Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Neurophysiology”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources
PubMed2005

Neurophysiologic changes in live related kidney transplant children and adolescents.

Uremic neuropathy is one of the most debilitating symptoms associated with end stage renal disease. In adults the only potential cure for uremic neuropathy is renal transplantation. No studies have investigated the neurophysiologic abnormalities among pediatric renal transplant recipients. The objective of this study is to describe the incidence, nature and factors affecting neurophysiologic abnormalities in young renal transplant recipients. Neurophysiologic study was performed for 31 of our live related pediatric renal transplant recipients; they were 21 males and 10 females. The mean age at transplantation was 13.2 +/- 3.1 yr. The neurophysiologic studies were performed at different time points after transplantation (range 12-60 months), with a mean period of follow-up after transplantation 3.2 +/- 1.1 yr. Electromyography of the following muscles was tested: abductor pollicis brevis of the thenar eminence, biceps brachii, extensor digitorum brevis and rectus femoris. The median and lateral popliteal nerves were tested for estimating the motor conduction velocity. Neuropathic changes were found in 19% of our cases with more affection of the distal muscles of lower limbs. Motor conduction velocities were reduced, distal latencies were lengthened, and motor unit action potentials were reduced or dispersed. The predictors for development of neuropathy by multivariate analysis were the cumulative steroid dose and graft dysfunction. These results suggest that neuropathy is prevalent among young pediatric renal transplants. The independent predictors for development of neuropathy are graft dysfunction and anemia. It is unclear how significant these findings are in view of absent clinical signs and symptoms. This may represent an early stage of a disease that is still silent.

Action Potentials↗
PubMed2006

Seronegative myasthenia gravis: comparison of neurophysiological picture in MuSK+ and MuSK- patients.

The aim of this study was to compare the neurophysiological and clinical pictures of a large sample of seronegative myasthenia gravis (SNMG) patients with and without anti-MuSK antibodies. Fifty-two consecutive SNMG patients were retrospectively evaluated. They had undergone an extended neurophysiological evaluation: repetitive nerve stimulation (RNS), single fiber EMG (SFEMG), and electromyography (EMG) with nerve conduction study. A muscle biopsy was performed in 11 of 52 patients, the edrophonium test in 44 of 52 patients and anti-AChR antibodies and anti-MuSK antibodies were tested in all patients. Anti-MuSK antibodies were detected in 25 SNMG patients (48.1%). The number of women in the MuSK+ group was significantly higher (P = 0.01) than in the MuSK- group. Seronegative MuSK+ patients are more severely affected and the deficit often involves the bulbar and the respiratory muscles. No statistically significant differences were observed in the edrophonium test between MuSK+ and MuSK- groups. The RNS test was abnormal in a significantly higher number of MUSK- patients than MUSK+ patients (P < 0.00001). With regard to SFEMG data, MuSK- patients were characterized to have more severe neurophysiological pattern. Our observations showed several differences between the clinical and neurophysiological pictures of MUSK+ and MUSK- patients.

Adult↗
PubMed1983

Synchrony in mother-infant interaction: a possible neurophysiological base.

The extent to which mothers and their infants can synchronize their activity levels and cycles of engagement and disengagement has been seen as fundamental to healthy affective development in the infant. Ten mothers and their infants were studied to consider the possibility of a neurophysiological base to synchronization potential. The infants' neurophysiological capacities were examined within two to three days of birth using the Brazelton Neonatal Behavioural Assessment Scale. The same infants and their mothers were assessed in their interactions after three months. The mothers' physiological responses to stimulation also were examined. Significant correlations were found between neonatal responsivity to stimuli and motor maturity, maternal stimulus screening capacity and the nature of the mother-infant interaction at three months. In particular, infants who were more socially responsive and attentive to stimuli had mothers with a greater capacity for 'screening out' redundant stimuli. Moreover, these same dyads spent more time in social engagement and had fewer cycles of disengagement. These findings, together with other studies, suggest that particular neurophysiological capacities of mothers and infants may be more conducive to the synchronization of their interactions than others. This raises the possibility that the chaotic asynchrony observed in clinically diagnosed mother-infant disturbances may have a neurophysiological base.

