Inflammatory tissue response in human soft tissue is caused by a higher particle load near carbon fiber-reinforced PEEK compared to titanium plates

Titanium as the leading implant material in locked plating is challenged by polymers such as carbon fiber-reinforced polyetheretherketone (CFR-PEEK), which became the focus of interest of researchers and manufacturers in recent years. However, data on human tissue response to these new implant materials are rare. Osteosynthesis plates and peri‑implant soft tissue samples of 16 healed proximal humerus fractures were examined (n = 8 CFR-PEEK, n = 8 titanium). Soft tissue was analyzed by immunohistochemistry and µCT. The entrapped foreign bodies were further examined for their material composition by FTIR. To gain insight into their origin and formation mechanism, explanted and new plates were evaluated by SEM, EDX, profilometry and HR-CT. In the peri‑implant soft tissue of the CFR-PEEK plates, an inflammatory tissue reaction was detected. Tissues contained foreign bodies, which could be identified as tantalum wires, carbon fiber fragments and PEEK particles. Titanium particles were also found in the peri‑implant soft tissue of the titanium plates but showed a less intense surrounding tissue inflammation in immunohistochemistry. The surface of explanted CFR-PEEK plates was rougher and showed exposed and broken carbon fibers as well as protruding and deformed tantalum wires, especially in used screw holes, whereas scratches were identified on the titanium plate surfaces. Particles were present in the peri‑implant soft tissue neighboring both implant materials and could be clearly assigned to the plate material. Particles from both plate materials caused detectable tissue inflammation, with more inflammatory cells found in soft tissue over CFR-PEEK plates than over titanium plates. STATEMENT OF SIGNIFICANCE: Osteosynthesis plates are ubiquitously used in various medical specialties for the reconstruction of bone fractures and defects and are therefore indispensable for trauma surgeons, ENT specialists and many others. The leading implant material are metals such as titanium, but recently implants made of polymers such as carbon fiber-reinforced polyetheretherketone (CFR-PEEK) have become increasingly popular. However, little is known about human tissue reaction and particle generation related to these new implant types. To clarify this question, 16 osteosynthesis plates (n = 8 titanium and n = 8 CFR-PEEK) and the overlying soft tissue were analyzed regarding particle occurrence and tissue inflammation. Tissue inflammation is clinically relevant for the development of scar tissue, which is discussed to cause movement restrictions and thus contributes significantly to patient outcome.

Functional outcomes before and after implant removal in patients with posttraumatic shoulder stiffness and healed proximal humerus fractures: does implant material (PEEK vs. titanium) have an impact? - a pilot study

Background

Posttraumatic shoulder stiffness remains a problem after proximal humerus fracture (PHF) despite good healing rates. The aim of this pilot study was to determine whether the implant material and overlying soft tissue have an effect on shoulder range of motion (ROM) before and after implant removal (IR).

Methods

16 patients (mean age 55.2 ± 15.3 (SD) years; 62.5% female) were included who underwent operative treatment with locking plates of either carbon fiber reinforced Polyetheretherketone (PEEK) (PEEKPower® humeral fracture plate, Arthrex, Naples, Florida, USA, n = 8) or titanium alloy (Ti) (Philos®, DePuy Synthes, Johnson & Johnson Medical, Raynham, Massachusetts, USA, n = 8) for PHF. All patients presented with a limited ROM and persistent pain in everyday life after the fracture had healed, whereupon IR was indicated. ROM before and after IR were compared as well as the Constant Score (CS) and the CS compared to the contralateral shoulder (%CS) 1 year after IR.

Results

In group PEEK, elevation was 116.3° ± 19.2° pre- and 129.4° ± 23.7° post-IR (p = 0.027). External rotation was 35.0° ± 7.6° pre- and 50.6° ± 21.8° post-IR (p = 0.041). External rotation with the humerus abducted 90° was 38.8° ± 18.1° pre- and 52.5° ± 25.5° post-IR (p = 0.024). In group Ti, elevation was 110.0° ± 34.6° pre- and 133.8° ± 31.1° post-IR (p = 0.011). External rotation with the humerus at rest was 33.8° ± 23.1° pre- and 48.8° ± 18.7° post-IR (p = 0.048). External rotation with the humerus abducted 90° was 40.0° ± 31.6° pre- and 52.5° ± 22.5° post-IR (p = 0.011). Comparison of the two implant materials showed no significant difference. The overall CS was 90.3 ± 8.8, the %CS was 91.8% ± 14.7%.

