Continuous Monitoring of Jugular Bulb Venous Oxygen Saturation for Evaluation of Cerebral Perfusion during Carotid Endarterectomy

In this study we examined whether continuous monitoring of jugular bulb venous oxygen saturation (SjO2) is applicable for the evaluation of cerebral hypoperfusion during carotid endarterectomy (CEA). The subjects were 25 patients who underwent elective CEA under general anaesthesia. After the carotid stump pressure (SP) was measured, SjO2 and the somatosensory evoked potentials (SEP) were monitored during the carotid test clamping for 10 min.　　 There was no alteration in cardiovascular and respiratory status during the test clamping. No correlation was observed between SEP amplitude and SP (r=0.16, p=0.25). However, at clamping, SjO2 decreased from 70 to 64% (p<0.01) with a reduction in SEP amplitude from 2.0 to 1.6μV (p<0.01). After declamping, SjO2 increased from 65 to 70% (p<0.01) with a recovery in SEP from 1.6 to l.9μV (p<0.01). The changes in SEP amplitude and SjO2 correlated (r=0.66, p<0.001).　　 These results suggest that continuous monitoring of SjO2 is superior to SP measurement in the prediction of cerebral hypoperfusion caused by carotid clamping and applicable to CEA

A novel bone-thinning technique for transcranial stimulation motor-evoked potentials in rats

Abstract Transcranial electrical stimulated motor-evoked potentials (tcMEPs) are widely used to evaluate motor function in humans, and even in animal studies, tcMEPs are used to evaluate neurological dysfunction. However, there is a dearth of reports on extended tcMEP recordings in both animal models and humans. Therefore, this study examined a new technique for stably recording tcMEPs over several weeks in six healthy female Sprague–Dawley rats. We thinned the skull bone using the skull base and spinal surgery technique to reduce electrical resistance for electrical stimulation. tcMEPs were recorded on days 1, 7, 14, 21, and 28 after surgery. The onset latency and amplitude of tcMEPs from the hindlimbs were recorded and evaluated, and histological analysis was performed. Stable amplitude and onset latency could be recorded over several weeks, and histological analysis indicated no complications attributable to the procedure. Thus, our novel technique allows for less invasive, safer, easier, and more stable extended tcMEP recordings than previously reported techniques. The presently reported technique may be applied to the study of various nerve injury models in rats: specifically, to evaluate the degree of nerve dysfunction and recovery in spinal cord injury, cerebral infarction, and brain contusion models

Establishment of longitudinal transcranial stimulation motor evoked potentials monitoring of the forelimbs and hindlimbs in an ischemic stroke rat model

Abstract Evaluation of motor function ischemic stroke rat models includes qualitative assessments such as the modified neurological severity score (mNSS). However, mNSS cannot evaluate the function of forelimbs and hindlimbs separately. We quantitatively assessed motor function in a middle cerebral artery occlusion (MCAO) rat model of ischemic stroke. We recorded transcranial stimulation motor evoked potentials (tcMEPs) from MCAO rats and measured the changes in onset latency and amplitude at the forelimbs and hindlimbs up to 28 days after stroke. All MCAO subjects showed hemiparesis. The amplitudes of tcMEPs in both fore- and hindlimbs were inversely correlated with mNSS scores, but the amplitudes in the forelimbs improved later than those in the hindlimbs. The onset latency of tcMEPs in the forelimbs and hindlimbs remained almost unchanged during the follow-up period. Our results showed the differences in tcMEPs amplitude recovery times between the forelimbs and hindlimbs after MCAO, which emphasizes the importance of separately evaluating forelimbs and hindlimbs in post-ischemic stroke models. This minimally invasive and longitudinal quantitative method could be useful for further research on diseases and neurogenesis