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Biomedical subjects

B Conrad

Publications and source records attributed to B Conrad.

At least 145 records · Page 8Linked to original sources
PubMed1990

[Extensive, continuous fasciculations of the lower leg as an isolated symptom--a clinical and electromyography follow-up].

10 patients suffering from a widespread continuous fasciculation of the lower extremities without any other neurological signs and symptoms are presented. A follow up study of 6 of these patients could be done. The fasciculation potentials were polyphasic with changing shape from discharge to discharge and appeared irregularly in most of the muscles of the legs. In 5 patients no change of clinical and neurophysiological signs could be detected over the period of observation, whereas in one patient a sensory polyneuropathy was evident in course of time. The findings illustrate that a state of widespread continuous fasciculations without other signs and symptoms is not predicative for the development of a amyotrophic lateral sclerosis.

Adult↗
PubMed1990

[Propofol infusion for sedation in regional anesthesia. A comparison with midazolam].

50 non-premedicated ASA class I or II patients were allocated randomly into two groups and received either a variable infusion of propofol or midazolam for sedation during orthopaedic surgery with regional blockade. To achieve a well-sedated patient with eyes closed and able to follow commands, the dose requirements for propofol were 1.25 mg/kg +/- 0.5 as a loading dose followed by a mean infusion rate of 3.17 mg kg-1 h-1 +/- 1.4 and for midazolam 0.073 mg/kg +/-0.02 and 0.074 mg kg-1 h-1 +/- 0.14. Steady-state plasma concentrations of propofol averaged 1.23 micrograms/kg +/- 0.75 and of midazolam 134 ng/ml +/- 62. Recovery was significantly shorter for propofol: 3.42 +/- 2.5 versus 8.05 min +/6.2 for midazolam. Perioperative cooperation was similar in both groups providing good or excellent conditions in 76% with propofol and in 52% with midazolam. 2h after discontinuation of the infusion 92% of the propofol patients were alert, while 36% of the midazolam were sleeping again. Cardiovascular effects of both drugs were minimal; however significant respiratory depression and/or airway obstruction developed in both groups (propofol 48%, midazolam 52%) requiring therapeutic intervention. Additional undesirable effects were: severe cough (propofol 40%, midazolam 20%), inadvertent movements (propofol 36%, midazolam 24%), confusion (propofol 24%, midazolam 20%), euphoria (propofol 44%), pain on injection (propofol 32%). The results of the study indicate that both drugs are useful and controllable sedative agents for surgery under regional anaesthesia, provided that measures for continuous monitoring of respiration and emergency care are guaranteed.

Anesthesia, Epidural↗
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

Dynamics of regional cerebral blood flow for various visual stimuli.

Isotope tracer methods for measuring regional cerebral blood flow or metabolism do not provide data on the dynamics of the fast adjustment of local cerebral blood flow. Measuring intracranial flow patterns of the posterior cerebral artery by means or 2 MHz pulsed transcranial Doppler ultrasonography demonstrated that detailed dynamic effects of various visual patterns on local cerebral perfusion can be recorded, and that visual stimuli of different complexity as well as the strategy of stimulus perception cause distinct flow velocity changes in the occipital cortex involved in information processing. This type of on--line analysis may become a powerful tool for detecting fast autoregulatory mechanisms in relation to purely functional cerebral changes.

Adolescent↗
PubMed1989

Decay and recovery of the stapedial reflex by prolonged stimulation in the diagnosis of myasthenia gravis.

The decay and recovery of stapedial reflex amplitude was investigated in 19 patients with myasthenia gravis and 30 control subjects. In 9 untreated patients the amplitude was reduced to less than 10% of the initial amplitude following continuous stimulation for 120 s, whereas the maximum decay in the control subjects was only 50%. In the group of treated patients the reflex decay showed individual variations. The rate of recovery after prolonged stimulation (5 min) was slower in the patient group, especially within the first 30 s of recovery. With increasing age, the rate of decay rose in the patient group as well as in the control group. The technical parameters necessary for obtaining information of clear diagnostic value are indicated, with which it was shown that the continuous prolonged stimulation of the stapedial muscle is a practical and valid method for the evaluation of patients with myasthenia gravis.

Adolescent↗
PubMed1989

Effect of cannabinoids on spasticity and ataxia in multiple sclerosis.

The chronic motor handicaps of a 30-year-old multiple sclerosis patient acutely improved while he smoked a marihuana cigarette. This effect was quantitatively assessed by means of clinical rating, electromyographic investigation of the leg flexor reflexes and electromagnetic recording of the hand action tremor. It is concluded that cannabinoids may have powerful beneficial effects on both spasticity and ataxia that warrant further evaluation.

Adult↗
PubMed1989

The role of short-term visuo-spatial memory in control of rapid multi-joint prehensive movements.

How memorized visuo-spatial information influences motor control and whether this information is able to replace the feedback processing in cases of visual deprivation was studied using an unrestrained finger- and hand-movement paradigm. Nineteen right-handed subjects were asked to grasp and lift a small block with the index finger and thumb of the right hand, as quickly as possible. The efficiency of motor performance was analysed by measuring the grasping time derived from tangential velocity profiles of the fingertips. The data revealed significantly shorter grasping times under continuous visual guidance than during blind grasping. Grasping times increased under conditions with stepwise prolongation of visual deprivation time prior to the movement onset. The results support the general concept that within the first seconds of visual deprivation, stored visuo-spatial information can partly compensate for the lack of continuous visual feedback.

