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T Brandt

Publications and source records attributed to T Brandt.

At least 37 records · Page 2Linked to original sources
PubMed2004

Diagnosis of vestibular imbalance in the blink of an eye.

BACKGROUND: In a recent study, the authors found that blinks in healthy volunteers always triggered ocular torsion quick phases during dynamic roll movements of the head. On the basis of this observation, they hypothesized that blinks in patients with a vestibular tone imbalance would also trigger torsional quick phases. METHODS: Using video-oculography with a fixation target, the authors recorded the ocular torsion position of the left eye of 37 participants while they made voluntary blinks once every 6 to 10 seconds. The participants were recruited from four groups: two age groups of healthy volunteers with a mean +/- SD age of 32 +/- 4 (n = 9) and 65 +/- 11 y (n = 9); patients with a unilateral vestibular disorder in an acute state (n = 12, 53 +/- 17 y); and those in a persisting state in which spontaneous nystagmus had already faded (n = 9, 65 +/- 13 y). RESULTS: In the control groups of healthy volunteers, blinks triggered no or only small quick phases on the order of 0.1 deg. In both patient groups blinks always triggered quick phases with significantly higher amplitudes of 1.85 +/- 1.02 deg and were followed by exponentially decaying slow-phases with time constants on the order of 1 to 2 seconds. Patients in the persisting state clearly differed from patients in the acute state in that their torsional spontaneous nystagmus had already vanished due to vestibular compensation. But surprisingly, these two groups did not show a large difference in terms of the effect of blinks on ocular torsion. The authors always observed torsional quick phases with the upper pole of the eye beating away from the side of the lesion. CONCLUSIONS: Blinks are able to trigger torsional quick phases in patients with both acute and persisting vestibular disorders. The side of the impairment can be determined from the direction in which the eye is rotated after a blink. Thus, ocular torsion recordings during blinks can be used as a simple clinical test for a vestibular tone imbalance, particularly during a persisting failure in which spontaneous nystagmus has resolved and can therefore no longer be used for diagnosis.

Adult↗
PubMed2004

[Chief symptom giddiness].

Vertigo follows headache as the second most common key symptom--not only in neurology and ENT medicine. Careful history-taking and a physical examination are sufficient for a correct diagnostic classification of most vertigo syndromes. In most cases, the etiology is benign, the course favorable, and treatment successful. In this brief overview, the clinical presentation and treatment of the most common peripheral and central vertigo syndromes are described, and the characteristics and treatment of the--to date too rarely diagnosed--subjective vertigo are described.

Diagnosis, Differential↗
PubMed2004

Treatment of episodic ataxia type 2 with the potassium channel blocker 4-aminopyridine.

Patients with episodic ataxia type 2 (EA2) can often be successfully treated with acetazolamide. The authors report three patients with EA2 (two with proven mutations in the CACNA1A gene) whose attacks were prevented with the potassium channel blocker 4-aminopyridine (4-AP; 5 mg tid). Attacks recurred after treatment was stopped; subsequent treatment alleviated the symptoms (mean follow-up time 6 months). These effects might be due to an improvement of the impaired functioning of Purkinje cells.

4-Aminopyridine↗
PubMed2004

Alpha-1-antitrypsin deficiency alleles are not associated with cervical artery dissections.

The authors searched for the presence of alpha-1-antitrypsin (AAT) deficiency alleles PiZ and PiS in 74 patients with spontaneous cervical artery dissections (sCADs) and in 74 healthy control subjects. In both groups, the authors found four carriers of deficiency alleles. The connective tissue morphology of one additional patient with sCAD with PiZM genotype and her relatives was studied in skin biopsies. The PiZ allele did not segregate with morphologic alterations of the dermal connective tissue in the family. Therefore, AAT deficiency alleles may not play a role in the etiology of sCAD.

Adult↗
PubMed2004

Vertical oscillopsia in bilateral superior canal dehiscence syndrome.