Acoustic Stimulation↗
PubMed2005

Neurophysiological correlates of mismatch in lexical access.

BACKGROUND: In the present study neurophysiological correlates related to mismatching information in lexical access were investigated with a fragment priming paradigm. Event-related brain potentials were recorded for written words following spoken word onsets that either matched (e.g., kan - Kante [Engl. edge]), partially mismatched (e.g., kan - Konto [Engl. account]), or were unrelated (e.g., kan - Zunge [Engl. tongue]). Previous psycholinguistic research postulated the activation of multiple words in the listeners' mental lexicon which compete for recognition. Accordingly, matching words were assumed to be strongly activated competitors, which inhibit less strongly activated partially mismatching words. RESULTS: ERPs for matching and unrelated control words differed between 300 and 400 ms. Difference waves (unrelated control words - matching words) replicate a left-hemispheric P350 effect in this time window. Although smaller than for matching words, a P350 effect and behavioural facilitation was also found for partially mismatching words. Minimum norm solutions point to a left hemispheric centro-temporal source of the P350 effect in both conditions. The P350 is interpreted as a neurophysiological index for the activation of matching words in the listeners' mental lexicon. In contrast to the P350 and the behavioural responses, a brain potential ranging between 350 and 500 ms (N400) was found to be equally reduced for matching and partially mismatching words as compared to unrelated control words. This latter effect might be related to strategic mechanisms in the priming situation. CONCLUSION: A left-hemispheric neuronal network engaged in lexical access appears to be gradually activated by matching and partially mismatching words. Results suggest that neural processing of matching words does not inhibit processing of partially mismatching words during early stages of lexical identification. Furthermore, the present results indicate that neurophysiological correlates observed in fragment priming reflect different aspects of target processing that are cumulated in behavioural responses. Particularly the left-hemispheric P350 difference potential appears to be closely related to fine-grained activation differences of modality-independent representations in the listeners' mental lexicon. This neurophysiological index might guide future studies aimed at investigating neural aspects of lexical access.

Adult↗
PubMed2004

Clinical, cognitive, and neurophysiologic correlates of short-term treatment with carbamazepine, oxcarbazepine, and levetiracetam in healthy volunteers.

BACKGROUND: The adverse effects of the antiepileptic drugs (AEDs) originally developed are well known, while those of the newer AEDs remain unclear. OBJECTIVE: To investigate clinical, cognitive, and neurophysiologic effects of carbamazepine, oxcarbazepine, and levetiracetam in healthy volunteers. METHODS: A double-blind crossover study was conducted in 10 volunteers. Eight-day treatment with carbamazepine, oxcarbazepine, levetiracetam, or placebo was administered in random order. Drug doses were titrated gradually to the daily target doses on day 7: carbamazepine 800 mg, oxcarbazepine 1200 mg, and levetiracetam 1500 mg. At baseline and at the end of each treatment period, participants underwent cognitive and neurophysiologic assessment. A washout period of 14 days between treatment periods was conducted. RESULTS: More adverse events were self-reported with carbamazepine (63%) than the other treatments (oxcarbazepine 12%, levetiracetam 20%, placebo 5%; p < 0.001 between the 4 groups). Carbamazepine induced the greatest motor slowing (p = 0.002), followed by oxcarbazepine (p = 0.01). Levetiracetam left baseline motor speed unchanged. All AEDs increased attention span from baseline values as shown on the Stroop test. Quantitative electroencephalogram (EEG) analysis showed that carbamazepine significantly increased the delta-theta power and reduced the frequency of alpha rhythm; oxcarbazepine induced smaller changes than carbamazepine. Levetiracetam did not change any EEG measurements. On color visually evoked potential (VEP) tests, carbamazepine induced a constant slowing of P1 latency, while oxcarbazepine induced changes only after the blue-black pattern. All color VEP measures for volunteers receiving levetiracetam were almost unchanged. CONCLUSIONS: After short-term treatment in healthy volunteers, carbamazepine induced major clinical and neurophysiologic changes. Oxcarbazepine was better tolerated than carbamazepine. Levetiracetam interfered least with clinical and neurophysiologic test results.

