome and its change after transplantation.

This study is to investigate the character of peripheral neuropathy associated with end stage liver disease and the effect of liver transplantation on peripheral neuropathy. Twenty-five patients admitted for a liver transplantation were involved in this study. All patients underwent neural conduction study before liver transplantation and 6 months after liver transplantation. Based on results of this study, motor amplitude score, motor velocity score (MVS), sensory amplitude score (SAS), and sensory velocity score were calculated. The changes between before and after liver transplantation were evaluated. The SAS and MVS substantially increased after transplantation. Nerve conduction study showed the improvement in sensory and motor nerve after liver transplantation.

Action Potentials↗
PubMed1995

[A chronic spinal cord compression model in a rat with a 354A tumor].

A posterior spinal cord compression model was produced in a rat with a 354 A tumor. Here we report the compression process using MRI (at 2.11 tesla), the progression of paralysis in the posterior limbs, the pathological changes in the neural tissues, and the spinal evoked potentials (SpEPs). A relatively flat spinal cord compression model was established by the interposition of free fatty tissue between the tumor and dura mater. The anteroposterior diameter of the compressed cord (AP), the width of the compressed cord (W), the cross-sectional areas of the spine (A), the mean of the anteroposterior diameters of the cord at the levels of the adjacent cephalic and caudal vertebral bodies (AP), and the mean of the cross-sectional areas of the cord at the levels of the adjacent cephalic and caudal vertebral bodies (A) were measured on axial views from MRI. Paralysis of the posterior limbs occurred in this model when A/A became less than 60%, AP/AP became less than 35% and AP/W became less than 20%. Pathological changes became apparent in the neural tissues when A/A became less than 50-60%, AP/AP became less than 25-30% and AP/W became less than 15%. Polyphasic wave-forms were noted when A/A became less than 60%, AP/AP became less than 35% and AP/W became less than 20%. When the A/A became less than 40%, the histopathological changes became marked. SpEPs could no longer be detected at this degree of compression, indicating that all neural conduction had been blocked.

Animals↗
PubMed2001

Direct tramadol application on sciatic nerve inhibits spinal somatosensory evoked potentials in rats.

We sought to determine the possible neural conduction blockade of tramadol and whether there is evidence of localized neural toxicity with spinal somatosensory evoked potential (SSEP) measurements. Male Wistar rats were used. SSEP, elicited by supramaximally stimulating the hind paw and recorded from the thoracolumbar and the first and second lumbar interspinous ligaments, was monitored. SSEPs were obtained before drug application as the pretreatment baseline and measured every 15 min after treatment for 2 h and at 60-min intervals thereafter until SSEP returned to baseline or for another 4 h. Two small strips of Gelfoam (0.6 x 1.0 cm(2)) soaked with the drug were placed under and over the left sciatic nerve for a 30-min period. Gelfoam was prepared with tramadol hydrochloride (Tramal; the US trade name is Ultram) 5, 2.5, and 1.25 mg, diluted if needed with saline to a total volume of 100 microL (5%, 2.5%, and 1.25%, respectively). The control data were obtained from the right side limb with normal saline by following the same method. Spinal SSEPs were measured after 48 h to detect the late neural damage. The results showed that direct tramadol application on sciatic nerves dose-dependently reduced both the amplitude and conduction velocity of SSEPs when compared with the pretreatment baseline. All SSEPs returned to pretreatment baseline, and no significant changes of SSEP between bilateral limbs were noted at the 48-h measurements. No evidence of irreversible conduction blockade indicative of local neural toxicity was seen. Pretreatment with naloxone 1 mg/kg failed to block the changes of SSEP produced by 2.5% tramadol 100 microL. We conclude that tramadol exerts a local anesthetic-type effect on peripheral nerves.

Analgesics, Opioid↗
PubMed2004

Peripheral nerve conduction study in workers exposed to a mixture of organic solvents in paint and lacquer industry.

