Head Specimens Research Articles

Insufficient blood supply of fovea capitis femoris, a risk factor of femoral head osteonecrosis

BackgroundA defective nutrient foramen in the fovea capitis femoris was hypothesized to reflect the blood circulation pattern of the femoral head, leading to insufficient blood supply and causing osteonecrosis of the femoral head.MethodsNormal and necrotic femoral head specimens were collected. The necrotic femoral head group was divided into a non-traumatic and traumatic subgroup. 3D scanning was applied to read the number, the diameter, and the total cross-sectional area of the nutrient foramina in the fovea capitis femoris. Chi-squared tests and independent t-tests were used to detect any differences in the categorical and continuous demographic variables. Logistic regression models were used to estimate the odds ratio (OR) for non-traumatic and traumatic osteonecrosis in different characteristic comparisons.ResultsA total of 249 femoral head specimens were collected, including 100 normal femoral heads and 149 necrotic femoral heads. The necrotic femoral head group revealed a significantly higher percentage of no nutrient foramen (p < 0.001), a smaller total area of nutrient foramina (p < 0.001), a smaller mean area of nutrient foramina (p = 0.014), a lower maximum diameter of the nutrient foramen (p < 0.001), and a lower minimum diameter of the nutrient foramen (p < 0.001) than the normal femoral head group. The logistic regression model demonstrated an increasing number of nutrient foramina (crude OR, 0.51; p < 0.001), a larger total area of nutrient foramina (crude OR, 0.58; p < 0.001), a larger mean area of nutrient foramina (crude OR, 0.52; p = 0.023), a greater maximum diameter of the nutrient foramen (crude OR, 0.26; p < 0.001), and greater minimum diameter of the nutrient foramen (crude OR, 0.20; p < 0.001) significantly associated with reduced odds of osteonecrosis of the femoral head (ONFH). The necrotic femoral head group was further divided into 118 non-traumatic and 31 traumatic necrotic subgroups, and no significant difference was observed in any characteristics between them.ConclusionsCharacteristics of the nutrient foramen in the fovea capitis femoris showed a significant defect of necrotic than normal femoral heads, and significantly reduced odds were associated with the higher abundance of the nutrient foramen in ONFH. Therefore, the condition of the nutrient foramen might be the indicator of ONFH.

Application of iodine staining technique for tumor identification in Micro-CT of mouse model with skull base-infratemporal fossa tumor

Objective To establish an animal model with malignant tumor in the skull base-infratemporal region, and to explore the role of iodine staining technique in identifying tumor tissues with Micro-CT data. Methods Sedation anesthesia was carried out on 12 BABL/c nude mice using inhaled isoflurane, and then WSU-HN6 cells that cultured and immortalized from human tongue squamous cell carcinoma were injected into the right infratemporal fossa via the submandibular area. The procedure was carried out under ultrasonographic guidance. The nude mice were sacrificed after 3 weeks observation. The head specimens were fixed and scanned by Micro-CT, and repeated scans were performed after staining with 3.75% compound iodine solution. Following decalcification in 20% EDTA for 2-4 weeks, the head specimens were embedded and sectioned. Hematoxylin and eosin staining and Pan-Keratin immunohistochemical staining were carried out. Bright-field microscopy and stereomicroscopy were used to visualize. The Micro-CT data were analyzed using iPlan software (Brainlab). Results Non-traumatic ultrasonography was used to guide HN-6 cells injection and confirm skull-base tumor formation in all the animals. Ultrasonographic guidance reduced the risk of cervical vessel injury when transferring tumor cells into the skull base space. An obvious asymmetrical appearance was detected via ultrasonography 3 weeks after tumor cell injection. The Micro-CT analysis showed that the bone was obviously damaged on the right side of the skull base, but the soft tissue image was unrecognizable. After four days staining with compound iodine solution, the morphology of the tumor and surrounding soft tissue could be clearly identified. Hematoxylin and eosin staining showed the tumor formation of the right infratemporal fossa region accompanied by bone destruction. Human keratin immunohistochemical staining showed that the tumor tissue originated from human squamous cell carcinoma, and the polynuclear osteoclasts could be seen at the margin of the skull base bone resorption. Conclusion The animal model with malignant tumor in the skull base-infratemporal region could be successfully established via submandibular injection under ultrasound-guidance. Bone changes of the skull were easily observed on Micro-CT, but the tumor counter was not able to be distinguished from surrounding soft tissue. The 3.75% compound iodine staining of the head specimen could help discern the tumor and surrounding soft tissue in more details.

