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K Papke

Publications and source records attributed to K Papke.

18 recordsLinked to original sources
PubMed2006

Late response to radiochemotherapy in pediatric glioblastoma: report on two patients treated according to HIT-GBM protocols.

High-grade gliomas in children are rare and the best treatment is undetermined. The German language group study HIT-GBM compares various induction protocols for subsequent patient cohorts. Currently, cisplatinum, etoposide, ifosfamide, and vincristine are given simultaneously with extended-field radiotherapy. Imaging is done 3 weeks after to define treatment response, followed by 6-weekly controls during consolidation with lomustine, vincristine, and prednisone. The authors report on 2 patients with incompletely resected glioblastoma multiforme in which response was lacking 3 weeks after radiochemotherapy but became evident 12 weeks later. This suggests that later time points are required to assess induction protocol response.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2001

Abdominal spiral CT in children: which radiation exposure is required?

We decided to test to what extent dose reduction is possible in abdominal spiral computed tomography (CT) in young children without loss of anatomic diagnostic information. A retrospective study was performed of 30 abdominal CT examinations of children aged 3 months to 7 years. These were divided into two groups: group A with reduced radiation exposure (tube current 50 mA, CT dose index CTDIFDA < or =0.83 mGy) and group B with standard radiation exposure (tube current > or =100 mA, CTDIFDA > or =1.66 mGy). Image quality was assessed using a four-part scale ('excellent', 'good', 'sufficient', 'poor') on visual image impression and visibility of 32 anatomical details. Five experienced radiologists read the CT scans independently who were blinded to the examination parameters. Differences in ranked data were evaluated with Wilcoxon's rank sum test. No difference between groups A and B was observed in visual image impression. Detail visibility was significantly lower in group A, but the differences were limited to right upper quadrant structures (portal vein, common bile duct, pancreatic head, adrenals) and to arterial branches. Significant differences in visibility rated as 'poor' were only found for the hepatic, splenic and renal arteries; all other structures showed no difference between groups A and B. A protocol with reduced radiation exposure (50 mA, CTDIFDA < or =0.83 mGy) allowed the demonstration of most anatomic structures in abdominal spiral CT in young children. For the precise demonstration of small details (e.g. structures of the right upper quadrant), a protocol with standard radiation exposure (> or =100 mAs) was superior.

Child↗
PubMed2000

Assessment of hemispheric language lateralization: a comparison between fMRI and fTCD.

The cerebral blood flow velocity (CBFV) in the basal arteries during a word-generation task was assessed by functional transcranial Doppler ultrasonography (fTCD) and by functional magnetic resonance imaging (fMRI). The study investigates how event-related CBFV modulations in the middle cerebral artery (MCA) relate to regional cerebral blood flow (rCBF) changes. Both fMRI and fTCD were used in 13 subjects (7 men, 6 women, aged 21 to 44 years). The maximum difference of relative CBFV changes between the left and right MCA during the word-generation task was used as the language laterality index (LIfTCD). For the fMRI examination during the nearly identical language task, the corresponding index was defined by LIfMRI = 100(N(L) - N(R))/(N(L) + N(R)), where N(L) and N(R) refer to the numbers of voxels activated in the left and right hemisphere, respectively. The evoked CBFV changes expressed by LIfTCD and the corresponding laterality index, LIfMRI, estimated by fMRI showed a close linear relation (regression analysis: r = 0.95, p < 0.0001). The results of this study demonstrate that language-related velocity changes in the MCAs relate to rCBF increases in a linear fashion. Since the laterality indices assessed by fMRI and fTCD are in such close agreement both techniques can therefore be used in a complementary way.

Adult↗
PubMed2000

Optimized activation of the primary sensorimotor cortex for clinical functional MR imaging.

BACKGROUND AND PURPOSE: One application of functional MR imaging is to identify the primary sensorimotor cortex (M1 and S1) around the central sulcus before brain surgery. However, it has been shown that undesirable coactivation of nonprimary motor areas, such as the supplementary motor area and the premotor area, can interfere with the identification of the primary motor cortex, especially in patients with distorted anatomic landmarks. We therefore sought to design a simple functional MR imaging paradigm for selective activation of the primary sensorimotor cortex. METHODS: Different paradigms using finger tapping for motor activation were examined and compared with respect to the distribution of activated voxels in primary and nonprimary cortical areas. Studies were conducted in 14 healthy volunteers using a blood oxygen level-dependent multislice echo-planar imaging sequence. RESULTS: The most selective activation of the primary sensorimotor cortex was obtained with a paradigm combining right-sided finger tapping as the activation condition with left-sided finger tapping as the control condition. Analysis of the signal time course of primary and nonprimary areas revealed that the highly selective primary motor activation was due to it being restricted to contralateral finger movements, as opposed to the nonprimary motor areas, which were activated by ipsilateral, contralateral, and bilateral finger movements alike. CONCLUSION: When performing functional MR imaging to determine the location of the primary sensorimotor cortex, one should compare unilateral voluntary movements as the activation condition with contralateral movements as the control condition to accentuate activation of the primary motor area and to suppress undesirable coactivation of nonprimary motor areas.

