Accuracy of Temporal Artery Thermometry as an Indicator of Core Body Temperature in Patients Receiving General Anesthesia.

PURPOSE: To evaluate the agreement of temporal artery temperature (Tat) with esophageal temperature (Tes) and oral temperature (Tor), and explore potential factors associated with the level of agreement between the thermometry methods in different clinical settings. DESIGN: A prospective repeated measures (induction, emergence, and postanesthesia care unit) design was used. METHODS: Temperature data were collected for 54 patients receiving general anesthesia. Analyses included descriptive statistics, paired t tests for the within-patient comparison of temperature methods, Bland-Altman plots to examine agreement between methods, and multiple linear regression to identify factors associated with the agreement between methods. FINDINGS: Tat was significantly higher compared with Tes and Tor (P < .05) and was poor at detecting hypothermia. The use of a muscle relaxant and surgical site were suggested to be associated with the difference between Tat and Tes at emergence. CONCLUSIONS: Tat is more convenient, but less accurate, than other thermometry methods. These inaccuracies are exacerbated by common anesthetic medications.

A comparison of temporal artery thermometers with internal blood monitors to measure body temperature during hemodialysis.

BACKGROUND: Thermometers that measure core (internal) body temperature are the gold standard for monitoring temperature. Despite that most modern hemodialysis machines are equipped with an internal blood monitor that measures core body temperature, current practice is to use peripheral thermometers. A better understanding of how peripheral thermometers compare with the dialysis machine thermometer may help guide practice. METHODS: The study followed a prospective cross-sectional design. Hemodialysis patients were recruited from 2 sites in Calgary, Alberta (April - June 2017). Body temperatures were obtained from peripheral (temporal artery) and dialysis machine thermometers concurrently. Paired t-tests, Bland-Altman plots, and quantile-quantile plots were used to compare measurements from the two devices and to explore potential factors affecting temperature in hemodialysis patients. RESULTS: The mean body temperature of 94 hemodialysis patients measured using the temporal artery thermometer (36.7 °C) was significantly different than the dialysis machine thermometer (36.4 °C); p < 0.001. The mean difference (0.27 °C) appeared to be consistent across average temperature (range: 35.8-37.3 °C). CONCLUSIONS: Temperature measured by the temporal artery thermometer was statistically and clinically higher than that measured by the dialysis machine thermometer. Using the dialysis machine to monitor body temperature may result in more accurate readings and is likely to reduce the purchasing and maintenance costs associated with manual temperature readings, as well as easing the workload for dialysis staff.

Conventional and novel body temperature measurement during rest and exercise induced hyperthermia.

Despite technological advances in thermal sensory equipment, few core temperature (TCORE) measurement techniques have met the established validity criteria in exercise science. Additionally, there is debate as to what method serves as the most practically viable, yet upholds the proposed measurement accuracy. This study assessed the accuracy of current and novel TCORE measurement techniques in comparison to rectal temperature (TREC) as a reference standard. Fifteen well-trained subjects (11 male, 4 female) completed 60min of exercise at an intensity equating to the lactate threshold; measured via a discontinuous exercise test. TREC was significantly elevated from resting values (37.2±0.3°C) at the end of moderate intensity exercise (39.6±0.04°C; P=0.001). Intestinal telemetric pill (TPILL) temperature and temporal artery temperature (TTEM) did not differ significantly from TREC at rest or during exercise (P>0.05). However, aural canal temperature (TAUR) and thermal imaging temperature (TIMA) were both significantly lower than TREC (P<0.05). Bland Altman analysis revealed only TPILL was within acceptable limits of agreement (mean bias; 0.04°C), while TTEM, TAUR and TIMA demonstrated mean bias values outside of the acceptable range (>0.27°C). Against TREC, these results support the use of TPILL over all other techniques as a valid measure of TCORE at rest and during exercise induced hyperthermia. Novel findings illustrate that TIMA (when measured at the inner eye canthus) shows poor agreement to TREC during rest and exercise, which is similar to other 'surface' measures.