Adult↗
PubMed2000

Neurophysiological findings and drinking levels in high-alcohol-drinking (HAD) and low-alcohol-drinking (LAD) rats.

BACKGROUND: Specific neurophysiological profiles, such as reduced P300 amplitude or altered spectral power in the EEG, have been associated with a risk for alcoholism in several clinical populations. In certain rodent models, high versus low alcohol consumption is associated with similar neurophysiological differences. For example, alcohol-preferring (P) rats have increased spectral power and decreased P300 amplitudes compared with alcohol-nonpreferring (NP) rats. In the present study, the neurophysiological profiles of high-alcohol-drinking (HAD) and low-alcohol-drinking (LAD) rats were assessed (1) to determine if their electrophysiological profiles are similar to P and NP rats and (2) to examine the relationship of these neurophysiological indices to ethanol drinking. METHODS: Ethanol-naive HAD and LAD rats were implanted with cortical and amygdalar recording electrodes. Baseline EEG and event-related potentials (ERPs) then were assessed. Subsequently, all rats were trained to self-administer ethanol by using a sucrose-substitution procedure. RESULTS: Baseline EEG and ERP (i.e., pre-ethanol exposure) were assessed based on line (HAD versus LAD) and actual ethanol consumption (high drinkers versus low drinkers). At baseline, ethanol-naive HAD rats displayed significantly greater power in the cortical EEG and decreased amygdala N1 ERP amplitude compared with ethanol-naive LAD rats. Similar EEG and ERP profiles have been observed when P and NP rats are compared. No differences in P300 between lines were observed, but high-drinking rats, independent of line, had significantly decreased P300 amplitude in the amygdala compared with low-drinking rats. CONCLUSIONS: These data suggest there are some similarities in EEG and ERP profiles of P and HAD rats compared with NP and LAD rats. Furthermore, the data suggest that decreased P300 amplitude in the amygdala is associated with increased limited access ethanol drinking.

Alcohol Drinking↗
PubMedDate not supplied

[Isolated posterior cord syndrome in Lyme s disease: a clinico neurophysiological study].

INTRODUCTION: Lyme disease, caused by spirochete Borrelia burgdorferi, is a multisystemic infectious disorder with prominent neurologic involvement, affecting both the peripheral and the central nervous system. Meningitis, cranial neuritis and radiculoneuritis are the usual manifestations in the acute phase, and peripheral neuropathy in the chronic phase. Other less common manifestations have been also described. Here we report one case of Lyme disease confirmed by PCR, with a previously undescribed neurological manifestation, and the neurophysiological studies performed before and after treatment. CLINICAL CASE: Our patient showed a chronic and progressive clinical picture consisting of instability on walking and distal paresthesia of lower limbs, suggestive of posterior column disfunction. The neurophysiological exam performed prior to treatment with ceftriaxone revealed bilateral absence of lower limbs somatosensory evoked potentials (SEPs), without alterations in the distal nervous conduction or in upper limbs SEPs. The exam performed after treatment revealed a partial recovery of lower limb SEP with presence of an evoked response in SEP of left lower limb, coincident with a transitory clinical improvement of paresthesia in the same extremity. CONCLUSIONS: Our findings reveal that posterior column disfunction can be a neurological manifestation of Lyme disease. Furthermore the neurophysiological study shows that this manifestation is partially reversible following treatment. Our study emphasize the importance of the neurophysiological tests for the diagnosis and follow up of neurological manifestations of Lyme disease.

