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PubMed1991

Evaluation of electrocochleographic audiogram determination in infants.

An evaluation was made of results of electrocochleography (ECoG) in a group of 75 children, tested during the last four years in the ENT department of the Leiden University Hospital. Eleven years was taken as the upper age limit; 79% of our group were younger than three and a half years. In only 60% of the children the cause of the hearing loss was clarified. In this group maternal rubella followed by meningitis and retardation were the most frequent cases of deafness. Cochlear microphonics (CM) could be measured in all the children. Examples are given of cochlear responses of children belonging to 6 different threshold categories. The responses of the largest category (56 children) with the highest loss (larger than 80 dB) were very abnormal. For the categories with less hearing loss the ECoG was not restricted to threshold determination and the origin of the hearing loss could be demonstrated, while a contribution of conduction loss could be derived from a horizontal shift of the latency-intensity function to higher intensity levels. The potentialities and limitations of ECoG and brainstem electric response audiometry (BERA) for threshold determination are discussed, particularly against the background of the time consumption of both procedures and the invasive character of ECoG.

Audiometry, Evoked Response↗

PubMed1985

Comparison between electrocochleography and glycerol test in the diagnosis of Meniere's disease.

Electrocochleography (ECoG) and glycerol test were performed in 51 Meniere ears. The positive rate of both tests was compared. The positive rate of ECoG and glycerol test was 63% and 51%, respectively. The ears with positive result of both tests and of either test were 15 of 51 ears (29%) and 43 of 51 ears (84%), respectively. The positive rate of ECoG was higher in ears with a moderate to severe hearing loss at high frequencies, while the positive rate of glycerol test was higher in ears with a moderate to severe hearing loss at low frequencies. The present study has demonstrated that ECoG is different in selectivity of detection of the endolymphatic hydrops from glycerol test and that the combination of both tests increases the detection rate of the endolymphatic hydrops in Meniere's disease.

Adult↗

PubMed1997

Pharmacokinetics and pharmacodynamics of 4-aminopyridine in awake guinea pigs.

The selective blockade of potassium channels on excitable membranes by 4-aminopyridine (4-AP) leads to facilitation of neurotransmitter release at a wide variety of synapses. This compound has been shown to be efficacious against lethality induced by saxitoxin (STX) and tetrodotoxin (TTX) in guinea pigs. To characterize the actions of 4-AP in guinea pigs we have investigated its pharmacokinetics (PK) and pharmacodynamics following a 2 mg/kg, intramuscular (im) dose in awake chronically instrumented (IN) animals. Animals were chronically instrumented for electrophysiologic recordings of diaphragmatic electromyogram (DEMG), lead II electrocardiogram (ECGII) and electrocorticogram (ECoG). Also, PK studies were carried out in uninstrumented (UN) guinea pigs. Blood and electrophysiologic data were collected at predetermined time intervals up to 4 hours post 4-AP administration. High performance liquid chromatography was used to determine plasma 4-AP concentrations. For IN and UN animals, plasma concentration-time data best fit a one-compartment model, and PK parameter estimates were similar for both groups. Peak plasma levels were found to occur between 16 and 17 min, and the half-lives of elimination were 65 and 71 min for IN and UN animals respectively. Heart and respiratory rates were elevated as early as 5 and 15 min respectively in response to 4-AP administration. The duration of action was approximately 1-1.5 half-lives of elimination beyond peak plasma levels. Maximum ECoG responses were observed between 12-15 min after 4-AP injection; some residual drug effects were still apparent at 240 min. The difference between the heart and respiratory rates and ECoG profiles suggests that these different physiological systems respond with varying degrees of sensitivity to plasma 4-AP concentrations. The stimulation of these systems is consistent with the action of 4-AP in reversing STX- and TTX-induced cardiorespiratory depression and decreased ECoG power in guinea pigs.

4-Aminopyridine↗

PubMed1993

Temporal lobectomy for intractable epilepsy: experience with 58 cases over 21 years.

