PubMed Health⌕ Search

Biomedical subjects

H Jokeit

Publications and source records attributed to H Jokeit.

At least 19 recordsLinked to original sources
PubMed2001

Seizures accelerate forgetting in patients with left-sided temporal lobe epilepsy.

Ten patients with refractory temporal lobe epilepsy performed a word-position association learning task every 24 hours during video EEG monitoring. On 55 occasions recall performance was tested 30 minutes and 24 hours after the initial learning phase. Patients with left- but not right-sided temporal lobe epilepsy exhibited impaired retention of word position if a seizure had occurred during the preceding 24-hour interval. Seizures may impair the consolidation of memory in patients with left-sided temporal lobe epilepsy beyond the chronic memory deficits caused by the underlying pathology.

Adult↗
PubMed2001

Lateralizing value of unilateral motor and somatosensory manifestations in frontal lobe seizures.

PURPOSE: To evaluate the lateralizing value of unilateral somatosensory aura, unilateral tonic posturing, head version, non-forced head turning, ictal cloni, dystonic posturing, and postictal nose wiping in seizures originating in the frontal lobe. METHODS: We included patients who had consecutively undergone presurgical evaluation with ictal video-EEG monitoring at our institution, had had resective epilepsy surgery involving the frontal lobe, and had remained seizure-free >1 year after operation. Twenty-seven patients aged 1-42 years (mean 18) met the inclusion criteria. Fifteen patients had right-sided, 12 patients had left-sided epileptogenic regions. Seizures recorded during EEG-video monitoring were re-evaluated by two investigators in order to identify lateralization signs in frontal lobe seizures. One of the investigators was blind to patients' clinical data. RESULTS: We analyzed 153 seizures of 27 patients. The most common unilateral phenomenon was the unilateral tonic posturing occurring in 48% of all the patients and in 25% of all seizures. Somatosensory aura and head version appeared exclusively contralateral whereas clonus occurred in 92% and unilateral tonic posturing in 89% of seizures contralateral to the epileptogenic region. Ictal non-forced head turning and postictal nose wiping showed no lateralizing significance. Dystonic posturing did not occur. CONCLUSIONS: Somatosensory aura, head version, ictal cloni, and tonic posturing are reliable lateralizing signs in frontal seizures. These signs may help in identifying the epileptogenic region during presurgical evaluation of patients suffering from frontal lobe epilepsy.

Adolescent↗
PubMed2001

Lack of aura experience correlates with bitemporal dysfunction in mesial temporal lobe epilepsy.

UNLABELLED: The diagnostic value of lack of aura experience in patients with temporal lobe epilepsy (TLE) is unclear. PURPOSE: To evaluate possible factors of bitemporal dysfunction in patients with mesial TLE who did not experience an aura in electroencephalography EEG/video monitoring for epilepsy surgery. METHODS: Ictal scalp EEG propagation patterns of 347 seizures of 58 patients with mesial temporal lobe sclerosis or non-lesional mesial TLE, interictal epileptiform discharges (IED), presence of unilateral mesial temporal lobe sclerosis in visual magnetic resonance imaging (MRI) analysis, prose memory performance, history or not of an aura, and postictal memory or absence of an aura were analyzed. The ictal EEG was categorized as follows. EEG seizure: (a) remaining regionalized, (b) non-lateralized, (c) showing later switch of lateralization or bitemporal asynchronous ictal patterns. RESULTS: Absent aura in monitoring was significantly correlated with absence of unitemporal MRI sclerosis (P=0.004), bitemporal IED (P=0.008), and propagation of the ictal EEG to the contralateral temporal lobe (P=0.001). Other historical data and interictal prose memory performance were not significantly correlated with absent aura. Ten of 11 patients without aura in monitoring also had absent or rare auras in their history. CONCLUSIONS: Lack of aura experience strongly correlates with indicators of bitemporal dysfunction such as bitemporal interictal sharp waves and bitemporal ictal propagation in scalp EEG, and absence of lateralized MRI sclerosis in patients with mesial TLE. The fact that absent auras are not correlated with episodic memory suggests a transient memory deficit, probably because of rapid propagation to the contralateral mesial temporal lobe.