Adult↗
PubMed1999

Clinical applications of functional MRI at 1.0 T: motor and language studies in healthy subjects and patients.

In this article we describe clinical applications of functional MRI (fMRI) at 1.0 T. All experiments were performed on a commercially available 1.0-T system (Magnetom Impact Expert, Siemens AG, Erlangen, Germany) using a blood oxygen level-dependent (BOLD)-sensitive multi-slice EPI technique (TE 66 ms, 4 mm slice thickness, 210 mm field of view, 64 x 64 acquisition matrix). Different paradigms for localization of the motor cortex and for language lateralization were tested in healthy subjects and patients. Methodological considerations concerning the development of the paradigms are also described. In all healthy subjects, motor activation elicited BOLD signal changes in the sensorimotor cortex, permitting identification of primary motor and sensory cortical areas. Furthermore, focal activation of different cortical areas by a language task was possible in 6 of 10 subjects. Nineteen motor studies were performed in 18 patients with supratentorial lesions, in most cases prior to neurosurgical procedures. In 14 studies, fMRI results demonstrated the localization of the motor hand areas relative to the lesion. The results proved valuable for preoperative planning and contributed to therapeutical decisions. We conclude that functional MRI for clinically relevant applications, such as localization of motor and language function, is feasible even at a field strength of 1.0 T without dedicated equipment.

Adult↗
PubMed1998

Factor V Leiden mutation is a risk factor for cerebral venous thrombosis: a case-control study of 55 patients.

BACKGROUND AND PURPOSE: Different coagulation disorders have been associated with cerebral venous thrombosis (CVT). Until now, fewer than 50 patients have been reported with CVT and the factor V Leiden (FVL) mutation. Although the prevalence of FVL-positive patients with CVT ranged from 10% to 25%, it was as low as 0.5% to 3% in the control groups. Most other studies had not systematically searched for concomitant risk factors or previous thromboembolic events. To better define the relevance of the FVL mutation in conjunction with additional risk factors in CVT, we conducted the present case-control study. METHODS: Fifty-five patients with CVT were compared with 272 healthy controls. A standardized interview regarding established risk factors for venous thrombosis and the patients' and their families' histories for thromboembolic events was performed. The presence of the FVL mutation was determined by polymerase chain reaction on DNA obtained from peripheral blood leukocytes. RESULTS: Of 55 patients, 8 (14.5%) were heterozygous for the FVL mutation compared with 17 of 272 controls (6.25%). The relative risk for the presence of FVL was 2.55 (95% confidence interval, 1.04 to 6.26; P=0.04). Additional risk factors for CVT were frequently found in both the presence and absence of FVL. Recurrence of venous thromboembolic events was more frequent in patients with the FVL mutation (5 of 8 patients, 62.5%) than in those without this anomaly (8 of 47 patients, 17%; P<0.005). CONCLUSIONS: Our study confirms the FVL mutation as the most relevant hereditary risk factor for CVT. Coexisting risk factors are usually involved in the initiation of CVT. Patients with the FVL mutation are at an increased risk for recurrent venous thrombosis.

Adolescent↗
PubMed1996

Variation of reaction time can be reduced by the time locked application of magnetic stimulation of the motor cortex.

It was the aim of this study to determine the influence of non-invasive magnetic stimulation on the performance of a visually induced reaction task. The experiment was performed in 8 healthy volunteers. After a visual stimulus subjects had to move their thumbs as soon as possible. The muscular reaction was recorded with surface EMG on both sides. After the visual go-signal a magnetic stimulus (Fig. 8 coil) was applied above the right or left motor cortex at varying time intervals (30 and 110 ms). The magnetic stimulus was randomly given or not. Short time intervals between visual and magnetic stimulus induced a shortening, long intervals induced a prolongation of the reaction time. The contralateral reaction time was always longer than the ipsilateral one. Compared with the reaction times without magnetic stimulation, the intraindividual standard deviation of the reaction times was markedly reduced by the application of the magnetic stimulation. This reduction was greater in ipsilateral than in contralateral recordings. The kind of the instruction had additional modifying effects.

Evoked Potentials↗
PubMed1995

The significance of three-dimensional MR-defined neurovascular compression for the pathogenesis of trigeminal neuralgia.

Three-dimensional MR tomography was used to examine the relationship between symptoms of trigeminal neuralgia and neurovascular compression of the nerve in 18 patients. The intensity of neurovascular interaction was classified according to neuroradiological criteria. We found that a radiologically defined compression or dislocation of the nerve by an artery was always associated with symptoms of trigeminal neuralgia. A simple contact between vessel and nerve, however, was also observed on the asymptomatic sides of 10 out of 18 patients. In 6 of 18 patients, in contrast, trigeminal neuralgia was present in spite of the absence of neurovascular contact. In accordance with a cited study based on autopsy and intraoperative findings, our findings indicate that, in a certain proportion of cases, trigeminal neuralgia may be caused by neurovascular compression alone, whereas in other cases, other pathogenetic factors may be involved to a varying degree or be even exclusively responsible for the development of trigeminal neuralgia. The possible significance of the method for a preoperative estimation of the success of microvascular decompression of the trigeminal nerve is discussed.

