Influence of unfused cranial bones on magnetoencephalography signals in human infants.

OBJECTIVE: To clarify the effects of unfused cranial bones on magnetoencephalography (MEG) signals during early development. METHODS: In a simulation study, we compared the MEG signals over a spherical head model with a circular hole mimicking the anterior fontanel to those over the same head model without the fontanel for different head and fontanel sizes with varying skull thickness and conductivity. RESULTS: The fontanel had small effects according to three indices. The sum of differences in signal over a sensor array due to a fontanel, for example, was < 6% of the sum without the fontanel. However, the fontanel effects were extensive for dipole sources deep in the brain or outside the fontanel for larger fontanels. The effects were comparable in magnitude for tangential and radial sources. Skull thickness significantly increased the effect, while skull conductivity had minor effects. CONCLUSION: MEG signal is weakly affected by a fontanel. However, the effects can be extensive and significant for radial sources, thicker skull and large fontanels. The fontanel effects can be intuitively explained by the concept of secondary sources at the fontanel wall. SIGNIFICANCE: The minor influence of unfused cranial bones simplifies MEG analysis, but it should be considered for quantitative analysis.

Normal values of the resistivity index of the pericallosal artery with and without compression of the anterior fontanelle.

BACKGROUND: Resistivity index (RI) of the pericallosal artery as is commonly measured during head ultrasound (US) examination in neonates. Some studies have shown that RI measured with gentle compression of the fontanelle provides additional information in cases of neonatal brain anomalies. OBJECTIVE: The purpose of this study was to establish normal RI values with and without compression in a large population of neonates with normal cranial ultrasound as a function of gestational age. MATERIALS AND METHODS: The authors of this retrospective study reviewed the RI of 323 infants with normal gray-scale cranial US and with a gestational age ranging 26-42 weeks. We conducted the exams both with and without compression of the anterior fontanelle and we studied changes in RI depending on gestational age, gender and type of delivery. RESULTS: Infants with a gestational age of more than 35 weeks tended to have a lower RI (P=0.011). The compression of the anterior fontanelle emphasized the change in RI with increasing gestational age, with higher gestational ages having a lower RI (P<0.001). The results concerning the percentage change between baseline RI and RI with compression showed that infants with higher gestational ages have a smaller percentage change in RI (P=0.002). CONCLUSION: We established the normal values for RI from 26 weeks to 42 weeks of gestation. The results of the study show the importance of taking the gestational age into consideration when evaluating the RI.

EEG in neonates: Forward modeling and sensitivity analysis with respect to variations of the conductivity.

The paper is devoted to the analysis of electroencephalography (EEG) in neonates. The goal is to investigate the impact of fontanels on EEG measurements, i.e. on the values of the electric potential on the scalp. In order to answer this clinical issue, a complete mathematical study (modeling, existence and uniqueness result, realistic simulations) is carried out. A model for the forward problem in EEG source localization is proposed. The model is able to take into account the presence and ossification process of fontanels which are characterized by a variable conductivity. From a mathematical point of view, the model consists in solving an elliptic problem with a singular source term in an inhomogeneous medium. A subtraction approach is used to deal with the singularity in the source term, and existence and uniqueness results are proved for the continuous problem. Discretization is performed with 3D Finite Elements of type P1 and error estimates are proved in the energy norm (H¹-norm). Numerical simulations for a three-layer spherical model as well as for a realistic neonatal head model including or not the fontanels have been obtained and corroborate the theoretical results. A mathematical tool related to the concept of Gâteau derivatives is introduced which is able to measure the sensitivity of the electric potential with respect to small variations in the fontanel conductivity. This study attests that the presence of fontanels in neonates does have an impact on EEG measurements.

Anterior fontanelle size among term neonates on the first day of life born at University of Gondar Hospital, Northwest Ethiopia.

