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Biomedical subjects

R Benecke

Publications and source records attributed to R Benecke.

At least 127 records · Page 7Linked to original sources
PubMed1988

[Chronic neuropathy of the suprascapular nerve in high performance athletes].

The clinical and electrophysiological examination of 36 top-level volleyball players showed a suprascapular neuropathy in 28% of the subjects. The most commonly observed clinical symptom was a focal severe atrophy of the m. infraspinatus, combined with loss of strength of the arm in abduction and external rotation. In contrast to previous reports on suprascapular neuropathies in volleyball players, the present investigation demonstrates an additional milder affection also of the nerve fibres supplying the m. supraspinatus.

Adult↗
PubMed1988

[Form of manifestations and course of brachial plexus lesions following medial sternotomy].

A prospective study is reported of the prevalence, the clinical picture and the course of plexus brachialis lesions following median sternotomy during heart operations. The study comprises 1,585 patients. In 22 patients (1.39%) a lesion of the lower plexus brachialis was found postoperatively. In 12 patients the plexus lesion was combined with an ipsilateral Horner syndrome. The present study suggests that in spite of cautious use of the sternal retractor, the appearance of a postoperative plexus lesion cannot be completely avoided. In contrast to a cranial incision of the retractor, which can be associated with a posterior fracture of the first rib, a caudal placement of the retractor seems to induce a superior luxation of the first rib and local hematoma without concurrent fracture. Re-examinations of the patients demonstrated a good prognosis of these plexus lesions, the Horner syndromes, however, may remain for a longer time period. It is advisable that patients who have to undergo a heart operation with median sternotomy should be informed beforehand about the possible side-effects described here.

Aortic Valve↗
PubMed1987

Intracranial flow patterns at increasing intracranial pressure.

In the course of a pilot study, changes in intracranial pressure were compared with the transcranial Doppler findings of the middle cerebral artery. The cases of five patients were discussed who developed dissociated brain death in spite of intensive therapeutic measures. The studies showed that changes of the intracranial pressure influenced the flow patterns considerably: at increasing intracranial pressure (decreasing cerebral perfusion pressure) a progressive reduction of the systolic and above all diastolic flow velocities and finally a pendular flow occurred. These changes could be recorded quantitatively by means of the "Pourcelot index" and the mean flow velocity. Acute changes of the intracranial pressure can be detected at an early stage by noninvasive transcranial Doppler studies and can be followed by adequate intensive therapy.

Adult↗
PubMed1987

Rapid micromethod for the analysis of mitotane and its metabolite in plasma by gas chromatography with electron-capture detection.

A rapid micromethod for 50-microliter samples is described for the analysis in plasma of mitotane (o,p'-DDD) and its metabolite (o,p'-DDE), using p,p'-DDD as internal standard. The compounds are extracted with heptane without sample pretreatment, and an aliquot is directly analysed by gas chromatography with electron-capture detection. Absolute recoveries for all three compounds were ca. 87% and coefficients of variation were less than 5%. The method is being used successfully for monitoring patients with Cushing's syndrome who receive chronic oral mitotane therapy.

Child↗
PubMed1987

Modulation of the long-latency reflex to stretch by the supplementary motor area in humans.

Surface-recorded, electromyographic responses to 200-ms ramp stretches were studied in the wrist flexor muscles from both arms of a patient with clinical and radiographic evidence of infarction in the right supplementary motor area (SMA). They were compared with those from 8 age-matched control subjects. The latencies of the spinal component of the stretch reflex were slightly longer than normal in both arms of the patient (normal subjects: 28.5 +/- 2.6 ms; patient: 35 ms, right arm and 32 ms left arm). However, the amplitude and duration of the short-latency response were identical in both arms. The onset of the long-latency response to stretch was symmetrical in both the patient's arms and was slightly later than normal (normal subjects 55.5 +/- 4.0 ms, patient: 72 ms right arm and 70 ms left arm); however, its duration was considerably prolonged in the arm contralateral to the SMA lesion (normal subjects: 44.8 +/- 6.0 ms; patient: 48 ms right arm. 105 ms left arm). These results are consistent with the hypothesis that the long-latency stretch reflex is mediated via a transcortical loop.

