Hyperostosis frontalis interna: what does it tell us about our health?

The clinical manifestations of hyperostosis frontalis interna: A qualitative systematic review of cases

Hyperostosis frontalis interna (HFI) is a condition defined as abnormal bone growth on the posterior aspect of the frontal bone. Despite uncertainties regarding its etiology and prognosis, clinicians typically consider HFI a benign pathology. There are no studies organizing all the possible manifestations of the disease. The present study aims to organize all the clinical manifestations of HFI within the current case report/series literature. A blinded PRISMA-guided search of HFI case reports and case series yielded 43 relevant articles and provided 110 patients for analysis. The symptoms presenting alongside HFI were extracted and tabulated. We found high-frequency clinical manifestations of HFI (>20% of patients) to include headaches, obesity, vertigo/dizziness symptoms, cognitive decline, and depression. An additional 15 symptoms were tabulated at frequencies found to be less than 20%. Based on our analysis, we suggest the constellation of high-frequency symptoms can offer a more comprehensive clinical picture of symptomatic HFI which may be valuable to consider for clinicians and future researchers in the field of HFI.

Hyperostosis Frontalis Interna in a Dry Indian Human Skull: A Case Report

Hyperostosis Frontalis Interna (HFI), a condition that has been sparsely explained till now, is a benign, asymptomatic, and irregular thickening of the endocranium of the frontal bone. It is found to be predominantly present in post-menopausal women during incidental X-ray or CT/MRI of the skull. The prevalence of HFI is documented in different populations, but in the Indian population, it is comparatively rare. Thus, we discuss a serendipitous finding of HFI in an Indian skull. This rare variation was noted in dry Indian human skulls. Gross features of the skull were noted, and it was an adult female skull. The area was decalcified, paraffin-embedded, and stained with Haematoxylin and Eosin. The skull bone was also subjected to plain X-ray/CT investigation. The X-ray skull of 50+ year female type features in anteroposterior and lateral view showed widening of the diploic spaces 8-10 mm with ill-defined hyperdense areas in the frontal region. Changes in computed tomography were noted. HFI often has nonspecific and benign symptoms. However, in severe cases, widespread clinical implications starting from headache, motor aphasia, parkinsonism, and depression can occur, and thus we all should be aware of it.

A Case Report of Hyperostosis Frontalis Interna

A routine dissection of an 89-year-old female cadaver who had died of cardiopulmonary arrest revealed a unique case of hyperostosis frontalis interna (HFI). Multiple layers of spongy bone growth deep to the internal table were coupled with asymmetrical nodular growths. Slight superior sagittal sinus growth was also noted, which is atypical of this condition. Additionally, this cadaver represents one of the rarer and more severe forms of HFI, class C. A clear consensus on whether HFI presents a clinical risk has not been reached. We hope that this report on a unique manifestation of HFI will help clinicians in evaluating patients with this condition.

Direct Comparison of the Tau PET Tracers 18F-Flortaucipir and 18F-MK-6240 in Human Subjects