The Infratemporal Retro-Eustachian Transposition of the Temporoparietal Fascial Flap for Clival Reconstruction After Endoscopic Endonasal Approach: An Anatomic Conceptual Technique.

Reconstruction after endoscopic endonasal approaches is a key element. Lower clivus reconstruction is difficult and most of the times a pedicled flap is not available. As the complexity and the dimensions of the exposure increase, a reliable reconstruction technique becomes more and more important. To describe the anatomic and technical nuances of the transposition of the temporoparietal fascial flap for lower clivus reconstruction. A specific temporoparietal fascial flap (TPFF) design and tunneling technique has been studied using 4 head specimens, microscopic and endoscopic surgical techniques, and neuronavigation. The L-shaped flap offers several advantages. It can be tunneled directly toward the lower clivus passing through the infratemporal fossa. The infratemporal retro-eustachian transposition of an L-shaped TPFF provides a vascularized tissue virtually without dimension limits. This is the only technique that allows the flap to be tunneled directly in the lower clivus with the most vascular portion being at the bottom of the defect. Clinical validation is still required since more issues may become relevant in a real-surgery setting. Though, due to its possible complications, this methodology needs further testing and should not be attempted in less experienced hands.

Assessment of potential strain injury to rectus capitis posterior minor muscles during whiplash type distortions of the cervical spine.

Whiplash type injuries resulting from a rear end motor vehicle accident (REMVA) are thought to be caused by excessive loading and displacement of structural components of the cervical spine. On impact, the seat propels the driver's torso forward relative to the head, resulting in forced flexion of the occipitoatlantal (OA) joint, accompanied by forced stretching of the rectus capitis posterior minor (RCPm) muscles. Flexion of the OA joint and stretching of the RCPm muscles continues to increase until the vehicle's headrest strikes the back of the driver's head. It is known that externally applied forces that attempt to move the OA joint beyond its anatomic barrier can result in fracture, dislocation, or soft tissue damage to its structural components. However, the magnitude of headrest backset, defined as the distance between the driver's head and the vehicle's headrest, that would result in RCPm muscles being stretched to a length that would put them at risk for a muscle strain injury is unknown. To quantify the relationships among flexion of the OA joint, RCPm muscle stretch, and backset, and to quantify the biomechanical response of RCPm muscles to increasing levels of axial load due to stretching. Unembalmed head and neck specimens from three White females aged 85, 63, and 70 years were obtained from the Anatomical Services Division at the University of Maryland. Donors had provided written consent allowing use of their body for research purposes. Using an analytic model of the OA joint, the relationships between flexion of the OA joint and RCPm muscle stretch as a function of backset were estimated. RCPm muscles were removed from the cadavers and forcibly stretched using a servomechanism controlled hydraulic testing machine to quantify the load/displacement properties. After testing, the tissues were sectioned, mounted, and stained using Masson's trichrome to selectively stain muscle fibers red and collagen blue. Forced flexion of the OA joint was seen to be directly related to the magnitude of headrest backset. For values of backset greater than 7.2cm, biomechanical testing of the RCPm muscles revealed that strain injuries ranged from the tearing of a few muscle fibers to complete rupture of the muscle and separation of the tendon at the posterior process of C1. Results showed that headrest backset at the time of vehicle impact is an important factor in estimating the risk of muscle strain injury to RCPm muscles. Muscle strain injury would be expected to impact the functional relationship between the RCPm muscles and the pain sensitive spinal dura. Physicians should be alert to the possibility that cervicogenic pain patients who have experienced whiplash associated with REMVA may show clinically relevant structural damage to the RCPm muscles on MRI.

The lateral cerebral peduncle approach to ventrally placed intra-axial midbrain tumors: A technical note