Adult↗
PubMed1987

The Bereitschaftspotential, L-DOPA and Parkinson's disease.

Bereitschaftspotentials (BPs) prior to extension movements of the index finger were studied in normal subjects and in patients with Parkinson's disease. In both, BPs were studied before and after L-DOPA therapy; in addition, the normal subjects were studied after dopamine antagonists. In both patients and normal subjects, L-DOPA caused an increase in the amplitude of the early part of the BP and of the point of peak negativity, just prior to EMG onset (N1) but it did not cause an increase of the late lateralized part of the BP (NS' of Shibasaki); in normal subjects dopaminergic antagonists caused a decrease in the amplitude of the N1. Control experiments suggested that the change caused by L-DOPA was not the result of slower movement or poorer triggering when OFF drugs. For patients with Parkinson's disease there was no correlation between the change in their peak BP negativity (N1) after L-DOPA and their change in clinical mobility; in addition, there was no difference in the peak BP negativity of patients OFF therapy and that of age-matched normals, though there was a slight decrease in the amplitude of the early part of the BP for the patients with Parkinson's disease; this was the same part that had been enlarged by L-DOPA therapy. These findings suggest that the N1 is not affected by Parkinson's disease and that the effect of dopaminergic drugs on the N1 is mediated by actions on dopaminergic mechanisms elsewhere than in the striatum, perhaps in the cerebral cortex itself. The effect of L-DOPA will need to be taken into account in subsequent studies of the BP in Parkinson's disease.

Adult↗
PubMed1987

Disturbance of sequential movements in patients with Parkinson's disease.

The following sequences of two single movements were examined in 10 patients with Parkinson's disease and compared with the performance of 9 normal subjects of similar age. Isometric opposition of thumb and fingers to a force of 30 N ('squeeze'), followed by isotonic elbow flexion ('flex') through 15 degrees with the same arm. 'Squeeze' with the left hand followed by 'flex' with the right elbow. Isotonic opposition of thumb and fingers ('cut') through 90 degrees followed by isotonic 'flex' with the same arm. Isotonic elbow 'flex' followed by isometric 'squeeze' with the same arm. All movements were self-paced. Subjects were given instructions to move as rapidly as possible and to start the second movement immediately after the end of the first. Patients were slower than normal when each single movement was performed separately. There was a further decrease in speed when two movements were executed sequentially. This was due to an increase in movement duration of each of the component movements, especially the second, and to an increase in the pause between the first and second movements. In both normals and patients, there was no correlation between the times taken to perform the first and second movements of any of the four sequences that were studied. Because of this we suggest that the two components of the sequence remained under the control of two separate motor programs. When performing the sequential tasks, normal subjects automatically chose an interval between the onsets of the two separate movements of about 230 ms, even in tasks in which the duration of the first movement was less than 200 ms. If normal subjects were instructed to begin the second movement with an interonset interval of less than 200 ms, the speed of the second movement was much slower. Patients with Parkinson's disease automatically chose a much longer interonset interval of 400-500 ms. In addition, they exhibited difficulty in switching from the first to the second movement in the sequence. We suggest that the problems exhibited by patients with Parkinson's disease when they try to perform two rapid sequential movements can be seen as a deficit in the capacity to switch from one motor program to another within an overall motor plan.

Adult↗
PubMed1987

Simple and complex movements off and on treatment in patients with Parkinson's disease.

The performance of a 15 degrees elbow flexion and a 30N hand squeeze was studied in nine normal subjects and in five patients with Parkinson's disease. The patients were studied when immobile after 12-18 hours withdrawal from antiparkinsonian drug therapy (OFF) and when more mobile after drugs (ON). Subjects performed each movement separately (simple movements) and both movements either simultaneously or sequentially (complex movements). The duration of both movements and the time between the onset of each movement in the sequential task (interonset latency) were measured. The patients OFF therapy had longer movement times than normal for both movements; these improved after levodopa but still were not normal. When the patients performed complex movements there was an extra slowness, over and above that seen for simple movements, in both movements of the simultaneous task and in the second movement of the sequential task. In addition, the interonset latency in the sequential task was longer than normal. After levodopa there was a more striking improvement in the movement times of complex movements than there had been for simple movements. The interonset latency in the sequential task was shorter than before therapy though still was not the same as in normal subjects. It is suggested that the basal ganglia are not only involved in the execution of simple motor programmes, but also play some role in the superimposition and sequencing of motor programmes.

