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Biomedical subjects

R Dengler

Publications and source records attributed to R Dengler.

At least 91 records · Page 5Linked to original sources
PubMed1999

Abnormalities of visual search behaviour in ALS patients detected with event-related brain potentials.

A number of recent reports have emphasized neuropyschological symptoms in ALS, including frontal functions, memory and attention. We investigated visual search behaviour of ALS in two types of tasks: a simple, relatively effortless parallel search task and a more complex attention-demanding serial search task. Behavioural parameters and cognitive event-related potentials (ERP) from 19 scalp channels were obtained from 13 ALS patients and 13 matched controls during task performance. ALS patients showed the same target detection rates as controls in the parallel task but were significantly impaired in the serial task. Performance was slower in the patients than in the controls. This slowing could be attributed to cognitive rather than motor impairments, by inspection of the latency of the P3 component, which was delayed by 120 ms in the patients. In addition, the ERPs in the serial task showed a grossly reduced P3 amplitude, indicating disturbed stimulus evaluation in the patients under these conditions. Changes of an early attention-sensitive ERP component suggest an attention deficit underlying the disturbances in search behaviour.

Adult↗
PubMed1999

Effects of acamprosate on memory in healthy young subjects.

OBJECTIVE: Several studies have shown acamprosate (calciumacetylhomotaurinate) to increase abstinence rates in weaned alcoholics. Chronic alcoholics often suffer from cognitive deficits. Since acamprosate appears to interact with N-methyl-D-aspartate (NMDA) receptors, a subclass of glutamate receptors playing an important role in learning and memory processes, this study was performed in order to investigate different cognitive functions during administration of acamprosate. METHOD: A randomized, double-blind, cross-over, placebo-controlled design, involving 12 healthy male volunteers was used. Acamprosate 2 g daily per os or placebo were administered for 7 days respectively, with a wash-out interval of 21 days between phases. Mood and different memory functions (i.e., working memory, delayed recall, recognition tasks) were assessed. RESULTS: It was shown that a dose of acamprosate 2 g/day for 7 days may produce an impairment in delayed free recall. Recognition tasks, short term working memory and mood were not altered. CONCLUSIONS: The present study supports the hypothesis that acamprosate impairs memory functions. This is in keeping with the concept of acamprosate acting as NMDA receptor antagonist. The limitations of the study are discussed.

Acamprosate↗
PubMed1999

Current treatment pathways in ALS: a European perspective.

This article presents the findings relating to the European subgroup of 91 patients in an international survey of the current diagnosis and treatment of patients with amyotrophic lateral sclerosis (ALS). The mean time between first symptoms and first consultation with a physician was 4.9 months, and mean delay in seeing a neurologist was then about 6 months, yielding a mean time from symptom onset to confirmation of diagnosis of 17.8 months. The time to confirmation of diagnosis was slightly longer for patients with symptoms of limb onset (18.5 months) than for those with bulbar onset (17.5 months). Cases with symptoms of upper-limb onset were diagnosed more rapidly (15.5 months) than those with symptoms of lower-limb onset (21.8 months). The diagnosis was confirmed in 51% of cases within 15 months of symptom onset, and a further 23% were diagnosed within 15-24 months; 55% of cases were confirmed within 4 months of consultation with a neurologist, and a further 14% within 4-6 months. The first physician seen was the general practitioner in 68% of cases. When the neurologist was the first physician seen (7% in Germany, 13% in Italy, 0% in Spain), diagnosis was achieved within 14 months in 67% of cases. EMG was performed in almost all patients. MRI and CT were widely used, possibly causing delays. Announcement of the diagnosis was made immediately to 85% of patients and within 1 month to a further 9%. Riluzole was prescribed for 76% of patients overall.

Aged↗
PubMed1998

[Autoimmune encephalopathy in Hashimoto's thyroiditis. A differential diagnosis in progressive dementia syndrome].

