PubMed Health⌕ Search

Biomedical subjects

K Krakow

Publications and source records attributed to K Krakow.

At least 19 recordsLinked to original sources
PubMed2001

Long-term continuation of levetiracetam in patients with refractory epilepsy.

The long-term continuation (retention) rate, efficacy, and safety data of the new antiepileptic drug levetiracetam (LEV) was evaluated in all patients with epilepsy exposed to the drug during its developmental program (n = 1,422). The retention rate was estimated to be 60% after 1 year and 32% after 5 years. Thirty-nine percent (512/1,325) of patients had a seizure reduction of > or =50%, and 13% (183/1,422) became seizure-free for at least 6 months. LEV seems an effective and well tolerated new antiepileptic drug.

Adolescent↗
PubMed2001

Functional MRI activation of individual interictal epileptiform spikes.

We used spike-triggered functional MRI in a patient with localization-related epilepsy to determine whether individual (as opposed to averaged) focal interictal epileptiform discharges (spikes) were associated with hemodynamic changes detectable with blood oxygen level-dependent functional MRI (fMRI). It was found that 15 of 43 spikes (34.9%) were associated with significant focal fMRI activation. Single event-related fMRI of interictal spikes is feasible in selected patients, giving complementary information to that provided by averaged fMRI data.

Brain Mapping↗
PubMed2001

Event-related fMRI with simultaneous and continuous EEG: description of the method and initial case report.

We report on the initial imaging findings with a new technique for the simultaneous and continuous acquisition of functional MRI data and EEG recording. Thirty-seven stereotyped interictal epileptiform discharges (spikes) were identified on EEG recorded continuously during the fMRI acquisition on a patient with epilepsy. Localization of the BOLD activation associated with the EEG events was consistent with previous findings and EEG source modeling. The time course of activation was comparable with the physiological hemodynamic response function (HRF). The new methodology could lead to novel and important applications in many areas of neuroscience.

Cerebrovascular Circulation↗
PubMed2001

Combined functional magnetic resonance imaging and diffusion tensor imaging demonstrate widespread modified organisation in malformation of cortical development.

A patient with a mild left hemiparesis and a malformation of cortical development in the right hemisphere was investigated with fMRI (functional magnetic resonance imaging) and DTI (diffusion tensor imaging). The motor cortex was studied using a finger tapping fMRI experiment. The fibre orientation was studied by displaying the principal eigenvector of the diffusion tensor in the spatially normalised brain of the patient and of control subjects. In addition, the anisotropy (directionality) of water diffusion of the patient was statistically compared with control subjects. The malformation was located in the right central region in the expected position of the motor cortex. fMRI showed activation anterior and posterior to the malformation. DTI disclosed that fibres with rostrocaudal orientation, presumably representing the pyramidal tract, were deviating from their normal orientation and passing around the malformation. There were widespread regions of reduced anisotropy affecting both hemispheres. In conclusion, fMRI and DTI provided concordant information showing widespread modified functional and structural organisation including regions which appeared normal on standard imaging.

Adult↗
PubMed2001

Spatio-temporal imaging of focal interictal epileptiform activity using EEG-triggered functional MRI.

EEG-triggered, blood oxygen level-dependent functional MRI (BOLD-fMRI) was used in 24 patients with localization-related epilepsy and frequent interictal epileptiform discharges (spikes) to identify those brain areas involved in generating the spikes, and to study the evolution of the BOLD signal change over time. The location of the fMRI activation was compared with the scalp EEG spike focus and the structural MR abnormality. Twelve patients (50%) had an fMRI activation concordant with the EEG focus and structural brain abnormalities where present (n = 7). In 2 other patients, the fMRI activation was non-concordant with electroclinical findings. The remaining 10 patients (41.7%) showed no significant fMRI activation. These patients had significantly lower mean spike amplitudes compared to those with positive fMRI results (p = 0.03). The time course of the BOLD response was studied in 3 patients and this revealed a maximum signal change 1.5 to 7.5 sec after the spike. In conclusion, EEG-triggered fMRI can directly identify the generators of interictal epileptiform activity, with high spatial resolution, in selected patients with frequent spikes. The superior spatial resolution obtainable through EEG-triggered fMRI may provide an additional non-invasive tool in the presurgical evaluation of patients with intractable focal seizures.

Action Potentials↗
PubMed2000

EEG recording during fMRI experiments: image quality.