A practical comparison of temporal artery thermometry and axillary thermometry in neonates under different environments.

AIM: Thermoregulatory stability and monitoring are crucial in neonatal care. However, the current standard of temperature measurement using Axillary Thermometry (AT) poses multiple limitations. Temporal Artery Thermometry (TT) is a promising new method, which thus begs the question: Can TT replace AT in neonates? Previous studies reveal conflicting results, with none involving a Southeast-Asian multi-ethnic neonatal population under different environments. METHODS: A 6-month prospective comparative study involving neonates managed in a tertiary neonatal centre. Subjects were divided into 4 groups based on the required nursing environment: A) Room air B) Phototherapy C) Radiant warmers D) Incubators. Six hundred and sixty-one paired TT and AT temperature readings were obtained, with concurrent FLACC scoring to evaluate the discomfort associated with each thermometry method. RESULTS: TT readings were higher than AT in all groups. The mean temperature difference between both methods (TT-AT) was lowest in Group A (0.10 ± 0.19°C), followed by Groups B (0.50 ± 0.33°C), C (0.97 ± 0.76°C) and D (1.15 ± 0.57°C) respectively. Bland-Altman analysis revealed good clinical agreement (± 0.5°C) between both methods in Group A (7-0.27,0.47). However, Groups B (-0.14,1.13), C (-0.51,2.45) and D (0.03,2.27) showed poor agreement. Multiple GEE analysis revealed Malay ethnicity to be an additional predictor of decreased TT-AT ( ß = -0.13, p = 0.012). Compared to TT, AT was associated with higher discomfort levels (p <0.001). CONCLUSIONS: Given the good agreement and increased comfort with TT use, our study confirms that TT is comparable to AT for neonates nursed in room air. TT is therefore recommended for the temperature screening and monitoring of neonates nursed on ambient air. Its use in other environments and factors predictive of comparability of both methods requires further study.

Temporal artery thermometry in children younger than 5 years: a comparison with rectal thermometry.

BACKGROUND: Temporal artery (TA) thermometry has come as one of the new methods for temperature measurement, especially in children in whom accurate temperature monitoring can save lives. The device which is convenient and simple to use is yet to gain popularity in several parts of the world, as there are conflicting reports of its accuracy. This study compares the accuracy of the TA thermometry in children younger than 5 years using the rectal thermometry as the gold standard. METHODS: Temperature was measured simultaneously in eligible children younger than 5 years from the forehead and rectum using the TA thermometer (TAT-2000C Exergen, USA) and standard mercury in glass rectal thermometer, respectively. The difference between the mean temperatures obtained by the 2 thermometry methods was tested using the paired t test. Pearson correlation coefficient, linear regression, and Bland-Altman plot were also used to test the relationship and agreement between the 2 instruments. The sensitivity, specificity, and positive and negative predictive values were also calculated. RESULTS: Overall, the mean TA temperature (37.80°C ± 1.07°C) was significantly lower than the mean rectal temperature (38.07°C ± 0.95°C), P < 0.001. In neonates, however, the mean difference was not significant, 0.02 ± 0.59 (P = 0.810). There was a significant positive correlation between the rectal and the temporal temperatures (r = 0.80, P < 0.01). The Bland-Altman plot showed wide variation in the limit of agreement between the rectal and the TA temperatures which ranged from -1.02°C to +1.56°C. The sensitivity of the TA thermometer was 64.6% and 83.5%, respectively, at a TA fever cutoff of 38.0°C and 37.7°C. CONCLUSIONS: Temporal artery thermometer is not accurate enough for the measurement of core body temperature in children younger than 5 years. However, it may be used as a tool for screening for fever in very busy clinics and emergency room at a fever cutoff of 37.7°C.

[Cerebral blood flow monitoring].