Sixty patients with intractable complex partial seizures underwent surgery between 1969 and 1990, and 58 of these underwent a temporal resection. Of 39 patients who had chronic subdural electrocorticography (ECoG) 37 subsequently underwent an anterior temporal lobectomy (ATL) and two had the electrodes removed without resection. Two patients had bilateral depth electrodes placed and then had an ATL. Fourteen patients with evidence of temporal structural lesions had temporal resections with intraoperative ECoG and five had resection without ECoG. Mean length of follow-up for all patients was 6 years. Fifty-five per cent of cases were seizure-free postoperatively, 7% almost seizure-free, 21% had worthwhile improvement and 17% no improvement. The outcome for patients with structural lesions was particularly good. Nine patients complained of mild memory impairment postoperatively and one had a severe amnestic problem. One patient with an unsuspected tumour developed a hemiparesis and dysphasia. One other patient had persistent dysphasia. No mortality was attributable to the surgery. It is concluded that ATL is an excellent operation for the treatment of intractable epilepsy arising from the temporal lobe and chronic subdural ECoG is a safe and reliable method for localizing the seizure origin.

Adolescent↗

PubMed1994

Neurodegeneration produced by intrahippocampal injection of paraquat is reduced by systemic administration of the 21-aminosteroid U74389F in rats.

The behavioural, electrocortical (ECoG) and neurodegenerative effects of intrahippocampal injection of paraquat, a well-known free radical producing agent, were studied in rats. Injection of paraquat (100 nmol) into one dorsal hippocampus produced limbic motor and ECoG seizures. These effects were accompanied at 24 h by severe damage to CA1, CA3 and CA4 hippocampal pyramidal neurones and dentate gyrus granule cells. In comparison to the cell number counted in control, untreated, side of the hippocampus, significant (P < 0.05) neuronal loss was observed in the CA1 and CA3 pyramidal cell layers of the treated hippocampus. A lower dose of the herbicide (10 nmol) did not produce consistent motor and ECoG effects and in no instance was significant neuronal loss observed. A pretreatment with U74389F [21-4-(2,6-di-l-pyrrodinyl-4-pyridinyl)-1-piperazinyl-pregna-1,4,9 (11)triene-3,20-dione monomethansulfonate] (30 mg/kg i.p., 15 min before paraquat) completely protected rats from motor and ECoG epileptogenic effects induced by intrahippocampal paraquat (100 nmol). This dose of U74389F also reduced the hippocampal damage typically produced by paraquat and no significant neuronal loss was reported in the CA1 and CA3 pyramidal cell layers. A lower dose of U74389F (10 mg/kg i.p.) did not afford any protection against the epileptogenic effects produced by paraquat (100 nmol); in these animals hippocampal damage was still evident though neuronal loss did not reach statistical significance. In conclusion, the present data show that systemic administration of U74389F possesses neuroprotective effects against seizures and neurodegeneration typically elicited by intrahippocampal injection of paraquat.

Animals↗

PubMed1992

Long-term ictal monitoring with subdural strip electrodes: prognostic factors for selecting temporal lobectomy candidates.

Long-term electrocorticographic (ECoG) monitoring data from subdural strip electrodes are analyzed to determine factors associated with seizure-free outcome from anterior temporal lobectomy. A total of 89 consecutive patients with complex partial seizures, in whom long-term ictal video/scalp electroencephalographic monitoring was insufficient to localize their epileptogenic focus, were subsequently evaluated with long-term ictal ECoG monitoring using subdural strip electrodes. Each patient underwent anterior temporal lobectomy based on the ictal ECoG data and has been followed for at least 1 year. The following parameters were found to be statistically significant in predicting a seizure-free outcome: unilateral onset, electrical onset pattern beginning as fast spike trains, absence of frontal lobe background desynchronization at onset, and an interhemispheric propagation time of greater than 8 seconds. Electrocorticographic criteria that were not associated with seizure outcome included: right- versus left-sided onset, time from electrical to clinical ictal onset, focality of onset (number of strip electrode contacts involved), and stereotypical ECoG onset. When present, the interictal focus was concordant with the ictal focus in most patients (96%), but was falsely lateralizing in 4% of cases. It is suggested that these data should improve patient selection for temporal lobectomy when subdural strip monitoring is used during preoperative evaluation.

