Karsten Papke

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(NL − NR)/(NL + NR), where NL and NR 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.

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 contanct 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.

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

Abstract. 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 × 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.

Diagnostic performance of a flat-panel detector at low tube voltage in chest radiography: a phantom study.

Rationale and Objectives:To evaluate a large area, cesium iodide amorphous silicon flat-panel detector (CsI/a-Si) at 3 tube voltages to detect simulated interstitial lung disease, nodules, and catheters. Methods:Simulated interstitial lung disease, nodules, and catheters were superimposed over a chest phantom. Images were generated at 125 kVp, 90 kVp, and 70 kVp at the same surface dose and reduced effective dose equivalent for 90 kVp and 70 kVp and printed on hard copies. Fifty-four thousand observations were analyzed by receiver operating characteristic (ROC). Results:Detectability of linear, miliary, reticular pattern, and nodules over lucent lung as well as of catheters and nodules over obscured chest areas increased at 90 and/or 70 kVp with higher Az values; however, only it was statistically significant for reticular pattern at 70 kVp and nodules at 90 kVp compared with 125 kVp (P <0.05). The detection of ground-glass pattern was worse at lower kVp (P >0.05). Conclusion:For most simulated patterns, differences in diagnostic performance at 70 kVp/90 kVp and 125 kVp were not significant, except for reticular pattern and nodules over lucent lung.

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.

Masive thymic enlargement associated with myasthenia gravis and hyperthyroidism

Referring to: Ichiki S, Komatsu C, Ogata H, Mitsudome A. A case of myasthenia gravis complicated with hyperthyroidism and thymic enlargement in childhood. Brain Dev (Tokyo) 1992; 14: 164-6. We read with great interest the report of Ichiki et al. [1] on hyperthyroidism (HT) and thymic hyperplasia (TH) complicating myasthenia gravis (MG) in a 13year-old girl. Ichiki et al. [1] gave the first report on the coexistence of these pathological conditions in a child and state that this coexistence has also been rarely described in adults. Thymectomy caused considerable improvement of MG in their patient. We have observed a male adult patient with the same coexistence of HT, MG and TH. Aged 28, he experienced diplopia and complained of increased sweating and restlessness. Diplopia subsided spontaneously but recurred two years later. Double vision was provoked by repetitive eye movements, the tensilon test was positive. Serum anti-acethylcholine receptor antibody (AChR-Ab) was increased (1.17 nmol/1). Furthermore, there was mild HT: T4 and T3 were 11.8 /~g/dl and 2.9 ng/ml, T4/TBG was 9.2. Thoracic CT showed thymic enlargement. The patient underwent thymectomy. Histological investigation of the thymus (240 g) revealed true TH, which is a very rare condition [2,3]; true TH is characterized by an increase in size and weight with a normal age-related microscopic appearance and has never been reported in association with MG. After surgery, the patients condition improved immediately. During a 3-year follow-up period, no drug therapy of MG has been necessary. HT did not increase. Our case supports the positive estimation of Ichiki et al. [1] concerning the therapeutic effect of thymectomy even if HT is complicating MG. For a more detailed comparison between the two cases, we would be interested in the total weight of the enlarged thymus in Ichiki et al. [1]. Furthermore, we would suggest further immuno-histological studies on the resected organ to detect whether also this case may have been a true TH. This might shed new light on a possible relationship between TH, MG and HT.