Cerebral ischemic events remain a major problem in patients undergoing cardiac and thoracic aortic surgery. Efforts to improve outcomes have been made in many aspects which include cerebral monitoring. New technology is making it possible to shed a light to the brain, which historically used to be a black box during general anesthesia in the operating room. Cerebral brain monitoring methods include cerebral oxymetry using near infrared spectroscopy, trans cranial Doppler, Jugular venous oxygen saturation, bispectral index, temporal artery pressure monitoring. Cerebral oxymetry probably is the most commonly used method among these based on its simplicity and reproducibility. Though it is easy to obtain numbers from cerebral oxymetry, it is important to understand the principle and the limitations to interpret the results, properly.

Clinical accuracy of a non-contact infrared skin thermometer in paediatric practice.

BACKGROUND: Rectal thermometry is considered the most reliable method for measuring the temperature in the paediatric population. Recently, a new non-contact skin infrared thermometer for children was introduced in the market with excellent acceptance by parents. METHODS: A prospective, analytical, cross-sectional study was designed in order to assess the effectiveness of the infrared non-contact thermometer (Thermofocus) in comparison with two other known methods used to measure body temperature. Children aged 1 to 48 months were included from the emergency room and inpatient unit. All patients selected were assessed with three different thermometers: (1) non-contact infrared thermometer (Thermofocus); (2) temporal artery thermometer (Exergen); and (3) rectal glass mercury thermometer. RESULTS: Four hundred and thirty-four patients were eligible to complete the study. One hundred and sixty-seven were identified with fever. The mean age of the patients studied was 14.6 ± 10.7 months. Both devices were strongly correlated with the rectal temperature: r = 0.950 for Exergen and r = 0.952 for Thermofocus. The mean difference in temperature between the rectal temperature and the non-contact thermometer was 0.029 ± 0.01 °C (P < 0.001), while the mean difference between the temporal artery thermometer and the rectal temperature was -0.20 ± 0.27 °C (P < 0.001). The sensitivity and specificity for the non-contact thermometer is 97%. The negative predictive value is 99%, which is especially important to rule out fever and avoid unnecessary laboratory work-up. CONCLUSIONS: The non-contact infrared thermometer is a reliable, comfortable and accurate option for measurement of temperature and is very useful for the screening of fever in the paediatric population. More studies are recommended to support the evidence found in this study and compare its accuracy with more complex devices.

Temperature measurement in pediatrics: a comparison of the rectal method versus the temporal artery method.

The purpose of this study was to determine if there is a difference between temperature readings obtained using two different electronic temperature devices: one measuring temporal artery temperature (TAT) and one measuring rectal temperature (RT). A comparative single-group design was used with each participant acting as his or her control. The sample consisted of 47 pediatric patients between 3 and 36 months of age. Data analysis revealed no statistically significant differences between TAT and RT; however, concerns related to statistical significance versus clinical significance are discussed.

Temporal artery Doppler spectrum morphology responses to tilt and LBNP as an early indicator of syncope.

OBJECTIVE: In a study to identify an early hemodynamic predictor of syncope, 12 men (25-40 yr) underwent 30 min of 80 degrees head-up tilt, followed by progressive lower body negative pressure (LBNP) until presyncope. METHODS: Temporal (supplying extracranial tissues: TEMP), middle cerebral (MCA), and superficial femoral (FEM) arterial flow velocity (V) and vascular resistance indices (VR) were evaluated continuously using Doppler ultrasound. Ratios of the Doppler V(MEAN) (V(MCA)/V(FEM) or V(MCA)/ V(TEMP)) were used to assess flow redistribution between these areas. RESULTS: The progression of the testing protocol showed increases in vascular resistance in all territories. At presyncope, both MCA(VR) and FEM(VR) were reduced while there was a large increase in TEMP(VR). Vasoconstriction of the vascular bed supplied by the temporal artery occurred early during central hypovolemia resulting in the appearance of negative velocity deflections, which could be used for the early detection of impending syncope. Analysis of the velocity ratios showed little change until the onset of presyncope where there was an increase in V(MCA)/V(TEMP) which confirmed that vasoconstriction of the vascular bed supplied by the TEMP artery contributed to cardiac output redistribution in favor of the brain, and a reduction in V(MCA)/V(FEM) suggesting a redistribution of cardiac output toward the legs. DISCUSSION: In 67% of the tests, the appearance of the negative component of V(TEMP) was an early sign of increasing TEMP(VR) that occurred before visually detectable changes in VE(FEM) or V(MCA) and within 5 min before presyncope. Such easily identifiable in real time Doppler signs allowed experimenters to anticipate test termination.