AIM: To compare levels of combined exposure to white spirit, toluene, butyl acetate, ethyl acetate, and xylene in the manufacturing of paint, cartridge, drying, and top-coat sections of paint and lacquer industry, and peripheral nerve conduction parameters in the exposed workers. METHODS: The exposed group comprised 120 workers while the control group included 110 workers who had never been exposed to the above listed organic solvents. Nerve conduction studies of the radial and tibial anterior nerve were performed in both groups. RESULTS: Motor and sensitive conduction velocity, as well as terminal latency of the radial and tibial anterior nerve showed significant changes in exposed workers in comparison to those of the control group (p<0.001). These parameters were significantly changed in workers with long length exposure to the toxic agents. In early stages of exposure, neural conduction parameters of the radial nerve were the most sensitive parameters in detecting subclinical peripheral nerve changes (p<0.001). There was significant correlation between the nerve conduction changes and urinary levels of hippuric and methyl-hippuric acids (p<0.01). CONCLUSION: The results of the study suggest neurotoxic effects of the mixture of white spirit, toluene, butyl acetate, ethyl acetate, and xylene detected in paint and lacquer industry. Standard measurement of the urinary levels of hippuric and methyl-hippuric acids could be a useful indicator of need for nerve conduction studies and the subclinical peripheral neuropathy screening in exposed workers.

Adult↗
PubMed2005

Effects of reduction mammoplasty on upper-limb nerve conduction across the thoracic outlet in women with macromastia: a prospective randomized study.

UNLABELLED: Macromastia is a common problem. The physical complaints include upper body pain and aches. There have been anecdotal reports of neurologic deficits in the nerves emanating from the lower trunk of the brachial plexus. This is thought to be due to pressure on the lower trunk from both the first rib and tilting forward of the coracoid process. Other anecdotal reports have centered on the correction of neuropraxia of the ulnar nerve following bilateral breast reduction (BBR). We investigate the effect of BBR on the electrophysiological function of the nerve supply to the upper limbs in women with macromastia. METHODOLOGY: Consecutive patients undergoing BBR were randomized into 2 groups, depending on time of surgery. None had any prior neurologic disorder. Each patient had a comprehensive neurologic assessment and 2 electrodiagnostic neurophysiologic tests. Group 1 had 2 tests, one before surgery and a second 3 months postsurgery, while Group 2 had 2 sets of tests, one initially and a second test 4 months later (control). The outcome measures include somatosensory evoked potential (SSEP) (median and ulnar), F-wave median and ulnar latencies. The F waves measure the integrity of neural conduction time from the anterior horn cells to the hypothenar and thenar muscles reflecting lower trunk function. The SSEP of the median nerve measure the integrity of the nerve fibers traversing the upper trunk of the brachial plexus and the ulnar nerve SSEP that of the lower trunk. There was no statistical difference in the conduction times. BBR does not have any effect on the upper limb nerve conduction times.

Adolescent↗
PubMed2005

An experimental model of an electrical injury to the peripheral nerve.

OBJECTIVE: Injury to the peripheral nerves is a common complication found in patients suffering from electrical burns. At present, there are many kinds of experimental models for electrical injury, but no report describes an animal-based experimental model for a relatively simple electrical injury to the peripheral nerves. We have designed and constructed a specific device to generate increasingly severe electrical shocks of a known voltage for the experiment. This device can simulate injuries of different degrees (minor, medium and severe) caused by shock to the right sciatic nerve of rats. METHOD: Thirty Sprague-Dawley rats were randomly divided into Group I (3600 V, n=10), Group II (1000 V, n=10) and Group III (500 V, n=10). The voltage required for the electrical shock was generated by the above-mentioned device and was adjusted to deliver 3600, 1000 and 500 V, respectively. The specific voltage, as mentioned above, was delivered three times to the right sciatic nerve of the rats. The shock duration was set to last for 10 ms. The time interval between the shocks was 3 min. Three rats were randomly selected from each group to observe changes in the morphology, electric physiology of the nerve and their histology the first, second and fourth week after injury. RESULTS: All rats survived the injuries. Leg function was partially impaired and swellings occurred on the injured extremity. However, by the second week after the injury the rats had recovered. Digit ulcers were observed by the fourth week after injury in Groups I and II. Neural electric physiology showed that the recovery rate of the neural conduction velocity (RNCV) disappeared in part or in whole immediately after the injury in experimental rats. RNCV recovered up to 65% in Group III and to 7% in Group II by the fourth week after injury, however, RNCV did not recover in Group I at all. Histology showed that blood vessel embolism occurred within the injured nerve. A large number of nerve fibres experienced Waller degeneration while the myelin sheath was vacuolated. The neural plate disintegrated largely by the first week after injury and the myelin sheath disintegrated into a loose structure by the second week after injury in Group I. Group II displayed a similar situation as Group I, wherein some nerve fibres experienced Waller degeneration and disintegration. Regenerative myelin appeared in some rats at about the fourth week after injury. The following changes were seen in Group III: The degree of neural injuries was different. The point of entry of the electric currents showed obvious Waller degeneration and disintegration of the myelin sheath, while some nerves showed a regenerated myelin sheath by the second week after injury. The morphology (such as quantity and diameter) of the injured myelin was basically normal by the fourth week after injury. CONCLUSION: This device can produce controlled injuries to the sciatic nerve giving different degrees of severity (minor, medium and severe), by means of varying the electrical shock voltage and shock duration on the rats. It is a useful model for experimental studies of injuries to peripheral nerves.