Tau PET tracers exhibit varying levels of specific signal and distinct off-target binding patterns that are more diverse than amyloid PET tracers. This study compared 2 frequently used tau PET tracers, 18F-flortaucipir and 18F-MK-6240, in the same subjects. Methods:18F-flortaucipir and 18F-MK-6240 scans were collected within 2 mo in 15 elderly subjects varying in clinical diagnosis and cognition. FreeSurfer, version 5.3, was applied to 3-T MR images to segment Braak pathologic regions (I-VI) for PET analyses. Off-target binding was assessed in the choroid plexus, meninges, and striatum. SUV ratio (SUVR) outcomes were determined over 80-100 min (18F-flortaucipir) or 70-90 min (18F-MK-6240) normalized to cerebellar gray matter. Masked visual interpretation of images was performed by 5 raters for both the medial temporal lobe and the neocortex, and an overall (majority) rating was determined. Results: Overall visual ratings showed complete concordance between radiotracers for both the medial temporal lobe and the neocortex. SUVR outcomes were highly correlated (r2 > 0.92; P ≪ 0.001) for all Braak regions except Braak II. The dynamic range of SUVRs in target regions was approximately 2-fold higher for 18F-MK-6240 than for 18F-flortaucipir. Cerebellar SUVs were similar for 18F-MK-6240 and 18F-flortaucipir, suggesting that differences in SUVRs are driven by specific signals. Apparent off-target binding was observed often in the striatum and choroid plexus with 18F-flortaucipir and most often in the meninges with 18F-MK-6240. Conclusion: Both 18F-MK-6240 and 18F-flortaucipir are capable of quantifying signal in a common set of brain regions that develop tau pathology in Alzheimer disease; these tracers perform equally well in visual interpretations. Each also shows distinct patterns of apparent off-target binding. 18F-MK-6240 showed a greater dynamic range in SUVR estimates, which may be an advantage in detecting early tau pathology or in performing longitudinal studies to detect small interval changes.

A rare case of hyperostosis frontalis interna in an 86-year-old Japanese female cadaver

Hyperostosis frontalis interna (HFI) is a condition characterized by abnormal bone outgrowth on the inner surface of the frontal bone. Most HFI cases occur in post-menopausal elderly women. The pathology of HFI development is uncertain. The estimated incidence of HFI ranges from 5 to 12% in Western countries, but few cases have been reported in the Japanese population. Here, we report a case of HFI in an 86-year-old Japanese female cadaver. Macroscopically, the internal surface of the frontal bone exhibited bilateral nodular protrusion with sparing of the midline, while the external surface was normal. According to the morphological classification of HFI proposed by Hershkovitz et al. this case belongs to type D, the most severe type. Using computed tomography (CT), we defined five layers, designated as I-V from the inner to the outer layer, in the nodular region of HFI; however, the normal frontal bone is composed of three layers. Histological results demonstrated that layers I, III, and V consisted of the cortical bone, and layers II and IV consisted of the trabecular bone. We also observed increases in the numbers of lamellar bone and blood vessels on the dural side of layer I, indicating increased vascularization and active osteogenesis. These results indicate that layer II represents a new diploe within the inner table, which split into layers I and III, suggesting that diploization within the inner table by activated remodeling may be involved in the development of hyperostosis in this case.

Hyperostosis frontalis interna in ancient populations from the Carpathian Basin - A possible relationship between lifestyle and risk of development

OBJECTIVE

The prevalence of hyperostosis frontalis interna (HFI) was examined in different periods of the Carpathian Basin from 4900 BCE to 17th century AD. The study seeks to evaluate temporal changes in HFI and the possible impact of lifestyle on it.

MATERIALS

The studied material consisted of 4668 crania from Hungary and Serbia.

METHODS

The crania were analyzed employing macroscopic and endoscopic examination.

RESULTS

In historic periods, sex and age played a pivotal role in HFI development. Among predominantly pastoralist populations of the 5th-8th and 10th centuries, prevalence of HFI was considerably higher than in the medieval populations of the 9th-17th centuries.

CONCLUSIONS

In addition to age and sex, other factors could be implicated in HFI development. The physiological effects of the pastoralist lifestyle and diet on insulin regulation could explain the increased risk of developing HFI in the 5th-8th and 10th-century populations.

SIGNIFICANCE

The study provides the first comprehensive dataset of HFI from different archaeological periods from the Carpathian Basin. It has implications for lifestyle and risk of HFI development in past populations.

LIMITATIONS

The archaeological periods are not equally represented.

SUGGESTIONS FOR FURTHER RESEARCH

In order to better understand the etiology of HFI, lifestyle factors can be used to elucidate the risk of developing HFI in ancient populations.