Lack of correlation between vasodilatation and pharmacologically induced immediate headache in healthy subjects.

BACKGROUND: The causal relationship between experimental headache and vasodilatation has not been fully clarified. In the present study, we combined headache and vascular data from eight experimental studies and conducted detailed statistical analyses. Given that substances used in all these experiments were vasodilators we examined a possible correlation between headache scores and increases in arterial diameter. METHODS: We identified nine studies and retrieved raw data in 89 healthy subjects (46 females, 43 males), mean age 27 years (range 18-59 years). The following variables were collected: maximal median headache intensity scores on a verbal rating scale (VRS) during immediate headache (0-120 minutes); the mean velocity of blood flow in the middle cerebral artery (V(meanMCA)); and the diameter of the frontal branch of the superficial temporal artery (STA) during the maximal median headache intensity. RESULTS: The scatter plots show no relationship between maximal headache score and the relative changes in V(meanMCA) and diameter of the STA. The main analyses of covariance showed a significant effect only of heart rate on headache (p = .014). The interaction tests were insignificant for all variables. CONCLUSIONS: The major outcome is a finding of no linear relationship between experimental immediate headache and dilatation of the MCA or STA.

Genomics of human intracranial aneurysm wall.

BACKGROUND AND PURPOSE: The pathogenesis of intracranial aneurysms (IAs) remains elusive. Most studies have focused on individual genes, or a few interrelated genes or products, at a time in human IA. However, a broad view of pathologic mechanisms has not been investigated by identifying pathogenic genes and their interaction in networks. Our study aimed to analyze global gene expression patterns in the IA wall. METHODS: To our knowledge, our group was the first to perform Illumina microarray analysis on human IA via comparison of aneurysm wall and superficial temporal artery tissues from 6 consecutive patients. We adopted stringent statistical criteria to the individual genes; genes with a false discovery rate <0.01 and >2-fold change were selected as differentially expressed. To identify the overrepresented biologic pathways with the differentially expressed genes, we performed hypergeometric testing of the genes selected by relaxed criteria of P<0.01 and fold change >1.5. RESULTS: There are 326 distinct differentially expressed genes between IA and superficial temporal artery tissues (>2-fold change) with a false discovery rate <0.01. Analysis of the Kyoto Encyclopedia of Genes and Genomes pathways revealed the most impacted functional pathways: focal adhesion, extracellular matrix receptor interaction, and cell communication. Analysis of the Gene Ontology also supported the involvement of another 2 potentially important pathways: inflammatory response and apoptosis. CONCLUSIONS: The differentially expressed genes in the aneurysm wall may shed light on aneurysm pathobiology and provide novel targets for therapeutic intervention. These data will help generate hypotheses for future studies.

The cholinomimetic agent carbachol induces headache in healthy subjects.

The parasympathetic nervous system is likely to be involved in migraine pathogenesis. We hypothesized that the cholinomimetic agonist carbachol would induce headache and vasodilation of cephalic and radial arteries. Carbachol (3 microg/kg) or placebo was randomly infused into 12 healthy subjects in a double-blind crossover study. Headache was scored on a verbal rating scale from 0-10. Velocity in the middle cerebral artery (V(MCA)) and diameter of the superficial temporal artery (STA) and radial artery (RA) were recorded. Nine participants developed headache after carbachol compared with three after placebo. The area under the curve for headache was increased after carbachol compared with placebo both during infusion (0-30 min) (P = 0.042) and in the postinfusion period (30-90 min) (P = 0.027). Carbachol infusion caused a drop in V(MCA) (P = 0.003) and an increase in STA diameter (P = 0.006), but no increase in the RA diameter (P = 0.200). In conclusion, the study demonstrated that carbachol caused headache and dilation of cephalic arteries in healthy subjects.