Animals↗
PubMed1977

Scleroedema (Buschke). A case report.

A case of scleroedema is reported in a 28-year-old man with severe neuromuscular involvement. Failure in neural conduction as well as muscular degeneration and necrosis were seen. Histopathological study showed resorption and formation of scar tissue probably secondary to ischaemia. In addition there was increase in neutral, sulphated and non-sulphated mucosubstances in the dermal and endomysial connective tissue.

Adult↗
PubMed1998

The effect of surgical medicaments on peripheral nerve function.

Surgical medicaments are often placed in close proximity to peripheral nerves and may be responsible for some postoperative sensory disturbances. In this study we investigated the effect of four medicaments -- BIPP, (bismuth iodoform paraffin paste), Whitehead's varnish (compound iodoform paint), Surgicel (oxidized regenerated cellulose) and Carnoy's solution (ethanol, chloroform and acetic acid) -- on peripheral nerve function. The experiments were carried out on the saphenous nerve in anaesthetized adult rats. Electrical stimuli (30 V, 0.1 ms duration) were applied to the saphenous nerve through electrodes placed distally (at the ankle) to evoke a compound action potential (CAP) which was recorded proximally (in the thigh). The CAP was recorded before, and for 2 h after, the application of the medicament to a 1 cm length of nerve between the electrodes. In other animals (n = 4 in each group) recordings were made after the medicament had been placed in a connective tissue pocket immediately overlying the nerve for a 2-week period. BIPP (n = 4) had no immediate or delayed effect on neural function, whereas Whitehead's varnish (n = 4) and Carnoy's (n = 4) solution both blocked neural conduction within 2 min of being placed adjacent to the nerve. The effect of Surgicel (n = 8) was more variable; axonal conduction was blocked within 2 h in five of the eight experiments undertaken. After the application of Whitehead's varnish or Surgicel for 2 weeks, the CAPs had regained characteristics which were similar to those of the controls, but after the application of Carnoy's solution they remained significantly diminished (P < 0.004). These results suggest that, with the exception of BIPP, the medicaments tested could be responsible for some postoperative sensory disturbances, and the effects of Carnoy's solution on neural function may be persistent.

Acetic Acid↗
PubMed1989

Electrophysiologic responses of human sural nerve to temperature.

The purpose of this study was to assess the conduction, specifically the latency and amplitude of the sensory nerve action potential (SNAP), of the sural nerve as a function of intraneural temperature of the leg. The electrophysiologic responses of the sural nerve were determined at different temperatures in 22 healthy adults. Distal sensory latency and amplitude of the sural SNAP was determined at 1 degree C intervals over a limb temperature range of 23 degrees to 40 degrees C. Limb temperature was monitored with a thermistor probe placed subcutaneously near the sural nerve. Ice bath soaks were used for cooling and infrared radiation for warming the limbs. An analysis of covariance was performed for the SNAP latencies and amplitudes to determine the effect of gender and leg (right or left) at each temperature level. No effect of gender or leg on neural conduction was detected in individual subjects. A regression analysis was then used on pooled data to determine the effect of temperature on sural SNAP latency and amplitude. An inverse linear change in the latency of sural SNAP was observed over the temperature ranges used. Mean latency increased 0.1 msec per 1 degree C increase in subcutaneous temperature. A direct relationship between amplitude of the SNAP and temperature was determined. Mean amplitude increased 0.3 muV per 1 degree C increase in subcutaneous temperature. The results of this study support previous reports, which state that SNAP latency is indirectly related to the intraneural temperature. Clinical electromyographers must monitor the temperature of the lower leg and foot whenever sensorineural conduction of the lower limbs is performed.

