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Biomedical subjects

D Dressler

Publications and source records attributed to D Dressler.

At least 91 records · Page 5Linked to original sources
PubMed1990

Central motor conduction time to bulbocavernosus muscle: evaluation by magnetic brain stimulation and testing of bulbocavernosus reflex.

Magnetic brain stimulation and bulbocavernosus reflex (BCR) testing were performed to evaluate the central motor conduction time (CMCT) to the bulbocavernosus muscle (BC). In six healthy subjects CMCT ranged from 13.81 ms to 16.9 ms with a mean value of 15.77 ms (SD 1.38 ms). This equals a central motor conduction velocity of about 40 m/s, which can only be realized in fast conducting pyramidal tract fibres. Testing of pyramidal tract function by BC-CMCT might improve the diagnosis of male sexual dysfunction.

Adult↗
PubMed1990

99mTc-hexamethylpropylene amine oxime SPECT and X-ray CT in acute cerebral ischaemia.

Early diagnosis of acute cerebral ischaemia is still unsatisfactory, because X-ray computed tomography (CT) does not reveal the site and extent of hypoperfusion within the first 24 h. Single photon emission computed tomography (SPECT) using 99mTc-hexamethylpropylene amine oxime (HMPAO) may offer earlier information, since the distribution of HMPAO follows the actual cerebral perfusion pattern. We therefore investigated 53 patients suffering from acute cerebral ischaemia (10 with transient ischaemic attacks, 9 with prolonged ischaemic reversible neurological deficits, 34 with completed stroke). SPECT and CT examinations were performed on days 1, 3, and 14. On day 1, SPECT revealed hypoperfused areas in 42 patients, whereas CT showed hypodensities only in 5. The sensitivity of SPECT was higher in cortical compared with subcortical ischaemia. In patients suffering from reversible neurological deficits SPECT normalized in the follow-up, corresponding to clinical improvement. In completed stroke, SPECT demonstrated variable perfusion patterns with hypo-, normo-, and hypoperfused areas on day 3 and especially on day 14. In contrast to CT, HMPAO SPECT leads to early diagnosis of cerebral ischaemia, in particular within the cerebral cortex.

Aged↗
PubMed1990

Polyradiculoneuritis following botulinum toxin therapy.

The development of Guillain-Barré syndrome is reported in a patient, who had previously received botulinum toxin type A injections into both orbicularis oculi muscles to treat idiopathic blepharospasm. The possibility of a causal relationship is discussed with consideration of the literature on adverse effects of vaccinations and of Clostridium botulinum and its toxin.

Blepharospasm↗
PubMed1989

Changes of transcranially evoked motor responses in man by midazolam, a short acting benzodiazepine.

The present study investigated the effects of midazolam, a short acting benzodiazepine, on muscle responses elicited by magnetic brain stimulation. During continuous midazolam infusion (0.3 mg/kg/h for up to 30 min) amplitudes and durations of transcranially elicited compound muscle action potentials decreased progressively while latencies remained unchanged. The results can be accounted for by midazolam enhancement of the inhibitory action of GABAergic cortical interneurons, which decreases the excitability of pyramidal cells and reduces the number of neurons available for generation of descending pyramidal tract activity.

Action Potentials↗
PubMed1989

The development of an epileptogenic focus. A case study with 99mTc-HMPAO SPECT.

A patient is described who developed complex partial seizures with secondary generalization 3 years after a severe viral encephalitis with a CT and EEG identified lesion in the left insular cortex and its surrounding structures. When the seizures first occurred CT and MRI as well as repeated interictal conventional EEG recordings were entirely normal. Single photon emission computed tomography (SPECT), however, revealed an area of increased 99mTc-hexamethyl propyleneamine oxime (HMPAO) uptake in the left insular cortex. After anticonvulsive therapy the seizures and the SPECT findings disappeared. 99mTc-HMPAO SPECT is a highly sensitive method for the demonstration of functional alterations in brain tissue. It can improve diagnosis of epilepsy and may provide additional information to monitor anticonvulsive therapy.

Adult↗
PubMed1989

[Narcolepsy syndrome--clinical aspects, diagnosis, therapy].

The present paper gives an updated overview over the clinical symptomatology, diagnostic procedures and therapy of the narcolepsy syndrome as a variable, disabling condition, whose diagnosis is sometimes not easy to make. Special attention is paid to new and promising diagnostic developments.

