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Biomedical subjects

A Straube

Publications and source records attributed to A Straube.

At least 109 records · Page 6Linked to original sources
PubMed1997

Characteristics of obsessive-compulsive symptoms in Tourette's syndrome, obsessive-compulsive disorder, and Parkinson's disease.

A high incidence of obsessions and compulsions is documented in basal ganglia disorders, especially in patients with Tourette's syndrome (TS). A comparison of patients with obsessive-compulsive disorder (OCD), TS, and Parkinson's disease (PD) revealed significantly higher total scores in both OCD and TS patients than in a healthy control group on the Maudsley obsessive-compulsive inventory (MOCI) and the Hamburg obsessive-compulsive inventory (HZI-K), two self-report measures of obsessive-compulsive symptoms. On most subscales (especially Checking, Ordering, and Counting/touching), TS patients scored higher than controls. Patients with Parkinson's disease merely scored higher on the subscale 'Ordering' of the HZI-K. Differences between OCD patients and TS patients were evident on the MOCI subscales 'Checking' and 'Slowness/Repetition' as well as on the MOCI total score and on the HZI subscales 'Cleaning' and 'Obsessive Thoughts'. On these scales, TS patients reported fewer symptoms than OCD patients. Stepwise discriminant analysis with preselected single items as variables was used to look for specific symptom patterns of OCD and TS. Seventy-eight percent of the patients could be correctly classified with respect to their diagnoses on the basis of only two items of the HZI-K. One item asks for fearful obsessive thoughts, which was found in 90% of the OCD patients; the second item represented echo phenomena, found in 56% of the TS patients. It is concluded that considering specific patterns of obsessive-compulsive psychopathology may contribute to a more reliable differential diagnosis in OCD and TS and help to avoid misdiagnosis of OCD in TS patients.

Adult↗
PubMed1997

Single-fiber electromyography, nerve conduction studies, and conventional electromyography in patients with critical-illness polyneuropathy: evidence for a lesion of terminal motor axons.

Nine patients at risk for critical illness polyneuropathy (CIP) were included in a prospective study. We performed nerve conduction studies, electromyography, and a stimulation single-fiber electromyography (SFEMG). Five of 9 patients were diagnosed as CIP because they developed abnormal spontaneous activity during the follow-up period. Their SFEMG revealed a significant increase in mean jitter (25%, P < 0.005). In 4 patients without abnormal spontaneous activity there was no significant increase in the mean jitter, although 1 of the latter 4 patients showed an increased jitter, indicating that abnormal SFEMG may precede abnormal spontaneous activity. Nerve conduction studies did not show any significant changes in both patient groups. Our findings suggest that CIP is a primarily axonal motor neuropathy. The increased jitter in patients with CIP indicates that CIP is a primarily axonal neuropathy with a lesion of terminal motor axons.

Adult↗
PubMed1997

Electromyography of the external anal sphincter in patients with Parkinson's disease and multiple system atrophy: frequency of abnormal spontaneous activity and polyphasic motor unit potentials.

Electromyographic studies of the external anal sphincter muscle have received increasing attention in the differential diagnosis of patients with parkinsonism. Based on the fact that the external anal sphincter muscle is partly innervated by fibers that originate in Onuf's nucleus in the segments S2-S4 of the spinal cord, an increased duration of the motor unit potentials (MUPs) and an increased polyphasia may reflect neuronal loss of these lower motor neurons characteristic for multiple system atrophy. We report the results of anal sphincter electromyography in 15 patients with clinically probable multiple system atrophy (MSA) and 10 patients with Parkinson's disease (PD). There was no significant difference between patients with MSA and patients with PD concerning the duration of MUPs, mean number of phases, and rate of polyphasic motor potentials. There was a tendency for a longer mean duration and increased polyphasia in patients with MSA compared to patients with PD. Spontaneous activity was recorded in 11 of 15 patients with MSA occurring especially in patients with MSA of the striatonigral type, but not in patients with PD. In this study, the duration of MUPs and the rate of polyphasia were unreliable criteria in the electrophysiological differential diagnosis of patients with parkinsonism. Abnormal spontaneous activity, although difficult to detect, is a more specific marker for neuronal degeneration of Onuf's nucleus occurring in patients with MSA.

Adult↗
PubMed1997

Unilateral cerebellar lesions affect initiation of ipsilateral smooth pursuit eye movements in humans.

