When muscle fibers are stimulated in the distal portion of the human biceps brachii, far enough from the end-plate region, a discrete single fiber activity can be picked up proximally by means of a selective recording electrode. The distally evoked potentials show a linear relationship between latency and distance and can be recorded also in curarized patients. The risk of stimulating the intramuscular nerve endings is remote and, when it occasionally happens, the indirectly evoked muscle activity can be distinguished from the direct one. As direct muscle stimulation is feasible and safe, propagation velocity along single fibers can be determined in situ over a long distance. The results obtained in 50 normal subjects are presented.

We studied 58 patients with partial or generalized epilepsy who had transcranial magnetic stimulation (TMS) of the brain motor regions. Short-term monitoring disclosed that the stimulation did not provoke seizures or EEG changes in any patient. Long-term follow-up disclosed that the epileptic condition was not made worse by TMS. TMS, as currently used for monitoring conduction in central motor pathways, does not induce seizures in drug-treated epileptic patients.

ObjectiveThe aim of this study was to investigate whether Transcranial Magnetic Stimulation (TMS) applied over the medial line of the scalp affects the subjective perception of continuous pain induced by means of electric stimulation. In addition, we wanted to identify the point of stimulation where this effect was maximum.MethodsSuperficial electrical stimulation was used to induce continuous pain on the dominant hand. At the beginning of the experiment we reached a pain rating of 5 on an 11-point numeric rating scale (NRS; 0 = no pain and 10 = maximum tolerable pain) for each subject by setting individually the current intensity. The TMS (five pulses at increasing intensities) was applied on 5 equidistant points (one per session) over the medial line of the scalp in 13 healthy volunteers using a double-cone coil to stimulate underlying parts of the brain cortex. In every experimental session the painful stimulation lasted 45 minutes, during which pain and distress intensities NRS were recorded continuously. We calculated the effect of adaptation and the immediate effect of the TMS stimulation for all locations. Additionally, an ALE (Activation Likelihood Estimation) meta-analysis was performed to compare our results with the neuroimaging literature on subjective pain rating.ResultsTMS stimulation temporarily decreased the pain ratings, and pain adaptation was suppressed when applying the TMS over the FCz site on the scalp. No effect was found for distress ratings.ConclusionsThe present data suggest that the medial cortex in proximity of the cingulated gyrus has a causal role in adaptation mechanisms and in processing ongoing pain and subjective sensation of pain intensity.

Plasma levels of carbamazepine, phenytoin and phenobarbital were monitored weekly over a period of 9 weeks in 20 epileptic patients unresponsive to treatment. No attempts were made to modify phenytoin and/or phenobarbital plasma levels; emphasis was on achieving carbamazepine plasma levels of 4 to 10 mug per milliliter. A remarkable drop in seizure frequency was attained within 2 to 3 weeks of monitoring, with carbamazepine plasma and concentrations within the desired range. Children disposed of the drug faster than adults. No effects of phenytoin and phenobarbital on carbamazepine plasma levels could be observed, while phenobarbital on carbamazepine plasma levels fluctuated remarkably without any relationship to carbamazepine levels. Transient leukopenia was present in most of the patients, while a significant reversible drop in red blood cells was observed in eight patients. The data reported confirm that with a careful monitoring of drug plasma levels, carbamazepine may exert a definite passive effect on seizure frequency in epileptic patients poorly responsive to therapy.

No abstract