Borrelia burgdorferi↗
PubMedDate not supplied

[Neurophysiology in Creutzfeldt-Jakob disease].

INTRODUCTION: Neurophysiological studies conducted in subjects who it is suspected are suffering from Creutzfeldt-Jakob disease (CJD) are usually aimed at searching for what is called a typical EEG. However, the EEG is a dynamic test and therefore subject to variations in time. Furthermore, there are other kinds of neurophysiological tests that may also be of interest, and the lack of typical traces in the new variant of the disease forces us to explore other diagnostic approaches. METHOD: We performed a clinical EEG correlation in the course of the evolution of the disease, in which we observed a significant variability throughout the different stages. We then review the neurophysiological studies that have been conducted on CJD, in which shortcomings and important discrepancies can be seen. CONCLUSION: EEG has proved to be a fundamental element in CJD probability diagnosis. It is also found that sleep and waking records, obtaining series of EEGs, the detection of poligraphic changes related with variations in the degree of consciousness and, lastly, studies conducted by means of other neurophysiological techniques associated with clinical data will all undoubtedly enable us to achieve higher efficiency in diagnosis

Blinking↗
PubMed1992

[The neurophysiological indices of neurotic patients with different types of individual character and their dynamics during group psychotherapy].

Based on the clinical and neurophysiological studies analysis is made of the prognostic importance of character accentuations as the most important factor of the personality premorbid condition of neurotic patients. 107 patients with different patterns of neuroses, who underwent group psychotherapy (a personality-oriented (reconstructive) variety). Analysis of the dynamics of the neurophysiological characteristics, made during group psychotherapy, supported the clinical data on varying curability of neurotic patients with different types of character accentuations. Patients with the hysteroid type character accentuation appeared more resistant to psychotherapy. In patients with the sthenic variety of hysteroid accentuation, the positive dynamics was recorded in but 30% of cases, in the asthenic variety of hysteroid accentuation, in 48.6% of cases. Patients with inhibited character traits turned out more pliable to group therapy. In the sensitive type accentuation, the positive dynamics of the neurophysiological characteristics was established in 65% whereas in psychasthenic accentuation, in 72% of cases. The neurophysiological correlations of the main types of character accentuations and their dynamics during group psychotherapy were also revealed.

Electrocardiography↗
PubMed2004

[Clinical and neurophysiologic aspects of surgical treatment of pharmacoresistant forms of epilepsy].

Surgical treatment of pharmacoresistant forms of epilepsy under neurophysiological monitoring is a key problem studied in A.L. Polenov Russian Neurosurgical Institute (Saint-Petersburg). A summary of long-term studies and main stages of surgical treatment development are presented. The indications and contra-indications, along with basic neurophysiologic strategic and tactic arguments of open and stereotaxic treatment of focal and generalized epilepsy based on neurophysiologic model which determines a role of epileptic focus, epileptic and inhibiting brain systems in spreading and arresting of seizure discharge at each disease stage are formulated. A program of clinico-neurophysiologic monitoring of temporal epilepsy in pre- and intraoperative periods is considered.

Anticonvulsants↗
PubMed2005

[Intraoperative neurophysiological monitoring of brain stem in a case of cavernoma in the pons].

Neurophysiological monitoring during surgery to avoid damaging of eloquent brain areas is a useful tool. We are performing intraoperative neurophysiological test to locate motor, sensitive and speech areas with cortical stimulation and cranial nerves during cerebellopontine cranial base surgery. Neurophysiological monitoring during brain stem surgery has been less described. Brain stem surgery implies a careful selection of patients for surgery given the high risk of morbidity and mortality. For this reason, conservative treatment is usually indicated when an asymptomatic cavernoma is incidentally found. Instead, when bleeding or neurological deficit appear, operative treatment may be indicated and then the goal of surgery is to avoid the disability linked to the natural history. We present the case of a 29 year old woman with diagnosis of multiple cavernomas. She was admitted at our hospital because she presented weakness and sensitive disturbance of left limbs and dizziness. The CT scan and MRI showed a pontine haemorrhage caused by a cavernous hemangioma. We operated her on using neurophysiological monitoring of VII, VIII, X and XII cranial nerves with electromyographic recordings. Postoperative disability could be reduced with a better knowledge of entry zone into the brain stem and early physiotherapy.