A patient sought treatment for vertical oscillopsia and impaired vision during locomotion, and unsteadiness of gait. Positive fistula tests and CT of the temporal bones confirmed a diagnosis of bilateral superior canal dehiscence. An impairment of the superior canal vestibulo-ocular reflex, documented by three-dimensional search coil eye movement recordings for oblique (single) and downward pitch head motion (bilateral canal testing), is proposed to induce vertical rather than torsional-vertical oscillopsia during locomotion.

Female↗
PubMed2004

[Paraplegic cycling using functional electrical stimulation. Experimental and model-based study of power output].

Cycling using functional electrical stimulation offers paraplegics the possibility of muscle and cardiovascular training as well as the chance for independent locomotion. To investigate whether this method might be suitable for a large group of paraplegics, the first German feasibility study of functional electrical stimulation (FES) cycling with seven paraplegic patients was started at the beginning of 2003. Even at the beginning of the study, and without training, these patients were able to drive distances of 0.5-1.6 km. To stimulate cardiovascular adaptation processes in the case of FES ergometer training or to cover useful distances in the case of FES cycling, a minimum amount of generated mechanical output power is required, which as a rule cannot be achieved yet. In this study, we point out two particular aspects of FES cycling, which impair power output: prolonged fatigue mode and viscous joint friction of the paraplegic FES cyclist. We discuss current possibilities for increasing output power and endurance.

Adult↗
PubMed2004

A method to create reference maps for evaluation of ultrasound images of carotid atherosclerotic plaque.

Ten formalin-fixed atherosclerotic carotid plaques removed by endarterectomy were molded into rectangular agar blocks containing fiducial markers on the top surface. Plaque and fiducial markers were imaged with 3-D multiangle ultrasound (US) spatial compounding as well as planar X ray. Subsequently, the blocks were decalcified, sliced, photographed and analyzed histologically. This gave a total of 123 slices. The plaque regions of the photographs were outlined and the outline adjusted to partly compensate for occasional displacement during slicing. Inside this outline, the material constitutions were found by incorporating the histologic information. From this set, slices with 1. too much tissue displacement due to cutting or 2. lack of identification of calcification as found by x ray, were removed. This resulted in 53 reference maps. The material types identified covered soft tissues, fibrous tissue, calcified tissue and unidentified tissues. The 53 reference maps can be used for direct automated quantitative comparison with US images.

Arteriosclerosis↗
PubMed2003

Treatment of downbeat nystagmus with 3,4-diaminopyridine: a placebo-controlled study.

BACKGROUND: Several drugs that primarily act on gamma-aminobutyrate or muscarinic receptors have been used to treat downbeat nystagmus (DBN) syndrome despite their having only moderate success and causing several side effects that limit their effectiveness. These drugs were tested under the assumption that DBN was caused by a disinhibition of a physiologic inhibitory cerebellar input on vestibular nuclei. OBJECTIVE: To evaluate the effects of a single dose of the potassium channel blocker 3,4-diaminopyridine (3,4-DAP), which is known to increase the excitability of Purkinje cells, on DBN in a prospective, placebo-controlled, double-blind study with a crossover design. METHODS: Seventeen patients with DBN due to cerebellar atrophy (5), infarction (3), Arnold-Chiari malformation (1), or unknown etiology (8) were included in the study (1 of 18 patients had to be excluded). Mean peak slow-phase velocity (PSPV) was measured before and 30 minutes after randomized ingestion of 20 mg of 3,4-DAP or placebo orally; at least 1 week later, the treatments were switched. RESULTS: 3,4-DAP reduced mean PSPV of DBN from 7.2 +/- 4.2 degrees /s (mean +/- SD) before treatment to 3.1 +/- 2.5 degrees/s 30 minutes after ingestion of the 3,4-DAP (p < 0.001, two-way analysis of variance). Placebo had no measurable effect. In 10 of 17 subjects, the mean PSPV decreased by >50% and in 12 of 17 by >40%. In parallel, the subjects had less oscillopsia and felt more stable while standing and walking. Nine of the subjects continued to take the drug with success. Except for transient minor perioral or digital paresthesia reported by three subjects and nausea and headache reported by one, no other side effects were observed. CONCLUSIONS: In this study, the authors demonstrated that a single dose of 3,4-DAP significantly improved DBN. In view of animal studies reporting that micromolar concentrations of 4-aminopyridine increased the excitability of Purkinje cells, it is suggested that the efficacy of 3,4-DAP may be due to an increase of the physiologic inhibitory influence of the vestibulocerebellum on the vestibular nuclei.