HISTORY AND CLINICAL FINDINGS: A 58-year-old woman, known for 10 years to have Hashimoto's thyroiditis, was admitted from another hospital where, after an initial period of unconsciousness, she had developed progressive severe dementia, abnormal arousal and generalized myoclonia. Jakob-Creutzfeldt disease (JCD) was suspected. INVESTIGATIONS: The electroencephalogram (EEG) showed marked slowing of the basic activity and episodes of triphasic waves. The titres of thyroid antibodies (TPO 764 kU/l, TgAk 398 kU/l) and of the antinuclear antibodies (ANA 1:1280) were raised, as was the erythrocyte sedimentation rate (80/120 mm and the cerebrospinal fluid albumin concentration (1 g/l). TREATMENT AND COURSE: The history and findings suggested autoimmune encephalitis (AIE) and treatment with prednisolone, 2 mg/kg body weight daily, was initiated, achieving lasting improvement of arousal within two days. 6 weeks later the EEG merely showed mild alteration of basic activity. The thyroid antibody titres were now within normal limits and the signs of inflammation were regressing. CONCLUSION: In case of rapidly progressive dementia autoimmune antibodies should be looked for in the differential diagnosis, because autoimmune disease may be the treatable cause.

Autoimmune Diseases↗
PubMed1998

Walking and fatigue in multiple sclerosis: the role of the corticospinal system.

Transcranial magnetic stimulation was used to study motor evoked potentials (MEPs) of leg muscles in controls and patients with multiple sclerosis (MS) before and after walking. In controls, MEP areas were significantly reduced after walking. A similar or greater reduction was seen in most patients, although there was a wide range of values. The M waves were unchanged. We conclude that walking induces functional changes of the corticospinal system and/or connected neurons contributing to central fatigue, especially in patients with MS.

Adult↗
PubMed1998

Alteration of early components of the visual evoked potential in amyotrophic lateral sclerosis.

Evoked potentials were recorded in three different visual experiments in 14 patients with amyotrophic lateral sclerosis (ALS) and 14 matched control subjects. Control subjects' evoked potentials (EPs) were characterized by an initial positivity in the 90-140 ms range (P1) at the temporo-occipital site. This component was absent from the group average of the ALS patients as well as the individual patients' EPs. As the P1 is known to emanate from inferior occipito-temporal areas, this finding provides electrophysiological evidence for a cortical involvement in ALS including visual areas.

Adult↗
PubMed1998

Differential effects of two motor tasks on ERPs in an auditory classification task: evidence of shared cognitive resources.

The aim of the study was to assess cognitive demands and fatigue during the execution of two different motor tasks. Event-related brain potentials (ERPs) were recorded from 15 healthy subjects while they concurrently performed, (1) one of two motor tasks, and (2) a three stimulus (70% standard tones, 15% target tones, 15% novel stimuli) auditory classification task. Both motor tasks required the externally paced adduction of the right thumb with the force task requiring a precise movement (feedback given) with about 50% of maximum force output (6 s on task, 4 s rest) while the displacement task required the same precise movement with only minimal force requirements. In separate sessions, both tasks were performed for about an hour with the subjects concurrently paying attention to the auditory task with button presses required for the target stimuli. This provided a dual task situation with trade-offs in P3b amplitude as a function of difficulty of the primary (motor) task. The P3b to the auditory target stimuli was reduced during the force session compared to the displacement session, indicating that the force-task placed a higher demand on cognitive resources. No differential effect of fatigue (time on task) could be ascertained over six consecutive parts of the session. The P3a component, a putative correlate of orienting of attention, showed a rapid attenuation over time but, attesting to its automatic nature, no effect of concurrent motor task. ERP components recorded timelocked to the movements showed a marked difference between the two tasks with the displacement task giving rise to higher amplitudes. Moreover, only for the force task an influence of time on task (fatigue) on the MP was found. The dual task methodology is a potentially useful tool to disentangle cognitive and motor components of central fatigue.

Acoustic Stimulation↗
PubMed1998

Supraglottal injection of botulinum toxin type A in adductor type spasmodic dysphonia with both intrinsic and extrinsic hyperfunction.

