["Headache World 2000". The most recent therapy strategies in headache].
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Biomedical subjects
Publications and source records attributed to A Straube.
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One of the suggested theories to explain some aspects of neglect in patients with right parietal lesions is the spatial distortion hypothesis. To determine whether a distorted representation of space can account for the performance of neglect patients in visuospatial tasks we asked 27 neglect patients to compare the width of two horizontally aligned bars. The bars were presented symmetric to the body midline or either on the left or right side of egocentric space. The size comparison data are in accordance with the hypothesis of a distorted egocentric representation based on a dynamic remapping of space. The results support the idea that the abnormalities observed in the size comparison tasks are due to a distorted internal representation of the outside world. There are some hints that this distortion could be based on a dynamic mapping of space determined by the distribution of visuospatial attention.
Infection or postinfectious phenomena have been postulated to play a role in the pathogenesis of children afflicted with the typical symptoms of Tourette's syndrome (TS). We investigated whether an increase of titers of antistreptococcal antibodies can be reproduced in our children with TS, and whether this increase is restricted to children. We examined the titers of two different antistreptococcal antibodies, antistreptolysin (ASL) and anitDNase B, both in children and adults. Titer s of ASO and antiDNase B were measured (1) in 13 children/adolescents suffering from TS and in an aged-matched comparison group;(2) in 23 adult patients, a comparison group of 23 aged-matched controls, and in another group of 17 aged-matched, non-medicated acute schizophrenics. ASO and antiDNase B titers were determined by laser nephelometry using a commercially available kit. Two antistreptococcal cut-off levels were compared (> 250 U/ml and 400 U/ml). As expected, increases ASO titers (>400 IU/ml) were found in a higher portion of children/adolescents with TS compared to controls. Regarding adults, titers >250 U/ml for both antistreptococcal antigens were found in significantly more TS patients than in schizophrenic patients or healthy control subjects. The mean values of ASO and antiDNase titers were significantly higher in both groups of TS patients compared to control children/adolescents, to the comparison groups of healthy adults and to schizophrenics. No difference in antistreptococcal titers was found between schizophrenics and the group of healthy adults. TS patients exhibited higher antistreptococcal titers than age-matched comparison groups of both children/adolescents and adults using different types of calculation. Our findings support the theory that a postinfectious immune mechanism may play a role in the pathogenesis of TS. The mechanism still needs to be elucidated.
Many automatic movements are open-loop, feed-forward motor programs (MP) that are kinematically well characterized by smooth speed and acceleration curves. However, it is unclear whether their internal representation consists of monolithic blocks or subroutines. This question was investigated using a learning paradigm of a writing task. Fifty-nine normal subjects were presented with two similar, but different new letters. Every subject practiced each letter in a series of 60 trials, with the order of letter series randomized. Every session was continuously recorded by a digitizing tablet. Using kinematic analysis, we measured the number of vertical acceleration peaks as an indication of the number of corrective movements (COM). Since COM declined as automatization was approached, we could quantitatively infer progress in motor learning under natural learning conditions. In the case of modular storage of MP, transfer in-between letters was expected due to the re-use of pre-learned motor subroutines. Statistical analysis showed that the exponential model described the data much better than the linear model (residual error: P<0.88 and P<0.00001, respectively), as expected for a learning paradigm. There was no difference between letters per se (P<0.77). Motor improvement differed significantly (P<0.02) between the first and the second series; there was a much greater reduction of COM in the second series (50.1 vs. 41.1%). This difference can be logically ascribed to transfer, indicating that automated movements are stored in motor subroutines.
In 1998 Minor et al. described a new variant of perilymphatic fistula: the "superior canal dehiscence syndrome". This syndrome is clinically characterized by recurrent attacks of vertigo and oscillopsia induced by loud noises or stimuli that result in changes in intracranial or middle ear pressure. It is caused by a dehiscence of bone overlying the superior (anterior) semicircular canal. Due to this dehiscence, a third, mobile window (in addition to the round and oval windows) is formed, and changes in pressure are pathologically transduced to the anterior semicircular canal. Although the superior canal dehiscence syndrome is not a rare condition, no other cases have yet been reported. Therefore, we describe a typical patient who suffered for many years from recurrent attacks of vertigo and oscillopsia induced by coughing and Valsalva's maneuvers. High resolution temporal bone CT scan showed a defect in the bone overlying the left anterior semicircular canal. Three-dimensional eye movement recordings using the search coil technique and subsequent vector analysis demonstrated that the eye movements were induced by excitation of the left anterior semicircular canal. We conclude that superior canal dehiscence syndrome is an important differential diagnosis in patients suffering from symptoms of a perilymphatic fistula, especially since it can be successfully treated by "plugging" of the affected semicircular canal. Such patients are thus spared unnecessary surgery of the middle ear.
Following organ transplantation, 30-60% of patients develop neurologic complications which can be classified as pre-existing deficits due to the underlying disease, complications during surgery, metabolic encephalopathies, neurotoxicity of immunosuppressant agents, opportunistic CNS infections, and secondary malignomas as indirect side effects of immunosuppression. While encephalopathies, seizures, or CNS infection can occur in all types of transplantation, some specific neurological complications exist for different types of organ transplantation. In this review, the clinical symptoms and treatment of both the common neurological complications as well as the particular neurological syndromes after liver, heart, and bone marrow transplantation are discussed.
We describe a 25-year-old male who developed, in the course of an acute exacerbation of his multiple sclerosis, cluster headache-like attacks which responded to oxygen therapy. Magnetic resonance imaging revealed a lesion in the area of the ipsilateral pontomedullary trigeminal nuclei. This symptomatic case and other published cases are most probably explained by an activation of the trigeminovascular system as it is assumed for primary headache syndromes.
