Neuronal activity alters local blood flow in brain tumour adjacent to the activating cortex

Physiological parameters after nonpharmacological analgesia in preterm infants: a randomized trial

AIM

To compare the influence of three different nonpharmacological interventions on cortical activation, heart rate and peripheral oxygen saturation (SaO2 ) after heelstick in preterm infants.

METHODS

Twenty five preterm infants between 24 0/7 and 32 0/7 weeks of gestational age were randomized to either oral sucrose (S), facilitated tucking (FT) or a combination of the two interventions (SFT) prior to five heelsticks each within the first 14 days of life. SaO2 , heart rate and oxygenation of the somatosensory cortex, measured by near infrared spectroscopy (NIRS), were analysed.

RESULTS

Hundred and twenty five heelsticks were performed. The heart rate increased significantly after heelstick in all three intervention groups (p < 0.004 in all groups). The increase was higher in the FT group compared with the other groups (S: p = 0.007; SFT: p = 0.004). There was no difference among the two groups receiving sucrose (S and SFT; p = 0.87). SaO2 did not change significantly after heelstick in all intervention groups. Near infrared spectroscopy measurements did not show a significant change in the curve but patients in the FT group showed a trend towards higher average oxygenation of the contralateral somatosensory cortex.

CONCLUSION

Oral sucrose seems to be more effective in reducing reaction to pain than FT. Application of both interventions did not show an additive effect.

Visualized characterization for cerebral response of acupuncture deqi: paradox underway

Acupuncture as an oriental natural healing therapy with prolonged history has been extensively utilized in the management of great numbers of disorders. Deqi, a renowned acupuncture needling sensation, is profoundly regarded as the predictor and also the prerequisite of a preferable acupuncture treatment efficacy. Till now, there is still no consistency being reached towards the mechanism of acupuncture Deqi as a result of the discrepancy for publicly acknowledged evidence. Recent visualized research on Deqi using modern technologies has demonstrated possible central mechanism towards it. However, there is a conspicuous paradox underway in the research of cerebral response to acupuncture Deqi. This paper provided a view of up-to-date studies using visualized tools to characterize the brain response to acupuncture Deqi, such as functional magnetic resonance imaging (fMRI) and positron emission tomography/computed tomography (PET/CT). The paradox was extruded to highlight certain reasons from a TCM view. It is hypothesized that acupoints located at different dermal sites, state of participant, and needling manipulation can all contribute to the current paradox. Hence, further studies on acupuncture Deqi should pay more attention to the strategy of experiment design with generalized measurement, valid sham control methods, and more to subjects in diseased condition.

Changes of cerebral blood oxygenation and optical pathlength during activation and deactivation in the prefrontal cortex measured by time-resolved near infrared spectroscopy

To determine the alterations in optical characteristics and cerebral blood oxygenation (CBO) during activation and deactivation, we evaluated the changes in mean optical pathlength (MOP) and CBO induced by a verbal fluency task (VFT) and driving simulation in the right and left prefrontal cortex (PFC), employing a newly developed time-resolved near infrared spectroscopy, which allows quantitative measurements of the evoked-CBO changes by determining the MOP with a sampling time of 1 s. The results demonstrated differences in MOP in the foreheads with the subjects and wavelength; however, there was no significant difference between the right and left foreheads (p > 0.05). Also, both the VFT and driving simulation task did not affect the MOP significantly as compared to that before the tasks (p > 0.05). In the bilateral PFCs, the VFT caused increases of oxyhemoglobin and total hemoglobin associated with a decrease of deoxyhemoglobin, while the driving simulation task caused decreases of oxyhemoglobin and total hemoglobin associated with an increase of deoxyhemoglobin; there were no significant differences in evoked-CBO changes between the right and left PFC. The present results will be useful for quantitative measurement of hemodynamic changes during activation and deactivation in the adults by near infrared spectroscopy.

Evaluation of extracranial-intracranial arterial bypass function by using near-infrared spectroscopy

OBJECT

It has been reported that extracranial-intracranial (EC-IC) arterial bypass surgery can be useful in preventing stroke in patients with hemodynamic compromise. Little is yet known, however, regarding the extent to which the bypass contributes to maintaining adequate cerebral blood oxygenation (CBO) and its temporal changes following surgery. The authors evaluated bypass function repeatedly by using near-infrared spectroscopy (NIRS) after surgery.

METHODS

The authors investigated 30 patients who had undergone EC-IC bypass surgery. Single-photon emission computerized tomography revealed a decrease in regional cerebral blood flow (rCBF) and a lowered rCBF response to acetazolamide. Changes in CBO were evaluated in the sensorimotor cortex during compression of the anastomosed superficial temporal artery (STA). When decreases in oxyhemoglobin (HbO2) and total hemoglobin (Hb) concentrations were observed, the bypass was considered to have maintained CBO in the sensorimotor cortex given that decreases in HbO2 and total Hb indicate cerebral ischemic changes. The bypass maintained CBO immediately after surgery in 36.7% of patients (Group I, 11 patients) and at some time after surgery, mostly within 1 year, in 43.3% of patients (Group II, 13 patients); however, it did not maintain it throughout the follow-up period in 20% of patients (Group III, six patients). Note that the preoperative rCBF in patients in Groups I and II was lower than that in patients in Group III (p < 0.004). In fact, the preoperative rCBF predicted whether a bypass would maintain CBO at a cutoff value of 24.5 to 25 ml/100 g/min. Among Groups I and II, 18 patients demonstrated an increase in deoxyhemoglobin during STA compression. The preoperative rCBF in these cases was lower than that in the six remaining patients (p < 0.006). Note that the preoperative rCBF predicted the postoperative deoxyhemoglobin response at a cutoff value of 22.2 to 24 ml/100 g/min.

CONCLUSIONS

The EC-IC bypass surgery can maintain CBO immediately after surgery or gradually within 1 year when the preoperative rCBF is below 24.5 to 25 ml/100 g/min. Furthermore, bypass flow plays a critical role in maintaining an adequate CBO when preoperative rCBF is below 22.2 to 24 ml/100 g/min.

Auditory-evoked cerebral oxygenation changes in hypoxic-ischemic encephalopathy of newborn infants monitored by near infrared spectroscopy

Recent neuronal activation studies have demonstrated the presence of regional cerebral blood flow (rCBF) increases in response to neuronal activation in normal newborns. In the present study, using near infrared spectroscopy (NIRS), we evaluated the evoked cerebral blood oxygenation (CBO) changes in hypoxic-ischemic encephalopathy (HIE) of newborns. We studied 20 normal newborns and 22 HIE newborns; mild HIE (n=9), moderate HIE (n=7), and severe HIE (n=6). The babies were from 1 to 3 days postdelivery. We measured the concentration changes of deoxyhemoglobin (Deoxy-Hb), oxyhemoglobin (Oxy-Hb), and total hemoglobin (Total-Hb) induced by auditory stimulation in the frontal lobes. The normal and HIE groups showed different Oxy-Hb and Total-Hb responses. In normal newborns, 19 out of 20 normal subjects showed increases of Oxy-Hb and Total-Hb, whereas 14 out of 22 subjects showed decreases of Oxy-Hb and Total-Hb during the stimulation (chi(2)=19.95, p<0.001). In addition, there was a strong negative correlation between HIE severity and changes of Total-Hb (r=-0.73, p<0.001). These results suggest that infants with HIE have decreased rCBF in the frontal lobes during auditory stimulation.