We describe the anatomical landmarks and surgical feasibility of a novel ‘safe’ brainstem entry zone to approach ventrally placed intra-axial midbrain tumors.The anatomy of the brainstem was specifically studied to evaluate safe surgical entry zone in the midbrain on two formalin fixed silicon injected cadaver head specimens. A novel entry point through the lateral one – fifth of the cerebral peduncle was identified to be ‘safe’ to approach lesions of the ventral midbrain. Three patients, having oculomotor schwannoma, peduncular glioma and a peduncular cavernoma were operated using this safe entry zone. To approach the midbrain, retrosigmoid lateral supracerebellar route was used in two patients and a basal subtemporal avenue was deployed in one patient. On the basis of fine microanatomical dissection on cadavers, a novel entry point through the lateral one-fifth of the cerebral peduncle, 5 mm anterior to the lateral mesencephalic sulcus and approximately 5 mm superior to the fourth nerve was identified. The proposed brainstem entry point traverses the parieto-temporo-occipital pontine fibers and the trajectory is between the corticospinal tracts ventrally and the substantia nigra dorsally. Three patients were operated successfully using the approach. There were no post-operative motor, sensory or extra-pyramidal deficits. The corridor through the lateral one-fifth of the cerebral peduncle presents a safe and relative ‘easy’ surgical route to approach ventrally placed intra-axial midbrain tumors.

Utilizing Plastinated Head and Neck Dissections for Doctorate of Dental Medicine (DMD) Anatomy Laboratories in a Curriculum Approaching Reorganization: The “Guinea Pig” Cohort's Experience

The University of Nevada Las Vegas’ School of Dental Medicine (UNLV SDM) recently acquired 36 Von Hagens plastinated head and neck specimens to be used in the first semester “Head and Neck Anatomy and Neuroscience” course. The 2020-entry class was the first cohort of students to supplement their digital-based anatomy curriculum with human specimens. From a student perspective, there was trepidation regarding the change and workload addition as previous cohorts did not use this educational approach yet successfully passed their board exams, were accepted into residency programs and found quality employment. Positive reports did document that the ability to conceptualize the three-dimensional anatomy was greatly enhanced. Previous cohorts informally reported that this addition would have enhanced their learning and retention. From a faculty perspective, considerations related to COVID social-distancing requirements, lecture hall availability and encouraging student preparedness were clear challenges. A regular frustration arose as plastination hinders an instructor's ability to follow structures and reflect more muscle or bone to demonstrate deeper anatomy. UNLV SDM is awaiting re-accreditation, which was delayed due to COVID, prior to executing a curriculum reorganization. Currently, first year students have a 26-credit semester with heavy workload, even in the smaller, modular courses. This creates major constraints on the students’ ability to master the content for assessments and retain the content for the NBDE board exam and clinical practice. Instructors modified structures lists, lecture topics for discussion and lab expectation continually throughout the semester to help students make the experience as meaningful as possible. This is a unique curricular reorganization as the contact hours for anatomy remain the same but the workload increases; many graduate-level health profession programs are decreasing workload and contact hours in anatomy.

STING enhances cell death through regulation of reactive oxygen species and DNA damage

Resistance to DNA-damaging agents is a significant cause of treatment failure and poor outcomes in oncology. To identify unrecognized regulators of cell survival we performed a whole-genome CRISPR-Cas9 screen using treatment with ionizing radiation as a selective pressure, and identified STING (stimulator of interferon genes) as an intrinsic regulator of tumor cell survival. We show that STING regulates a transcriptional program that controls the generation of reactive oxygen species (ROS), and that STING loss alters ROS homeostasis to reduce DNA damage and to cause therapeutic resistance. In agreement with these data, analysis of tumors from head and neck squamous cell carcinoma patient specimens show that low STING expression is associated with worse outcomes. We also demonstrate that pharmacologic activation of STING enhances the effects of ionizing radiation in vivo, providing a rationale for therapeutic combinations of STING agonists and DNA-damaging agents. These results highlight a role for STING that is beyond its canonical function in cyclic dinucleotide and DNA damage sensing, and identify STING as a regulator of cellular ROS homeostasis and tumor cell susceptibility to reactive oxygen dependent, DNA damaging agents.

HPV DNA genotyping, HPV E6*I mRNA detection, and p16INK4a/Ki-67 staining in Belgian head and neck cancer patient specimens, collected within the HPV-AHEAD study