Adolescent↗
PubMed2000

Amplitude envelope correlation detects coupling among incoherent brain signals.

Cognitive processing involves gamma-activation over broad cortical regions. Phase coupling of these activities has rarely been reported for areas far apart. Other forms of coupling are generally not detected by conventional measures. Here, we use amplitude envelope correlation (AEC), which can detect signal coupling without phase coherence, even among different frequencies. We apply it to subdural recordings from humans performing a visual delayed match-to-sample task and systematically compare it with spectral amplitude and coherence. The different measures often show divergent results. In particular, AEC reveals y-coupling completely missed by coherence. We argue that coherence and AEC are adapted to different cortical mechanisms of short- and long-range interactions, respectively.

Adult↗
PubMed2000

EEG predicts surgical outcome in lesional frontal lobe epilepsy.

BACKGROUND: Because of the relatively poor results of frontal lobe epilepsy (FLE) surgery, identification of prognostic factors for surgical outcome is of great importance. METHODS: To identify predictive factors for FLE surgery, we analyzed the data of 61 patients (mean age at surgery 19.2) who had undergone presurgical evaluation and resective surgery in the frontal lobe. Postoperative follow-up ranged from 0.5 to 5 years (mean 1.78). Fifty-nine patients had MRI-detectable lesions. Histopathologic examination showed dysplasia (57.4%), tumor (16.4%), or other lesions (26.2%). Thirty postoperatively seizure-free patients were compared with 31 non-seizure-free patients with respect to clinical history, seizure semiology, EEG and neuroimaging data, resected area, and postoperative data including histopathology. RESULTS: Three preoperative and two postoperative variables were related to poor outcome: generalized epileptiform discharges, generalized slowing, use of intracranial electrodes, incomplete resection detected by MRI, and postoperative epileptiform discharges. The only preoperative factor associated with seizure-free outcome was the absence of generalized EEG signs. Multivariate analysis showed that only the absence of generalized EEG signs predicts the outcome independently. Moreover, the occurrence of a somatosensory aura, secondarily generalized seizures, and negative MRI was identified as additional independent risk factors for poor surgical results. CONCLUSIONS: The absence of generalized EEG signs is the most predictive variable for a seizure-free outcome in FLE surgery. Furthermore, nonlesional MRI, somatosensory aura, and secondarily generalized seizures are risk factors for poor surgical results.

Adolescent↗
PubMed2000

Are ictal vocalisations related to the lateralisation of frontal lobe epilepsy?

The purpose was to analyse whether non-speech vocalisations in seizures originating in the frontal lobe do have lateralising value. Patients were included who had undergone presurgical evaluation with ictal video-EEG monitoring at the Epilepsy Centre, had had resective epilepsy surgery involving the frontal lobe, and who had remained seizure free>1 year postoperatively. Twenty seven patients aged 1-42 years (mean 18) met the inclusion criteria. Age at epilepsy onset ranged from 1 month to 41 years (mean 7.1 years). All selected patients had a unilateral MRI detected lesion within the frontal lobe. Fifteen patients had right sided, 12 patients had left sided epileptogenic zones. Seizures recorded during EEG-video monitoring were re-evaluated to identify the occurrence of ictal vocalisations. Pure ictal vocalisations were distinguished from ictal sound productions due to motor or vegetative seizure activity (for example, cloni or respiratory sounds). Pure ictal vocalisation occurred in 11 patients of whom nine had a left frontal epileptogenic zone (p<0.01). It is concluded that ictal vocalisation could be an additional lateralising sign in frontal lobe epilepsy. The results suggest that not only speech, but vocalisation at a subverbal level also shows a left hemispheric dominance in humans.