Action Potentials↗
PubMed1976

Early detection of diabetic visceral neuropathy. An electrophysiologic study of bladder and urethral innervation.

The segmental and supraspinal innervation of the detrusor muscle and periurethral striated musculature was studied in 27 patients with diabetes mellitus by gas cystometry, integrated sphincter electromyography, and spinal evoked-response latency measurements. Slowing of neural conduction velocities was a consistent finding in all the patients, even when cystometry did not show abnormalities. Thus, neuropathy in the segmental innervation of the bladder and urethra was documented.

Adolescent↗
PubMed2000

Visual electrophysiological responses in subjects with cerebral autosomal arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL).

OBJECTIVES: To evaluate visual electrophysiological responses in subjects with cerebral autosomal arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). METHODS: Three subjects (one male and two females, mean age 55.3+/-2.9 years) belonging to an Italian family already diagnosed with CADASIL through clinicopathological and genetic studies and 14 control subjects (6 males and 8 females, mean age 52.7+/-3.6 years) were enrolled in the study. Flash electroretinogram (ERG), oscillatory potentials (OPs) and simultaneous recordings of pattern electroretinogram (PERG) and visual evoked potentials (VEPs) were assessed in all 3 subjects with CADASIL and age-matched controls. RESULTS: Subjects with CADASIL showed: reduced ERG, OP and PERG (N35-P50, P50-N95) amplitudes with respect to our normal limits; delayed PERG (N35, P50) and VEP (P100) implicit times when compared with our normal limits; and VEP (N75-P100) amplitudes and retinocortical times within our normal limits. CONCLUSIONS: Subjects with CADASIL present a dysfunction in the outer, middle and innermost retinal layers when the index of neural conduction in the postretinal visual pathways is normal. The delay in visual cortical responses observed in subjects with CADASIL may be ascribable to retinal impairment with a possible functional sparing of the postretinal visual structures.

Dementia, Multi-Infarct↗
PubMed1998

[Neurophysiologic findings in radio-humeral epicondyle pathology].

A number of authors assumed a compression syndrome of the radial nerve or its branches to be responsible for the heterogenous classified picture of radiohumeral epicondylopathy. Various structural and functional stenoses have been discussed as possible causes. We performed electromyographies on the extensor muscles, subdividing from the radial epicondyle and found significant (p < 0.05) changes in 27/51 patients regarding latency, velocity of neural conduction and rate of polyphasic potentials. Especially affected were the extensor carpi radialis brevis and extensor digitorum muscle. These findings were confirmed by torque measurements and histologic observations from both muscular and tendon biopsies. In summary, we believe the model of a neurogenous origin of radio-humeral epicondylopathy to be an appropriate explanation.

Biopsy↗
PubMed2003

Early visual function impairment in CADASIL.

The authors carried out genetic analyses and visual electrophysiologic evaluations in six asymptomatic sons and daughters of patients with symptomatic cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Three subjects showed Notch3 Cys146Tyr missense mutation and a dysfunction of the outer, middle, and innermost retinal layers, with normal neural conduction in postretinal visual pathways, whereas in the remaining subjects without genetic mutations, no electrophysiologic abnormalities were found. An early vascular retinal impairment in CADASIL may precede the onset of clinical manifestations.

Adolescent↗
PubMed2002

Chronic placental insufficiency has long-term effects on auditory function in the guinea pig.