Adult↗
PubMed1987

[Possibilities and limits of determining central motor conduction latencies in the human].

It was the aim of the present study to define the normal range of latencies to muscle compound action potentials of different muscles in the upper and lower extremity elicited by transcranial cortex stimulation (see Tab. 1). It was demonstrated that parameters, such as voluntary background innervation (see Fig. 1) and stimulation strength (see Fig. 2) have great influence on both the latencies and the amplitudes of these responses (see Figs. 3 and 4). Thus, as a prerequisite for an interpretation of latencies to cortically evoked responses as being normal or abnormal is a detailed description of the conditions under which the responses have been obtained. Additionally the individual conduction distances along the central and peripheral motor pathways have to be taken into account (see Fig. 5). Furthermore it is shown that the combination of cortex stimulation and stimulation on spinal level with the aim of a fractionated determination of central motor conduction velocities suffers from several limitations. The main limitation arises from the observation that the excited parts of the motor system are non-congruent (see Fig. 6). Isolated high-cervical tract stimulation exciting motoneurones of the upper extremity frequently could not be performed since the excitation threshold of the motor roots is much lower than that of the descending motor tracts (see Fig. 6 and 7).

Body Height↗
PubMed1987

[Gas chromatographic determination of nitroglycerin in human plasma].

A selective and sensitive method for the determination of nitroglycerin in human plasma is described. The drug and 1,3-dinitrobenzene as internal standard were extracted from plasma with n-hexane followed by a concentration step. A further cleaning of extract is not necessary. Measurements are made by GLC on a packed OV-17/QF-1 column using electron capture detection. The standard curve for the determination of nitroglycerin was linear over the concentration range from 0.2 to 30 ng/ml plasma. The detection limit was 0.1 ng/ml. The assay may be used for pharmacokinetic studies as well as drug monitoring in the clinical laboratory.

Chromatography, Gas↗
PubMed1987

[Postoperatively developing serratus paresis as a legal problem].

It is demonstrated in five exemplary cases that a neuralgic amyotrophy with particular involvement of the long thoracic nerve was the cause of a postoperative serratus paresis. In any case liability claims, it is essential for an expert's opinion on postoperative serratus paresis to differentiate this pathology from intraoperative injuries caused by pressure. Above all the interval between operation and the first manifestation of symptoms, as well as the development of distinct pain count against an intraoperative plexus lesion.

Adult↗
PubMed1986

Aspects of speech motor control: programing of repetitive versus non-repetitive speech.

The aim of the present study was to investigate whether time to program repetitive speech movements (RS) would be distinct from time to program non-repetitive speech movements (NRS) when the length of sequences is kept constant. Using an oral reading task, latencies for the initiation of RS and NRS were measured under two conditions which allowed delineation of the time necessary for perceptual processing separated from actual motor programing. The results show that latencies for NRS were significantly longer than for RS, indicating that the nature of an utterance, not simply its length, is a determinant of program complexity.

Adult↗
PubMed1986

Simple and complex movements in a patient with infarction of the right supplementary motor area.

The role played by the supplementary motor area (SMA) in the higher-level organization of motor behaviour (motor programming) has been highlighted by the study of cerebral blood flow during voluntary movements in normal humans. We present a detailed physiological investigation from a patient with a right SMA lesion and show that the right SMA plays a role in programming simultaneous and sequential movements in both arms, though the contralateral arm was the more severely impaired. In addition, we obtained evidence to suggest that the precentral motor cortex may be more responsive to peripheral perturbations when the modulating influence of the SMA is absent. In view of the similarity of the physiological findings in this subject to those in patients with Parkinson's disease, we suggest that the defect of motor programming in Parkinson's disease is likely to reflect functional deafferentation of the SMA.

Aged↗
PubMed1986

Motor strategies involved in the performance of sequential movements.