Conclusion

There was no significant difference in ROM, CS and %CS with respect to plate materials, although lower cell adhesion is reported for the hydrophobic PEEK. However, all patients showed improved functional outcomes after IR in this pilot study. In patients with shoulder stiffness following locked plating for PHF, implants should be removed and open arthrolysis should be performed, independently from the hardware material.

Level of evidence

II

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05061-x.

Open reduction and internal fixation of displaced head-split type humeral fractures and role of the rotator-interval approach

Background

Open reduction and internal fixation (ORIF) of humeral head split fractures is challenging because of high instability and limited visibility. The aim of this retrospective study was to investigate the extend of the approach through the rotator interval (RI) on the reduction quality and functional outcome.

Methods

37 patients (mean age: 59  ±  16 years,16 female) treated by ORIF through a standard deltopectoral (DP) approach were evaluated. The follow-up period was at least two years. In 17 cases, the approach was extended through the RI. Evaluation was based on radiographs, Constant scores (CS) and DASH scores.

Results

In group DP, “anatomic” reduction was achieved in 9 cases (45%), “acceptable” in 5 cases (25%), and “malreduced” in 6 cases (30%). In group RI, “anatomic” reduction was seen in 12 cases (71%), “acceptable” in 5 cases (29%), and “malreduced” in none (p  =  0.04). In the DP group, the CS was 60.2  ±  16.2 and the %CS was 63.9  ±  22.3, while in the RI group, the CS was 74.5  ±  17.4 and the %CS was 79.1  ±  24.1 (p  =  0.07, p  =  0.08). DASH score was 22.8  ±  19.5 in DP compared to RI: 25.2  ±  20.6 (p  =  0.53).

Conclusions

The RI approach improves visualization as it enhances quality of fracture reduction, however functional outcomes may not differ significantly.

Type of study and level of proof

Retrospective, level III

[Individual aspects in eldery patients with fragility fractures]

BACKGROUND

Due to our ageing population, the number of elderly patients who are treated in the emergency department due to low-energy trauma (e.g., tripping) continues to rise. These minor accidents often result in fragility fractures classically located in the proximal humerus, distal radius, spine, pelvis, and near the hip joint. Pre-existing conditions, polypharmacy, and general frailty increase the risk of fragility fractures in this patient population.

METHODS

Geriatric trauma fractures and especially insufficiency fractures of the posterior pelvic ring are often difficult to diagnose by plain X‑ray. Therefore, in geriatric trauma patients, cross-sectional imaging, e.g., computed tomography (CT), dual-energy CT (DECT), or magnetic resonance imaging (MRI), should be considered early for reliable evaluation of a suspected fracture. This also allows for the identification of older fractures. Particularly in cognitively impaired elderly patients, difficult examination conditions or an unclear fall event, cross-sectional imaging is often indicated. However, this may also involve risks, e.g., use of contrast medium in patients with impaired renal function, so that each case must be considered individually. Furthermore, the diagnosis and treatment of osteoporosis, which is an underlying disease that leads to fragility fractures, is of particular importance. In the diagnostic workup, measurement of bone density using dual energy X‑ray absorptiometry (DXA) is the standard method according to guidelines. In specific situations, high-resolution peripheral quantitative CT (HR-pQCT) may also be used.

CONCLUSION

Due to the special challenges of correctly detecting fragility fractures and being able to quickly initiate adequate therapy, good cooperation between radiologists and trauma surgeons is necessary.

Varus malposition relates to functional outcomes following open reduction and internal fixation for proximal humeral fractures: A retrospective comparative cohort study with minimum 2 years follow-up

BACKGROUND

The aim of this study was to evaluate functional outcomes in patients with varus malposition following open reduction and internal fixation of displaced proximal humeral fractures.

METHODS

Data of 685 patients with a mean age of 67±15.8 years (67% female), that were treated by open reduction and internal fixation for a displaced proximal humeral fracture at a level 1 trauma center, were analyzed. On standardized x-ray imaging, the degree of varus displacement was measured over a minimum of two years follow-up and patients were divided into three groups. Group A: anatomic or <10° of varus or valgus malposition, group B: 10-20° of varus malposition and group C: >20° varus malposition, while anatomic head-shaft-angle was defined 135° The groups were compared with regards to functional outcomes by means of the Constant Score (CS).