Adult↗
PubMed1993

Suppression of visual perception by transcranial magnetic stimulation--experimental findings in healthy subjects and patients with optic neuritis.

The influence of noninvasive magnetic brain stimulation by a magnetic coil (MC) placed over the occiput on perception and correct reporting of a briefly presented set of 3 letters of the alphabet was examined in 15 patients with prolonged VEP latencies due to neuritis of the optic nerve. The results derived from observing these patients were compared to the results obtained from an age-matched control group of 20 healthy voluntary subjects examined under the same experimental conditions. In both groups it was possible to demonstrate that transcranial magnetic stimulation is able to suppress recognition of the letters if applied with a certain delay time after a brief presentation of the visual stimulus. The groups were compared to each other with regard to the delay with which it was possible to demonstrate the most effective suppression. In the healthy subjects, this delay was found between 60 and 100 msec. In the patients, it was prolonged to 80-140 msec. This prolongation was closely related to the VEP latency (P100). Furthermore, visual suppression and the influence on it by different parameters were studied in detail in healthy subjects; the visual suppression depends on visual (e.g., brightness, duration) and magnetic (e.g., intensity) stimulus conditions. The method described seems to be of considerable value in the investigation of basic mechanisms of visual perception. This includes pathophysiological changes caused by optic neuritis and possibly other disorders affecting the visual system.

Adult↗
PubMed1993

Complete bilateral oculomotor palsy: the only clinical sign of subarachnoid hemorrhage in leukemia.

We report the original case of a patient with acute myelogenous leukemia who presented with a painless, complete bilateral oculomotor palsy during induction chemotherapy. Headache, signs of meningeal irritation or further neurological symptoms were absent throughout the course of illness. The CT revealed a subarachnoid hemorrhage (SAH). Within a day of the onset of symptoms, the oculomotor palsy subsided completely with no residual damage. To our knowledge, this is the first described case of SAH in leukemia with complete bilateral oculomotor palsy being the only clinical symptom. Furthermore, the spontaneous remission of this pathological condition is an extremely rare event.

Aged↗
PubMedDate not supplied

Sympathetic skin response in patients with amyotrophic lateral sclerosis.

To determine a possible involvement of the autonomic nervous system in amyotrophic lateral sclerosis (ALS), measurement of the sympathetic skin response (SSR) was performed in 15 patients with definite ALS. Findings were compared with those in 20 normal controls. In ALS patients the mean SSR latencies recorded from the palms and soles were both significantly prolonged (p < 0.05) and the amplitudes were reduced as compared with normal persons. In 5 patients, SSR potentials were completely lacking in one or even more extremities. Our data strongly suggest subclinical involvement of the autonomic nervous system in ALS as assessed by the SSR response. In our patients the extent of autonomic dysfunction was not related to the stage or the duration of disease.

Adult↗
PubMedDate not supplied

Involvement of the autonomic nervous system in patients with syringomyelia--a study with the sympathetic skin response.

In order to determine the function of the autonomic nervous system in syringomyelia, the sympathetic skin response (SSR) was performed in 13 patients with syringomyelia and 20 healthy controls. SSR was recorded from both palms and soles. In patients with syringomyelia, we found absent responses, prolonged latencies and reduced amplitudes. SSRs could be recorded in 15 out of the examined 26 upper extremities. The latencies were prolonged in 12 of these cases. In the lower limbs, 11 SSRs could be obtained. In 4 of these cases the latencies were prolonged. The SSR latencies recorded from the palms and soles were both significantly prolonged (p < 0.05) and the amplitudes were reduced (p < 0.05) as compared to normal persons. Our data strongly suggest involvement of the autonomic nervous system in syringomyelia as assessed by the SSR response (in upper and lower extremities). In our patients, the extent of autonomic dysfunction was not related to the stage or the duration of disease.

Adult↗
PubMedDate not supplied

Somatosensory evoked potentials after magnetic stimulation at different points of the body in normal subjects and in patients with syringomyelia.

Somatosensory evoked potentials (SEPs) were elicited by magnetic stimulation of the tibial nerve, gastrocnemic muscle and by stimulation over the spinous processes of lumbar vertebra 5 (L 5), thoracic vertebra 9 (Th 9) and cervical vertebra 7 (C 7). The first SEP-positivity (P1-latency) was measured in a group of 20 controls and in another group of 18 patients with syringomyelia. The P1-latencies of the latter group following the stimulations over Th 9 and C 7 were significantly longer than those of the controls. Furthermore a correlation between electrophysiological findings and clinical data of the patients could be proven. Thus the method emerged as an appropriate tool for the investigation of the central part of the sensory system and for the diagnosis of spinal abnormalities.

Adult↗