4-Aminopyridine↗
PubMed2003

[The most common form of dizziness in middle age: phobic postural vertigo].

Up to now, there have been only a few valid epidemiological investigations of dizziness or vertigo as key symptoms. According to an analysis of 4,214 patients examined between 1989 and 2002 in an outpatient dizziness unit, benign peripheral paroxysmal positional vertigo (BPPV) and phobic postural vertigo (PPV) constitute the two most frequent syndromes. In this study, the relative age and sex distribution of both disorders was analysed. In the age group from 20 to 50 years, PPV was comparatively the most frequent form of dizziness, with a share of 22% to 26%. When left untreated, PPV becomes chronic in most cases and leads to considerable impairments, also at work. However, when diagnosed correctly, it can be treated successfully in more than 70% of cases. Thus, it takes on considerable medical and socioeconomic significance and should be part of the diagnostic repertoire of every doctor.

Adult↗
PubMed2003

Dominance for vestibular cortical function in the non-dominant hemisphere.

The aim of this (15)O-labelled H(2)O bolus positron emission tomography (PET) study was to analyse the hemispheric dominance of the vestibular cortical system. Therefore, the differential effects of caloric vestibular stimulation (right or left ear irrigation with warm water at 44 degrees C) on cortical and subcortical activation were studied in 12 right-handed and 12 left-handed healthy volunteers. Caloric irrigation induces a direction-specific sensation of rotation and nystagmus. Significant regional cerebral blood flow increases were found in a network within both hemispheres, including the superior frontal gyrus/sulcus, the precentral gyrus and the inferior parietal lobule with the supramarginal gyrus. These areas correspond best to the cortical ocular motor centres, namely the prefrontal cortex, the frontal eye field and the parietal eye field, known to be involved in the processing of caloric nystagmus. Furthermore, distinct temporo-parietal activations could be separated in the posterior part of the insula with the adjacent superior temporal gyrus, the inferior parietal lobule and precuneus. These areas fit best to the human homologues of multisensory vestibular cortex areas identified in the monkey and correspond to the parieto-insular vestibular cortex (PIVC), the visual temporal sylvian area (VTS) and areas 7 and 6. Further cortical activations were seen in the anterior insula, the inferior frontal gyrus and anterior cingulum. The subcortical activation pattern in the putamen, thalamus and midbrain is consistent with the organization of efferent ocular motor pathways. Cortical and subcortical activation of the described areas was bilateral during monaural stimulation, but predominant in the hemisphere ipsilateral to the stimulated ear and exhibited a significant right hemispheric dominance for vestibular and ocular motor structures in right-handed volunteers. Similarly, a significant left hemispheric dominance was found in the 12 left-handed volunteers. Thus, this PET study showed for the first time that cortical and subcortical activation by vestibular caloric stimulation depends (i) on the handedness of the subjects and (ii) on the side of the stimulated ear. Maximum activation was therefore found when the non-dominant hemisphere was ipsilateral to the stimulated ear, i.e. in the right hemisphere of right-handed subjects during caloric irrigation of the right ear and in the left hemisphere of left-handed subjects during caloric irrigation of the left ear. The localization of handedness and vestibular dominance in opposite hemispheres might conceivably indicate that the vestibular system and its hemispheric dominance, which matures earlier during ontogenesis, determine right- or left-handedness.

Adult↗
PubMed2003

Anterior canal failure: ocular torsion without perceptual tilt due to preserved otolith function.