Incidence and risk factors for symptomatic cerebral hyperperfusion after superficial temporal artery-middle cerebral artery anastomosis in patients with moyamoya disease.

BACKGROUND: Superficial temporal artery-middle cerebral artery anastomosis for moyamoya disease prevents cerebral ischemic attack by improving CBF, whereas recent evidence suggests that the temporary neurologic deterioration because of postoperative cerebral hyperperfusion could occur despite its low-flow revascularization. The present study investigates the incidence and the risk factors for symptomatic hyperperfusion after STA-MCA anastomosis in patients with moyamoya disease. METHODS: We prospectively performed N-isopropyl-p-[(123)I]iodoamphetamine single-photon emission computed tomography 1 and 7 days after STA-MCA anastomosis on 80 hemispheres of 58 consecutive patients with moyamoya disease (approximately 2-62 years old, 34.4 years old in average). Mean follow-up period was 22.7 months. Symptomatic cerebral hyperperfusion was defined as the presence of the significant increase in CBF at the site of the anastomosis that is responsible for the apparent neurologic sign. RESULTS: Twenty-one patients (22 sides, 27.5%) temporarily had symptomatic cerebral hyperperfusion, who were subjected to intensive blood pressure control. Postoperative magnetic resonance imaging/angiography showed the thick high signal of bypass without ischemic changes in all 21 patients. Adult-onset (P = .013) or hemorrhagic-onset patients (P = .027) had significantly higher risk for symptomatic hyperperfusion. There was no difference in intraoperative temporary occlusion time between each group. No patients had permanent neurologic deficit because of hyperperfusion. CONCLUSION: The STA-MCA anastomosis is a safe and effective treatment of moyamoya disease, although adult-onset and/or hemorrhagic-onset patients had higher risk for symptomatic hyperperfusion. We recommend routine CBF measurement especially for these patients because the management of hyperperfusion is contradictory to that of ischemia.

Comparison of temporal artery, mid-forehead skin and axillary temperature recordings in preterm infants <1500 g of birthweight.

AIM: Preterm infants are prone to temperature maintenance problems due to immature thermoregulatory mechanism and relatively large body surface area. The objective of the present study was to evaluate the performance of a new non-invasive infrared thermometer applied to the mid-forehead and temporal artery in comparison with axillary temperature recordings by mercury-in-glass thermometer, and to determine the discomfort caused by these procedures in preterm infants on incubator care. METHODS: The present comparative prospective study was composed of 34 preterm infants <1500 g of birthweight nursed in an incubator. Temperature recording from mid-forehead, temporal artery and axilla were recorded six times a day for 7 days since the end of the first week of life. For pain assessment, the premature infant pain profile (PIPP) was used. RESULTS: The mean mid-forehead, temporal artery and axillary temperatures were 36.72 +/- 0.08, 36.81 +/- 0.09 and 36.71 +/- 0.07 degrees C, respectively. No statistically significant difference was noted between the means of mid-forehead and axillary temperatures. The mean temporal artery temperature was statistically higher than the means of the mid-forehead and axillary temperatures. The PIPP scores of the mid-forehead, temporal artery and axillary temperature measurements were 5.07 +/- 0.36 degrees C, 5.18 +/- 0.43 degrees C and 7.59 +/- 0.84 degrees C, respectively. The mean PIPP score of axillary temperature measurements was statistically higher than the means of mid-forehead and temporal artery measurements. CONCLUSIONS: The infrared skin thermometer applied to the mid-forehead is a useful and valid device for easy and less painful measurement of skin temperature in preterm infants <1500 g of birthweight.

Graft selection in cerebral revascularization.

