Multiple A waves in Guillain-Barré syndrome.

In 13 of 14 patients with Guillain-Barré syndrome (GBS), we observed multiple A waves in at least one limb nerve on routine electroneurographic studies within 7 days after onset of symptoms. The patient without A waves had a severe axonal type of GBS with tetraplegia and almost complete loss of M responses following electrical stimulation of limb nerves. In the remaining 13 patients, on average 8 +/- 2 (mean +/- SD) A waves were present in each tibial nerve (n = 24) and 4 +/- 1 A waves in each peroneal nerve (n = 26). About half of the A waves were below 50 microV in amplitude, whereas amplitudes were higher than 120 microV in only 22 of 299 A waves. Of these A waves, 68 were not constantly elicitable. There was a significant correlation between the number of A waves up to 50 ms poststimulus and the reduction in amplitude of the compound muscle action potential when elicited with proximal compared to distal stimulation in the peroneal (n = 26, P < 0.0005; Kendall's tau) and tibial nerves (n = 24, P < 0.002). Therefore, in GBS both conduction block and A waves are presumably signs of inflammatory nerve lesions. The existence of multiple A waves soon after onset of symptoms seems to be a sensitive sign of GBS.

[The importance of 24-hour-blood pressure monitoring in hemodynamic and thromboembolism-induced cerebral infarcts]. / Die Bedeutung der 24-h-Blutdruckmessung bei hämodynamisch und thromboembolisch bedingten Hirninfarkten.

Night and day blood pressure profiles of 45 patients with cerebral infarction of hemodynamic or thromboembolic origin were assessed to detect subsequent changes of circadian blood pressure variability. The data were also analysed for a possible relationship between variability of circadian blood pressure, site of cerebral infarction and activation of the autonomic nervous system. Patients with a stroke of hemodynamic origin, when compared to a control group, manifested significantly greater variability of circadian blood pressure (diastolic: -25.2 +/- 4.5% vs. -13.8 +/- 6.5%; p < 0.005). Patients who showed the greatest decrease in vasomotor reactivity (< 40%) developed a prolonged disturbance of the blood-brain barrier. This disturbance regressed slowly only after the pathological 24-hour blood pressure profile had normalized. By way of contrast, patients with cerebral infarctions due to thromboembolic events, when compared to normal individuals, showed a distinctly decreased circadian blood pressure variability (diastolic: -5.2 +/- 6.9%). Initially 40% of these patients presented a pathological increase of nocturnal blood pressure. Circadian blood pressure variability was positively correlated with serum concentration of norepinephrine (r = 0.79; p < 0.01). Patients with a stroke affecting the insular cortex manifested an increase of nocturnal blood pressure significantly more often (66.7% vs. 11.8%; p < 0.005), indicating increased sympathetic activation. They had higher serum levels of norepinephrine (540 +/- 110 pg/ml vs. 290 +/- 178 pg/ml) as compared to patients without damage to the insula and also a significantly higher incidence of prolonged QT intervals and cardiac arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)

[Initial studies of the possibility of selective ablation of arteriosclerotic vascular changes using laser-induced shock waves]. / Erste Untersuchungen zur Möglichkeit einer selektiven Ablation arteriosklerotischer Gefässveränderungen mit Hilfe laserinduzierter Stosswellen.

We studied the effect of laser-induced shock waves in 94 arterial segments from freshly obtained autopsy material. In analogy to the well-established method of shock-wave based lithotripsy, the new principle of our treatment depends on an indirect interaction of the laser energy with the arterial wall via laser-induced mechanical shock waves (angiotripsy). We used a Nd:YAG laser, 1064 nm, 8-20 ns pulse-length to create shock waves that effected smooth craters in arteriosclerotically affected arteries. The histological examination found no thermal damage. Shock waves applied to the healthy and normal arterial wall only resulted in focal intimal ablation and in a minor loosening of the medial structures. The examination of the irrigation solution by means of a laser-guided, high-resolution analysis of the particles revealed that, in 97%, the particles created by our shock wave angiotripsy showed a diameter of less than 5 mm and an area of less than 25 mm2. Based on these first in vitro results, it seems possible to ablate arteriosclerotically affected tissue without significant damage to normal wall segments. Further in vitro and in vivo studies are required to evaluate the clinical implications of this new therapeutic approach.