Arousal↗
PubMed1989

Electric and magnetic stimulation of human motor cortex: surface EMG and single motor unit responses.

1. The effects of different forms of brain stimulation on the discharge pattern of single motor units were examined using the post-stimulus time histogram (PSTH) technique and by recording the compound surface electromyographic (EMG) responses in the first dorsal interosseous (FDI) muscle. Electrical and magnetic methods were used to stimulate the brain through the intact scalp of seven normal subjects. Electrical stimuli were applied either with the anode over the lateral central scalp and the cathode at the vertex (anodal stimulation) or with the anode at the vertex and the cathode lateral (cathodal stimulation). Magnetic stimulation used a 9 cm diameter coil centred at the vertex; current in the coil flowed either clockwise or anticlockwise when viewed from above. 2. Supramotor threshold stimuli produced one or more narrow (less than 2 ms) peaks of increased firing in the PSTH of all thirty-two units studied. Anodal stimulation always produced an early peak. The latencies of the peaks produced by other forms of stimulation, or by high intensities of anodal stimulation, were grouped into four time bands relative to this early peak, at intervals of -0.5 to 0.5, 1-2, 2.5-3.5 and 4-5.5 ms later. Peaks occurring within these intervals are referred to as P0 (the earliest anodal), P1, P2 and P3 respectively. 3. At threshold, anodal stimulation evoked only the P0 peak; at higher intensities, the P2 or more commonly the P3 peak also was recruited. The size of the P0 peak appeared to saturate at high intensities. 4. In five of six subjects, cathodal stimulation behaved like anodal stimulation, except that there was a lower threshold for recruitment of the P2 or P3 peak relative to that of the P0 peak. In the other subject, the P3 peak was recruited before the P0 peak. 5. Anticlockwise magnetic [corrected] stimulation, at threshold, often produced several peaks. These always included a P1 peak, and usually a P3 peak. A P0 peak in the PSTH was never produced by an anticlockwise stimulation [corrected] at intensities which we could explore with the technique. 6. Clockwise magnetic [corrected] stimulation never recruited a P1 peak; in most subjects a P3 peak was recruited first and at higher intensities was accompanied by P0 or P2 peaks. 7. On most occasions when more than one peak was observed in a PSTH, the unit fired in only one of the preferred intervals after each shock. However, double firing was seen in five units when high intensities of stimulation were used.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1989

[Botulinum toxin in therapy of craniocervical dystonia].

Craniocervical dystonias are a major therapeutic problem, since in the majority of cases various drug regimens as well as surgical interventions either fail or are accompanied by serious side effects. Botulinum toxin, well known as a biological toxin which blocks the cholinergic neuromuscular synapse, proved to be a new and successful concept in the treatment of these disorders. In the present study, mechanisms of action, clinical indications and practical use of botulinum toxin are described.

Botulinum Toxins↗
PubMed1988

[Fractionated determination of central motor conduction times using stimulation of the cortex, spinal tract and spinal nerve roots: possibilities and limits].

Two different approaches of determining central motor conduction times were investigated. Both methods were based on calculations of latency differences of muscle compound action potentials. First, using multilocal stimulation of the descending motor system at different levels (motor cortex, motor tracts at spinal level, motor roots) and recording from one reference muscle (Figs. 1 and 2). Second, using unilocal stimulation over the motor cortex and recording from a number of paravertebral muscles at levels from C7 to L5 (Figs. 3 and 4). With multilocal stimulation of the motor pathways, muscle response potentials are observed which differ in amplitude, duration and configuration depending on the site of stimulation (Figs. 1 and 2). This finding points to the incongruency of excited fibres within the descending motor pathways. The causes underlying this phenomenon and the resulting limitations for determining central motor conduction times are discussed. The new approach using recordings of cortically evoked responses on different levels in paravertebral muscles does not suffer from the methodical limitations of the multilocal stimulation and may be of higher clinical validity for the localization of circumscript spinal processes.

Adult↗
PubMed1988

[The role of magnetic stimulation in diagnosis of the peripheral nervous system].