To clarify the role of the cerebellum in pursuit initiation (first 100 msec), we used infrared oculography to examine the effect of unilateral cerebellar lesions on the initial (0-20 msec) and later (80-100 msec) periods as well as the steady-state response (200-300 msec) of horizontal smooth pursuit in 10 patients with unilateral cerebellar lesions. These results were compared with those of 17 age-matched healthy subjects. Smooth pursuit was elicited with a step-ramp target movement with randomized horizontal directions and velocities of 10 degrees/sec and 30 degrees/sec. In the first 20-msec pursuit, velocity was 22% lower toward the side of the cerebellar lesion than away from it and 16% lower in the period 80 to 100 msec (normal differences, 2% and 3%). Later (200-300 msec), the ipsiversive/contraversive difference was smaller, but pursuit velocity in both directions was significantly lower in patients than in normals. No lesion affected the floccular region and/or the nodulus/uvula. Five lesions extended so far medially that they could have affected the medial deep cerebellar nucleus (fastigial nucleus). The remaining five were in the lateral hemisphere in areas previously considered uninvolved in pursuit generation. Our findings prove that the cerebellum participates in human pursuit initiation and that lesions in the lateral cerebellum possibly affect smooth pursuit.

Adolescent↗
PubMed1997

Saccades in Gilles de la Tourette's syndrome.

Gilles de la Tourette's syndrome (GTS) is presumed to be an inherited disorder with an unclear pathophysiology. An involvement of the basal ganglia is suspected. Besides vocal tics, one of the main symptoms is the presence of motor tics. As eye movements are a specialized part of the motor system, we investigated whether they differed in some typical way in GTS patients. To study the control of saccades in GTS, different paradigms were used to elicit saccades, which were either externally triggered and visually guided or internally triggered and without visual target. GTS patients (n = 10) showed a significant increase of the latency of antisaccades, a highly impaired performance of sequences of memory-guided saccades, and an isolated reduction of the peak velocity in the antisaccades. Overall the results were similar to those found with similar paradigms in patients with Huntington's disease (HD). In analogy to the known pathology of HD, these findings can be attributed to ascending loops from the basal ganglia that inappropriately activate the frontal cortex, especially some of the eye movement-related areas there. This impairment seems to be a rather specific effect, since some oculomotor features that are preserved by structures of the frontal cortex, such as the effect of a fixation target on saccadic latency ("gap effect"), were normal.

Adolescent↗
PubMed1997

Drug therapy for acquired pendular nystagmus in multiple sclerosis.

Acquired pendular nystagmus (APN) is regularly accompanied by oscillopsia and impairment of static visual acuity. Therapeutic approaches to APN remain controversial, and there is no generally accepted therapeutic approach. We tested 14 patients who had suffered from APN caused by multiple sclerosis for several years; 12 patients presented with fixational pendular nystagmus (increasing during fixation) and 2 with spontaneous pendular nystagmus. All 11 patients with fixational pendular nystagmus who were given memantine, a glutamate antagonist, experienced complete cessation of the nystagmus. In contrast, scopolamine caused no (6 of 8) or only a minor (10-50%) reduction of the nystagmus (2 of 8). It was concluded that memantine is a safe treatment option for APN.

Adult↗
PubMed1997

[An unusual combination of carotid artery-cavernous sinus fistula and sinus thrombosis. Successful therapy with anticoagulation].

Dural carotid cavernous fistulas (DCCF) can be associated with venous thrombosis. We report on a rare case of a patient who developed a venous infarct, which was diagnosed on CT and MRI. The DCCF predominantly drained through a frontobasal cortical vein into the superior sagittal sinus. The shunt volume was small and was therefore thought not to be sufficient to explain the massive ocular signs, such as severe exophthalmus and reduction of visual acuity. We therefore postulated a venous congestion owing to a secondary spontaneous venous thrombosis of the draining venous pathways to be responsible for the ocular signs. Under anticoagulative medication, the patient's signs and symptoms improved gradually. Control angiography after 3 months showed that the DCCF had disappeared. In the presence of DCCF, anticoagulation should always be considered when a venous thrombosis is suspected.

Arteriovenous Fistula↗
PubMed1997

[Opsoclonus and ocular flutter].

Ocular flutter is an ocular motor disorder consisting of involuntary back-to-back saccades in the horizontal plane without a saccadic interval. In opsoclonus, these pathological eye movements occur not only in the horizontal but also in the vertical plane. Originally, opsoclonus was described as irregular, conjugate, chaotic and partially continuous rapid eye movements. In this review, the clinical picture, differential diagnosis, etiology, natural course and therapeutic concepts for these eye movement disorders are described. It is stressed that continuous and intermittent forms of opsoclonus can be distinguished and that these differences usually correlate with the severity of the underlying disease. In contrast, the intermittent forms of opsoclonus and ocular flutter are usually only distinguished by the lack of a vertical eye movement component in ocular flutter.