Electroencephalographic (EEG) monitoring during functional magnetic resonance imaging (fMRI) experiments is increasingly applied for studying physiological and pathological brain function. However, the quality of the fMRI data can be significantly compromised by the EEG recording due to the magnetic susceptibility of the EEG electrode assemblies and electromagnetic noise emitted by the EEG recording equipment. We therefore investigated the effect of individual components of the EEG recording equipment on the quality of echo planar images. The artifact associated with each component was measured and compared to the minimum scalp-cortex distance measured in normal controls. The image noise originating from the EEG recording equipment was identified as coherent noise and could be eliminated by appropriate shielding of the EEG equipment. It was concluded that concurrent EEG and fMRI could be performed without compromising the image quality significantly if suitable equipment is used. The methods described and the results of this study should be useful to other researchers as a framework for testing of their own equipment and for the selection of appropriate equipment for EEG recording inside a MR scanner.

Adolescent↗
PubMed2000

[Coping behaviors in Parkinson's disease].

In 45 patients with Parkinson's disease, we investigated coping behavior and its correlations to demographic and disease-related data, locus of control, depression, and psychosocial adaptation. Active, problem oriented, and self-reorganizing strategies were predominantly used and regarded as especially helpful by the 27 men and 18 women (age: 56 years; duration of illness: 9 years). While age and sex were not associated with coping, external locus of control correlated positively to "depressive coping" and duration of illness correlated negatively to "distraction and self-affirmation." Coping strategies regarded as maladaptive and a small degree of internal locus of control correlated to unfavourable results for depression and satisfaction.

Adaptation, Psychological↗
PubMed2000

Auditory processing across the sleep-wake cycle: simultaneous EEG and fMRI monitoring in humans.

We combined fMRI and EEG recording to study the neurophysiological responses associated with auditory stimulation across the sleep-wake cycle. We found that presentation of auditory stimuli produces bilateral activation in auditory cortex, thalamus, and caudate during both wakefulness and nonrapid eye movement (NREM) sleep. However, the left parietal and, bilaterally, the prefrontal and cingulate cortices and the thalamus were less activated during NREM sleep compared to wakefulness. These areas may play a role in the further processing of sensory information required to achieve conscious perception during wakefulness. Finally, during NREM sleep, the left amygdala and the left prefrontal cortex were more activated by stimuli having special affective significance than by neutral stimuli. These data suggests that the sleeping brain can process auditory stimuli and detect meaningful events.

Acoustic Stimulation↗
PubMed2000

Fixation-off sensitivity as a model of continuous epileptiform discharges: electroencephalographic, neuropsychological and functional MRI findings.

A case of fixation-off sensitivity (FOS) in an asymptomatic adult is presented and studied as a model for continuous epileptiform discharges. Video-electroencephalographic (EEG) revealed continuous bilateral occipital spike wave discharges during elimination of central vision, which were shown to be associated with transitory cognitive impairment demonstrated by neuropsychological testing. Functional MRI showed activation of parieto-occipital and frontal brain areas during the fixation-off discharges. This localization was confirmed with 64-channel EEG source analysis. The applied methods provided additional information on the pathophysiology of epileptiform discharges.

Adult↗
PubMed2000

Recovery of visual field constriction following discontinuation of vigabatrin.

Epilepsy patients treated with vigabatrin may develop symptomatic or asymptomatic concentric visual field constriction due to GABA-associated retinal dysfunction. The prevalence and course of this side effect are not established yet; in previously reported adult patients the visual disturbances seem to be irreversible. We present two patients with a significant improvement of visual field constriction and retinal function after the discontinuation of vigabatrin. These findings suggest that vigabatrin-associated retinal changes are at least partly reversible in some patients, and that these patients may benefit significantly from a withdrawal of vigabatrin. Larger scale clinical studies are needed to identify predictive factors both for the occurrence and reversibility of vigabatrin-associated visual field defects.

4-Aminobutyrate Transaminase↗
PubMed2000

Simultaneous assessment of brain tissue oxygenation and cerebral perfusion during orthostatic stress.

Simultaneous registration of cerebral tissue oxygenation parameters obtained by near infrared spectroscopy (NIRS), intracranial blood flow velocity (CBFV) measured by transcranial Doppler sonography (TCD) and basic cardiovascular parameters was carried out during a passive 80 degrees head-up tilt table test in 15 patients with a history of orthostatic syncope and 20 control subjects. In normals, the cardiovascular parameters showed a specific course after changing to a vertical position: the heart rate increased, the mean arterial blood pressure remained unchanged, and the CBFV decreased. The NIRS measurements showed an increase in deoxyhemoglobin (HHb) and a decline in oxyhemoglobin (O(2)Hb) and the regional oxygen saturation (RSAT). Patients had a significantly more prominent decline in arterial blood pressure (p < 0.001), CBFV (p < 0.001) and RSAT (p = 0.04). Five patients experienced symptoms of (pre)syncope during the experiment, which were associated with a further sudden and marked (>10%) drop of O(2)Hb. The results indicate that the combination of TCD and NIRS increases the understanding of hemodynamic and metabolic changes during orthostatic stress, which may lead to individually suited therapeutic procedures.