BackgroundThe main risk factors for head and neck cancer (HNC) are tobacco and alcohol use. However, an important fraction of oropharyngeal cancer (OPC) is caused by human papillomaviruses (HPV), a subgroup with increasing incidence in several western countries. MethodsAs part of the HPV-AHEAD study, we assessed the role of HPV infection in 772 archived tissue specimens of Belgian HNC patients: 455 laryngeal (LC), 106 oral cavity (OCC), 99 OPC, 76 hypopharyngeal (HC), and 36 unspecified parts of the head and neck. All specimens were tested for HPV DNA (21 genotypes); whereof all HPV DNA-positives, all HPV DNA-negative OPCs and a random subset of HPV DNA-negatives of the other HNC-sites were tested for the presence of type-specific HPV RNA and p16INK4a over-expression. ResultsThe highest HPV DNA prevalence was observed in OPC (36.4 %), and was significantly lower (p < 0.001) in the other HNCs (OCC:7.5 %, LC:6.6 %). HPV16 was the most common HPV-genotype in all HNCs. Approximately 83.0 % of the HPV DNA-positive OPCs tested HPV RNA or p16-positive, compared to about 37.5 % and 44.0 % in OCC and LC, respectively. Estimation of the attributable fraction of an HPV infection in HNC was very similar for HPV RNA or p16 in addition to DNA-positivity; with 30 % for OPC, and 3 % for OCC and LC. ConclusionOur study confirms the heterogeneity of HPV DNA prevalence across anatomical sites in HNC, with a predominance of HPV16 in all sites. The estimated proportion of HPV-driven HNC in Belgium, during the period 1980–2014, was 10 times higher in OPC compared to OCC and LC.

Endoscopic Anatomy of the Chorda Tympani: Systematic Dissection, Novel Anatomic Classification, and Surgical Implications.

A transcanal endoscopic approach enables visualization of the variable course of the chorda tympani inside the middle ear. The chorda tympani is the longest intrapetrous branch of the facial nerve. Despite having been investigated in several studies, a description of its tympanic tract from an endoscopic point of view is lacking in the literature. We performed transcanal endoscopic dissections of 44 human cadaveric head and ear specimens. The entry point of the chorda tympani into the middle ear was classified into four categories according to its location, and as covered or dehiscent according to its appearance. The chordal eminence (CE) was defined as absent, shallow, intermediate, prominent, or fused, based on its shape and extension. The relationship of the chorda tympani to adjacent bony and ligamental structures was assessed. The tympanic tract of the chorda tympani was divided into three portions. The periannular segment was dehiscent in 54.5% of specimens, with type II being the most frequent entry point configuration (52.3%). In the interossicular segment, the nerve consistently passed lateral to the incus and medial to the malleus. The course of the intrapetrous segment was independent from the conformation of the tensor fold and supratubal recess. The transcanal endoscopic approach allows a detailed description of tympanic segment of the chorda tympani. Novel anatomic classifications of the chorda tympani and CE are proposed herein to highlight their possible surgical implications during otologic procedures.

Endoscopic Transorbital Approaches to Anterior and Middle Cranial Fossa: Exploring the Potentialities of a Modified Lateral Retrocanthal Approach

Among the new perspectives to revolutionize skull base surgery, there are the transorbital neuroendoscopic (TONES) approaches to reach the anterior and middle cranial fossa (ACF and MCF). We conceived to explore the potentialities of a modified superiorly and medially extended lateral retrocanthal (LRC) approach. Six head specimens were dissected. Applying the established conic model and the key surgical landmark of sphenofrontal suture, we tested the feasibility of a modified LRC to reach ACF and MCF; computed tomography (CT) scans were performed before and after dissection to obtain a morphometric analysis of the surgical corridors using a polygonal surfaces model. Through our anatomical study, we were able to identify and explore 3 different surgical corridors to reach the ACF and MCF: the superomedial, the superolateral, and the inferolateral. The superomedial corridor appeared most suitable to reach the medial part of the ACF and the optic-carotid region, whereas through the superolateral and inferolateral corridors it was possible to reach and explore the lateral part of ACF and MCF. The mean volumes of the 3 surgical corridors calculated on post-dissection CT scans were: 12.72 ± 1.99, 5.69 ± 0.34, and 6.24 ± 0.47 cm3, respectively. The development of TONES approaches has not replaced the traditional open or endoscopic approach; nonetheless, identification of surgical corridors and the possibility to combine them represent a major breakthrough. Clinical studies are necessary to demonstrate their validity and test the effectiveness, safety, and reproducibility of TONES approaches in managing lesions harboring in the ACF and MCF.

