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Biomedical subjects

G Pozzessere

Publications and source records attributed to G Pozzessere.

At least 37 records · Page 2Linked to original sources
PubMed1988

Early detection of neurological involvement in IDDM and NIDDM. Multimodal evoked potentials versus metabolic control.

Clarification of the extent and mechanisms of damage to the central nervous system in diabetes is a frontier of current neurological research. Our aim was to obtain ample electrophysiological documentation of possible neurological abnormalities in both insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) diabetic patients with a short duration of disease and without overt complications, taking into account metabolic control. Group 1 comprised 11 IDDM patients, and group 2 included 14 NIDDM patients treated with diet alone; the duration of disease was less than 4 yr, and no concomitant clinical complications were present. Age- and sex-matched normal subjects formed groups 3 and 4. Pattern visual evoked potentials (VEP), brain stem auditory evoked potentials (BAEP), and somatosensory evoked potentials (SEP; after the stimulation of both median and tibial nerves) were recorded in all subjects, and metabolic control was evaluated in terms of glycemia and glycosylated hemoglobin. In group 1, significant abnormalities were found in the latency values of VEP, median SEP, and tibial SEP compared with control subjects. Similar latency abnormalities were shown in group 2 for VEP, median SEP, and tibial SEP values and for wave I latency of BAEP. Glycosylated hemoglobin values were correlated with BAEP and SEP abnormalities in many patients in both groups. Furthermore, in group 2, glycemic values correlated with SEP abnormalities. We therefore conclude that neurophysiological abnormalities are present at different levels in IDDM and NIDDM patients only a few years after clinical diagnosis and before the appearance of overt complications, and these abnormalities seem to be correlated with metabolic control status.

Adult↗
PubMed1987

Prognostic value of early somatosensory evoked potentials during carotid surgery: relationship with electroencephalogram, stump pressure and clinical outcome.

The authors have reported on the prognostic value of continuous monitoring of somatosensory evoked potentials (SEP) in a survey of 25 patients who underwent carotid surgery. SEP recordings were correlated with the EEG, stump pressure (SP) values and clinical outcome. A non-cephalic reference was used for SEP recordings to allow the analysis of both subcortical and cortical components. During surgery the conduction time between SEP peaks relating to the subcortical components remained stable or showed minimum variations in all patients. During carotid clamping, SEP variations were observed in 9 out of 25 cases (36%). The application of an intraluminal shunt was accompanied by the return to normal values in 7 out of 9 patients. In the remaining two cases SEP abnormalities continued post-operatively and were accompanied by new neurological deficits. EEG changes during carotid clamping were associated with SEP modifications in 6 out of 7 cases, although they were not always correlated. Results confirm that SEP recordings provide useful data concerning the function of the CNS in anaesthetized patients and that, being sensitive to CBF changes, SEP monitoring acts as an indicator of cerebral ischaemia.

Adult↗
PubMed1987

Subacute necrotizing encephalomyelopathy (Leigh's disease): clinical correlations with computerized tomography in the diagnosis of the juvenile and adult forms.

A computerized tomography (CT) scan was performed on 6 surviving patients with a suspected diagnosis of subacute necrotizing encephalomyelopathy of the juvenile and adult forms. Bilateral low density areas were observed in the putamina in all cases. This CT pattern conformed with the characteristic pathological changes of the disease. Once the possibility of Wilson's disease or an earlier episode of acute cerebral hypoxia, syndromes which both display a similar appearance in CT, is excluded, a diagnosis of subacute necrotizing encephalomyelopathy may be considered in cases showing bilateral low density areas in the basal ganglia, especially in the putamina, and with a consistent clinical history.

Adolescent↗
PubMed1987

Event-related potentials as a tool in the evaluation of cognitive functions in young subjects through the execution of a simple task.

Event-related potentials (ERPs) were recorded in 20 student volunteers. Three recordings were performed using aural stimuli of 4,000 (rare tones) and 250 Hz. In the target recording subjects were asked to count the rare tones. Endogenous and exogenous components of ERP recordings were analyzed. During the target recording N2 and P3 components were observed at 200 ms and approximately 300 ms, respectively, in addition to N1 (100 ms) and P2 (180 ms). The N2 and P3 waves are indicative of analysis at a higher cognitive level and have been termed the 'response set'. The P3 wave appeared to be stable in all subjects and may represent a useful electrophysiological method to explore mnemonic and cognitive functions in man.

Adolescent↗
PubMed1986

Parkinson disease: electrophysiological (CNV) analysis related to pharmacological treatment.

The contingent negative variation (CNV) was studied in a group of patients with Parkinson's disease. Testing was carried out 3 times: after a pharmacological wash-out period and at 15 and 30 days after the start of treatment with L-DOPA and bromocriptine. Peak and area CNV increased significantly after each treatment. The post-imperative negative variation (PINV) was observed in 6 out of 10 patients. The correlation found between electrophysiological functioning (CNV) measures and pharmacological treatment supports the view that dopaminergic brain activity mediates the generation of the slow negative event-related brain potentials.

