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Biomedical subjects

G Pawłowski

Publications and source records attributed to G Pawłowski.

26 records · Page 2Linked to original sources
PubMedDate not supplied

[Effect of diazepam on somatosensory evoked potentials].

Somatosensory evoked potentials (SEP) were recorded in 15 patients with extrapyramidal disturbances after intravenous administration of 10 mg of diazepam (Relanium, Polfa). Cortical SEP were recorded before and after operations and thalamic SEP were recorded during stereotaxic interventions on thalamic nuclei VL and Vim. The results demonstrated that diazepam had a significant positive influence on the recording of SEP, eliminating muscular artifacts caused by increased muscular tonus and extrapyramidal tremor. Diazepam had no evident effect on the SEP and caused no changes of the short-latency specific cortical SEP. This effect was, however, evident on the later components of the SEP and it seemed to affect mainly the N63 wave whose amplitude was always reduced or absent. In the postoperative investigations the cortical SEP in the hemisphere operated on (contralateral to the site of stimulation) were reduced in the phase of short-latency components. In the ipsilateral hemisphere the cortical SEP remained similar to the normal ones, and after diazepam their amplitude was markedly reduced. Intraoperatively recorded thalamic SEP showed after diazepam a considerable decrease of the amplitude of all components, sometimes the curve was completely flat, including the specific phase of the potential. On the other hand, diazepam failed to extinguish cortical SEP which showed even a greater amplitude of short-latency and long-latency components than in the records obtained without this drug, with the exception of disappearing N63 component.

Adult↗
PubMedDate not supplied

[Effect of cryosurgery of the thalamic nuclei on somatosensory evoked potentials].

Somatosensory evoked potentials were recorded in two groups of patients with extrapyramidal syndromes including: 1) parkinsonian syndromes, 2) spasmodic torticollis. In the first group stereotactic lesions were produced at the borderline between VOp and Vim nuclei, and in the second group they were situated in VOa and VOi thalamic nuclei. Short-latency components of the potentials were analysed assuming that they were the specific parts of the somatosensory potential and their value was doubtless, in contrast to the late latency components. It was found that stereotaxic lesions the VOa and VOp thalamic nuclei caused no disappearance of the short-latency potentials but reduced their amplitude. In cases with oscillation potentials recorded before the operation, they disappeared after the operation and this disappearance was correlated with clinical improvement.

Adult↗
PubMedDate not supplied

[Thalamic somatosensory potentials after peripheral stimulation and cortical somatosensory potentials after electric stimulation of thalamic nuclei VOa and VOp (preliminary report)].

In patients with extrapyramidal syndromes thalamic action potentials were recorded during operations with a five-point brain electrode and in the same cases somatosensory evoked potentials were recorded from the skull. Thalamic potentials were recorded after peripheral stimulation, and evoked potentials from the skull were recorded after electrostimulation of thalamic nuclei VOa and VOp. At the thalamic level a short-latency positive-negative potential had a maximal amplitude in one only lead, which confirmed sharp projection of body surface into various thalamic nuclei. Somatosensory evoked potentials recorded from the skull in response to stimulation of thalamic nuclei were usually biphasic and stimulation of VOa and VOp nuclei gave potentials with similar configuration of phases. This confirms the divergence of the projection fibres from the thalamus to the cortex.

Adult↗
PubMedDate not supplied

[Computerized infusion test. I. The method].

Biophysical aspects and the method of the Computerized Infusion Test (CIT) developed in the Neurosurgical Clinic of the Medical Research Center, Polish Academy of Sciences, are presented. The CIT is a development of classical methods of estimating the cerebrospinal fluid outflow resistance. It is based on a clinically tested mathematical model of the intracranial pressure-volume compensating mechanisms. The CIT enables the etrapolation of the infusion curve in cases when it is impossible to reach the upper steady during the constant infusion test because of the ICP exceeding values estimated as being critical.

Computers↗
PubMedDate not supplied

[Computerized infusion test. II. Clinical use].

In 39 patients with intracranial lesions the resorption resistance was measured using an own computerized infusion test. A high usefulness of this test was demonstrated in the diagnosis of hydrocephalus and for establishing indications to ventriculocardiac valve implantation. In patients after craniocerebral injuries a rise was observed of the resorption resistance immediately after trauma in cases with subarachnoid haemorrhage. Later on, this resistance decreased gradually reaching a stable value after 1-2 years. Data obtained in the infusion test make possible establishing of optimal intracranial pressure and choice of an appropriate valve. The determination can be performed intraoperatively.

Brain Injuries↗
PubMedDate not supplied

[Effect of electric stimulation of the amygdaloid body and hippocampus on bioelectrical activity recorded from these structures and from skull surface in epilepsy].

The authors discuss the morphology of records of spontaneous and stimulated bioelectric activity in an analysis of selected 15 EEG records using electric stimulation of deep temporal structures using relatively low parameters of stimulation (optimal: 2--3 V, 50 Hz, 1 msec, duration 5 sec). Attention is called also to the fact that seizure activity is absent in leads from skull surface during long-lasting bioelectric seizure activity in deep cerebral structures. It is concluded that induction of afterdischarges and analysis of the directions of their spread may be of practical importance from the point of view of diagnosis and therapy. The authors state also that induction of bioelectric afterdischarges in deep temporal structures, particularly in the hippocampus caused in these patients no disturbances of consciousness and memory.

Action Potentials↗
PubMedDate not supplied

[Application of physiological loadings in evaluation of intracranial volume-pressure relations. II. Clinical studies].

The effects of physiological loadings (venous pressure increase, postural changes, pCO2 increase) on intracranial volume-pressure relations were studied. The standardized increase of venous outflow pressure was found to be a good test for the evaluation of CSF outflow routes. Standardized venous outflow pressure increase in Queckenstedt test seems to be especially useful.

Adult↗