Blood Flow Velocity↗
PubMed1999

Fast, accurate, and reproducible automatic segmentation of the brain in T1-weighted volume MRI data.

A new fast automated algorithm has been developed to segment the brain from T1-weighted volume MR images. The algorithm uses automated thresholding and morphological operations. It is fully three-dimensional and therefore independent of scan orientation. The validity and the performance of the algorithm were evaluated by comparing the automatically calculated brain volume with semi-automated measurements in 10 subjects, by calculating the brain volume from repeated scans in another 10 subjects, and by visual inspection. The mean and standard deviation of the difference between semi-automated and automated measurements were 0.56% and 2.8% of the mean brain volume, respectively, which is within inter-observer variability of the semi-automated method. The mean and standard deviation of the difference between the total volumes calculated from repeated scans were 0.40% and 1.2% of the mean brain volume, respectively. Good results were also obtained from a scan of abnormal brains.

Adult↗
PubMed1999

Coping with refractory epilepsy.

We investigated the coping behaviour and its correlation with demographic and illness-related data, depression, locus of control and psychosocial adaptation in 40 patients with intractable epilepsy with primarily or secondarily generalized tonic-clonic seizures. Three standardized self-reporting questionnaires were applied, which are the Freiburg Questionnaire of Coping with Illness (FKV), the von Zerssen Depression Scale (D-S), and the IPC-questionnaire measuring generalized locus of control beliefs; the Social Interview Schedule (SIS), a semi-structured interview, was used to measure the psychosocial adaptation. Active, problem-focused and compliance strategies were predominantly used and regarded as most helpful. Hence, the epileptic patients use similar coping patterns reported in patients with other non life-threatening chronic diseases. The level of depression was moderate and in the range of other chronic somatic diseases. The use of coping patterns, which are regarded as maladaptive, was correlated with distinct depression, a small degree of internal locus of control beliefs and poor psychosocial adaption. These results indicate the possibility to improve psychosocial adjustment by supporting effective strategies.

Adaptation, Psychological↗
PubMed1999

[Transverse myelopathy as a complication following long-term intrathecal application of morphine in chronic back pain].

Serious neurological complications following long-term intrathecal application of opiates have seldom been published. This report describes complications which developed three months after reimplantation of a spinal catheter for pain therapy. The symptoms which occurred were paraparesis of the legs with sensory loss and urinary retention. A regression of these symptoms occurred only after explantation of the spinal catheter-pump-system. Possible reasons and consequences are discussed.

Analgesics, Opioid↗
PubMed1999

Reproducible localization of interictal epileptiform discharges using EEG-triggered fMRI.

We report preliminary experiences using fMRI triggered by EEG to localize the site of interictal epileptiform activity. EEG was recorded in the scanner and monitored on-line; the recording quality was good enough to allow the clear identification of spikes in the EEG. Snap-shot EPI was performed 2-4 s after an epileptiform discharge ('spike') or after at least 10 s of background activity ('rest') was observed. A pixel-by-pixel t-test was performed between the 'rest' and the 'spike' images to determine areas of significant activation. Significant activation was obtained in a patient with epilepsy. To assess the reliability and reproducibility of the technique, the patient was scanned on four separate occasions with similar areas being activated in all the studies, confirming the validity of the result.

Brain↗
PubMed1999

EEG-triggered functional MRI of interictal epileptiform activity in patients with partial seizures.

EEG-triggered functional MRI (fMRI) offers the potential to localize the generators of scalp EEG events, such as interictal epileptiform discharges, using a biological measurement as opposed to relying solely on modelling techniques. Although recent studies have demonstrated these possibilities in a small number of patients, wider application has been limited by concerns about patient safety, severe problems due to pulse-related artefact obscuring the EEG trace, and lack of reproducibility data. We have systematically studied and resolved the issues of patient safety and pulse artefact and now report the application of the technique in 24 experiments in 10 consecutive patients with localization-related epilepsy and frequent interictal epileptiform discharges (spikes or spike wave). At least two experiments were performed for each patient. In each experiment, 10- or 20-slice snapshot gradient-echo planar images were acquired approximately 3.5 s after a single typical epileptiform discharge (activation image) and in the absence of discharges (control image). Between 21 and 50 epileptiform discharges were sampled in each experiment. The significance of functional activation was tested using the t test at 95% confidence on a pixel-by-pixel basis. Six of the 10 patients showed reproducible focal changes of the blood oxygen level-dependent (BOLD) signal, which occurred in close spatial relationship to the maximum of the epileptiform discharges in the concurrent EEG. No reproducible focal BOLD signal changes were observed in the remaining four patients. In conclusion, EEG-triggered fMRI is now a sufficiently developed technique to be more widely used in clinical studies, demonstrating that it can reproducibly localize the brain areas involved in the generation of spikes and spike wave in epilepsy patients with frequent interictal discharges.

Adult↗