Cerebral revascularization constitutes an important treatment modality in the management of complex aneurysms, carotid occlusion, tumor, and moyamoya disease. Graft selection is a critical step in the planning of revascularization surgery, and depends on an understanding of graft and regional hemodynamics, accessibility, and patency rates. The goal of this review is to highlight some of these properties.

Operative nuances of an occipital artery to posterior inferior cerebellar artery bypass.

Occipital artery to posterior inferior cerebellar artery bypasses remain an important tool for cerebrovascular neurosurgeons, particularly in the management of complex aneurysms of the posterior inferior cerebellar artery requiring proximal occlusion or trapping. The procedure requires meticulous technique and attention to detail. The authors outline their technique for accomplishing this bypass emphasizing nuances for complication avoidance.

Minimally invasive superficial temporal artery to middle cerebral artery bypass through a minicraniotomy: benefit of three-dimensional virtual reality planning using magnetic resonance angiography.

OBJECT: The aim of the authors in this study was to introduce a minimally invasive superficial temporal artery to middle cerebral artery (STA-MCA) bypass surgery by the preselection of appropriate donor and recipient branches in a 3D virtual reality setting based on 3-T MR angiography data. METHODS: An STA-MCA anastomosis was performed in each of 5 patients. Before surgery, 3-T MR imaging was performed with 3D magnetization-prepared rapid acquisition gradient echo sequences, and a high-resolution CT 3D dataset was obtained. Image fusion and the construction of a 3D virtual reality model of each patient were completed. RESULTS: In the 3D virtual reality setting, the skin surface, skull surface, and extra- and intracranial arteries as well as the cortical brain surface could be displayed in detail. The surgical approach was successfully visualized in virtual reality. The anatomical relationship of structures of interest could be evaluated based on different values of translucency in all cases. The closest point of the appropriate donor branch of the STA and the most suitable recipient M(3) or M(4) segment could be calculated with high accuracy preoperatively and determined as the center point of the following minicraniotomy. Localization of the craniotomy and the skin incision on top of the STA branch was calculated with the system, and these data were transferred onto the patient's skin before surgery. In all cases the preselected arteries could be found intraoperatively in exact agreement with the preoperative planning data. Successful extracranial-intracranial bypass surgery was achieved without stereotactic neuronavigation via a preselected minimally invasive approach in all cases. Subsequent enlargement of the craniotomy was not necessary. Perioperative complications were not observed. All bypasses remained patent on follow-up. CONCLUSIONS: With the application of a 3D virtual reality planning system, the extent of skin incision and tissue trauma as well as the size of the bone flap was minimal. The closest point of the appropriate donor branch of the STA and the most suitable recipient M(3) or M(4) segment could be preoperatively determined with high accuracy so that the STA-MCA bypass could be safely and effectively performed through an optimally located minicraniotomy with a mean diameter of 22 mm without the need for stereotactic guidance.

Temporal artery thermometry utilization in pediatric emergency care.

OBJECTIVE: To determine the effectiveness of temporal artery thermometry (TAT) as an alternative for temperature assessment of children 1 to 4 years of age in the pediatric emergency department. METHODS: Prospective cross-sectional study conducted at an urban children's hospital emergency department. TAT and rectal temperatures are compared in a convenience sample of children 1 to 4 years of age. Comparison of the temperatures is performed using Pearson correlation coefficient and regression analysis. RESULTS: TAT and rectal temperatures are measured in 42 children 1 to 4 years of age. TAT predicts 83% of rectal temperatures. A receiver operating characteristic curve analysis shows that a cutoff of 37.7 degrees C or greater for fever in TAT is equivalent to rectal temperature greater than or equal to 38.3 degrees C with 100% sensitivity and 93.5% specificity. CONCLUSION: TAT is an effective screening tool in identifying fever in children 1 to 4 years of age.

Effects of superficial temporal artery-middle cerebral artery bypass on hemodynamics and clinical outcomes in the patients with atherosclerotic stenosis in the intracranial segment of internal carotid artery and middle cerebral artery.