RESULTS

In 565 patients with anatomic to minor <10° varus or valgus malposition (Group A), the mean CS was 72.5 ± 18.8 points. The %CS to the uninjured side was 87.2 ± 24.1 and the age and gender normalized nCS was 84.7 ± 21.7. In comparison, in group B (10-20° varus) the mean CS was 64.7 ± 16.9, the mean %CS was 84.5 ± 18.3 and the mean nCS was 76.2 ± 20.6. In group C (>20° varus) the mean CS was 54.1 ± 19.5, the mean was %CS: 72.3 ± 26.4 and the mean nCS was 64.8 ± 23.8 (p = 0.02, p = 0.03, p = 0.01). Overall, the CS, %CS and nCS correlated significantly with the degree of varus position (Pearson correlation, r = 0.23, r = 0.21, r = 0.25).

CONCLUSION

Varus malposition is related to inferior functional outcomes compared to anatomic healing in patients treated by open reduction and internal fixation for proximal humeral fractures. The data supports suggestions to prevent varus malposition in open reduction and internal fixation. In severe >20° of varus malposition, revision surgery should be considered.

Fluid resuscitation after severe trauma injury : U-shaped associations between tetrastarch dose and survival time or frequency of acute kidney failure

BACKGROUND

Using tetrastarch for fluid resuscitation after a severe trauma injury may increase risks of death and acute kidney injury. The importance of tetrastarch dose, however, is unknown.

METHODS

A retrospective observational study was performed in two trauma centres using data on type and amount of fluids (balanced crystalloids or tetrastarch) used for pre- and acute in-hospital shock management. We evaluate independent associations between the relative and absolute volumes of tetrastarch and 90-day survival time or the frequency of severe acute kidney failure (AKF).

RESULTS

We studied 271 patients who had sustained a severe blunt trauma injury (average predicted mortality according to the Revised Injury Severity Classification Score (RISC) 15.1 ± 1.4% [mean, standard deviation]), and who had required more than 2 days of intensive care therapy. In all, 75.3% of patients had received tetrastarch with a crystalloid/colloid ratio of 2.93 ± 2.60. The 90-day mortality was 11.1%, and 7.8% of the patients developed severe AKF. After adjusting for confounders, we found a U-shaped, nonlinear association between absolute or relative volumes of tetrastarch and survival time (p = 0.003 and 0.025, respectively). Optimal relative volumes of tetrastarch approximately ranged from 20 to 30% of total fluids. Giving less than about 1000 ml, or more than about 2000 ml tetrastarch was significantly associated with an increased risk of developing severe AKF (p = 0.023).

CONCLUSIONS

There was a complex U‑shaped association between the tetrastarch dose and morbidity/mortality of patients after a severe trauma injury. The optimal crystalloid/tetrastarch ratio for acute shock management appears to range from about 2.5 to 4.0.

Impact of an extreme dry and hot summer on water supply security in an alpine region

Climate change will induce an increasing drought risk in western and southern Europe and a resulting increase in water stress. This paper investigates the impact of both the extreme hot and dry summer of 2003 and the PRUDENCE CHRM climate change scenario summer for 2071-2100 on the monthly water balance (available water resources versus water demand) within the Kitzbueheler Region in the Austrian Alps. As a baseline period the climate normal period from 1961 to 1990 was chosen. In both summer scenarios total flow and ground water recharge decrease substantially, due to the decrease in precipitation and increase in evapotranspiration However, regional water availability is still sufficient to serve all water demand stakeholders. As a result of decreased snow cover duration, flow seasonality changes within the CHRM scenario. Especially springs are very vulnerable to these climatological conditions; average local groundwater recharge is reduced by 20% up to 70% within both scenarios. Due to the hydrogeological characteristics of the case study area and the typical small structured alpine water supply infrastructure, local deficits can occur. But also groundwater aquifers in the valleys show a decrease in water availability. These results are supported by observations made in 2003 throughout Austria and Switzerland.