Hyperostosis Frontalis Interna in a Child With Severe Traumatic Brain Injury

Hyperostosis frontalis interna is an unexplained irregular thickening of the inner table of the frontal bone. Hyperostosis frontalis interna was first identified in 1719 by Morgagni as a symptom of a more generalized syndrome characterized by virilism and obesity. Most current studies have shown hyperostosis frontalis interna to be a sex- and age-dependent phenomenon, and females manifest a significantly higher prevalence of hyperostosis frontalis interna than males. In this article, the authors report the clinical case of hyperostosis frontalis interna in a 7-year-old child who had severe traumatic brain injury in the past; review the related literature; and discuss the clinical, radiological, and therapeutic features of this condition.

Hyperostosis frontalis interna in female historic skeletal populations: Age, sex hormones and the impact of industrialization

OBJECTIVES

This analysis aims to investigate the impact of industrialization on the prevalence of Hyperostosis Frontalis Interna (HFI), focusing on the roles of age and parity to examine the claim that longevity and changing reproductive patterns have led to increased rates in modern populations.

MATERIALS AND METHODS

A total of 138 individuals from two documented London skeletal assemblages of the Industrial period were analyzed employing macroscopic observation, digital radiography and MicroCT scanning to establish the prevalence rates of HFI according to modern clinical standards. Statistical analysis was also undertaken on a sub-sample of 51 females of post-menopausal age to identify any relationship between parity and HFI.

RESULTS

The majority of cases of HFI were found in older females, reflecting clinical observations. The prevalence rates of HFI corresponded well to those predicted from the proportion of old age females present within populations. Age was therefore shown to be a predominant factor in HFI presence. A plateau in HFI prevalence was noted from the age of 50-59 years onwards. No statistically significant relationship was found between parity and HFI.

DISCUSSION

When recorded consistently, HFI was positively correlated with age and longevity but had also increased among old age females over time. Our results suggest that nulliparity co-occurs with HFI but is not a primary factor in its pathogenesis. Key factors in HFI presence in females are likely to be increased androgens and the dysregulation of insulin and insulin-like growth factor-1.

3D-Microarchitectural patterns of Hyperostosis frontalis interna: a micro-computed tomography study in aged women

Although seen frequently during dissections and autopsies, Hyperostosis frontalis interna (HFI) - a morphological pattern of the frontal bone thickening - is often ignored and its nature and development are not yet understood sufficiently. Current macroscopic classification defines four grades/stages of HFI based on the morphological appearance and size of the affected area; however, it is unclear if these stages also depict the successive phases in the HFI development. Here we assessed 3D-microarchitecture of the frontal bone in women with various degrees of HFI expression and in an age- and sex-matched control group, hypothesizing that the bone microarchitecture bears imprints of the pathogenesis of HFI and may clarify the phases of its development. Frontal bone samples were collected during routine autopsies from 20 women with HFI (age: 69.9 ± 11.1 years) and 14 women without HFI (age: 74.1 ± 9.7 years). We classified the HFI samples into four groups, each group demonstrating different macroscopic type or stage of HFI. All samples were scanned by micro-computed tomography to evaluate 3D bone microarchitecture in the following regions of interest: total sample, outer table, diploe and inner table. Our results revealed that, compared to the control group, the women with HFI showed a significantly increased bone volume fraction in the region of diploe, along with significantly thicker and more plate-like shaped trabeculae and reduced trabecular separation and connectivity density. Moreover, the inner table of the frontal bone in women with HFI displayed significantly increased total porosity and mean pore diameter compared to controls. Microstructural reorganization of the frontal bone in women with HFI was also reflected in significantly higher porosity and lower bone volume fraction in the inner vs. outer table due to an increased number of pores larger than 100 μm. The individual comparisons between the control group and different macroscopic stages of HFI revealed significant differences only between the control group and the morphologically most pronounced type of HFI. Our microarchitectural findings demonstrated clear differences between the HFI and the control group in the region of diploe and the inner table. Macroscopic grades of HFI could not be distinguished at the level of bone microarchitecture and their consecutive nature cannot be supported. Rather, our study suggests that only two different types of HFI (moderate and severe HFI) have microstructural justification and should be considered further. It is essential to record HFI systematically in human postmortem subjects to provide more data on the mechanisms of its development.

