Increased sympathetic activity contributes to hypertension in patients with chronic renal disease. ACE inhibition controls hypertension and decreases sympathetic hyperactivity.

No abstract

Multifocal motor neuropathy (MMN) is characterized by a slowly progressive, asymmetric weakness of the limbs without sensory loss. The arms are usually affected to a greater extent than the legs, and distal muscles more than proximal muscles. The distribution of electrophysiological abnormalities and its correlation with weak muscle groups in MMN have not been investigated systematically. The aim of the present study was to assess whether electrophysiological abnormalities have a preferential or random distribution, whether electrophysiological abnormalities in a nerve correlate with weakness in the innervated muscles, and whether these results are relevant for the development of optimal electrodiagnostic protocols. We compared the pattern of weakness and electrophysiological abnormalities in 39 patients with a lower motoneuron syndrome and a positive response to intravenous immunoglobulins. All patients underwent an extensive standardized electrophysiological examination. Electrophysiological evidence of demyelination was found more often in the nerves of the arms and was distributed randomly over lower arm, upper arm and shoulder segments. Electrophysiological evidence of axonal loss presented more frequently in longer nerves, occurring most often in the leg nerves. For the arm nerves, it is possible that the length dependence of axonal loss is due to the random distribution of demyelinating lesions that lead to axonal degeneration. Weakness was associated with features of demyelination and axonal loss in the nerves of the arm, and with features of axonal loss in leg nerves. However, a substantial number (approximately one-third) of electrophysiological abnormalities were found in nerves innervating non-weakened muscles. These results imply that in MMN, conduction block is most likely to be found in long arm nerves innervating weakened muscles, but if conduction block cannot be detected in these nerves, the electrophysiological examination should be extended to other arm nerves including those innervating non-weakened muscles.

A standardized, perceptually based description of hoarseness is of importance for clinical purposes (e.g. therapy evaluation) as well as in research on voice disorders. The reliability and relevance of perceptual parameters are investigated. The GRBAS scale parameters quite well fit the criteria: low intrajudge and interjudge variance but high intervoice variance. The best correlation between judges (0.7) is found for the overall grade of severity. Impressions of the asthenicstrained voice quality are less consistent, but still show a significant interjudge correlation. The overall grade of severity seems to be mainly determined by the component breathiness. Roughness and breathiness are negatively correlated with each other. Tonus is correlated neither with roughness nor breathiness. The GRBAS profiles significantly differ between the different pathological groups.

No abstract

The purpose of this study was to estimate the time needed to warm an extremity prior to measuring nerve conduction. In 8 normal subjects tibial and sural nerve conduction variables were measured during cooling and warming of the leg in water of 18 degrees C and 36 degrees C, respectively. During cooling, nerve conduction velocity (NCV) decreased and distal motor latency (DML), duration, and area of the compound muscle action potentials (CMAP), and compound nerve action potentials (CNAP) increased. The reverse occurred during warming. During cooling or warming the change in these variables became progressively smaller with time. The time course could therefore be described by an exponential relation, the parameters of which were determined. On the basis of these data, correlations were calculated between the skin temperature at the start of the investigation and the warming time needed to obtain a good estimate of nerve conduction variables at 36 degrees C. The use of correction factors, instead of actual warming, yielded acceptable errors only for NCV and not for the other variables.

No abstract

The conductivity of the human skull plays an important role in source localization of brain activity, because it is low as compared to other tissues in the head. The value usually taken for the conductivity of skull is questionable. In a carefully chosen procedure, in which sterility, a stable temperature, and relative humidity were guaranteed, we measured the (lumped, homogeneous) conductivity of the skull in five patients undergoing epilepsy surgery, using an extended four-point method. Twenty-eight current configurations were used, in each of which the potential due to an applied current was measured. A finite difference model, incorporating the geometry of the skull and the electrode locations, derived from CT data, was used to mimic the measurements. The conductivity values found were ranging from 32 mS/m to 80 mS/m, which is much higher than the values reported in other studies. Causes for these higher conductivity values are discussed.