Impact of snowmaking on alpine water resources management under present and climate change conditions

Owing to less natural snow reliability as a result of climate change on the one hand, and the demand of higher standards by winter tourists on the other hand, the production of artificial snow in ski resorts has increased substantially during the last 20 years and is likely to increase further in future. Little research has been conducted on the impact of snowmaking as a water demand stakeholder on a regional water balance. In this paper, a regional water balance (water demand-water resources) is analysed for the greater Kitzbueheler Region in the Austrian Alps, for the current situation and a future climate change scenario (2 degrees C warming). For this temperature rise a significant reduction in natural snow cover duration and snow accumulation is predicted, an effect that increases with lower altitudes and differs between the winter months. Due to the shortening of the winter season, a change in seasonality of river flows and available water resources (ground and surface water) occurs. Both increase in winter, and decrease in spring. The water demand for improvement snowmaking increases, especially in the month of March. However, December proved to be the critical month due to the large amounts of water required for base snowmaking both now and in future. These results stress the necessity of reservoir storage for base snowmaking on a regional level. Water availability during other months but winter is sufficient to fill these reservoirs.

Intercellular signalling within vascular cells under high D-glucose involves free radical-triggered tyrosine kinase activation

AIMS/HYPOTHESIS

Diabetes mellitus is associated with endothelial dysfunction in human arteries due to the release of superoxide anions (*O(2)(-)) that was found to occur predominantly in smooth muscle cells (SMC). This study was designed to elucidate the impact of high glucose concentration mediated radical production in SMC on EC. Pre-treatment of vascular SMC with increased D-glucose enhanced release of *O(2)(-).

METHODS

Microscope-based analyses of intracellular free Ca(2+) concentration (fura-2), immunohistochemistry (f-actin) and tyrosine kinase activity were performed. Furthermore, RT-PCR and Western blots were carried out.

RESULTS

Interaction of EC with SMC pre-exposed to high glucose concentration yielded changes in endothelial Ca(2+) signalling and polymerization of f-actin in a concentration-dependent and superoxide dismutase (SOD) sensitive manner. This interaction activated endothelial tyrosine kinase(s) but not NFkappaB and AP-1, while SOD prevented tyrosine kinase stimulation but facilitated NFkappaB and AP-1 activation. Erbstatin, herbimycin A and the src family specific kinase inhibitor PP-1 but not the protein kinase C inhibitor GF109203X prevented changes in endothelial Ca(2+) signalling and cytoskeleton organization induced by pre-exposure of SMC to high glucose concentration. Adenovirus-mediated expression of kinase-inactive c-src blunted the effect of pre-exposure of SMC to high glucose concentration on EC.

CONCLUSIONS/INTERPRETATION

These data suggest that SMC-derived *O(2)(-) alter endothelial cytoskeleton organization and Ca(2+) signalling via activation of c-src. The activation of c-src by SMC-derived radicals is a new concept of the mechanisms underlying vascular dysfunction in diabetes.

In human hypercholesterolemia increased reactivity of vascular smooth muscle cells is due to altered subcellular Ca(2+) distribution

There is evidence that, besides an attenuated endothelium-dependent relaxation, functional changes in smooth muscle contractility occur in experimental hypercholesterolemic animals. Unfortunately, little is known of the situation in human arteries, and the intracellular mechanisms involved in the modulation of vascular smooth muscle function in human hypercholesterolemia are still unclear. Thus, besides acetylcholine-induced endothelium-dependent relaxation, smooth muscle reactivity to KCl, norepinephrine (NE) and phenylephrine (PE) was evaluated in uterine arteries from 34 control individuals (CI) and 22 hypercholesterolemic patients (HC). Contractions to KCl, norepinephrine and phenylephrine were enhanced by 1.3-, 2.1- and 3.5-fold in vessels from HC. Furthermore, the Ca(2+) signaling in the perinuclear cytosol, which promotes cell contraction, and that of the subplasmalemmal region, which contributes to smooth muscle relaxation, were examined in freshly isolated smooth muscle cells. In cells from HC, increases in perinuclear Ca(2+) concentration ([Ca(2+)](peri)) in response to 30 mM KCl and 300 nM NE were increased by 67 and 93%, respectively. In contrast, the increase in the subplasmalemmal Ca(2+) concentration ([Ca(2+)](sub)) to 10 microM NE was reduced in cells from HC by 33%. No further differences in perinuclear and subplasmalemmal Ca(2+) signaling were found in cultured smooth muscle cells from CI and HC (primary culture 4-6 weeks after isolation). These data indicate a significant change in the subcellular Ca(2+) distribution in smooth muscle cells from HC. In addition, production of superoxide anions (O(2)(-)) was increased 3.8-fold in uterine arteries from HC. Treatment of smooth muscle cells with the O(2)(-)-generating mixture xanthine oxidase/hypoxanthine mimicked hypercholesterolemia on smooth muscle Ca(2+) signaling. From these findings, we conclude that during hypercholesterolemia, besides a reduced endothelium-dependent relaxation, changes in smooth muscle reactivity take place. Thereby, smooth muscle contractility is increased possibly due to the observed changes in subcellular Ca(2+) signaling. The observed increased O(2)(-) production in HC might play a crucial role in the alteration of smooth muscle function in hypercholesterolemia.