Meta-analysis of associations between human brain volume and intelligence differences: How strong are they and what do they mean?

Positive associations between human intelligence and brain size have been suspected for more than 150 years. Nowadays, modern non-invasive measures of in vivo brain volume (Magnetic Resonance Imaging) make it possible to reliably assess associations with IQ. By means of a systematic review of published studies and unpublished results obtained by personal communications with researchers, we identified 88 studies examining effect sizes of 148 healthy and clinical mixed-sex samples (>8000 individuals). Our results showed significant positive associations of brain volume and IQ (r=.24, R(2)=.06) that generalize over age (children vs. adults), IQ domain (full-scale, performance, and verbal IQ), and sex. Application of a number of methods for detection of publication bias indicates that strong and positive correlation coefficients have been reported frequently in the literature whilst small and non-significant associations appear to have been often omitted from reports. We show that the strength of the positive association of brain volume and IQ has been overestimated in the literature, but remains robust even when accounting for different types of dissemination bias, although reported effects have been declining over time. While it is tempting to interpret this association in the context of human cognitive evolution and species differences in brain size and cognitive ability, we show that it is not warranted to interpret brain size as an isomorphic proxy of human intelligence differences.

Potential effect of skull thickening on the associations between cognition and brain atrophy in ageing

BACKGROUND

intracranial volume (ICV) is commonly used as a marker of premorbid brain size in neuroimaging studies as it is thought to remain fixed throughout adulthood. However, inner skull table thickening would encroach on ICV and could mask actual brain atrophy.

OBJECTIVE

we investigated the effect that thickening might have on the associations between brain atrophy and cognition.

METHODS

the sample comprised 57 non-demented older adults who underwent structural brain MRI at mean age 72.7 ± 0.7 years and were assessed on cognitive ability at mean age 11 and 73 years. Principal component analysis was used to derive factors of general cognitive ability (g), information processing speed and memory from the recorded cognitive ability data. The total brain tissue volume and ICV with (estimated original ICV) and without (current ICV) adjusting for the effects of inner table skull thickening were measured. General linear modelling was used to test for associations.

RESULTS

all cognitive ability variables were significantly (P < 0.01) associated with percentage total brain volume in ICV measured without adjusting for skull thickening (g: η(2) = 0.177, speed: η(2) = 0.264 and memory: η(2) = 0.132). After accounting for skull thickening, only speed was significantly associated with percentage total brain volume in ICV (η(2) = 0.085, P = 0.034), not g or memory.

CONCLUSIONS

not accounting for skull thickening when computing ICV can distort the association between brain atrophy and cognitive ability in old age. Larger samples are required to determine the true effect.

Assessing the performance of atlas-based prefrontal brain parcellation in an aging cohort

OBJECTIVE

It is unclear whether atlas-based parcellation is suitable in aging cohorts because age-related brain changes confound the performance of automatic methods. We assessed atlas-based parcellation of the prefrontal lobe in an aging population using visual assessment and volumetric and spatial concordance.

METHODS

We used an atlas-based approach to parcellate brain MR images of 90 non-demented healthy adults, aged 72.7 ± 0.7 years, and assessed performance.

RESULTS

Volumetric assessment showed that both single-atlas- and multi-atlas-based methods performed acceptably (intraclass correlation coefficient [ICC], 0.74-0.76). Spatial overlap measurements showed that multi-atlas (dice coefficient [DC], 0.84) offered an improvement over the single-atlas (DC, 0.75-0.78) approach. Visual assessment also showed that multi-atlas outperformed single atlas and identified an additional postprocessing step of cerebrospinal fluid removal, enhancing concordance (intraclass correlation coefficient, 0.86; DC, 0.89).

CONCLUSIONS

Atlas-based parcellation performed reasonably well in the aging population. Rigorous performance assessment aided method refinement and emphasizes the importance of age matching and postprocessing. Further work is required in more varied subjects.