The way in which saccadic eye movements are elicited influences their latency and accuracy. Accordingly, different tasks elicit different types of saccades. Using the tasks steps, gap, memory, scanning and antisaccade, we analyzed combined eye and hand movements to determine whether both motor systems share control strategies. Errors and latencies were measured to examine whether changes in eye motor behavior are reflected in hand motor behavior. Directional and variable errors of eye and hand changed differently according to the tasks. Moreover, errors of the two systems did not correlate for any of the tasks investigated. Contrary to errors, mean latencies of eye movements were organized in the same pattern as hand movements. A correlation of latencies indicates that both motor systems rely on common information to initiate movement. Temporal coupling was stronger for intentional tasks than for reflexive tasks.
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Three experiments were performed to determine how an error signal for driving saccadic adaptation is derived from visual information processing. The first experiment demonstrated that an intrasaccadic displacement of a visual background does not influence saccadic adaptation when a small foveal target is used. The second experiment showed that when a different type of target, a 4.8 deg annulus, is used an intrasaccadic background shift influences the adaptive process. The third experiment showed that the size of the saccade target determines the size of the attention focus around the time of a saccade. These findings suggest that the attention focus selects the visual information used for a trans-saccadic comparison in order to generate the error signal.
We studied the excitability of the motor cortex using transcranial magnetic stimulation (TMS) in 12 patients with migraine with aura (MA) and nine patients with familial hemiplegic migraine (FHM). Motor thresholds at rest, the duration of the cortical and peripheral silent period and intracortical inhibition and facilitation using paired-pulse TMS at intervals of 2 to 15 ms were measured with patients free of attacks for at least 48 h. In contrast to previous reports we could not find any significant differences between patient groups and compared to controls (n=17) in the parameters tested. The results suggest that there are no interictal changes of excitability of the motor cortex in migraine. This study does not support the concept of general cortical hyperexcitability in migraine secondary to a genetic predisposition or a structural alteration of inhibitory interneurones in the cortex due to repeated parenchymal insults during attacks.
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A shift of the visual attention focus is known to precede saccades. However, how the metrics of both this presaccadic attention shift and the saccade are coupled is still unclear. We altered the saccade size by short-term saccadic adaptation to determine whether the attention focus would still be shifted to the location of the saccade target or to the modified postsaccadic eye position. The results showed that saccadic adaptation had no influence on the presaccadic attention shift. Thus either different processes determine the metrics of the attention shift and of the saccade or saccadic adaptation causes only modifications on a lower hierarchical level of saccade programming, thereby not influencing the metrics of the attention shift.
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The gain of visually triggered saccades depends on orbital position. Centrifugal saccades have smaller gains and are slower than centripetal saccades elicited by the same target amplitude. We determined whether internally triggered saccades, e.g. scanning or memory saccades, exhibit the orbital position dependency evident in visually guided saccades. The search coil technique was used to record eye movements of healthy subjects while they performed horizontal 12.5 degree saccades under three paradigms (gap, scanning and memory saccades). Orbital position influenced externally triggered gap saccades but not the gain or peak eye velocity of scanning or memory saccades. These findings do not support the idea that position dependency caused by orbital mechanics is compensated for at the level of the common brainstem burst generator. Instead our results are consistent with the view that cortical output reflects the differences evident in the gain of visually triggered centrifugal and centripetal saccades.
Our objective was to investigate how cooling of the arm and vision influence pointing movements in healthy subjects and patients with cerebellar limb ataxia due to clinically proven multiple sclerosis. An infrared video motion analysis system was used to record the unrestricted, horizontal pointing movements toward a target under three different conditions involving a moving, stationary, or imaginary target; a visual, or acoustic trigger; and vision or memory guidance. All three tasks were performed before and after cooling the arm in ice water. Patients had more hypermetric and slower pointing movements than controls under all tested conditions. Patients also had significantly larger three-dimensional finger sway paths during the postural phase and larger movement angles of the wrist joint. Memory-guided movements were the most hypermetric recorded in both groups. Cooling of the limb had no effect on amplitude or peak velocity of the pointing movement in either group under all tested conditions, but significantly reduced the three-dimensional finger sway path during the postural phase in patients with limb ataxia. Cooling-induced reduction of the finger sway was largest in those patients with the largest finger sway before cooling. In conclusion, the cooling-induced reduction of the proprioceptive afferent inflow, most probably of group I spindle afferents, reduces postural tremor of patients with cerebellar dysfunction.
Rare headache syndromes that are so fare not yet admitted to the classification system of the International Headache Society are the SUNCT syndrome (short-lasting, unilateral, neuralgiform headache attacks with conjunctival injection and tearing), the hemicrania continua and the red ear syndrome. The clinical characteristics, differential diagnoses and therapeutic strategies of these pathophysiologically unclarified diseases are presented with three casuistic reports.
This study investigates how visually guided saccades and subsequent corrective saccades are affected by a secondary target step occurring at different times during the primary saccade. Eye movements of human subjects were measured by means of a differential infrared light reflection technique while the subjects performed visually guided saccades to a laser spot in darkness. The target was stepped backward or onward during the targeting saccade. While the intrasaccadic target step did not influence gain, peak velocity or skewness of the primary saccade, it had a significant effect on the subsequent corrective saccade when the secondary target step occurred during the deceleration phase of the primary saccade: the latency of the corrective saccade was significantly increased compared with the one performed under the single-step control condition. This increase also occurred when single target steps were presented randomly intermixed with backward and onward double target steps and even between selected sub-samples of saccades with identical postsaccadic visual error. If the target step occurred early during the primary saccade, the latency of the corrective saccade was not changed. This indicates that visual information sampled during the deceleration phase of a saccade can lead to a cancellation of the normal trigger mode of corrective saccades.