Endoscopic Endonasal Approach to the Ventral-Medial Portion of Posterior Paramedian Skull Base: A Morphometric Perspective of Surgical and Radiologic Anatomy

This study aims to provide morphometric analysis of endoscopic endonasal approach (EEA) to the ventral-medial portion of posterior paramedian skull base. Furthermore, it aims to investigate the surgical exposure obtained through EEA with and without eustachian tube (ET) removal, emphasizing the role of contralateral nostril (CN) access. Five fresh adult head specimens were prepared for dissection. A predissection and a postdissection computed tomography study was performed. A surgically oriented classification into 4 regions was used: 1) tubercular region; 2) occipital condyle region; 3) parapharyngeal space (PPhS) region; and 4) jugular foramen (JF) region. The Student t-test was used to compare angulations and measures of EEA with access from the ipsilateral and CN, respectively, with and without ET removal. EEA to the ventral-medial portion of posterior paramedian skull base encompasses 2 medial trajectories (transtubercular and transcondylar) and 2 lateral pathways to the PPhS and JF. The CN access, without removal of the ET, allows a complete exposure of the petrous and intrajugular portion of the JF and superior PPhS without exposition of the parapharyngeal segment of internal carotid artery. The ipsilateral nostril approach with ET removal allows to obtain a wider exposure, reaching the medial sigmoid part of the JF. No significant differences exist in regard to transtubercular and transcondylar approaches. This study suggests that EEA to posterior paramedian skull base allows the realization of a corridor directed to the jugular tubercle, occipital condyle, medial PPhS, and ventral-medial JF. The CN approach with ET preservation can expose the petrous and intrajugular parts of the JF and PPhS. Case series are needed to demonstrate benefits and drawbacks of these approaches.

A new landmark for lingual artery identification during transoral surgery: Anatomic-radiologic study.

A landmark for the identification of the lingual artery (LA) through a transoral perspective can provide surgeons with an easy method to prevent and manage intraoperative bleeding during transoral approach to the base of tongue (BOT). Thirteen tongue and five head and neck specimens were dissected to identify and assess the reliability of the lingual point (LP) as a new landmark for the LA at BOT. The pathway of 42 LAs was radiologically evaluated; axial depth and vertical offset were measured for each LA. Dissection study: a description of LP is provided; the LA was easily identified in all specimens (36/36 sides) using LP as a landmark. Radiologic study: the mean depth of the LA was 4.2 mm, the mean vertical offset was 1.3 mm. LP is a simple and reliable landmark for identification of the LA, potentially helping surgeons to prevent and manage intraoperative bleeding.

Questionnaire-based survey regarding the opinion of general pathologists on the need for oral pathology services.

Context:Oral and maxillofacial pathology (OMFP) is a subspecialization having a masters course in India. Due to lesser number of oral pathologists in the country, the biopsy material from the head and neck is catered to by the general pathologist.Aim:This survey was conducted to acquire responses from general pathologists and gathering knowledge on their perspective of oral pathology.Methods:Pathologists at various medical institutions and at laboratories all over Karnataka were requested to answer a questionnaire comprising 13 questions pertaining to the need and scope of oral pathology.Results:In total, 37 (57%) general pathologists completed the questionnaire, of whom 97% (36) were aware of the specialty and 30 (81%) perceived a need for it. Eleven (30%) of them referred oral biopsy specimens to oral pathologists. The most common sources of diagnostic difficulty were identified as odontogenic tumors and cysts. Twenty-six (70%) pathologists felt the need for a short-term posting for their postgraduates in oral pathology, while 28 (76%) of them expressed their opinion about considering an oral pathologist as a part of their team when diagnosing complex head and neck pathologies. Twelve (71%) of them mentioned that they sometimes found that head and neck lesions took longer time to diagnose.Conclusion:Although the utilization of OMFP specialists’ services in the state is quite low, general pathologists strongly feel the need for OMFP training as head and neck specimens form a considerable proportion of biopsies received by them.

Endoscopic endonasal pituitary hemi-rotation approach to the upper clivus: anatomical study and clinical report.

To report on the endoscopic endonasal pituitary hemi-rotation approach (EPHRA) in a preclinical setting and in a preliminary clinical experience. EPHRA was performed in five fresh-frozen head and neck specimens (a total of 10 sides) and in a selected case of a right-sided dorsum sellae chordoma. The approach described allowed exposure of the lateral part of the upper clivus in all the specimens and in the case reported. To evaluate the maximum possible degree of hypophyseal hemi-rotation, the hemi-rotation angle (HRA) of the approach was measured and reported for all sides of the specimens. In 9 out of 10 cadaver head sides, and in the clinical case, it was possible to avoid sectioning of the inferior hypophyseal artery. No complications occurred during or after the procedure. EPHRA represents an addition to the techniques already described and finds indications in case of non-massive neoformations of the lateral upper clivus. Clinical applications and limitations still need to be clarified in further clinical studies.