Patients with adductor type spasmodic dysphonia (SD) often exhibit both glottal and supraglottal hyperfunction. Based on the hypothesis that a "ventricular muscle" may contribute to the hyperfunction in these cases, eight patients with adductor type SD were treated with bilateral injection of botulinum toxin type A into the ventricular folds. Four weeks after injection, ventricular fold hyperfunction was absent in all cases. Number of voice breaks, standard deviation of fundamental frequency, and shimmer were significantly improved. Voice range profiles of the speaking voice were significantly extended in dynamic and frequency range. Side effects were a breathy phonation and mild swallowing difficulties without aspiration for about 1 week. Patients' self-rating concerning strangled and breathy voicing demonstrated an interval of acceptable voice quality between 1 week and 4 months after injection in all cases. Results suggest that supraglottal injection in patients with SD of both glottal and supraglottal hyperfunction, as a new approach, can normalize supraglottal activity and improve glottal voicing. Based on our experience with other patients with adductor type of SD, this injection technique is as efficient as injection into the thyroarytenoid muscle. Nevertheless, it remains to be proved that a pathologic ventricular muscle activity is addressed by this technique or if it is based on spreading to the thyroarytenoid muscle.

Acoustics↗
PubMed1998

Recognition memory deficits in amyotrophic lateral sclerosis assessed with event-related brain potentials.

OBJECTIVES: Amyotrophic lateral sclerosis (ALS) has been shown to cause neuropsychological deficits. The present investigation sought to delineate memory deficits by recording cognitive event-related potentials (ERPs). SUBJECTS AND METHODS: Eight ALS patients and 8 matched controls were subjected to a 2-phase recognition memory test. During the first phase words were presented consecutively on a video-screen with one-third of the words being repeated. The subject had to press buttons according to whether a word had been repeated or not. During the second phase (delay 1 h) a second list containing 33% old items from phase 1 and 66% new words was shown with an old/new decision required. RESULTS: ALS patients showed less accurate recognition in the second phase. The ERPs of the controls showed a reliable difference between old and new items in both phases. This difference was nearly absent in the patients in both phases. CONCLUSION: The ERP pattern suggests abnormal memory processes in ALS. The results are compared with data from similar experiments in Huntington's and Alzheimer's disease and are interpreted in terms of an encoding deficit in ALS.

Adult↗
PubMed1998

[Psychosomatic aspects of idiopathic spasmodic torticollis. Results of a multicenter study].

Idiopathic spasmodic torticollis (IST) is one of the most frequent dystonic movement disorders. Its classification as a focal dystonia, as well as its treatment with botulinum toxin resulted in groups of patients being regularly seen by neurologic specialists. In a multicentre study, we investigated psychosocial changes, coping and psychopathology, and their interrelations with signs, symptoms and course. 256 patients were included in the study (59.3% women, 40.7% men). The mean age was 49.1 years. Rotating torticollis occurred more often than latero-retrocollis and antero-retrocollis. A family history of IST was seen in 3.1% of the total sample. 34% of the patients had additional dystonic symptoms. Most frequently, these affected the upper extremities (13%), less often the legs. 19.1% of the patients had experienced a period of complete remission. The General Symptom Index of the SCL 90-R in 27% of the patients ranged above the double standard deviation of the normal controls, indicating a clinically significant psychopathology.

Adaptation, Psychological↗
PubMed1997

An electrophysiological analysis of altered cognitive functions in Huntington disease.

BACKGROUND: Neuropsychological deficits are a main feature of Huntington disease (HD) with previous data suggesting involvement of memory functions and visual processing. OBJECTIVE: To increase the knowledge about cognitive malfunction in HD in the domains of visual processing and memory by the use of modern electrophysiological techniques (event-related potentials [ERPs]). DESIGN: A case-control design was used. Three ERP paradigms were used; a parallel visual search paradigm allowed for the simultaneous processing of a multi-element visual array in search of a target stimulus, while a serial search paradigm with varied numbers of distractor items necessitated a serial one by one scanning of the arrays. The third experiment was a word-recognition memory task. SETTING: The measurements were obtained in a neurophysiological laboratory of a university hospital. PATIENTS AND CONTROLS: Nine patients with HD and 9 control subjects matched for age, sex, and education were studied. MAIN OUTCOME MEASURES: Components of averaged ERPs were quantified by latency and amplitude measures and subjected to statistical analysis. Behavioral measures (search time, hit rate, and recognition accuracy) were assessed as well. RESULTS: The early visual components showed a significant latency shift (delay of about 50 milliseconds) in HD. In the search paradigms the P3 components differentiating target and standard stimuli were virtually absent in HD as was the ERP effect indexing word recognition. This was accompanied by a marked delay in search times and lower hit rates in the search tasks and a grossly reduced recognition accuracy in the memory task. CONCLUSIONS: The results suggest marked impairments of patients with HD in early visual sensory processing (early components). Deficits in visual search might be attributed to an impairment to deploy attentional resources across the visual field and/or an inability to control eye movements. The ERPs in the memory task differed grossly from similar data obtained by others in patients with Alzheimer disease, suggesting a different neural basis for the amnesia in HD.