The present study analyses the strategies adopted by normal subjects when they are asked to make two separate movements as rapidly as possible one after the other. Five subjects performed the following sequential movements in their own time. 1) Squeeze an isometric force transducer between fingers and thumb to a force of 30 N and then flex the elbow of the same arm through 15 degrees. 2) Squeeze the transducer with one hand and then flex the elbow of the other arm. 3) Perform an isotonic opposition of finger and thumb and then flex the elbow of the same arm. 4) First flex the elbow through 15, 30 or 45 degrees and then squeeze the transducer. 5) Flex and then extend the elbow as rapidly as possible. In tasks 1-4 there was no correlation between the times taken to complete the two separate components of the sequence. Because of this we suggest that the two movements remained under the control of two separate motor programmes. In contrast, in task 5, the times taken for the two components were correlated and hence we suggest that in this case a single programme was used to perform the sequence. In tasks 1-3, in which the mean duration of the first movement was some 135-162 ms, there was a mean pause of about 85 ms before the start of the second movement. Subjects tended to chose a minimum inter-onset latency between the start of the first and the start of the second movement of a sequence of some 230 ms. The reason for this appeared to be that if subjects were encouraged to decrease their inter-onset latencies to less than 200 ms, the speed of the second movement decreased sharply. However, if the duration of the first movement was prolonged as in task 4, the second movement could be delayed, although there now was little or no pause between the two movements. We conclude that when a single motor programme is run, it is followed by a "relative refractory period". If a second programme is run within this period, it cannot be executed without loss of speed. Switching from one motor programme to another is achieved with an optimal minimum delay of 200 ms. Sequential movements which are controlled by a single programme do not share this limitation.

Adult↗
PubMed1986

Performance of simultaneous movements in patients with Parkinson's disease.

Ten right-handed patients with Parkinson's disease and 9 normal subjects performed five different types of movements as rapidly as possible in their own time: isotonic elbow flexion through an angle of 15 deg ('flex'); isometric squeezing of a force transducer between thumb and fingers ('squeeze'); isotonic finger flexion ('cut'); simultaneous performance of both 'flex' and 'squeeze'; simultaneous performance of 'flex' and 'cut'. The patients performed the separate movements of 'flex', 'squeeze' and 'cut' more slowly than normals. However, a more striking deficit was seen when a 'flex' and a 'squeeze' had to be performed at the same time, and with the same arm. There was an additional increase in movement times over and above that seen in the separate movements alone. If the patients used both arms ('flex' with the right, 'squeeze' with the left), rather than one, or when a 'flex' and a 'cut' had to be combined in the same arm, only a slight increase in movement times was observed. In normals, however, the speed of individual movements of 'flex', 'squeeze' or 'cut' was the same irrespective of whether they were performed separately or simultaneously. In any one subject, movement times for the separate components of 'flex' and 'squeeze' varied independently during the performance of the simultaneous movement. Because they remain independent, we suggest that when 'flex' and 'squeeze' are performed at the same time, two separate motor programmes are superimposed to produce the combined movement. In Parkinson's disease there may be a deficit in superimposing two separate motor programmes which leads to the pronounced slowness of simultaneous movements with the same arm. Comparison of movement times for a 'flex' (but not for a 'squeeze') in the separate and simultaneous movements showed that the degree of clinical akinesia was more closely related to the additional slowness in simultaneous movements than to the slowness seen when the movements were performed separately. The degree of disturbance in superimposing separate motor programmes may determine the amount of clinical akinesia in patients with Parkinson's disease.

Adult↗
PubMed1986

Associated postural adjustments in Parkinson's disease.

Postural activity in muscles of the back and legs associated with voluntary forward elevation of the arm at the shoulder with the subject standing was examined in 14 patients with Parkinson's disease and nine normal individuals. The time of onset of EMG activity in each of the postural muscles, relative to the onset of activity in the prime mover, was the same for both patient and normal groups and did not depend on load. The amplitude of the EMG bursts and their frequency of occurrence, was less in patients off drug treatment and immobile, than when mobile on therapy. We conclude that the timing of associated postural adjustments is normal in Parkinson's disease, although their size may be decreased.

Adult↗