Bromocriptine↗
PubMed1985

Pain, anxiety, and contingent negative variation: a clinical and pharmacological study.

Contingent negative variation (CNV) behavior was studied in 16 volunteers who were suffering from spontaneous recurrent pain syndromes (idiopathic trigeminal neuralgia, classic migraine). The subjects were divided into two groups, "more anxious" and "less anxious," based on psychometric tests (MMPI and STAI X2). The CNV recordings were carried out, respectively, in basal resting state, during an episode of pain, while under anxiolytic treatment, and lastly, during an episode of pain while under anxiolytic therapy. CNV voltage decrease and frequent appearance of postimperative negative variation (PINV) were observed when pain was present during the recording session. These phenomena were more marked when the pain was accompanied by a greater degree of anxiety. Finally, our results suggest that this slow evoked potential is sensitive to various degrees of anxiety and to pain perception in man, making it useful in the investigation of pain as a complex sensation.

Adult↗
PubMed1985

Pattern visual evoked potentials and flash electroretinogram in clinically definite multiple sclerosis.

The authors have studied, by means of pattern visual evoked potential (VEP) and flash electroretinogram (ERG) recordings, a group of 15 patients affected by definite multiple sclerosis. All of the subjects examined presented a clinical history indicating involvement of the visual pathways; VEPs were altered in a high percentage of eyes examined (93.3%), while a lower percentage of abnormal ERGs was seen (20% of eyes examined). The only type of ERG alteration found consisted of a pathologic b wave voltage increase, observed mainly with red flash stimuli. This finding could be attributed to an involvement of centrifugal optic nerve fibers having inhibitory functions on retinal cells.

Adult↗
PubMed1984

Prognostic evaluation of brainstem hematomas: the role of CT scan and brainstem auditory evoked potentials.

6 cases of brainstem hematoma were studied utilizing CT scan and brainstem auditory evoked potential (BAEP) recordings. CT scan did not contribute to an early discrimination between primary and secondary hematomas. Size of the hematoma and the presence of blood in the CSF did not represent evident signs in differentiating benign from unfavourable brainstem hematomas or hemorrhages. BAEP recordings showed the presence of electrophysiological anomalies at the level of the lesion, demonstrating that bleeding as well as tumor in the brainstem can provoke a focal damage.

Adult↗
PubMed1984

Electrophysiological (CNV) analysis of personality traits under stress.

Contingent negative variation (CNV) recordings were performed in 55 healthy volunteers under stress condition (experimentally induced pain). A total of 20 subjects were included in the control group (no painful administration). In the tested group (n = 35) the painful stimulus was delivered before S1, between S2 and S1, and before S2. In the control group there were no changes in CNV parameters. Conversely, among the tested group a positive correlation was found between CNV values (whenever the painful stimulus was administered before S1 as well as before S2) and the highest scores in the State Trait Anxiety Inventory X 2 test. In addition, all individuals displayed the appearance of a positive deflection with a latency of about 300 ms from S2 when the experimental stress was given before S2. Furthermore, the postimperative negative variation (PINV) appeared in 13 out of 35 subjects. There was a strong correlation between the latter electrophysiological phenomenon and the Nowlis test. Our findings suggest that CNV study is useful for the investigation of personality traits in human beings under stress conditions.

Adult↗
PubMed1983

Subjective posttraumatic syndrome. A comparison of visual and brain stem auditory evoked responses.

Evoked responses testing including pattern visual evoked potentials (VEPs) and brain stem auditory evoked potentials (BAEPs) were performed in 57 subjects suffering from subjective posttraumatic syndrome (SPTS). 36 of them had loss of consciousness after head injury. Abnormalities were found in 12 subjects out of 57 (21%). In addition, the pathological findings by percentage were: 25% in subjects who had loss of consciousness after head injury (9 cases out of 36) and 14% in subjects without loss of consciousness (3 cases out of 21). Evoked response alterations were more frequent in subjects with frontal and/or occipital trauma; BAEP abnormalities were found to be more frequent than VEPs. Our findings suggest that evoked responses testing could be a useful noninvasive technique to evidence an organic dysfunction of CNS in some subjects with SPTS.

Adult↗
PubMed1982

Electrophysiological measures (CNV--EEG) and nitrous oxide at low doses in man.

Nitrous oxide (N2O) is a widely used inhalational anesthetic gas, but its exact mode of action and its distribution in the CNS are not yet well known. The aim of this research was to study the effects of N2O at low doses (10 percent) in the CNS of humans. Five healthy volunteers were tested. Contingent Negative Variation (CNV), Reaction time (RT) and quantified EEG recordings were taken while subjects were breathing air and then N2O. A significant reduction of the post-imperative positive CNV components during N2O inhalation was observed; no changes in EEG power spectrum and RT values were seen. These results could be consistent with an early N2O interference with processes underlying CNV resolution, while vigilance and attention were still maintained.

Adult↗
PubMed1982

[Quantified EEG and CNV changes during inhalation of nitrous oxide].