BACKGROUND: Anterior fontanelle is the largest, prominent and most important fontanelle, which is used for clinical evaluation. It is mainly characterized by its size and shape variation and is possibly influenced by gender, race and genetics. Understanding the variation of anterior fontanelle is used for recognition of different medical disorders and abnormal skeletal morphogenesis. OBJECTIVE: To determine the mean size of anterior fontanelle among term neonates on the first day of life born at University of Gondar Hospital, Gondar Town, Northwest Ethiopia, 2018. METHODS: Descriptive cross sectional study design was undertaken in 384 term and apparently healthy neonates, using standard methods. Descriptive analysis, student t-test, one way ANOVA and Pearson correlation coefficient were implemented. RESULTS: In this study, the mean size of anterior fontanelle in term neonates was 3.00 ± 0.62 cm (range 1.70-5.50 cm). The mean size of anterior fontanelle was 3.10 ± 0.66 cm for males, and 2.88 ± 0.57 cm for females. There was statistically significant difference in anterior fontanelle size in neonates of different genders (p<0.001), mode of delivery (p<0.001) and duration of labour (p = 0.006). However, the size of anterior fontanelle was not significantly affected by the birth order, onset of labour and socio-demographic variables of the mother except occupation of the mother (p = 0.01). There was a significant positive correlation between the mean size of anterior fontanelle with birth weight (r = 0.11; p = 0.04) and head circumference (r = 0.17; p = 0.001). CONCLUSIONS: At term, male neonates had significantly larger anterior fontanelle than female neonates and anterior fontanelle size has a direct relationship with birth weight and head circumference.

Evaluation of fontanel size variation and closure time in children followed up from birth to 24 months.

OBJECTIVE Anterior fontanel size and closure time can be useful clinical signs for the early diagnosis of diseases. Knowing age-related normal variations is important to decide on further investigations. The authors of this study aimed to describe fontanel size variation according to age, determine fontanel closure time, and identify the optimal method for assessing fontanel size. METHODS For this prospective cohort study, 321 healthy term babies who fulfilled the inclusion criteria were consecutively recruited. Percentile charts for the mean anterior fontanel size and oblique measurements from birth to 24 months of age were created. RESULTS The mean fontanel closure time was 9.7 ± 5.0 months (girls 10.3 ± 4.7 months, boys 9.2 ± 5.1 months). No differences were observed between the traditional method and oblique measurements. Early fontanel closure was not associated with microcephaly. CONCLUSIONS Oblique measurements can be used because they are as accurate as the traditional method. Children with fontanels measuring above the 95th percentile should be monitored closely and investigated further for potentially associated diseases.

[Development of anterior fontanelle in Chinese children in 2015].

Objective: To observe the development of the anterior fontanel (AF) in healthy Chinese children from 1 to 36 months, and to assess the relationship between the closure of the AF and physical development in Chinese children. Method: This was a cross-sectional evaluation of the AF in a series of 104 147 healthy children between June 2015 and October 2015 from nine cities in China. The size and closure of AF of the children were measured and recorded, and the age for the closure of AF was calculated using probit analysis. The data in 2015 were compared with the data from the same surveys in 1985, 1995 and 2005 respectively. Result: (1) Totally, 104 147 healthy children (52 216 boys and 51 931 girls; range 1 month to 36 months) from nine cities enrolled in this cross-sectional study. (2)The size of AF gradually decreased with age, and the mean size of AF was 2.0(95% confidence interval (CI)2.0-2.1) cm at the age of 1 month, 0.6(95% CI 0.5-0.6) cm at the ages of 12-14 months, and 0.0(95% CI 0.0-0.0) cm at the ages of 21-23 months, respectively. (3) The percentage for the closure of AF was 0.1% at the age of 3 months, 67.5% at the ages of 15-17 months. The oldestt age for closure was 35 months. The mean age for the closure of AF was 14.5 months (95% CI 14.4-14.6), and the 3rd and 97th centiles of the age for the closure of AF were 6.6 and 22.4 months. (4) Over the past 30 years from 1985 to 2015, no significant change was found regarding the mean age for the closure of AF in children from urban area, contrarily, the mean age was 1.1 months earlier in suburban area. (5) The height and weight of children in the closed AF group were significantly higher than those of children in unclosed AF group(all P<0.01), but no significant difference was found regarding the head circumference between the two groups. Conclusion: The size of AF at 1 month was maximum, then decreases gradually with age, and the mean age for the closure of AF was 14.5 (95% CI 14.4-14.6) months. No significant correlation was found between the development of AF and the head circumference, but there was a positive correlation between the development of AF and the height and weight. There was no significant change regarding the secular trend of the age for the closure of AF.

The effect of fontanel on scalp EEG potentials in the neonate.