Adult↗
PubMedDate not supplied

[Neurophysiological studies of the neuromuscular junction].

INTRODUCTION: The role played by neurophysiological studies (NPS) in the diagnosis of diseases affecting neuromuscular transmission (NMT) is based on the study of the failure of muscle fibres to achieve a sufficient degree of depolarisation for the junction potential to reach the appropriate threshold and attain a muscular action potential. This totally or partially blocked impulse will give rise to different types of responses in neurophysiological tests. AIMS: To analyse the different NPS as diagnostic methods in diseases that affect NMT. DEVELOPMENT: The article offers a review of the concept of the safety margin at the neuromuscular junction and a description of the most common neurophysiological techniques currently in use--repetitive stimulation, as well as conventional or single fibre electromyography (EMG) with voluntary activation or axonal electrical activation. The most frequent findings in diseases affecting NMT are also discussed. CONCLUSIONS: NPS will be useful to confirm or reject the clinical diagnosis, to exclude other concomitant neuromuscular diseases, to establish whether the process is pre- or post-synaptic, to monitor the clinical course of the disease (when it is both natural or in response to the medical or surgical treatment) and also to enable the physician to determine the status of NMT in cases of clinical remission, as well as to detect subclinical disorders. Single fibre EMG studies are the most sensitive method of neurophysiological diagnosis when dealing with these diseases.

Action Potentials↗
PubMed2005

Usefulness of a comprehensive neurophysiological assessment for early diagnosis and prognosis of traumatic brachial plexus injuries.

PURPOSE: To illustrate how a thorough neurophysiological evaluation allows early diagnosis and prognosis of traumatic brachial plexus injuries. METHODS: As examples, we report on the case of two patients with acute traumatic brachial plexus injuries for whom a comprehensive neurophysiological evaluation allowed early diagnosis and prognosis. RESULTS: Neurophysiological findings were consistent with complete proximal (root) lesion in one patient and a severe neuroapraxic block between Erb point and axilla in the other one. CONCLUSIONS: The two reported acute cases of traumatic brachial plexus injuries demonstrated the high diagnostic and prognostic value of the neurophysiological tests when fully utilized.

Accidents, Traffic↗
PubMed1985

A neurophysiologic investigation of thoracic outlet syndrome.

Earlier reports have been conflicting as regards the value of neurophysiologic measurements in the diagnosis of thoracic outlet syndrome (TOS), presumably due to differences in selection of patients and in selection and standardization of neurophysiologic tests. The object of the present study was to assess the value of extensive conventional neurophysiologic measurements for the diagnosis of brachial plexus compression in patients with clinical TOS as determined from standardized criteria. The results are discussed in the light of expected neurophysiologic findings at different degrees of brachial plexus compression.

Adolescent↗
PubMed1978

Neurophysiological observations after chronic styrene exposure.