Characterizing Cochlear implant artefact removal from EEG recordings using a real human model

Electroencephography (EEG) recordings from CI listeners are contaminated by electrical artefacts that make it difficult to extract neural responses. Previously, we have removed these artefacts by means of interpolation and spatial filtering. However, the extent to which this method can effectively reduce electrical artefacts has not been fully investigated. Here, we assessed the effectiveness of interpolation and spatial filtering to remove electrical artefacts using recordings from a human head specimen implanted with a CI.•Electrical artefacts were obtained using amplitude-modulated (AM'ed) pulse trains presented at several pulse rates (100-to-902 pps) or using high rate pulse trains (902 pps) in which either a pair of electrodes or AM frequencies alternated periodically at a rate of 1Hz.•By adding auditory change complex (ACC), auditory steady-state response (ASSR), or auditory change following response (AC-FR) template waveforms to the contaminated recordings, we show that interpolation allows for effective artefact removal for pulse rates below 400 pps whilst interpolation and spatial filtering are effective at higher pulse rates, with minimal distortions for ACC and AC-FR, and with a degree of amplitude- and phase-distortions for ASSR.•Recordings from CI listeners agreed with simulations, demonstrating that reliable responses can be recovered.

Prevalence of pathological neck of femur fractures in patients undergoing arthroplasty at a tertiary referral hospital

ABSTRACT BACKGROUND: This study aimed to determine the prevalence of pathological neck of femur (NOF) fractures at a tertiary referral hospital through histological examination of specimens in all NOF fracture patients undergoing hip arthroplasty. A secondary aim was to determine whether the current practice of sending all femoral heads for histological evaluation, to avoid missing unsuspected malignancies, is financially warranted. METHODS: A retrospective folder review of patients who underwent arthroplasty for NOF fractures was conducted. Patients with suspected pathological fractures were managed by the divisional Bone Tumour Unit while fragility traumatic fractures were managed by the Arthroplasty Unit. All femoral heads were sent for histological analysis regardless of suspicion of pathological fracture. Quotes from the public and private sector were sought to determine cost implications of sending femoral head specimens for histology. RESULTS: A total of 311 patients were included. Of these, 11 patients (4%) had suspected pathological fractures, with fragility/traumatic fractures being diagnosed in the remaining 300 patients (97%). Histology results were available for 195 patients (63%), including all the patients with suspected pathological fractures. No unexpected malignant histological results were observed, while nine of the suspected pathological fracture group had pathological fractures, confirmed with histology. CONCLUSION: Pathological lesions were identified in 3% of patients undergoing arthroplasty for NOF fractures in our population, which is higher than other reports in the literature. Routine histological screening of femoral heads to exclude pathological fracture might not be necessary and cost effective, as pathological lesions can accurately be identified by clinical and radiographic evaluation. Level of evidence: Level 4 Keywords: femoral head histology, pathological fracture, neck of femur fracture, metastases, hip arthroplasty

Human Papillomavirus Testing in Head and Neck Squamous Cell Carcinoma: Impact of the 2018 College of American Pathologists Guideline Among Referral Cases at a Large Academic Institution.

Given the growing clinical significance of human papillomavirus status in oropharyngeal squamous cell carcinoma, the College of American Pathologists established a set of evidence-based recommendations for high-risk human papillomavirus testing for publication in a guideline. To evaluate the impact of the recommendations on human papillomavirus ancillary test ordering habits by comparing compliance before and after the guideline was published. We retrospectively reviewed head and neck squamous cell carcinoma biopsy or resection specimens from outside institutions during a 2.5-year period around guideline publication to determine whether human papillomavirus testing was performed in accordance with the guideline. Human papillomavirus testing deviated from the guideline in 45 of 107 cases (42.1%) before and 93 of 258 cases (36.0%) after its publication (P = .29). This included 6 of 26 cases of oropharyngeal squamous cell carcinoma (23.1%) before and 5 of 55 cases (9.1%) after (P = .16), with 5 of 5 (100.0%) after due to not performing p16 immunohistochemistry. This also included 30 of 68 cases of nonoropharyngeal carcinoma (44.1%) before and 69 of 163 (42.3%) after the guideline was published (P = .88), with 29 of 30 (96.7%) before and 67 of 69 (97.1%) after due to unnecessary use of p16 immunohistochemistry. Nodal metastasis testing deviated in 9 of 13 cases (69.2%) before and 19 of 40 cases (47.5%) after (P = .21) with marked variability in testing, including 3 of 9 (33.3%) before and 8 of 19 (42.1%) after, for not confirming certain p16 immunohistochemistry-positive tumors with human papillomavirus-specific testing. Pathologists continue to deviate from the testing guideline significantly in everyday practice. Further education and discussion about the appropriate handling of head and neck cancer specimens may be needed.