OBJECTIVE: To define how fontanels affect scalp EEG potentials in neonates. METHOD: Realistic finite element method head models were generated with and without fontanels. The electrical activity of the whole cortex was simulated using distributed 54,620 concurrently active cortical dipoles with a uniform random distribution of current densities (0-40 µA/cm2). The overall effects of fontanels on scalp potentials were calculated from finite element forward solution in the vicinity the fontanel region by relative difference measure (RDM*) and magnification factor (MAG), and the skull conductivity was systematically varied from 0.003 to 0.3S/m. RESULTS: The neonatal scalp EEG topographies are comparable in models with and without fontanels, with highest amplitudes directly above the anterior fontanel. Quantitatively, comparison of these models elicits negligible differences (RDM*) ∼2% and MAG ∼1.0). However, fontanel contribution to scalp potential was shown to increase sharply with decreases in skull conductivity. CONCLUSIONS: These results suggest that fontanels may affect neonatal scalp EEG much less than traditionally assumed, and the effect is strongly dependent on skull conductivity. SIGNIFICANCE: Most neonatal EEG studies can be adequately performed without assuming distortions by fontanels.

Anterior fontanelle closure and size in full-term children based on head computed tomography.

INTRODUCTION: This study investigates radiographically acquired normative ranges of anterior fontanelle closure (AFC) and surface area (SA) in healthy full-term infants. METHODS: High-resolution head computed tomography (CT) scans were retrospectively reviewed for AFC and AF dimensions to allow approximation of AF SA. RESULTS: Between 15 and 23 head CT scans per monthly age-group (0-24 months) were reviewed, totaling 464 scans. AFC frequency increased steadily from age 10 (16%) to 20 months (88%), reaching higher than 50% at age 16 months (53%). The AF was closed in 3% to 5% of infants at 5 to 6 months. AF median SA increased from 769.3 mm(2) (age 0 months) to 1022.2 mm(2) (2 months), then declined steadily. CONCLUSIONS: This study provides reference charts detailing AFC frequency and AF SA as a function of age. Wide variability of AFC timing and AF size among healthy infants suggest that early or delayed AFC may represent normal variants.

Pilot investigation of anterior fontanelle photoplethysmographic signals and their suitability in estimating arterial oxygen saturation.

There is a need for more reliable, non-invasive and alternative measurement sites for the monitoring of arterial blood oxygen saturation in critically ill newborns at times of peripheral compromise. A pilot investigation on 14 Intensive Care Unit (ICU) newborns was conducted utilizing custom-made reflectance photoplethysmographic (PPG) sensors placed at the fontanelle and foot. The results suggest that the fontanelle is sensitive to changes in saturation, where saturation values obtained from the custom sensor were compared against commercial pulse oximeter values and results from a blood gas analyzer, however careful placement of the sensor at the fontanelle is an issue that needs further investigation.

Development of an optoelectronic sensor for the investigation of photoplethysmographic signals from the anterior fontanel of the newborn.

There is a need for more reliable, non-invasive and alternative measurement sites for the monitoring of arterial blood oxygen saturation in critically ill newborns at times of peripheral compromise. The anterior fontanelle, a unique anatomical feature of the newborn, has been presented as an alternative site for the estimation of oxygen saturation. A multi-wavelength non-invasive optoelectronic sensor has been designed and developed for the investigation of photoplethysmographic (PPG) signals and blood oxygen saturation values from the fontanelle. In vivo thermal tests of the optical sensor show that under normal operating conditions the heating at the skin surface was negligible (<0.1 °C). Good quality PPGs with large amplitudes and high signal to noise ratio were recorded at all three (red, infrared and green) wavelengths prior to clinical measurements.

Changes in cerebral oxygenation and hemodynamics during cranial ultrasound in preterm infants.

OBJECTIVES: To evaluate whether application of a transducer on the anterior fontanelle during cranial ultrasound (US) examination effects cerebral hemodynamics and oxygenation in preterm infants. STUDY DESIGN*: During cranial US examination, changes in cerebral blood oxygenation (cHbD) and cerebral blood volume (CBV) were assessed using near infrared spectrophotometry (NIRS) in 76 infants (GA 30.7 (4.1)wk, BW 1423 (717)g) within two days after birth. Ten of these infants (GA 29.1 (1.6)wk, BW 1092 (455)g) were studied again at a postnatal age of one week. RESULTS*: We obtained stable and consistent NIRS registrations in 54 infants within the first two days after birth. Twenty-eight of these infants showed a decrease in cHbD (0.59 (0.54) micromol/100g) during the scanning procedure while CBV did not change. Twenty-four infants showed no changes in NIRS and 2 infants showed an atypical NIRS response during cranial US examination. At the postnatal age of one week, stable and consistent NIRS registrations were obtained in 7 infants. None of these infants showed changes in NIRS variables during cranial US examination. CONCLUSIONS: Application of an US transducer on the anterior fontanelle causes changes in cerebral oxygenation and hemodynamics in a substantial number of preterm infants. ( *values are expressed as median (interquartile range)).