Biomedical subjects

M V Meraviglia

Publications and source records attributed to M V Meraviglia.

3 recordsLinked to original sources

PubMed2005

Electroencephalographic background desynchronization during cerebral blood flow reduction.

OBJECTIVE: The aim of this study is to evaluate the usefulness of a spectral function detecting cerebral hypoperfusion. METHODS: Continuous electroencephalographic monitoring was employed during 47 consecutive carotid endarterectomies. Patients were assigned to 3 different groups according to the entity of electroencephalographic changes during carotid clamping (major changes: group A; moderate changes: group B; no change: group C). The desynchronization function, indicating the reduction of the 8-15 Hz band power, and the desynchronization index were calculated. RESULTS: Group A function decreased within 20s from clamping, with a constant slope (7.14). Desynchronization indexes were: 76.85% (group A), 40.23% (group B) and 15.29% (group C). Difference among groups was statistically significant (P < 0.0001). A case of syncope due to asystole is also reported, showing the same pattern in the descending phase of the function. CONCLUSIONS: The stereotyped time course of the desynchronization function describes the cerebral reaction to significant blood flow reduction. Values of desynchronization index exceeding 65% seem to correctly detect patients with cerebral hypoxic risk. SIGNIFICANCE: The analysis of the 8-15 Hz band desynchronization is helpful in the evaluation of cerebral hypoperfusion during carotid endarterectomy. This method could be employed in monitoring different clinical situations of ischemia.

Aged↗

PubMed2000

Computer-assisted EEG monitoring during carotid endarterectomy.

The purpose of this study was to develop a reliable method of EEG analysis during carotid endarterectomy. EEGs of 104 patients under general anesthesia were processed by three different methods: a) "on-line" visual analysis during surgery, b) "off-line" visual analysis in laboratory, and c) computer analysis. To identify pathological EEGs, variability and asymmetry indexes of the 0.5-3.5 Hz and 8-15 Hz bands, absolute power and variability indexes of spectral edge frequency (SEF), and main dominant frequency were evaluated. On-line visual analysis showed clamp-related modifications in 29 EEGs (27.9%). Off-line visual analysis detected 24 pathological EEGs (23.1%): 18 with major changes and 6 with moderate changes. Computer analysis showed 21 EEGs (20.19%) with at least one altered index and 7 (6.7%) with altered variability for both SEF and 8-15 Hz power. The statistical analysis was significant for SEF variability and for 8-15 Hz power variability and asymmetry (P < 0.0001, analysis of variance test). While SEF and 8-15 Hz power variability did not appear influenced by anesthesia and single electrode artifacts, 8-15 Hz power asymmetry index was confounded by the presence of contralateral internal carotid occlusion. The data show that the use of these spectral indexes adds objective information to visual analysis, supporting and making easier intraoperative strategies. Their routine clinical use does not involve additional costs remaining technical requirements unchanged compared to traditional recording.

Aged↗

PubMed1994

Electrophysiologic studies in tarsal tunnel syndrome. Diagnostic reliability of motor distal latency, mixed nerve and sensory nerve conduction studies.

The tarsal tunnel syndrome (TTS) is an entrapment of the posterior tibial nerve at the ankle, which, like carpal tunnel syndrome, improves with surgery but needs an instrumental diagnosis to exclude other diseases. This study was performed to evaluate the diagnostic value of nerve conduction tests proposed for the diagnosis of TTS. Of the 13 patients who were investigated 12 had secondary unilateral and 1 idiopathic bilateral TTS. One or more neurophysiologic parameters were abnormal in all cases. The diagnostic value of each neurophysiologic parameter was calculated by comparing conduction on the affected side with conduction on the healthy side of each patient with TTS. The accuracies of the sensory nerve action potential and mixed nerve action potential, both after stimulation of the plantar nerves, were almost the same, with sensory nerve action potentials more sensitive and less specific and mixed nerve action potentials less sensitive and more specific. Because from the clinical point of view we must be more afraid of false-positive results, the mixed nerve action potential is recommended for presurgical diagnosis of TTS. Coexistence of mixed nerve and sensory nerve action potential abnormalities, especially if asymmetric, are highly indicative of TTS.

Action Potentials↗