Magnetic stimulation has recently been introduced as a new method for stimulation of neuronal tissues. Up to now most investigators were emphasized the advantages of this method for the investigation of the central nervous system. With this paper we want to show that magnetic stimulation may also be useful for the examination of the peripheral nervous system. Both, magnetic and electrical stimulation, seem to employ the same stimulation mechanisms in the nervous tissue. The results obtained with both methods should therefore be comparable. By measuring EMG-latencies after electrical and magnetic stimulation (Fig. 1) the exact site of magnetic stimulation can be determined. Magnetic stimulation offers major advantages over electrical stimulation: 1) Magnetic stimulation is a painless method even when high stimulus intensities are used. 2) Magnetic stimulation can reach deep neuronal structures that are not easily accessible using electrical stimulation (Fig. 2, Fig. 3). 3) Using a wide range of stimulus intensities (Fig. 4, Fig. 5) magnetic stimulation provides a much better descrimination of different components of the compound muscle action potential than electrical stimulation. Magnetic stimulation seems to be a promising new method for the electrodiagnostic examination of pain- sensitive patients, especially when deep-lying peripheral nerves have to be investigated.

Electric Stimulation↗
PubMed1988

[Transcranial brain stimulation. Methods and results].

Since the end of last century direct electric brain stimulations have produced remarkable neurophysiological results. Unfortunately, this method can be used only during neurosurgical operations. With the introduction of transcranial electric brain stimulation in 1980, for the first time, it became possible to perform brain stimulations on non-anaesthetized subjects. Magnetic brain stimulation, available since 1985, allows brain stimulation without any discomfort of the subject. This paper is dealing with methodological aspects of both methods and presents first results of neurophysiological and clinical applications.

Brain↗
PubMed1986

A 'Southern Cross' method for the analysis of genome organization and the localization of transcription units.

A 'Southern Cross' hybridization method is described which permits the rapid restriction mapping of DNA molecules, up to 40 kb in size, for at least ten enzymes in a single operation. The procedure allows the full set of 32P-end-labelled fragments derived from one restriction enzyme digest to intersect and attempt to hybridize to the gel-separated fragments of as many as ten unlabelled digests immobilized on parallel sheets of filter paper. A two-dimensional array of hybridization spots is revealed on each recipient paper, indicating which radioactive and non-radioactive DNA fragments have sequences in common. A restriction map can then be directly and simply deduced from the matrix of hybridization spots in each cross-blot. The method affords advantages over other procedures for obtaining restriction maps in terms of the time required, the number of restriction enzymes that can be mapped, and the potential for eliminating ambiguity. It is also sufficiently sensitive to detect DNA rearrangements and restriction-site polymorphisms in moderately complex genomes. Furthermore, the procedure is applicable to other aspects of the study of genome organization: for example, the exon and intron areas of a segment of cloned genomic DNA can be identified by cross-hybridizing a set of radioactive restriction fragments from the genomic clone against immobilized RNA from a cell type of interest.

DNA Restriction Enzymes↗
PubMed1984

Changes of somatosensory evoked potentials in man as correlates of transcortical reflex mediation?

Somatosensory evoked potentials (SSEP) from the scalp of the sensori-motor cortex were recorded together with long latency reflexes in the EMG of the contralateral biceps muscle in 17 human subjects, who were instructed to compensate a sudden biceps stretch. In this 'compensate' condition the earliest deviation from the shape of the SSEP obtained in a 'let go' situation (exhibiting only short latency reflexes) occurred as early as 35-40 ms. The results indicate that SSEP changes associated with the occurrence of long latency reflexes might be compatible with a transcortically mediated reflex activity.

Adult↗
PubMed1982

A silicone-nylon laminated dressing (IP-758) for closure of excised or débrided burn wounds.

A synthetic dressing (IP-758) consisting of a silicone membrane with a laminated layer of nylon fabric was evaluated in patients as a substitute for biological materials to cover excised areas of burn wounds. During a 3-day interval, the tissue developed a tightly adherent bond to the synthetic dressing. The IP-758 conformed to irregularly-shaped regions and stretched with the movements of the wound surface. Seventeen burned children from 3 to 12 years of age and 1 adult are included in this study. In 12 cases, the mean area covered with the synthetic ranged from approximately 39 to 118 cm2. The average dressing remained in place for 3 days and was replaced once. Microbiological sampling (wet swab technique) of the area under the IP-758 after application of second dressing was compared with open control sites treated with topical antibiotics. The results with Staphylococcus aureus, a frequent contaminant, were similar for the two test areas. The IP-758 site in 6 patients contained an average of 10 3 S. aureus per swab test. Immediately following removal of the adherent IP-758 and control of local bleeding, the wounds in most patients provided excellent sites for autografts. The IP-758 dressing is well-tolerated, elastic and adherent to the burn wound permitting maturation of the wound to readily accept autografts.

Adult↗