OBJECTIVE: To observe the effects of superficial temporal artery-middle cerebral artery bypass (STA-MCA bypass) on hemodynamics and clinical outcomes in the patients with atherosclerotic stenosis in the intracranial segment of internal carotid artery and (or) middle cerebral artery. PATIENTS AND METHODS: The data of 63 patients who had the symptoms of cerebral ischemia in recent 3 months, intracranial segment of internal carotid artery (ISICA) and (or) middle cerebral artery (MCA) stenoses or occlusion showed by digital subtraction angiography (DSA), and reduced cerebral perfusion displayed by CT perfusion (CTP) imaging were retrospectively collected in this study. According to the patient's choice of different treatment methods (STA-MCA bypass and drugs), these patients were allocated into two groups: Bypass group (30 cases) and Drug group (33 cases). Postoperative symptoms, anastomotic patency and hemodynamics were observed in the Bypass group. Post-treatment ischemic events and clinical outcomes were recorded in the two groups and were compared between the two groups. RESULTS: In the Bypass group, DSA all showed anastomotic patency in 28 patients (93.3%, 28/30), and the improvement rate of CTP was all significantly higher in the patients with stage-III CTP than in the patients with stage-II CTP at post-operative 3 days and 6 months (95% vs 60%). Post-treatment ischemic event incidence (13.3% vs 48.5%) and annual stroke rate (6.7% vs 25.6%) were significantly lower in the Bypass group than in the Drug group (All P < 0.05). Pre-treatment National Institutes of Health Stroke Scale (NIHSS) score and Modified Rankin Scale (MRS) score were not significantly different between the two groups, but the NIHSS (2.87±0.19 and 2.4±0.19 vs 4.03±0.47 and 3.97±0.49) and MRS (1.13±0.09 and 1.0±0.07 vs 1.55±0.14 and 1.52±0.15) all were significantly lower in the Bypass group than in the Drug group at post-treatment 6 and 24 months (all P < 0.05). CONCLUSION: STA-MCA bypass can improve cerebral blood perfusion and reduce the incidence of stroke in the patients who have ISICA and (or) MCA-related symptoms, 70%-100% of stenosis, and above stage-ⅠCTP. However, this conclusion remains to be further confirmed.

Effect of pituitary adenylate cyclase-activating polypeptide-27 on cerebral hemodynamics in healthy volunteers: A 3T MRI study.

Pituitary adenylate cyclase-activating polypeptide (PACAP) has emerged as an important signaling peptide in migraine pathogenesis. Recently, we have shown that the less-abundant PACAP isoform, PACAP27, induced migraine and headache in patients equipotently to PACAP38. The present study examined the effect of PACAP27 on cerebral hemodynamics in healthy volunteers using high resolution magnetic resonance angiography (MRA). Eighteen healthy volunteers received infusion of PACAP27 (10 pmol/kg/min) or placebo over 20 min and were scanned repeatedly in fixed intervals for 5 h in a double-blind, randomized, placebo-controlled study. The circumference of extra-intracerebral arteries was measured and compared with PACAP38 data. We found significant dilation of middle meningeal artery (MMA) (p = 0.019), superficial temporal artery (p = 0.001) and external carotid artery (p = 0.039) after PACAP27 infusion compared to placebo. Whereas the middle cerebral artery (MCA) (p = 0.011) and internal carotid artery (ICA) (pICAcervical = 0.015, pICAcerebral = 0.019) were constricted. No effects on basilar artery (p = 0.708) and cavernous portion of ICA were found. Post hoc analyses revealed significant larger area under the curve for MMA after PACAP38 compared to PACAP27 (p = 0.033). We also found that PACAP27 induced headache in nine out of twelve (75%) volunteers and one (17%) after placebo. In conclusion, PACAP27 induced headache and dilated extracerebral arteries (>5 h) and slightly constricted MCA in healthy volunteers. Post hoc analysis of PACAP38 data compared with PACAP27 showed that PACAP isoforms dilates MMA with significantly different magnitude.