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Biomedical subjects

K Krakow

Publications and source records attributed to K Krakow.

31 records · Page 2Linked to original sources
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↗
PubMed1999

Coping with Parkinson's disease and refractory epilepsy. A comparative study.

Coping strategies and their correlations with demographic and illness related data, depression, locus of control, and psychosocial adaptation were investigated in 45 patients with Parkinson's disease and 40 patients with intractable epilepsy. Three standardized self-report questionnaires were applied: 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 psychosocial adaptation. Active, problem-focused and compliance strategies were predominantly used and regarded as most helpful in both groups of patients. Hence, Parkinson and epilepsy patients used similar coping patterns despite the strong dissimilarities of symptoms and illness-associated burdens. The level of depression was not significantly different in both groups and in the range of other chronic somatic diseases. The use of coping patterns, which are regarded as maladaptive, was correlated with distinct depression and a poor psychosocial adaption. In conclusion, no indications for illness-specific coping patterns were found in patients with Parkinson's disease and epilepsy. In both groups, certain coping strategies are associated with good and others with poor psychosocial adjustment. These results indicate the possibility of improving psychosocial adjustment by supporting effective strategies.

Adaptation, Psychological↗
PubMed1999

Multimodal MR imaging: functional, diffusion tensor, and chemical shift imaging in a patient with localization-related epilepsy.

PURPOSE: To demonstrate the integration of complementary functional and structural data acquired with magnetic resonance imaging (MRI) in a patient with localization-related epilepsy. METHODS: We studied a patient with partial and secondarily generalized seizures and a hemiparesis due to a malformation of cortical development (MCD) in the right hemisphere by using EEG-triggered functional MRI (fMRI), diffusion tensor imaging (DTI), and chemical shift imaging (CSI). RESULTS: fMRI revealed significant changes in regional blood oxygenation associated with interictal epileptiform discharges within the MCD. DTI showed a heterogeneous microstructure of the MCD with reduced fractional anisotropy, a high mean diffusivity, and displacement of myelinated tracts. CSI demonstrated low N-acetyl aspartate (NAA) concentrations in parts of the MCD. CONCLUSIONS: The applied MR methods described functional, microstructural, and biochemical characteristics of the epileptogenic tissue that cannot be obtained with other noninvasive means and thus improve the understanding of the pathophysiology of epilepsy.

Adult↗
PubMed1998

Identification of EEG events in the MR scanner: the problem of pulse artifact and a method for its subtraction.

Triggering functional MRI (fMRI) image acquisition immediately after an EEG event can provide information on the location of the event generator. However, EEG artifact associated with pulsatile blood flow in a subject inside the scanner may obscure EEG events. This pulse artifact (PA) has been widely recognized as a significant problem, although its characteristics are unpredictable. We have investigated the amplitude, distribution on the scalp, and frequency of occurrence of this artifact. This showed large interindividual variations in amplitude, although PA is normally largest in the frontal region. In five of six subjects, PA was greater than 50 microV in at least one of the temporal, parasagittal, and central channels analyzed. Therefore, we developed and validated a method for removing PA. This subtracts an averaged PA waveform calculated for each electrode during the previous 10 s. Particular attention has been given to reliable ECG peak detection and ensuring that the average PA waveform is free of other EEG artifacts. Comparison of frequency spectra for EEG recorded outside and inside the scanner, with and without PA subtraction, showed a clear reduction in artifact after PA subtraction for all four frequency ranges analyzed. As further validation, lateralized epileptiform spikes were added to recordings from inside and outside the scanner: PA subtraction significantly increased the proportion of these spikes that were correctly identified and decreased the number of false spike detections. We conclude that in some subjects, EEG/fMRI studies will be feasible only using PA subtraction.

Adult↗
PubMed1998

Modified approach for the selective treatment of temporal lobe epilepsy: transsylvian-transcisternal mesial en bloc resection.

OBJECT: The authors propose a novel surgical approach for amygdalohippocampectomy (AH) in patients with temporal lobe epilepsy. Via a transsylvian-transcisternal route, the parahippocampal gyrus is directly exposed from its medial aspect, thus allowing a standardized en bloc resection of the temporomesial epileptogenic structures--the amygdala, anterior hippocampus, parahippocampal gyrus, and subiculum. Additional anatomical studies have been performed for standardization of this approach. METHODS: From 1990 to 1996, 32 patients presenting with medically intractable mesial temporal lobe epilepsy underwent AH via the transsylvian-transcisternal approach. Preoperative computerized tomography and magnetic resonance imaging revealed temporomesial lesions in 16 patients. Histopathological examination revealed cavernous malformations in seven patients, low-grade astrocytomas in four, hamartomas in three, and gangliogliomas in two patients. Specimens obtained in patients with no lesions were diagnosed as hippocampal sclerosis in all cases. No patient experienced permanent morbidity. Nine percent of the patients developed a temporary partial oculomotor nerve palsy. Only one patient developed a postoperative visual field deficit with a contralateral quadrantanopsia. With respect to seizure outcome, all patients benefited from surgery. At follow-up evaluation (mean 26.4 months), 80% of the patients were free from seizures (Engel Class I). Eight patients in this group were no longer receiving medication. Seventeen percent had experienced only one to several seizures since surgery (Engel Class II) and 3% reported a worthwhile improvement (Engel Class III). CONCLUSIONS: In contrast to previously described standard techniques for AH, the transsylvian-transcisternal approach presented in this study offers improved anatomical orientation and intraoperative control over the mesial temporal lobe and preserves the lateral as well as the laterobasal temporal lobe.

Adolescent↗