Evoked potentials in patients with non-neurological Wilson's disease.

In Wilson's disease neurological manifestations result from the damage in the basal ganglia, even if a widespread degeneration of the brain occurs. The few studies performed using evoked potentials with the aim of identifying subclinical dysfunction in the three major sensory pathways have never shown abnormalities in patients without neurological manifestations. To verify this observation we studied 12 patients suffering from Wilson's disease in a pre-neurological stage by using pattern visual evoked potentials (VEPs), somatosensory evoked potentials (SEPs) to median nerve stimulation and brainstem auditory evoked potentials (BAEPs). Four of these patients had not yet been treated with penicillamine or trientine (triethylenetetramine dihydrochloride), while the remaining 8 patients were on treatment for at least 1 year. In 3 patients of this second group and in 1 patient of the first group we observed a significant (3 SD over the mean) increase in P100 wave latency, while SEPs and BAEPs were found to be abnormal in only 1 patient, respectively.

Low voltage bifocal electrical stimulation of the motor cortex.

Currently, non-invasive cerebral motor area stimulation is performed by magnetic or high voltage bifocal electrical stimulation. These techniques require non-conventional stimulators. The present study, performed on 28 normal subjects between 18 and 73 years of age, was designed to standardize a method of bifocal stimulation of motor cortex which uses low voltage conventional stimulators and therefore can be routinely used in electrophysiological laboratories. The hand motor area was stimulated by surface electrodes applied in Cz (cathode) and 8 cm lateral on the bimetal line (anode). Under the electrodes infiltration with Xylocaine 2% was made. Duration and intensity of the rectangular pulses were 150 microseconds and 200-250 Volts, respectively. The motor evoked potential (MEP) was recorded from opponens pollicis muscle by concentric needle electrodes and a slight voluntary contraction was made to facilitate the motor response. MEP latency and central motor conduction time (CMCT) were calculated for both sides. A significant relation with age and height in normal subjects was found only for the MEP latency. We computed also the equations expressing the normal variability between the sides of MEP latency and of CMCT.

Interaction of tonic labyrinth and neck reflexes in man.

Interaction of tonic labyrinth and neck reflexes was studied in 3 healthy volunteers by analyzing changes in Soleus H-Reflex (SHR) area in relation to both lateral tiltings and neck rotations. By using a Kermath chair each subject was tilted laterally from the vertical to the left and to the right up 15 degrees in steps of 5 degrees and at the same time the longitudinal body axis, keeping the head fixed, was rotated to the right and to the left up to 15 degrees in steps of 5 degrees. All combinations of lateral tiltings and neck rotations were tested. Each test position was followed by a return to 0 degree for both rotation and tilting (control position). Twelve H-reflexes of right soleus muscle were recorded in each test and control position and the changes in RSHR area were expressed as percentage variations from the mean value absorbed in the pretest and post-test control position. Our data indicate that in man, as in animals, labyrinth and neck reflexes act in the opposite direction, and that in the static condition their contribution to postural stabilization is equal.