[Somatosensory potentials evoked in patients with epilepsy recorded from the scalp and from the exposed cortex during surgery]. / Somatosensoryczne potencjaly wywolane u chorych na padaczke rejestrowane z powierzchni czaszki i bezposrednio z powierzchni kory mózgowej w czasie operacji.

Somatosensory evoked potentials (SEP) were recorded from the scalp in 47 patients and intraoperatively from the exposed cortex in 30 persons with various forms of focal epilepsy. SEP from stimulation of the median nerve were recorded from the standard derivations: F3, F4, C3, C4, T3, T4, P3, P4 and/or electrodes placed on the exposed cortex. Primary cortical negative (N20) and positive (P20) responses were analyzed. Surface recordings were normal in majority of cases (79%). The most common abnormality was the lack of cortical waves in the damaged area (mostly frontal region) or the absence of cortical responses in the whole hemisphere when central area was involved. Comparing cortical responses obtained before and during operation we found that they were similar (polarization, latency) in the majority of cases there was no response before and intraoperatively. SEP are primarily influenced by organic brain damage symptoms, but not by functional brain changes.

[Preoperative and intraoperative studies of evoked potentials in patients with spinal cord injury]. / Przed- i sródoperacyjne badanie potencjalów wywolanych u chorych z uszkodzeniem rdzenia.

Preoperative recording of evoked potentials after stimulation of the tibial nerve was followed by similar intraoperative recording in 6 patients with cauda and conus terminalis tumours and 2 patients with intervertebral disc prolapse at lumbar level. The shape and latency of these potentials were sensitive indicators of the level and degree of damage to the nervous elements in this area. The selectivity of the method was significantly higher during intraoperative recording. Monitoring of these potentials may serve for control of the integrity of sensory pathways during neurosurgical interventions.

[Somatosensory potentials evoked by stimulation of the median nerves recorded during the operation from the surface of the cerebral cortex in patients with temporal lobe epilepsy]. / Somatosensoryczne potencjaly wywolane draznieniem nerwów posrodkowych rejestrowane sródoperacyjnie z powierzchni kory mózgowej u chorych z padaczka skroniowa.

Somatosensory evoked potentials obtained by stimulation of the median nerve were analysed. The potentials were recorded from 237 points of exposed cortex in 34 patients with temporal lobe epilepsy with epileptogenic focus in the left lobe in 17 cases, and in the right lobe in 17 cases. Only N 20 and P 20 responses were analysed, considering potentials with amplitude above 0.3 uV. No response was obtained from 40.7% of points on the right side, and from 48.7% points on the left. On the right side negative potentials prevailed (56.8%) and on the left side positive potentials were more frequent (32.8%). A characteristic feature of the recorded potentials was their low amplitude and shorter latency of the positive deflection in which they differed from the potentials evoked from the primary sensorimotor cortical representation of the hand. The authors put forward the hypothesis that the recorded potentials are generated by secondary sensory areas and sensory representation in the external cortex of the temporal lobes.