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

Transcranial magnetic stimulation of the human brain: responses in muscles supplied by cranial nerves.

The present investigation demonstrates that time-varying magnetic fields induced over the skull elicit distinct types of responses in muscles supplied by the cranial nerves both on the ipsilateral and the contralateral side. When the center of the copper coil was positioned 4 cm lateral to the vertex on a line from the vertex to the external auditory meatus, bilateral responses in the masseter, orbicularis oculi, mentalis, and sternocleidomastoideus muscles with a delay of about 10 to 14 ms after the stimulus occurred. Similar to the transcranially evoked muscle responses in hand muscles, the responses in the cranial muscles can be influenced in latency and amplitude by background excitation. It is concluded that these responses are induced by excitation of the face-associated motor cortex followed by multiple I-waves in the corticonuclear tract with both ipsilateral and contralateral projections to the corresponding motoneurones. Additionally, at higher stimulation strengths "short-latency" ipsilateral responses in muscles supplied by the trigeminal, facial, and accessory nerves occurred which we suggest are induced by direct stimulation of the peripheral cranial nerves in their intracisternal course. The present study confirms the bilateral projection of corticonuclear tracts in awake unanesthetised human subjects which has been observed by electrical stimulation on the exposed cortex during surgical procedures already decades ago. The present investigation will serve as a basis for the assessment of pathophysiological mechanisms involving the corticonuclear system or the peripheral cranial nerves in their proximal parts in awake humans.

Adult↗
PubMed1988

Evaluation of intracranial pressure from transcranial Doppler studies in cerebral disease.

The extent to which estimations of intracranial pressure can be derived from intracranial flow patterns was studied. The blood flow velocity in the middle cerebral artery was recorded with the EME TC 2-64 transcranial Doppler (TCD) device in 26 patients suffering from various severe cerebral diseases. Simultaneously the mean intracranial pressure (ICP) was measured by means of an epidural device. Arterial carbon-dioxide tensions were monitored by blood gas analysis. In all patients it was observed that the middle cerebral artery flow patterns changed distinctly when the ICP increased; these changes were distinguished by a decrease of the mean flow velocity and an increase of the Pourcelot index. A good correlation between the ICP and the flow parameters (especially the product mean systemic arterial pressure x Pourcelot index/mean flow velocity) was found in a select group of 13 patients, in whom comparable initial conditions existed and in whom additional parameters influencing the TCD recordings could be kept constant (r = 0.873; P less than 0.001).

Adult↗
PubMed1988

Complex repetitive discharges in the iliopsoas muscle.

A prospective electromyographic investigation of lower limb muscles in patients with different neurogenic disorders showed that complex repetitive discharges (CRD) were observed predominantly and often only in the iliopsoas muscle. Analysis of the EMG findings in acute and chronic lesions shows that CRD are a feature of a chronic proximal motor axon lesion. Furthermore, the frequently focal occurrence of CRD in the iliopsoas muscle in clinically distal diabetic polyneuropathies suggests that this muscle and its nerves represent a locus minoris resistentiae.

Acute Disease↗
PubMed1988

Analysis of muscle responses elicited by transcranial stimulation of the cortico-spinal system in man.

Anodal stimulation of the central area of the scalp can produce visible twitches of various contralateral muscles. In a number of recent reports the technique of transcranial motor stimulation in man has been used to demonstrate abnormal evoked muscle responses in various diseases affecting descending motor pathways. The present paper deals with the systematic study of physiological influences and wave forms of these motor responses in normal subjects. It is demonstrated that they depend strongly on the stimulus strength, the placement of stimulating electrodes and the amount of background voluntary innervation. The presented normal values obtained under standardized conditions may serve as a basis for the decision on whether responses in an individual subject are abnormal or not.

Action Potentials↗
PubMed1988

Successful treatment of tardive and spontaneous dyskinesias with corticosteroids.

Three patients, 2 with tardive dyskinesia and 1 with senile chorea, were successfully treated with corticosteroids during an observation period of up to 5 months. Permanent complete relief or pronounced improvement of the dyskinesias was observed at a dosage of 5 mg prednisolone/day. Possible interactions between the putatively hyperactive dopaminergic system and corticosteroids are discussed.

Adrenal Cortex Hormones↗
PubMed1988

Transcranial Doppler ultrasonography of carotid-basilar collateral circulation in subclavian steal.

The combination of a carotid-basilar and a vertebro-vertebral collateral circulation was verified directly in a patient with a complete subclavian steal by means of transcranial Doppler ultrasonography. The patient showed permanently reversed blood flow in the basilar artery. The subclavian steal influenced the hemodynamics of the circle of Willis at rest and during functional tests of the collaterally supplied arm. Our investigation provides the first direct experimental evidence of increased blood flow velocity in the carotid artery after decompressing the collaterally supplied arm.

Arm↗
PubMed1988

[Thoraco-abdominal manifestation of diabetic neuropathy].

The differential diagnostic importance of the thoraco-abdominal manifestation of diabetic neuropathy, with special reference to the neurophysiological findings is underlined. The cases of six patients are described who suffered from severe, burning pain of varying location (area of the lower thoracic aperture, lower abdomen, scapulae, back). In all six patients pathological spontaneous activity of different location and intensity could be found bilaterally in the paravertebral muscles. Their segmental location correlated with the individual experience of pain.

Abdomen↗