Increased superoxide anion formation in endothelial cells during hyperglycemia: an adaptive response or initial step of vascular dysfunction?

In diabetes mellitus, the risk for cardiovascular complications and development of atherosclerosis is increased compared with healthy individuals. Recently evidence was provided that increased production of superoxide anions occurs in endothelial cells during hyperglycemia. In order to evaluate the potential impact of the enhanced formation of this oxygen radical for vascular cell dysfunction and its role in tissue adaptation, it is essential to assess the effect of superoxide anions on endothelial cell function. Here, we present new data and review our previous work on the effects of superoxide anions on endothelial vascular function, such as intracellular Ca2+ signal cascade, formation and bioactivity of nitric oxide. Based on the presented data we discuss superoxide anion production as a two faced phenomenon. In lower concentrations, superoxide anions are mediators of an endothelium adaptation to ensure endothelial vasomotion control. However, in higher concentrations superoxide anions disrupt endothelial-smooth muscle crosstalk resulting in vessel wall dysfunction and vascular wall dysfunction.

Human diabetes is associated with hyperreactivity of vascular smooth muscle cells due to altered subcellular Ca2+ distribution

Alterations of vascular smooth muscle function have been implicated in the development of vascular complications and circulatory dysfunction in diabetes. However, little is known about changes in smooth muscle contractility and the intracellular mechanisms contributing to altered responsiveness of blood vessels of diabetic patients. Therefore, smooth muscle and endothelial cell function were assessed in 20 patients with diabetes and compared with 41 age-matched control subjects. In rings from uterine arteries, smooth muscle sensitivity to K+, norepinephrine (NE), and phenylephrine (PE) was enhanced by 1.4-, 2.3-, and 9.7-fold, respectively, and endothelium-dependent relaxation was reduced by 64% in diabetic patients, as compared with control subjects. In addition, in freshly isolated smooth muscle cells from diabetic patients, an increased perinuclear Ca2+ signaling to K+ (30 mmol/l >73%; 60 mmol/l >68%) and NE (300 nmol/l >86%; 10 micromol/l >67%) was found. In contrast, subplasmalemmal Ca2+ response, which favors smooth muscle relaxation caused by activation of Ca2+-activated K+ channels, was reduced by 38% in diabetic patients as compared with control subjects, indicating a significant change in the subcellular Ca2+ distribution in vascular smooth muscle cells in diabetic patients. In contrast to the altered Ca2+ signaling found in freshly isolated cells from diabetic patients, in cultured smooth muscle cells isolated from control subjects and diabetic patients, no difference in the intracellular Ca2+ signaling to stimulation with either K+ or NE was found. Furthermore, production of superoxide anion (*O2-) in intact and endothelium-denuded arteries from diabetic patients was increased by 150 and 136%, respectively. Incubation of freshly isolated smooth muscle cells from control subjects with the *O2- -generating system xanthine oxidase/hypoxanthine mimicked the effect of diabetic patients on subcellular Ca2+ distribution in a superoxide dismutase-sensitive manner. We conclude that in diabetic subjects, smooth muscle reactivity is increased because of changes in subcellular Ca2+ distribution on cell activation. Increased *O2- production may play a crucial role in the alteration of smooth muscle function.

Submaximal stimulation of porcine endothelial cells causes focal Ca2+ elevation beneath the cell membrane