Adolescent↗

PubMed2005

Characterizing magnetic spike sources by using magnetoencephalography-guided neuronavigation in epilepsy surgery in pediatric patients.

OBJECT: The authors sought to validate magnetoencephalography spike sources (MEGSSs) in neuronavigation during epilepsy surgery in pediatric patients. METHODS: The distributions of MEGSSs in 16 children were defined and classified as clusters (Class I), greater than or equal to 20 MEGSSs with 1 cm or less between MEGSSs; small clusters (Class II), 6 to 19 with 1 cm or less between; and scatters (Class III), less than 6 or greater than 1 cm between spike sources. Using neuronavigation, the MEGSSs were correlated to epileptic zones from intra- and extraoperative electrocorticography (ECoG), surgical procedures, disease entities, and seizure outcomes. Thirteen patients underwent MEGSSs: nine had clusters; two had small clusters, one with and one without clusters; and three had scatters alone. All 13 had scatters. Clusters localized within and extended from areas of cortical dysplasia and at margins of tumors or cystic lesions. All clusters were colocalized to ECoG-defined epileptic zones. Four of 10 patients with clusters and/or small clusters underwent complete excisions, and six underwent partial excision with or without multiple subpial transections. In the three patients with scatters alone, ECoG revealed epileptic zones buried within MEGSS areas; these regions of scatters were completely excised and treated with multiple subpial transections. Coexisting scatters were left untreated in nine of 10 patients. Postoperatively, nine of 13 patients were seizure free; the four patients with residual seizures had clusters in unresected eloquent cortex. Three patients in whom no MEGSSs were demonstrated underwent lesionectomies and were seizure free. CONCLUSIONS: Magnetoencephalography spike source clusters indicate an epileptic zone requiring complete excision. Coexisting scatters remote from clusters are nonepileptogenic and do not require excision. Scatters alone, however, should be examined by ECoG; an epileptic zone may exist within these distributions.

Adolescent↗

PubMed2000

Organization of cortical activities related to movement in humans.

The extent and function of synchronization of oscillatory elements in the human sensorimotor cortex during movement remains unclear. Here we determine whether synchronization is distributed in both the spatial and frequency domains and whether it changes according to task. Electrocorticographic (ECoG) signals were recorded from presumed nonpathological areas simultaneously with electromyographic (EMG) signals from upper limb muscles during isometric and phasic movement tasks in humans with subdural electrodes in situ for investigation of epilepsy. Functional mapping of the sensorimotor cortex was performed by previous electrical stimulation through the same ECoG electrodes used for recording. Significant coherence between ECoG and EMG was seen at discrete frequencies in the range of 7-100 Hz. There was no predilection for coherence within a given frequency band to be associated with cortical sites that had been functionally defined as producing contralateral arm motor responses on stimulation. However, coherence with muscle in the 7-14 and 15-30 Hz band tended to be associated with ECoG sites that lay close to or within the central sulcus as determined intraoperatively. The spatial pattern and frequency of coherence changed with different tasks, although similarities in the coherence pattern remained for tasks that shared common features. These findings provide support for the hypothesis that that synchronization at specific frequencies links cortical activities into a functional ensemble during voluntary movement.

Arm↗

PubMed2000

Electrocochleography and gentamicin therapy for Ménière's disease: a preliminary report.