Adult↗
PubMed1997

[Bleeding atheroma. A nuclear magnetic resonance tomography differential diagnosis of dissection of the carotid artery].

Improved methods of imaging the cerebral vascular system have increased the detection of traumatic or spontaneous dissection of the vertebral and carotid arteries. Especially MRI allows direct demonstration of intramural hematomas that are a sign of dissection of the vessel wall. We report on a patient who had an acute onset of dysarthria and monocular blurred vision, which recurred several times. Doppler ultrasound showed stenosis in both internal carotid arteries with reduced velocity of the flow; angiography confirmed the stenosis, showing a long stretch of stenosis (70%) of the right and a short stretch of stenosis (60%) of the left internal carotid arteries. MRI demonstrated a narrowing of the lumen by an intramural mass, whose signal characteristics were typical for blood. The MRI findings were thus consistent with the diagnosis of a spontaneous dissection of the carotid arteries. Since the Doppler ultrasound follow-up showed no change during the following 3 days, we interpreted the MRI findings as an indication of bleeding in an atheroma. The carotid disobliteration, performed first on the left side and later on the right side, confirmed this interpretation. Since stenosis due to a fissuring atheroma or bleeding in an atheroma requires different therapy than a dissection, it is thus important to consider the possible differential diagnosis in interpreting the MRI.

Arteriosclerosis↗
PubMed1997

Periodic limb movements during sleep are a frequent finding in patients with Gilles de la Tourette's syndrome.

Gilles de la Tourette's syndrome (GTS) and restless legs syndrome (RLS) are two different neurological disorders with common features such as involuntary movements. In both disorders a disturbance of the dopaminergic system has been considered among other possible mechanisms. Since periodic leg movements (PLMS) during sleep are the predominant objective finding in RLS, the aim of this study was to investigate sleep parameters in GTS patients with particular emphasis on PLMS. Seven drug-free patients with GTS and seven age- and sex-matched healthy controls were studied polysomnographically, including superficial electromyogram (EMG) leads on all four extremities. A high number of PLMS were found in five of seven, and periodic arm movements in four of seven GTS patients. Total sleep time was significantly lower (P < 0.05) in the GTS patients than in the controls, which confirms earlier findings. The presence of PLMS in GTS might point towards evidence for a pathophysiological relationship between GTS and RLS, which, however, is not supported by the different responses to pharmacological treatments.

Adolescent↗
PubMed1997

Inverse dynamics as a tool for motion analysis: arm tracking movements in cerebellar patients.

Kinematic analysis of limb movements can be used to evaluate motion of patients with movement disorders. Those with clinically mild to moderate impairment, however, often show only small, insignificant deviations in the measured trajectories compared to those of healthy controls. Furthermore, kinematic data alone do not give sufficient information about internal quantities such as muscle activation or joint moments. In order to improve the sensitivity of motion analysis of limb movements, we propose the use of inverse dynamics, since it allows biomechanical quantities to be determined without restricting movement. We developed an inverse dynamic model of the upper limb with 9 degrees of freedom. Spatial positions (Cartesian coordinates) of anatomical landmarks, which were recorded by an infrared video-based three-dimensional motion analysis system, are transformed into body-related Cardan angles. The model determines joint moments and powers at the shoulder, elbow, and wrist. Arm tracking movements in a patient with a mild cerebellar ataxia and a healthy control demonstrate that the model allows a clear differentiation between normal and abnormal limb movements, even if no significant differences are noted in the recorded trajectories. We conlude that inverse dynamic modeling can be an effective tool for motion analysis in patients with cerebellar disorders. It also gives further insight into the parameters that may be controlled by the central nervous system.

Arm↗
PubMed1997

Visually induced motion perception and visual control of postural sway in congenital nystagmus.

