Intraoperative electroneurodiagnostics (transcranial electrical motor evoked potentials) to evaluate the functional status of anterior spinal roots and spinal nerves during brachial plexus surgery.

Intradural spinal root lesions cannot be recognized by dissecting the brachial plexus and lead to ineffective surgery if they remain undetected. Therefore, patients need to undergo a diagnostic procedure to assess the intradural status of the spinal roots. Although motor recovery is the main goal of brachial plexus surgery, the techniques currently applied do not permit adequate evaluation of the anterior root. In search of an alternative, we performed intraoperative motor evoked potentials. Ninety spinal nerves in 19 patients suffering from brachial plexus lesions were dissected. Twenty-seven spinal nerves were avulsed; 8 nerves were disrupted and 17 were completely scarred, resulting in 25 stumps. Thirty-eight nerves appeared to be undamaged. On central stimulation, nerve compound action potentials were recorded from the exposed spinal nerves. Nerve compound action potentials could only be recorded from 21 stumps and from 32 apparently undamaged nerves. No recordings were obtained from 4 stumps and 7 spinal nerves in continuity. According to these findings, it is highly probable that surgery would have been insufficient in 10 spinal nerves if intraoperative motor evoked potentials had not been performed. We conclude that (1) intraoperative motor evoked potentials are an effective means for investigating the functional status of anterior motor roots and motor fibers in exposed spinal nerves, and (2) the use of motor evoked potentials should be considered during brachial plexus surgery to improve interventions.

Kinetics and disposition of fluorescein-labelled liposomes in healthy human subjects.

The in vivo kinetics and organ uptake of multilamellar liposomes have been studied in healthy volunteers. Sodium fluorescein-containing liposomes composed of equimolar amounts of egg phosphatidylocholine and cholesterol were injected into a peripheral vein in 4 healthy subjects. Blood samples collected from the femoral artery, hepatic vein and pulmonary artery, were analysed for liposomal dye content. The results, showing involvement of the reticuloendothelial system (RES) in the removal of liposomes, confirmed those previously obtained with radiolabelled preparations. Use of an innocuous liposomal marker (sodium fluorescein) and conventional vascular catheterization techniques, as employed here, may provide a reliable and clinically acceptable approach to establishing disease-induced changes in the kinetics of uptake of drug-containing liposomes by the RES, and thus help in the design of protocols for effective treatment.

[Value of ECG-telephone transmission in determining symptomatic heart-rhythm disorders]. / Wertigkeit der EKG-Telefon-Telemetrie in der Erfassung symptomatischer Herzrhythmus-Störungen.

The ECG-telephone-transmission (TTM) was used to record an ECG-strip during a typical symptomatic period in patients complaining of symptoms possibly caused by arrhythmias (palpitations, dizziness, paroxysm tachycardia, pulse irregularities; angina and dyspnea only if other reasons could be excluded). Patients complaining of syncope only were not admitted, because of the inability to make a telephone call successfully during such a symptomatic period. The ECG was transmitted to the CCU using a frequency modulation technique. In 60% of 196 patients an ECG-TTM could be achieved during a typical symptomatic period, whereas arrhythmias as cause for the symptoms could be excluded in 51 patients (26%). The remaining 66 patients (34%) demonstrated various arrhythmias ranging from simple SVPB and PVC to total AV-block and sustained VT. TTM, an easy-to-perform and cost-effective method allowed a successful ECG registration during a symptomatic period in almost two-thirds of symptomatic patients. In these patients arrhythmias could be verified or excluded as cause of the symptoms.

A 16-fold semi-microelectrode for intracortical recording of field potentials.

A 16-fold semi-microelectrode with 10 x 10 sq. microns contacts at distances of 150 microns, produced by means of thin-film technology, is described. These small dimensions are required to study the laminar electrophysiological differences within the cerebral cortex.

[The effect of tissue resistance on rheography]. / Der Einfluss des Gewebewiderstandes auf die Rheographie

Herewith a formula for the computation of the relative stroke volume in limbs is derived, taking into account the differences between the electrical resistivity of blood and tissues, respectively. In order to properly estimate the influence of this difference in resistivity, the appropriate variables were measured in 20 different persons. Results from these tests indicated that the value for tissue resistivity, on the average, was about 30% above that of the resistivity of blood. Consequently, computations of the stroke volume in limbs that neglect this essential difference in resistivity, contain a systematical error in measurement, amounting to 30%. It is the purpose of this paper to portray a method of considerably reducing this error, without the necessity--in each specific case--to measure blood resistivity.