OBJECTIVE: It is widely held that an enlarged summating potential (SP) relative to the eighth nerve action potential (AP) is a reflection of endolymphatic hydrops. Aminoglycosides are an accepted treatment for incapacitating Ménière's disease and are known to affect both sensory and secretory cells of the inner ear. The intent of this study was to determine whether this effect on secretory cells could be objectively confirmed by virtue of changes in the electrocochleogram (ECoG) of patients receiving gentamicin therapy for Ménière's disease. STUDY DESIGN: This was a prospective longitudinal study of repeated ECoG measures in three groups of subjects. Ménière's patients undergoing gentamicin treatment were compared with two control groups: individuals with stable Ménière's disease and normal-hearing control subjects. SETTING: The study was conducted at a tertiary referral center. PATIENTS: The sample included 21 normal-hearing subjects, 15 patients with stable unilateral Ménière's disease, and 12 with disabling unilateral Ménière's disease. INTERVENTIONS: For patients with disabling Ménière's disease, gentamicin was administered transtympanically. Audiograms, impedance tests, and ECoG were performed twice for all subjects. MAIN OUTCOME MEASURES: The SP and AP amplitudes, AP latency, and SP/AP ratio of the EcoG were measured. RESULTS: A statistically significant reduction in the SP/AP ratio was observed after gentamicin administration (analysis of variance interaction effect: F2 = 5.64; p = 0.0065). CONCLUSIONS: The significant reduction in the SP/AP ratio in the gentamicin-treated Ménière's group supports the hypothesis that gentamicin improves the electrophysiologic function of the cochlea, possibly by reducing the severity of the associated endolymphatic hydrops.

Acoustic Impedance Tests↗

PubMed2000

Electrocorticography.

Electrocorticography (ECOG), the intra-operative recording of cortical potentials, has played an important role in the surgical management of patients with medically refractory epilepsy. It has been used 1) to localize the epileptogenic tissue; 2) map out cortical functions; and 3) predict the success of the surgery. Despite its common use, few studies have been done to prove its effectiveness in these areas. The technique used in children for recording ECOG is very similar to that used in adults except for the limitations imposed by the child's age. Anaesthesia must often be used. Based upon a computerized medical literature search, a review of this procedure was done. Pre-resection localization, and post-resection prediction of outcome was done for temporal and extra-temporal resection, both lesional and nonlesional. Most of the available studies were in adult patients. All were retrospective in nature. Evidence for the role of pre-resection ECOG in determining the degree of resection felt necessary to obtain good clinical outcome was limited. Similarly the post-resection ECOG predication of surgical outcome was restricted.

Brain Mapping↗

PubMedDate not supplied

Effect of repetitive umbilical cord occlusions on neuronal brain activity measured by the cerebral function analyzing monitor and histologic outcome in immature fetal sheep.

OBJECTIVE: To examine the effect of repetitive total umbilical cord occlusions on electrocortical brain activity as measured by cerebral function analyzing monitoring (CAFM) and the histologic outcome in immature sheep fetuses. STUDY DESIGN: We performed brief repeated total umbilical cord occlusions, two every 5 minutes, in 12 immature sheep fetuses (at 90 days of gestation, term 147 days) until fetal mean arterial pressure dropped below 50% of baseline value during two successive occlusions. A pair of electrodes was inserted on the parietal dura for recording of electrocortical brain activity (ECoG). Off-line ECoG signal processing consisted of amplitude integrated analysis (CFAM) and spectral analysis. Fetal blood gas analyses were performed at regular intervals just before subsequent umbilical cord occlusions. Three days after the occlusion neuronal damage was evaluated histologically in three regions of the fetal brain. RESULTS: CFAM amplitide parameters decreased significantly during the first occlusion and remained so during the entire repetitive occlusion period (analysis of variance [ANOVA]; P <.05). Spectral analysis of the ECoG signal demonstrated no changes in the distribution of frequency bands. Progressive acidemia and hypotension developed with ongoing occlusions. Five fetuses died at the end or shortly after the entire repetitive occlusion period. No neuronal damage or macroscopic intraventricular and/or germinal matrix hemorrhage was observed in the surviving fetuses. CONCLUSION: Repetitive umbilical cord occlusions in immature sheep fetuses resulted in functional, not structural changes of the fetal brain in surviving fetuses. At this gestational age, amplitude analysis is more sensitive than spectral analysis of the ECoG signal to functional changes of the compromised fetal brain.