The present study constitutes an approach to the action mechanisms of nitrous oxide (N2O) by assessing both the subjective effects induced by the inhalation of this anaesthetic gas, and their electrophysiological correlates, i.e., spontaneous EEG, analyzed by a Fourier algorithm, AEP and CNV. The experiment was conducted single blind in 9 volunteers under 3 recording conditions: inhalation of air, of a mixture of 25% N2O--75% O2, and of a mixture of 50% N2O--50% O2. A latin-square design was used. Polymorphic effects of N2O were evidenced on behaviour and on CNS: some of the behavioural manifestations could evoke a depression of SNC: muscle relaxation with difficulty of motor initiation, psychomotor slowing, slower EEG with diminution of the percent alpha component and increase in the percent theta and delta, loss of amplitude of both exogenous (N1) and endogenous (P300) components of the AEP. Conversely, other manifestations were observed that are compatible with an activation of the CNS: increase of sensory perceptions, appearance of perceptual illusions, maintenance of a high CNV amplitude and lengthening of its duration. This dual effect of N2O suggests a dissociative action at the different levels of the CNS.

Adult↗
PubMed1982

[Positron tomographic study of the behavior of 13N-labeled nitrous oxide in the human brain].

The synthesis of 13N-labelled nitrous oxide was made following NICKLES' method. After a partial denitrogenisation by breathing pure oxygen for 3 min, the subject inhaled a bolus of 13N-labelled nitrous oxide diluted in 2 l of oxygen (a mixture of 5% 13N2O and 95% O2). After an apnea of 30 sec the subject began to breathe in a closed respiratory system containing a mixture of 10% N2O and 90% O2. Eight images of the brain taken at level OM + 3 in 4 subjects showed an important uptake in the cerebellum and in the frontal and temporal cortex. Six min after inhalation of the bolus, the radioactivity in the cerebellum showed a clear decrease, whereas little decrease was observed in the frontal cortex and only a slight decrease in the temporal cortex. In order to suppress the activity due to the vascular comportment, an experiment was performed under the same conditions as the previous one, but using sodium pyrophosphate containing tin and 25 mCi of Tc-99m pertechnetate. The correction factors vary from 0.394 to 0.894 depending on the R.O.I. The activity curves after correction showed a predominance in the frontal cortex. It can therefore be concluded that some specific zones of the brain are receptive to N2O and in particular the frontal cortex. These results were compared with the data obtained from the electrophysiological recording of the frontal region of the brain (C.N.V.: Contingent Negative Variation).

Adult↗
PubMedDate not supplied

Early complications in type 1 diabetes: central nervous system alterations preceded kidney abnormalities.

Abnormalities of the central nervous system (CNS), as discerned by neuroelectrophysiological studies, and an impaired, charge-related, differential filtration of protein at kidney level as evaluated by selective protein clearance, have recently been shown in diabetes of short duration and without any apparent complication. In order to explore the time of appearance and possible correlations, CNS and kidney abnormalities have been evaluated in parallel both in short-term and long-standing type 1 diabetic subjects. Two groups of patients were studied: Group 1 (no. 15), with no previously known clinical sign of complications and less than 5 years from diagnosis; Group 2 (no. 15) with more than 10 years of disease and with or without clinical signs of diabetic complications. Twenty age and sex comparable normal subjects were included in the study (Group 3). Short-latency multimodal evoked potentials (visual-VEP, brainstem auditory-BAEP, median and tibial somatosensory m- and t-SEP) and charge and/or size selective protein clearances (albumin, anionic immunoglobulins, neutral/cationic immunoglobulins) were evaluated. In Group 1, 27% of patients showed neurophysiological abnormalities (P < 0.05 vs. Group 3) while one showed proteinuria. In Group 2, 60% of patients showed electrophysiological changes (P < 0.0001 vs. Group 3) while 67% showed abnormal charge or size selective proteinuria (P < 0.0001 vs. controls) with a significant association between the abnormalities of CNS and of charge selective proteinuria (P < 0.05). Thus, CNS abnormalities may be detected even in patients with diabetes of short duration and are later associated with subclinical kidney abnormalities. These findings stress the value of the multimodal evoked potential evaluation as a sensitive and early diagnostic approach to the study of diabetic complications.

Adult↗
PubMedDate not supplied

Monitoring of somatosensory evoked potentials in cerebral ischemia: an experimental model.

We have studied Mongolian gerbils using somatosensory evoked potentials (SEP) recordings before, during and after an ischemic event. In six experimental animals, cerebral ischemia was reproduced by clamping both carotid arteries for ten minutes. Two recordings were made during this period at 4' and 8'. An additional four recordings were made after removal of the clamp at 4', 8', 12' and 20'. Four animals were utilized as a control group, and were subjected to the identical experimental protocol, with the exclusion of carotid artery clamping. During ischemia we observed an evident alteration of the SEP recordings in the experimental animals, and a more or less rapid recovery during the post-ischemic period. This experimental model may be useful for the monitoring and the evaluation of the evolution of cerebro-vascular damage during the post-ischemic period.

Animals↗