Very low birth weight and growth-restricted infants have an increased risk of auditory impairments. It is uncertain whether these impairments are related to adverse pre-, peri- or postnatal events. We aimed to determine whether a period of chronic placental insufficiency (CPI) in the guinea pig results in long-term alterations to auditory function. Near mid-gestation, CPI was induced via unilateral ligation of the uterine artery. At 8 weeks of age, auditory brainstem responses (ABRs) were recorded in response to unilateral acoustic stimulation in prenatally-compromised (PC, n=8) and control animals (n=8). Stimuli consisted of 100 micros clicks, presented at 33 pulses per second (pps) and tone pip stimuli at frequencies of 2, 4, 8, 16 and 32 kHz. To examine temporal response properties, click stimuli were also presented at rates of 66, 132 and 200 pps. Normal ABR waveforms were elicited by both click and tone pip stimuli in all animals. Moreover, there was no difference between control and PC animals in stimulus detection thresholds across the frequencies examined. Using high rate click stimuli, PC animals demonstrated a significant increase in both the latency of wave III (normalised to 33 pps) and the wave I-III inter-peak interval compared to the controls. We hypothesise that these functional changes reflect alterations in myelination of the auditory brainstem and/or changes in synaptic efficacy. The results suggest subtle deficits in neural conduction in the PC guinea pig at maturity, and may have implications for speech perception abilities of low birth weight or prenatally affected infants.

Acoustic Stimulation↗
PubMed1999

Correlation of acetylator phenotype with peripheral, autonomic and central neuropathy in Northern Indian non-insulin-dependent diabetes mellitus patients.

OBJECTIVES: Genetic susceptibility to diabetic neuropathy has been suspected and tentatively explored; however, diabetic autonomic and central neuropathies are poorly investigated areas. Previous trials correlating types of diabetes and diabetic neuropathy with acetylator dimorphisms have not been conclusive. The present study was designed to test peripheral neuropathy, autonomic neuropathy and integrity of central conduction pathways in patients of non-insulin-dependent diabetes mellitus (NIDDM), and to correlate the findings with the acetylator phenotype. METHODS: Twenty-six patients of NIDDM with stable glycaemic control and 11 age- and sex-matched control subjects were recruited, clinically examined and investigated with glycaemic and lipid profile, renal function tests, nerve conduction studies (sensory and motor), auditory brain stem evoked responses (ABERs) and somatosensory evoked potentials (SEPs). Acetylator status of the subjects was determined by sulphadimidine test. RESULTS: Out of 26 NIDDM patients, eight (30.7%; group 1A) were slow acetylators and 18 (69.3%; group 1B) were fast acetylators. The distribution of slow and rapid acetylators in both the groups was similar. Glycaemic and lipid profiles and 24-h urinary albumin excretion in groups 1A and 1B were also similar. Motor nerve conduction velocity, latency of F wave, sensory nerve conduction and amplitudes of sensory nerve action potentials were not different between fast and slow acetylator NIDDM patients. On testing for ABERs, there were no statistically significant differences in peak latencies of waves I, III and V; interpeak latencies (IPLs) I-III, III-V and I-V; amplitude of waves I, III and V on both sides between NIDDM patients and controls. However, peak latencies of wave III (P < 0.01), wave V (P < 0.005), IPLs I-III and I-V (P < 0.005), IPLs III-V (P < 0.05), and amplitudes of wave I (P < 0.05) and wave V (P < 0.05) on the left side were significantly different in slow acetylator NIDDM patients. Increase on the right side for the same group was statistically significant for IPLs I-III and I-V (P < 0.05). SEPs showed no statistically significant difference between NIDDM patients and controls, and slow and fast acetylator NIDDM patients. CONCLUSIONS: No significant association of acetylator status with peripheral neuropathy in NIDDM subjects was observed in the present study. However, central neural conduction, primarily tested by ABERs, was significantly delayed in slow acetylators compared with fast acetylator NIDDM patients. Hence, there may be a predisposition to neuropathy in this group of patients, and such a predisposition may be better detected by studying central rather than peripheral nervous conduction pathways in NIDDM patients.

Adult↗
PubMed1980

Relative vulnerability of the brain and spinal cord to ischemia.

In this experiment CER and SER were monitored as blood flow was progressively lowered by lowering the systemic arterial pressure below the lower limits of autoregulation (bleeding). Blood flow in the brain and dorsal column of the spinal cord was monitored and recorded with the hydrogen clearance method. Long tract neural conduction in the spinal cord appeared quite refractory to the effects of ischemia and disappeared only after 8--18 min of essentially absolute ischemia. The CER was more sensitive to the effects of ischemia, disappearing first in one animal and returning later in all of the animals. The SER returned in all animals after re-infusion of the blood and re-establishment of the blood flow even after a 13--23 min period of absolute ischemia and a 5 min period of electrical silence.

Animals↗