A patient with anterior semicircular canal dehiscence syndrome underwent surgical patching that caused an isolated dysfunction of the left anterior semicircular canal postoperatively. He exhibited significant ocular torsion toward the side of the affected labyrinth (17 degrees excyclotropia of the ipsilateral eye), but no displacement of the subjective visual vertical. This dissociation suggests that an isolated ocular torsion may occur after an anterior semicircular canal lesion. A combined ocular torsion and subjective visual vertical tilt, which is usually seen with vestibular lesions, requires an associated otolith dysfunction.

Eye Diseases↗
PubMed2003

Prothrombin G20210A mutation, but not factor V Leiden, is a risk factor in patients with persistent foramen ovale and otherwise unexplained cerebral ischemia.

BACKGROUND: Paradoxical embolism via persistent foramen ovale (PFO) is suspected to be a frequent cause of stroke in younger patients. We investigated whether the prevalence of the risk factors for venous thrombosis factor V Leiden (FVL) and prothrombin G20210A mutation (PT G20210A) is increased in this group of patients. METHODS: We examined FVL and PT G20210A mutation in 220 patients (group 1) with cerebral ischemia associated with a PFO and without other etiology, in 196 patients with cerebral ischemia of an etiology other than PFO (group 2), and in 362 healthy subjects (group 3) from the same region in Germany. RESULTS: Heterozygosity for the PT G20210A mutation was more common in group 1 (5.0%) than in group 3 (1.4%; sex- and age-adjusted odds ratio 3.66; 95% CI 1.25-10.75; p = 0.01). By contrast, the mutation was not more common in group 2 (2.6%; odds ratio 1.50; 95% CI 0.42-5.41; p = 0.5). Prevalences of FVL were not different between groups. CONCLUSIONS: We identified PT G20210A but not FVL - the strongest genetic risk factor for deep venous thrombosis - to be significantly associated with stroke attributed to PFO. These findings rise doubts about the concept of paradoxical brain embolism as the dominating mechanism in stroke associated with PFO.

Adult↗
PubMed2003

Nonlinear nystagmus processing causes torsional VOR nonlinearity.

The eye movement component that rotates around the line of sight, i.e., the ocular torsion, is in many aspects different from horizontal and vertical eye movements. While ocular torsion is mediated only by reflexive pathways like the torsional vestibulo-ocular and optokinetic reflexes (TVOR and OKN, respectively), horizontal and vertical components are also subject to intentional control mechanisms that are mediated by the saccadic and the pursuit systems. Dynamic properties of torsional eye movements are also very distinct. While horizontal and vertical VOR components show a gain close to unity and a small neural integration leakage with a time constant around pi=30 s, the TVOR shows a smaller gain of 0.4 and also a greater leakage with pi=2 s. During slow head rotations in roll, the TVOR is even less compensatory. At small stimulation levels the gain drops to a value of 0.2 and proves thus to be nonlinear, i.e., to depend on the stimulus magnitude. In a recent study, we hypothesized that this nonlinearity might be the result of a nonlinear processing of nystagmus quick phases rather than a nonlinearity in direct or integrator TVOR pathways. In the present study, we experimentally tested this hypothesis by measuring ocular torsion responses at different head rotation speeds. In addition to the conventional approach of analyzing slow-phase velocity (SPV) gains, we also analyzed properties of nystagmus quick phases. This method proved to be suitable for determining whether nonlinear processing of nystagmus frequency is responsible for the TVOR nonlinearity.

Computer Simulation↗
PubMed2002

Sequence analysis of the COL5A2 gene in patients with spontaneous cervical artery dissections.

The authors searched for mutations in the gene that codes for the alpha2 chain of type V procollagen in 10 patients with spontaneous cervical artery dissections (sCAD). Two patients carried a missense mutation affecting the predicted C-propeptide (T1227S; D1429V). A third patient carried two mutations (V509A and P830L) in the same alpha2(V) chain. The T1227S mutation and the V509A/P830L haplotype also were detected among 50 healthy subjects. The D1429V substitution was detected neither in a series of 150 healthy control subjects nor among 50 additional patients with sCAD.

Amino Acid Sequence↗