Animals↗

PubMed1977

[Evaluation by electrocorticogram of the protective action of piridoxilate against cerebral hypoxia in rats].

Piridoxilate, at the concentration of 120 mg/kg i.p. in rats, enhanced resistance of these animals to hypoxia (N2 : O2 3,2 %). The electrocorticogram (ECOG) is used to indicate the effectiveness of the drug in lowering the time of electrographic silence, on control (n=19) and pretreated rats (n=12). The ECOG was recorded also during the recovery period under pure oxygen. In pretreated rats, the ECOG records became flat in approximately 551 sec (versus 269 sec on the control group). The latent period of successive steps of cerebral anoxia were delayed in pretreated rats exposed to hypoxia. During the recovery period, piridoxilate seems to enhance the restoration of normal ECOG, as a function of the duration of hypoxia.

Animals↗

PubMedDate not supplied

[Some changes in bioelectrical activity of the brain during short regulated exposure to pulsed electrical fields].

It was shown that short (10 s) exposures of white rats being at rest to impulse (1 ms) electromagnetic fields (170 A/m) at a fixed frequency of pulse sequence in the range of the theta-rhythm do not change the contribution to the electrocorticogram (ECoG) of the harmonic whose frequency corresponds to the frequency of pulse sequence. By contrast, treatments with a frequency-pulse modulation at which the interpulse intervals corresponding to the frequency of the harmonic being studied were not observed throughout the range of exposure but at which their high correlation was provided, assisted in decreasing the contribution of the harmonic to the ECoG spectrum. If the functional state of the central nervous system was changed by drugs leading to the predominance of the short-wavelength activity in the ECoG, both regimes of exposure significantly affected the contribution of the harmonic in the ECoG, whose direction and dynamics depended on the excitability of neurons.

Animals↗

PubMed1990

Nitrous oxide: suppression of focal epileptiform activity during inhalation, and spreading of seizure activity following withdrawal.

Intraoperative brain surface electrocorticography (ECoG) is an integral part of the surgical excision of epileptogenic foci. If surgical excision is performed under general anesthesia, anesthetics should be selected that do not seriously interfere with the ECoG. We report a case where nitrous oxide appeared to suppress focal epileptiform activity at the time of intraoperative ECoG, and subsequent withdrawal of nitrous oxide produced generalized electrical seizure activity. We recommend that low concentrations of volatile anesthetics may be preferrable to nitrous oxide when ECoG is performed during epilepsy surgery in anesthetized patients.

Journal Article↗

PubMed2005

[Expression of metabotropic glutamate receptor 1alpha in different brain areas of the kindled epilepsia models of rats by Coriaria lactone].

OBJECTIVE: To detect the expression of Metabotropic Glutamate Receptor 1alpha (MGLUR1alpha) in the different brain areas of the kindled epilepsia models of rats by Coriaria Lactone (CL). METHODS: Thirty male SD rats were divided into 3 groups and were given intramuscular injections of 0.75, 1.0 and 1.25 ml/kg Coriaria Lactone respectively. 5 rats in the control group were given intramuscular injection of 1.0 ml/kg saline. After the kindling models were completed, the EcoG of all groups were recorded with the multi-electrophysiology recorder to view whether the EcoG of kindled rats accord with their seizures and to know whether there are differencees in EcoG among the kindled, non-kindled and control groups. The coronary sections of brain tissue were HE stained and MGLUR1alpha immunohistochemistry stained, and were observed under light microscope. RESULTS: The kindled rats had all grade (Simialowski scale) seizures after CL injection and their seizures accorded with their EcoG features. The MGLUR1alpha expression of kindled rats in hippocampus and temporal cortex outside hippocampus was stronger than that of non-kindled and control rats (P < 0.05); the strong expression was noted to be of no obvious difference between neuron and glia. CONCLUSION: The MGLUR1alpha expression of kindled rats in hippocampus and temporal cortex outside hippocampus is stronger than that of non-kindled and control. It is possible that MGLUR1alpha participates in epileptic seizures.