Adolescent↗
PubMed1999

Bilateral reductions of hippocampal volume, glucose metabolism, and wada hemispheric memory performance are related to the duration of mesial temporal lobe epilepsy.

In refractory temporal lobe epilepsy (TLE) temporal lobe structures and functions are continuously or intermittently affected by abnormal brain electrical events, noxious neurochemical agents, and metabolic disturbances. There is conflicting evidence regarding the relationship between the duration of refractory mesial TLE and quantitative measures of temporal lobe functions and volumes of the hippocampi. Twenty patients (aged 28 +/- 7 years, 14 males) with an initial precipitating injury before the age of 5 years were subjected to high-resolution magnetic resonance imaging, fluoro-2-deoxy-d-glucose positron-emission tomography (PET), and the Wada test. We investigated whether the duration of unilateral refractory TLE (12 left, 8 right) affects hippocampal volume, glucose metabolism, or Wada hemispheric memory performance. Ipsilateral to the epileptogenic zone the hippocampal volume, metabolism, and Wada hemispheric memory performance were reduced compared to the corresponding contralateral measures. The duration of epilepsy controlled for age at investigation, side of seizure origin, underlying cause, and sex were negatively correlated with ipsi- and contralateral hippocampal volume, hippocampal metabolism, and Wada hemispheric memory performance. Moreover, ipsilateral Wada hemispheric memory performance and contralateral hippocampal glucose metabolism were correlated with the frequency of habitual seizures. Refractory TLE seems to be associated with a slow but ongoing bilateral temporal lobe damage. These cross-sectional results require verification by longitudinal studies carried out over a period of more than two decades.

Adolescent↗
PubMed1999

Long term effects of refractory temporal lobe epilepsy on cognitive abilities: a cross sectional study.

OBJECTIVE: Intractable epilepsy is related to various transient and chronic brain electric and neurochemical disturbances. There is increasing evidence that chronic epilepsy induces secondary neuronal metabolic and structural decline. However, there is no convincing evidence that the cognitive abilities of patients deteriorate with increasing duration of intractable epilepsy. METHODS: To examine whether duration of refractory temporal lobe epilepsy (TLE) is related to generalised cognitive impairment, psychometric intelligence based on the full scale intelligence quotient (FSIQ, WAIS-R) was determined in 209 patients with unilateral TLE. For analyses of variance (ANOVA) patients were grouped into three categories: <15, 15-30, and >30 years of refractory TLE. RESULTS: An ANOVA and a multiple regression analysis showed that duration of TLE affects FSIQ. Patients with >30 years of TLE performed worse than patients with 15 or 30 years of TLE. The factors side of seizure origin and type of lesion on MRI did not reach significance. A second ANOVA including education as factor showed that in patients with higher educational attainment, the mean FSIQ was stable for a longer duration of TLE than in less educated patients. Retesting 6 months after anterior temporal lobectomy seizure free patients (n=85 of 127) had an higher FSIQ but showed a similar duration effect before and after anterior temporal lobectomy. The variables age at epilepsy onset, education, frequency of interictal epileptiform discharges, frequency of habitual and generalised seizures, serum concentration of antiepileptic drugs, and polypharmacy were statistically controlled. CONCLUSIONS: Psychometric intelligence of patients with a longer duration of refractory TLE were most severely impaired. Consequently, refractory TLE seems to be associated with slow but ongoing cognitive deterioration. It is assumed that epilepsy related noxious events and agents exhaust the compensatory capacity of brain functions. However, as in dementia and Alzheimer's disease, higher educational attainment as an indicator of higher brain reserve might delay the cognitive decline.

Adult↗
PubMed1998

Hemispheric asymmetries in category-specific word retrieval.