Ontogenetic endocranial shape change in alligators and ostriches and implications for the development of the non-avian dinosaur endocranium.

Birds and crocodiles show radically different patterns of brain development, and it is of interest to compare these to determine the pattern of brain growth expected in dinosaurs. Here we provide atlases of 3D brain (endocast) reconstructions for Alligator mississippiensis (alligator) and Struthio camelus (ostrich) through ontogeny, prepared as digital restorations from CT scans of stained head and dry skull specimens. Our morphometric analysis confirms that ostrich brains do not change significantly in shape during postnatal growth, whereas alligator brains unfold from a cramped bird-like shape in the hatchling to an elongate, straight structure in the adult. We confirm that birds exhibit paedomorphic dinosaur endocranial traits such as retaining an enlarged and compact brain shape in the adult, whereas crocodiles show peramorphic traits where the brain elongates with growth as the skull elongates. These atlases of ontogenetic stages of modern bird and crocodilian endocrania provide a basis for comparison of non-avian dinosaur endocasts and consideration of the divergence of the "avian" and "crocodilian" modes of brain development and heterochronic change on phylogenies.

Anatomical Features of the Deep Cervical Lymphatic System and Intrajugular Lymphatic Vessels in Humans.

Background: Studies in rodents have re-kindled interest in the study of lymphatics in the central nervous system. Animal studies have demonstrated that there is a connection between the subarachnoid space and deep cervical lymph nodes (DCLNs) through dural lymphatic vessels located in the skull base and the parasagittal area. Objective: To describe the connection of the DCLNs and lymphatic tributaries with the intracranial space through the jugular foramen, and to address the anatomical features and variations of the DCLNs and associated lymphatic channels in the neck. Methods: Twelve formalin-fixed human head and neck specimens were studied. Samples from the dura of the wall of the jugular foramen were obtained from two fresh human cadavers during rapid autopsy. The samples were immunostained with podoplanin and CD45 to highlight lymphatic channels and immune cells, respectively. Results: The mean number of nodes for DCLNs was 6.91 ± 0.58 on both sides. The mean node length was 10.1 ± 5.13 mm, the mean width was 7.03 ± 1.9 mm, and the mean thickness was 4 ± 1.04 mm. Immunohistochemical staining from rapid autopsy samples demonstrated that lymphatic vessels pass from the intracranial compartment into the neck through the meninges at the jugular foramen, through tributaries that can be called intrajugular lymphatic vessels. Conclusions: The anatomical features of the DCLNs and their connections with intracranial lymphatic structures through the jugular foramen represent an important possible route for the spread of cancers to and from the central nervous system; therefore, it is essential to have an in-depth understanding of the anatomy of these lymphatic structures and their variations.

Iterative reconstruction and deep learning algorithms for enabling low-dose computed tomography in midfacial trauma

The objective of this study was to quantitatively assess the image quality of Advanced Modeled Iterative Reconstruction (ADMIRE) and the PixelShine (PS) deep learning algorithm for the optimization of low-dose computed tomography protocols in midfacial trauma. Six fresh frozen human cadaver head specimens were scanned by computed tomography using both standard and low-dose scan protocols. Three iterative reconstruction strengths were applied to reconstruct bone and soft tissue data sets and these were subsequently applied to the PS algorithm. Signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) were calculated for each data set by using the image noise measurements of 10 consecutive image slices from a standardized region of interest template. The low-dose scan protocol resulted in a 61.7% decrease in the radiation dose. Radiation dose reduction significantly reduced, and iterative reconstruction and the deep learning algorithm significantly improved, the CNR for bone and soft tissue data sets. The algorithms improved image quality after substantial dose reduction. The greatest improvement in SNRs and CNRs was found using the iterative reconstruction algorithm. Both the ADMIRE and PS algorithms significantly improved image quality after substantial radiation dose reduction.