Adult↗
PubMed1997

Botulinum A toxin therapy: neutralizing and nonneutralizing antibodies--therapeutic consequences.

Although muscle-relaxant doses of botulinum A toxin (BoNT/A) are generally lower than doses stimulating the immune system, specific antibodies are raised in a substantial number of patients. As a rule, this necessitates the termination of treatment. Therefore, a reliable determination of specific anti-BoNT/A antibodies is helpful and we introduced, for this purpose, a novel in vitro toxin-neutralizing assay based on a nerve-muscle preparation. We measured the antibody titers in four groups of subjects: Group 1 comprised 75 randomly selected patients of a total of 295 who responded to treatment with Dysport in our local clinic. Five patients, in group 2, were nonresponders. Group 3 consisted of 32 untreated volunteers and group 4 of 8 subjects immunized with a toxoid more than 10 years ago. Two of the responders had marginal titers of neutralizing antibodies, while they were present in all nonresponders. The sera of all responders were also tested for nonneutralizing antibodies by ELISA. Their occurrence, however, was of no consequence to the therapeutic success. The blood samples of volunteers were free from specific antibodies, whereas antibodies persisted in the immunized subjects for longer than a decade. Patients from various clinics who had been treated unsuccessfully with the toxin-14 patients had received BOTOX, 7 had been treated with Dysport, and 7 with both products-all had neutralizing antibodies. Whether there was an antibody response depended on the amount of toxin administered. We believe, however, the effective toxin dose can be reduced by so much as to make antibody production highly improbable.

Animals↗
PubMed1997

Impact of riluzole on the relationship between patient and physician.

To date, there has been little systematic research on the patient-physician relationship in amyotrophic lateral sclerosis (ALS). Important factors in this relationship are the emotional state, or mood, of the patients and their expectations of successful therapeutic intervention. In many patients there is a gradual deterioration of mood with disease progression-a view supported by studies comparing the initial and late phases of the disease. The few studies examining patients' expectations of therapy revealed a strong desire to be informed about the disease and its course without destroying every hope. In the later stages of the disease patients expected compassion and help with immediate problems. To our knowledge there has been no systematic study on the attitude of physicians towards ALS patients. The lack of effective treatment and the wish to avoid full information about the poor prognosis are almost unique problems involved in dealing with ALS patients. The new option to treat with a drug that slows disease progression provides some alleviation for the physician. Riluzole, at least, partially meets this expectation. Although its efficacy is too limited to satisfy fully the wishes of patients and physicians, it is the first available drug that has been shown to slow disease progression. Thus, it may bring to an end the feeling that there is nothing that can be done for these patients. In our experience this provides relevant alleviation in the management of ALS patients.

Amyotrophic Lateral Sclerosis↗
PubMed1997

Botulinum A toxins: units versus units.

We investigated the efficacies and potencies of two commercial preparations of botulinum neurotoxin type A (BoNt/A) reputed to differ in potency. Tests were conducted in vitro using the mouse phrenic nerve-hemidiaphragm which is an approved tool for measuring clostridial toxicity. In addition, in a double-blind trial on volunteers, varying amounts of one product were injected into the Musculus extensor digitorum brevis of the left foot, while equal amounts, i.e. units, of the other preparation were injected into the same muscle of the right foot. Compound muscle action potentials (CMAPs) were recorded before and at various points in time after the injections. As opposed to wide-spread anecdotal reports, no difference in effectiveness was found. The dose-response curves obtained from the mouse organ preparation with both commercial products equalled one another in potency (number of units) and corresponded to previous toxicity tests in mice conducted elsewhere. Dose-response curves from volunteers were also identical for both commercial preparations. The time course of paralysis and recovery of muscle function did not differ either. At lower concentrations of toxin, however, restoration of muscle function was more rapid than at higher concentrations. Since the results obtained from man and the animal organ preparation are in excellent accord, we conclude that 1 unit of Botox corresponds to 1 unit of Dysport.

Action Potentials↗