We examined whether 53 adult non-aphasic patients with either left (22) or right temporal lobe lesions (31) demonstrate dissociable patterns of hemispheric asymmetries in category-specific word fluency tasks. The patients were asked to articulate as many appropriate words as possible within 60 or 90 s in response to six target categories. There was no effect of patient groups on the overall fluency. However, patients with a left-sided temporal lobe lesion were impaired retrieving words to 'initial letters' and to the category 'animals'. Right temporal lobe patients were impaired retrieving 'tools' and words referring to specific visual attributes. There were no fluency differences for 'food-supermarket goods' and 'flat interior'. We conclude that temporal lobe damage can result in category-specific impairments in word retrieval depending on the affected hemisphere.

Adolescent↗
PubMed1998

Noninvasive determination of language lateralization by functional transcranial Doppler sonography: a comparison with the Wada test.

BACKGROUND AND PURPOSE: Functional transcranial Doppler ultrasonography (fTCD) can assess event-related changes in cerebral blood flow velocities and, by comparison between sides, can provide a measure of hemispheric perfusional lateralization. It is easily applicable, insensitive to movement artifacts, and can be used in patients with less than perfect cooperation. In the present study we investigated the validity of fTCD in determining the hemispheric dominance for language by direct comparison of fTCD with intracarotid amobarbital anesthesia (Wada test). METHODS: fTCD and the Wada test were performed in 19 patients evaluated for epilepsy surgery. By the Wada test, 13 patients were classified as left-hemisphere dominant and 6 as right-hemisphere dominant for language. fTCD was based on the continuous bilateral measurements of blood flow velocities in the middle cerebral arteries and event-related averaging during a cued word generation task previously shown to activate lateralized language areas in normal adults. RESULTS: In 4 patients fTCD assessment was not possible because of lack of an acoustic temporal bone window. In the remaining 15 candidates, determination of language dominance was concordant with the Wada test in every case. Moreover, the correlation of the lateralization measures from both procedures was highly significant (r=.92, P<.0001). CONCLUSIONS: This strong correlation validates fTCD as a noninvasive and practical tool for the determination of language lateralization that can be applied for clinical and investigative purposes.

Adolescent↗
PubMed1997

Prefrontal asymmetric interictal glucose hypometabolism and cognitive impairment in patients with temporal lobe epilepsy.

Depressions of regional cerebral metabolism beyond the epileptogenic zone have been demonstrated in patients with intractable temporal lobe epilepsy. However, their clinical relevance, and the causes of prefrontal metabolic asymmetries are less well understood. We investigated 96 temporal lobe epilepsy patients by FDG-PET and neuropsychological assessment who had a corresponding unilateral temporal hypometabolism, left hemisphere speech dominance, full scale IQ of > 70 and no extratemporal lesion in MRIs. The regional glucose metabolism was determined in each patient in homologous regions including prefrontal cortex, and normalized to whole brain metabolism. Regional differences of > 10% were regarded as asymmetrical. Prefrontal metabolic asymmetries were more frequent in patients with left temporal lobe epilepsy (21 left, six right) and a history of secondarily generalized seizures. A multivariate analysis of variance revealed a main effect for prefrontal metabolic asymmetry on neuropsychological 'frontal lobe measures', including verbal and performance intelligence measures. Prefrontal metabolic asymmetry was not related to 'measures of episodic memory', presence of psychiatric symptoms or frontal interictal epileptiform discharges. We conclude that prefrontal metabolic asymmetry is associated with cognitive impairment. Patients with temporal lobe epilepsy of the left speech dominant hemisphere and a history of secondarily generalized seizures are at considerable risk of developing prefrontal metabolic asymmetry.

Adult↗
PubMed1997

Individual prediction of change in delayed recall of prose passages after left-sided anterior temporal lobectomy.