Thirty-three styrene exposed workers from three different industrial sites were examined with electroencephalography and motor and sensory neurography. The three groups had respective styrene exposures of clearly above the threshold limit value (50 ppm), at about this level, and clearly below it. The neurophysiological results were compared with those of a group of normal controls and a group of 17 patients judged to suffer from sequelae after long-term heavy exposure to organic solvents (mainly painters). Ten subjects in the styrene group presented signs of a mild sensory neuropathy with polyphasic sensory responses of a low amplitude. The same pattern was commonly found among the reference group heavily exposed to solvents. The ten subjects in the styrene group with mild polyneuropathy had a significantly higher age and significantly heavier styrene exposure than the rest of the group. Age difference could not explain the difference in the neurophysiological parameters, and therefore the contributing role of styrene exposure has to be considered. The electroencephalographic analysis showed no changes of the dominant alpha frequency. An increased amount of diffuse slow activity was seen in many of the heavily exposed mixed-solvent cases and was seen in some of the styrene-exposed cases without a clear relation to degree of exposure. An increased occurrence of fast activity in central and precentral areas of the brain was found in the styrene group, as well as in the mixed-solvent group. This pilot study indicates that the same type of neurophysiological changes from the strictly normal are seen among workers exposed to styrene as those found among a group of patients judged to suffer from sequelae after chronic exposure to various organic solvents. The neurophysiological "profile" is (a) sensory nerve responses with low amplitude and long duration, (b) somewhat low sensory conduction velocities, (c) close to normal motor neurographic findings, and (d) an increased amount of fast activity in central and precentral regions in the electroencephalogram in combination with normal occipital alpha activity.

Action Potentials↗
PubMed1980

[Status of neurophysiologic research in psychiatry].

Neurophysiological studies in psychiatry have two trends: study of the mechanisms of normal and abnormal brain actvity and the use of the neurophysiological techniques to diagnose brain function in different mental pathology. The essential progress of both trends is based on the wide use of computers and mathematical analysis during recent decade. The drawback of the present state of clinical neurophysiology is its inadequate interrelation with the trends and concepts of experimental neurophysiology.

Brain↗
PubMed1999

Neurophysiological assessment in the diagnosis of botulism: usefulness of single-fiber EMG.

We report the clinical, serological, and neurophysiological findings in seven patients with foodborne botulism caused by ingestion of black olives in water. The clinical picture was characterized by mild symptoms with a long latency of onset and by involvement of cranial and upper limb muscles; only one patient, a child, developed respiratory failure. Spores of Clostridium botulinum were found in stools in some but not all cases. Conventional neurophysiological tests had low sensitivity; abnormal findings were present only in the patient with severe clinical involvement, in whom compound muscle action potentials (CMAPs) appeared reduced. Repetitive nerve stimulation at a high rate showed pseudofacilitation and not true posttetanic facilitation, but single-fiber electromyography (SFEMG) showed abnormalities of neuromuscular transmission in every case. Neurophysiological evaluation, particularly SFEMG, is important because it allows rapid identification of abnormal neuromuscular transmission while bioassay studies are in progress.

Action Potentials↗
PubMed2006

Role of intraoperative neurophysiology in primary surgery for obstetrical brachial plexus palsy (OBPP).

OBJECTIVE: Management of conducting neuroma-in-continuity in primary surgery for obstetrical brachial plexus palsy (OBPP) is still discussed controversially. We present our experience with intraoperative neurophysiological recordings in the management of lesions in continuity in OBPP. METHODS: A series of ten children with lesions in continuity of the upper brachial plexus is presented. Due to recordable compound nerve action potentials (CNAPs) and muscle response to motor stimulation across the neuroma, five children underwent external neurolysis of neuroma only (neurolysis group). Due to lack of recordable CNAPs or muscle response, resection of neuroma and interpositional nerve grafting were performed in another five children (resection and grafting group). Functional recovery after at least 30 months of follow-up was assessed. RESULTS: There was a marked difference in functional recovery between the neurolysis and the resection and grafting group. Especially, recovery of shoulder function was disappointing after external neurolysis of conducting neuroma-in-continuity. At the end of follow-up, results of shoulder and elbow function after resection of neuroma followed by interpositional nerve grafting were better without exception. CONCLUSION: Intraoperative neurophysiological recordings face certain difficulties when used in small children with OBPP. Due to overoptimistic assessment of prognosis after intraoperative CNAP recordings and motor stimulation, the functional results after neurolysis of conducting neuroma-in-continuity are disappointing. Resection of neuroma-in-continuity, conducting or not, offers the best opportunity for maximal functional recovery of the compromised upper limb in OBPP. The role of intraoperative neurophysiological techniques should be confined to the diagnosis of root avulsions.

Adolescent↗