In congenital nystagmus (CN) the threshold for detecting motion of visual objects is increased. To determine whether this increase is due to a deterioration of visual motion signals or whether visual-vestibular interactions (which are necessary to judge object-motion in space) are also involved we examined how CN patients use visual motion signals to evaluate self-motion in perceptual and behavioral tasks. Using an optokinetic drum we measured the minimum optokinetic acceleration necessary to induced motion perception of the visual environment in CN patients. This threshold was significantly elevated in the CN patients compared with normals (20.1 deg/s2 to 3.25 deg/s2). We further addressed the question whether the elevation of this threshold is due to a deficiency in evaluating visual motion in general or to a specific modification affecting the percept of visual object-motion with respect to the inertial reference only. We thus measured the latency of visually induced self-motion perception, which was found to be very similar or even slightly smaller (1.7 +/- 0.7 s) compared with normals (2.2 +/- 1.7 s). Moreover, subjects with CN were found to use vision quite efficiently for the visual stabilization of posture (Romberg quotient 2.0 +/- 1.16), even if they did not reach the level of normals (Romberg quotient 3.7 +/- 1.1). The results indicate that CN affects the estimate of object-motion in a specific and much more severe way than the estimate of self-motion. The minimal effect of CN on self-motion perception can be explained by the low pass characteristics of the optokinetic input to self-motion perception. The specific deficiency in detecting object-motion indicates that adaptation to CN occurs on the level of visual--vestibular interactions for the perception of visual object-motion and not on the level of visual motion signals.

Adolescent↗
PubMed1997

Cholinergic sprouting in the rat fascia dentata after entorhinal lesion is not linked to early changes in neurotrophin messenger RNA expression.

After unilateral entorhinal cortex lesion cholinergic septohippocampal fibres sprout in the denervated fascia dentata. This process is dependent on neurotrophin changes following the lesion. Thus, there is an up-regulation of nerve growth factor and brain-derived neurotrophic factor messenger RNA expression in the denervated granule cells which is detectable 4 h postlesion and returns to control levels by 24 h. Here, using a competitive polymerase chain reaction and in situ hybridization, a transient neurotropin messenger RNA increase could be demonstrated bilaterally following unilateral electrolytic entorhinal cortex lesion. Treatment of the animals with the N-methyl-D-aspartate receptor antagonist dizocilpine maleate blocked this messenger RNA increase, suggesting an involvement of this receptor type in the neurotrophin changes. However, in spite of this blockade, the typical cholinergic sprouting response as visualized with acetylcholinesterase histochemistry was present in animals four weeks after entorhinal cortex lesion. These data suggest that brief initial changes in neurotrophin messenger RNA expression in dentate granule cells are not responsible for the induction of the cholinergic sprouting. Changes in neurotrophin messenger RNA expression occurring immediately postlesion may be linked to glutamate release from entorhinal terminals resulting from the electrolytic lesion of the projection cells in the entorhinal cortex. We hypothesize that later changes in neurotrophin expression, for example in glial cells, are more likely to be related to the cholinergic sprouting process.

Acetylcholinesterase↗
PubMed1997

A CPH-like picture in two patients with an orbitocavernous sinus syndrome.

Two patients with retroorbital pain syndromes with or without paresis of cranial nerves developed weeks after ipsilateral headache resembling chronic paroxysmal hemicrania (CPH) but without autonomic features. These findings might support the hypothesis that CPH may be caused by a pathological process in the region of the cavernous sinus, as has been proposed for the Tolosa-Hunt syndrome (THS).

Adult↗
PubMed1997

Recovery of ChAT immunoreactivity in axotomized rat cholinergic septal neurons despite reduced NGF receptor expression.

Previous studies have suggested that target-derived nerve growth factor (NGF) is essential for the survival of cholinergic basal forebrain neurons. Thus, axotomy of septohippocampal neurons in adult rats resulting in the withdrawal of target-derived NGF caused a dramatic loss of choline acetyltransferase (ChAT)-immunoreactive neurons in the medial septum-diagonal band complex. We have recently shown that this loss of immunolabelled neurons does not indicate cell death, since many septohippocampal cholinergic neurons recover their immunoreactivity for ChAT after a long survival time despite disconnection from target-derived neurotrophins. One possibility would be that these surviving ChAT-immunoreactive neurons have gained access to other, probably local, NGF sources. Here we provide evidence that the recovery of ChAT immunoreactivity after axotomy is not accompanied by a similar recovery of NGF receptor expression in these neurons. In situ hybridization for p75NTR mRNA and trkA mRNA 6 months after bilateral fimbria-fornix transection revealed a substantial loss of labelled cells. In addition, there was a persisting loss of p75NTR-immunoreactive and NGF-immunoreactive medial septal neurons. Cholinergic neurons in controls did not express NGF mRNA, but were heavily immunostained for NGF protein due to receptor-mediated uptake. These data suggest that at least some cholinergic septohippocampal neurons re-express ChAT either independently of NGF or with a reduced need for NGF.