1. Endothelial cell activation is correlated with increased cytosolic Ca2+ concentration, often monitored with cytoplasmic Ca2+ dyes, such as fura-2 and Calcium Green-1. We tested the hypothesis that during weak stimulation of porcine coronary artery endothelial cells, focal, subplasmalemmal Ca2+ elevations occur which are controlled by cell membrane Na(+)-Ca2+ exchange near mitochondrial membrane and superficial endoplasmic reticulum (SER). 2. Bulk Ca2+ concentration ([Ca2+]b) was monitored using fura-2 or Calcium Green-1 and subplasmalemmal Ca2+ concentration ([Ca2+]sp) was determined with FFP-18. The distribution of the SER network was estimated using laser scanning and deconvolution microscopy. 3. Sodium fluoride (10 mmol l-1) and submaximal concentrations of bradykinin (Bk; 1 nmol l-1) stimulated Ca2+ entry with no increase in [Ca2+]b. Although inositol 1,4,5-trisphosphate formation and intracellular Ca2+ release in response to both stimuli were similar, Ca2+ entry in response to NaF exceeded that in response to 1 nmol l-1 BK by fourfold, suggesting additional effects of NaF on Ca+ entry pathways but stimulation via intracellular Ca2+ release. 4. Prevention of Na(+)-Ca2+ exchange activity by decreasing extracellular Na+ unmasked intracellular Ca2+ release in response to NaF and 1 nmol l-1 Bk, indicated by an increase in [Ca2+]b. Thereby, NaF depleted Bk-releasable Ca2+ pools, while mitochondrial Ca2+ content (released with FCCP or oligomycin) and the amount of Ca2+ stored within the cells (released with ionomycin) was increased compared with cells treated with NaF under normal Na+ conditions. The NaF-initiated increase in [Ca2+]b and depletion of Bk-releasable Ca2+ pool(s) in the low-Na+ condition was diminished by 25 mumol l-1 ryanodine, indicating the involvement of Ca(2+)-induced Ca2+ release (CICR). 5. In simultaneous recordings of [Ca2+]sp (with FFP-18) and [Ca2+]b (with Calcium Green-1), 1 nmol l-1 Bk or 10 mmol l-1 NaF yielded focal [Ca2+] elevation in the subplasmalemmal region with no increase in the perinuclear area. 6. Treatment with 10 mumol-1 nocodazole caused the SER to collapse and unmasked Ca2+ release in response to 1 nmol l-1 Bk and 10 mmol l-1 NaF, similar to low-Na+ conditions, while the effect of thapsigargin was not changed. 7. These data show that in endothelial cells, focal, subplasmalemmal Ca2+ elevations in response to small or slow IP3 formation occur due to vectorial Ca2+ release from the SER towards the plasmalemma followed by Ca2+ extrusion by Na(+)-Ca2+ exchange. While these local Ca2+ elevations are not detectable with Ca2+ dyes for the determination of [Ca2+]b, prevention of Ca2+ extrusion or SER disruption yields increases in [Ca2+]b partially due to CICR. 8. All of the data support our hypothesis that in weakly stimulated endothelial cells, intracellular Ca2+ release and [Ca2+] elevation are limited to the subplasmalemmal region. We propose that the SER co-operates with associated parts of the plasma membrane to control Ca2+ homeostasis, Ca2+ distribution and Ca2+ entry. The existence of such a subplasmalemmal Ca2+ control unit (SCCU) needs to be considered in discussions of Ca2+ signalling, especially when cytoplasmic Ca2+ dyes, such as fura-2 or Calcium Green-1, are used.

Brain temperature discriminates between neonates with damaged, hypoperfused, and normal brains

Brain temperature depends on the balance of cerebral heat production and heat loss via cerebral circulation and head surface. We investigated whether brain temperature and heat loss via the head surface differed in neonates with abnormal cerebral metabolism or circulation. We measured the core temperature of the head noninvasively by the zero-gradient method, skin temperature of the head, the heat flux from the head, and esophageal and operative environmental temperature in seven healthy neonates, seven neonates with cerebral damage, and two neonates with cerebral hypoperfusion caused by an incurable congenital heart disease. Cerebral blood flow velocity in the anterior cerebral artery and systemic blood pressure were also measured. Brain temperature profile was measured in two premature infants with external ventricular drainage. Core temperature of the head, considered to represent brain temperature, was up to 1.5 degree C higher in infants with cerebral hypoperfusion than in normal neonates. The core temperature of the head was higher than the esophageal temperature in all except two infants with the most severe cerebral damage. The difference between core temperature of the head and esophageal temperature was 0.72 +/- 0.12 degree C in normal neonates, 0.16 +/- 0.4 degree C in infants with cerebral damage, and ranged from 0.9 to 1.2 degree C in infants with cerebral hypoperfusion. The relationship of core of the head to esophageal temperature discriminated between all 16 newborn infants according to their brain pathologic condition, except one infant with a mild ischemic-hypoxic encephalopathy. In conclusion, brain temperature depends on cerebral perfusion and level of brain injury.(ABSTRACT TRUNCATED AT 250 WORDS)