Animals↗

PubMed2006

[Significance of some otologic function tests in diagnosis of Meniere's disease].

OBJECTIVE: To investigate the significance of vestibular function battery and electrocochleogram on diagnosis of Meniere's disease. METHOD: Patients with Meniere's disease were given pure tone hearing threshold test, auditory brainstem responses (ABR), electrocochleogram (ECoG), vestibular bithermal caloric test and vestibular evoked myogenic potentials (VEMP) test. RESULT: (1) As for the bithermal caloric test, the percentage of the abnormal canal paresis (CP) at three durations, i.e. , 0 to approximately 5 years, 6 to approximately 10 years and over 11 years were 56.9%, 75.9% and 61.6% respectively. The total positive rate was 50.0%. CP and duration of Meniere's disease had low correlation (P < 0.05). (2) The percentage of the abnormal VEMP at three durations, i.e., 0-5 years,6-10 years and over 11 years were 57.4%, 60% and 57.1% respectively. The total positive rate was 58.0%. The duration of Meniere 's disease with normal and abnormal VEMP had no significant difference( P >0.05). (3) The percentage of the abnormal ECoG at three durations, i.e., 0-5 years, 6-10 years and over 11 years were 72.1%, 73.3% and 81.3% (49/68,22/30 and 13/16) respectively. The total positive rate was 76.9%. The duration of Meniere's disease with normal and abnormal ECoG had no significant difference (P >0.05). CONCLUSION: Diagnosis of Meniere's disease is mainly based on the medical history. If it could combine with ECoG, bithermal caloric test and VEMP, the diagnosis would be earlier and more accurate.

Adolescent↗

PubMed1989

[Physiologic reactions during the slaughter of cattle and sheep with and without stunning].

In a first trial the cortical activity of cattle and sheep was tested using only an electrocorticogram (ECoG). The results showed a shorter phase after sticking or the ritual slaughter cut respectively, until the ECoG disappears in stunned animals. However, considering the time between stunning and the cervical state, the interval until disappearance of the ECoG was prolonged in the stunned animals. The observed time differences, however, are only a tendency and not statistically confirmed. Insofar, concerning animal protection, the different slaughter methods could be regarded equivalent. A second trial was designed in a manner to allow a more exact interpretation of the ECoGs and was completed by measuring visually and somatosensorically evoked potentials. Additionally, in contrast to the first trial, only adult cattle were used here. The results revealed shorter intervals until disappearance of cortical activities when using captive-bolt stunning. Also the variance was much lower in this trial than after ritual slaughter. The mean of the time differences was relatively low (5.5 seconds). It was especially remarkable that after captivebolt stunning absolutely no evoked potentials could be registrated, whereas these potentials lasted for 77 seconds (somatosensorically evoked potentials) and 55 seconds respectively (visually evoked potentials) after the ritual slaughter cut. Thus, after ritual slaughter a nervous conduction was measured up to 126 seconds in the extreme cases. However, from the results obtained it can not be concluded whether or not pain sensitivity occurred in the animals.

Abattoirs↗

PubMed1986

[Spectrum of high-frequency oscillations of the electrocorticogram and their nature].

A gradual amplitude decrease towards higher frequencies was found in the spectrum (25-400 Hz) of the ECoG of the curarized rabbit. This gradual decrease of the amplitude continued to exist under the action of d-amphetamine, physostigmine, atropine, chlorpromazine and thiopental despite changes in the spectrum characteristic of every agent. These changes allowed finding the boundary near 40 Hz between high frequencies (HF) and conventional ECoG. The amplitudes of all HF components changed in the same direction independently of the ECoG. Unanimous changes suggest common genesis of HFs and a gradual decrease of the amplitude in the spectrum supports their synaptic but not spike origin. In the light of the concept of the EEG quantum the conventional ECoG represents synchronization and HFs express fluctuations of the quantum flow.

Animals↗