Animals↗
PubMed1997

Characteristics of saccadic gain adaptation in rhesus macaques.

We adapted the saccadic gain (saccadic amplitude/target step amplitude) by requiring monkeys to track a small spot that stepped to one side by 5, 10, or 15 degrees and then, during the initial targeting saccade, jumped either forward or backward by a fixed percentage of the initial step. Saccadic gain increased or decreased, respectively, as a function of the number of adapting saccades made in that direction. The relation between gain and the number of adapting saccades was fit with an exponential function, yielding an asymptotic gain and a rate constant (the number of saccades to achieve 63% of the total change in gain). Backward intrasaccadic target jumps of 15, 30, and 50% of the initial target step reduced the asymptotic gain by an average of 12.2, 23.1, and 36.4%, respectively, with average rate constants of 163, 368, and 827 saccades, respectively. During 50% backward jumps, some saccades, especially those to larger target steps, became slower and lasted longer. Forward intrasaccadic jumps of 30% increased the asymptotic gain by 23.3% (average rate constant of 1,178 saccades). After we had caused adaptation, we induced recovery of gain toward normal by requiring the animal to track target steps without intrasaccadic jumps. Recovery following forward adaptation required about one third fewer saccades than the preceding gain increase. Recovery following backward adaptation required about the same average number of saccades as the preceding gain decrease. The first saccades of recovery were slightly less adapted than the last saccades of adaptation, suggesting that a small part of adaptation might have been strategic. After 50% backward jumps had reduced saccadic gain, the hypometric primary saccades during recovery were followed by hypometric corrective saccades, suggesting that they too had been adapted. When saccades of only one size underwent gain reduction, saccades to target steps of other amplitudes showed much less adaptation. Also, saccades in the direction opposite to that adapted were not adapted. Gain reductions endured if an adapted animal was placed in complete darkness for 20 h. These data indicate that saccadic gain adaptation is relatively specific to the adapted step and does not produce parametric changes of all saccades. Furthermore, adaptation is not a strategy, but involves enduring neuronal reorganization in the brain. We suggest that this paradigm engages mechanisms that determine saccadic gain in real life and therefore offers a reversible means to study their neuronal substrate.

Adaptation, Physiological↗
PubMed1997

Participation of caudal fastigial nucleus in smooth pursuit eye movements. II. Effects of muscimol inactivation.

We studied the effect of temporarily inactivating the caudal fastigial nucleus (CFN) in three rhesus macaques trained to make smooth pursuit eye movements. We injected the gamma-aminobutyric acid A agonist muscimol into one or both CFNs where we had recorded pursuit-related neurons a few minutes earlier. Inactivating the CFN on one side impaired pursuit in one monkey so severely that it could not follow step-ramp targets moving at 20 degrees/s, the target velocity that we used to test the other two monkeys. We tested this monkey with targets moving at 10 degrees/s. In all three monkeys, unilateral CFN inactivation either increased the acceleration of ipsilateral step-ramp pursuit (in 2 monkeys, to 144 and 220% of normal) or decreased the acceleration of contralateral pursuit (in 1 monkey, to 71% of normal). Muscimol injected into both CFNs in two of the monkeys left both ipsilateral and contralateral acceleration nearly normal in both monkeys (101% of normal). Unilateral CFN inactivation also impaired the velocity of maintained pursuit as the monkeys tracked a target moving at a constant velocity or oscillating sinusoidally. Averaged across both types of movements in all three monkeys, gains for ipsilateral, contralateral, upward, and downward pursuit were 94, 67, 84, and 73% of normal, respectively. Unilateral CFN inactivation also impaired the monkeys' ability to suppress their vestibuloocular reflex (VOR). Averaged across the two monkeys VOR gain during suppression increased from 0.06 to 0.25 during yaw rotation and from 0.21 to 0.59 during pitch rotation. Bilateral CFN inactivation reduced pursuit gains in all directions more than unilateral injection did. In the two monkeys tested, ipsilateral, contralateral, upward, and downward gains went from 94, 86, 85, and 74% of normal, respectively, after we inactivated one CFN to 88, 73, 80, and 64% of normal after we also inactivated the second CFN. We can explain many, but not all, of the effects of CFN activation on smooth pursuit with the behavior of CFN neurons, and the assumption that the activity of each CFN neuron helps drive pursuit movements in the direction that best activates that neuron. We conclude that the CFN, like the flocculus-ventral paraflocculus, is a cerebellar region involved in control of smooth pursuit.

Animals↗