Prognostic variables for individual memory outcome after left anterior temporal lobectomy (ATL) were studied in 27 patients with refractory temporal lobe epilepsy. The difference between pre- and postoperative performance in the delayed recall of two prose passages (Story A and B) from the Wechsler Memory Scale served as measure of postoperative memory change. Fifteen independent clinical, neuropsychological, and electrophysiological variables were submitted to a multiple linear regression analysis. Preoperative immediate and delayed recall of story content and right hemisphere Wada memory performance for pictorial and verbal items explained very well postoperative memory changes in recall of Story B. Delayed recall of Story B, but not of Story A, had high concurrent validity to other measures of memory. Patients who became seizure-free did not differ in memory change from patients who continued to have seizures after ATL. The variables age at epilepsy onset and probable age at temporal lobe damage provided complementary information for individual prediction but with less effectiveness than Wada test data. Our model confirmed that good preoperative memory functioning and impaired right hemispheric Wada memory performance for pictorial items predict a high risk of memory loss after left ATL. The analyses demonstrate that the combination of independent measures delivers more information than Wada test performance or any other variable alone. The suggested function can be used routinely to estimate the individual severity of verbal episodic memory impairment that might occur after left-sided ATL and offers a rational basis for the counseling of patients.

Adolescent↗
PubMed1996

Reorganization of memory functions after human temporal lobe damage.

Hemispheric (re-)organization of episodic memory functions after temporal lobe damage (TLD) was investigated by the intracarotid amobarbital procedure in patients suffering temporal lobe epilepsy. Memory of the speech-dominant left hemisphere was intact after right-sided TLD independent of the age at manifestation. In contrast, the right hemisphere mediated memory well only after early left-sided TLD. These findings suggest a predisposition of the speech-dominant left hemisphere for the encoding of episodic memory, and indicate that for left-sided TLD the right hemisphere may compensate memory encoding sufficiently only if the damage occurred within a critical period in childhood.

Brain Damage, Chronic↗
PubMed1994

Different event-related patterns of gamma-band power in brain waves of fast- and slow-reacting subjects.

Fast- and slow-reacting subjects exhibit different patterns of gamma-band electroencephalogram (EEG) activity when responding as quickly as possible to auditory stimuli. This result appears to confirm long-standing speculations of Wundt that fast- and slow-reacting subjects produce speeded reactions in different ways and demonstrates that analysis of event-related changes in the amplitude of EEG activity recorded from the human scalp can reveal information about event-related brain processes unavailable using event-related potential measures. Time-varying spectral power in a selected (35- to 43-Hz) gamma frequency band was averaged across trials in two experimental conditions: passive listening and speeded reacting to binaural clicks, forming 40-Hz event-related spectral responses. Factor analysis of between-subject event-related spectral response differences split subjects into two near-equal groups composed of faster- and slower-reacting subjects. In faster-reacting subjects, 40-Hz power peaked near 200 ms and 400 ms poststimulus in the react condition, whereas in slower-reacting subjects, 40-Hz power just before stimulus delivery was larger in the react condition. These group differences were preserved in separate averages of relatively long and short reaction-time epochs for each group. gamma-band (20-60 Hz)-filtered event-related potential response averages did not differ between the two groups or conditions. Because of this and because gamma-band power in the auditory event-related potential is small compared with the EEG, the observed event-related spectral response features must represent gamma-band EEG activity reliably induced by, but not phase-locked to, experimental stimuli or events.

Acoustic Stimulation↗
PubMed1994

Event related dynamics of 40 Hz electroencephalogram during visual discrimination task.

Visual priming tasks were presented to human subjects in two conditions: first, the warning stimulus contained information on the target stimulus, second, the warning stimulus only cued that a target was to come. The subjects had to respond as fast as possible to target stimuli with a certain button press. In both conditions 40 Hz EEG power showed reliably event related dynamics. Considering the differences between both conditions, 40 Hz power and motor response time effect sizes were found to be correlated 200 ms following warning stimuli. These results demonstrate that dynamics of 40 Hz activity are related to stimulus evaluation in sensorimotor processing during a visual discrimination task.

Cues↗