Frontal sinus fractures: guidelines to management

The appropriate management of frontal sinus fractures is controversial. Experience with 78 frontal sinus fractures over a 9-year period was reviewed, and the fractures were classified into anterior wall, anterobasilar, and frontal skull fracture extensions. The presence of a concomitant CSF leak or an air-fluid level in the sinus was a diagnostic clue of posterior wall involvement. Ablation or obliteration of the fractured frontal sinus is not necessary. Primary reconstruction of the sinus and nasofrontal duct drainage constitute the preferred treatment. "Cranialization" of a severely damaged sinus is performed by excision of the posterior wall plugging of the nasofrontal duct and reconstruction of the anterior wall. Reconstruction of the anterior wall with primary bone grafting may be necessary in selected patients.     

Ontogeny of the partial secondary wall of the otoccipital region of the endocranium in prehatching Alligator mississippiensis (Archosauria, Crocodylia)

The ontogeny of the posterior otic and anterior occipital portions of the neural endocranium of prehatching Alligator mississippiensis was investigated by reconstruction from sectioned material. In Stage 6 of this species, in which the endochondral ossification of the otoccipital region of the neural endocranium is only in its very early stage, two bony outgrowths-laminae-are present at the external wall of the posterior portion of the neural endocranium. The anterior lamina arises from the external surface of the basal plate at the level of the posterior margin of the subcapsular process; the posterior lamina arises from the external surface of that portion of the pila occipitalis that forms the posteroventral wall of the metotic fissure. During ontogeny, both laminae lying in the anteroposterior sequence ossify in membrane, fuse together, grow laterodorsally, and fuse with the lateral wall of the lateral semicircular canal and the crista parotica. This lamina forms a new, secondary wall enclosing the posterior section of the otic capsule and contains the large external jugular foramen (or foramen vagi) in its basal portion. The laminae, designated lamina juxtaotica anterior and posterior (lamina juxtaotica when fused together), have not been recorded previously in crocodylians and are absent in all other Recent reptiles. From the functional point of view, the juxtaotic lamina 1) forms the margins of the external jugular foramen, and 2) forms the floor of the posterior section of the Eustachian tube. In birds, the structure called the metotic cartilage, which arises in ontogeny as an independent element, has a similar position as the juxtaotic lamina. However, the two structures differ in their developmental origins and their relation to the Eustachian tube and the ramus hyomandibularis of the facialis nerve. Moreover, there is no external jugular foramen in birds.     

The lamina cribrosa in the eyes of rats, hamsters, gerbils and guinea pigs

The scleral lamina cribrosa in the eyes of adult rats, hamsters, gerbils and guinea pigs was examined by ordinary histology and by scanning electron microscopy after soft tissue digestion. The complexity of the lamina, when mounted for scanning electron microscopy, was graded on a scale of 0 to 4.5 by three independent observers under X 60 magnification in a stereo microscope. The observers were unaware of the species and were offered the 44 specimens twice in random order. The average variance attributable to an observer was 22 +/- 3% (SE) of the total variance of the gradings. The rat eyes had the least developed lamina cribrosa, with only 1-2 layers of sparse connective tissue. The mean complexity grading of 12 rat eyes was 1.6 +/- 0.15. The lamina cribrosa of the eyes of gerbils and guinea pigs was much more developed with at least 3 layers of abundant connective tissue, the mean grades of complexity being 3.4 +/- 0.09 and 3.5 +/- 0.15, respectively, in 12 eyes of each species. The lamina cribrosa in the hamster eyes was somewhat more developed than that of the rat, but much less than that of the gerbil and guinea pig. The mean grade of complexity was 2.4 +/- 0.14 in 8 eyes. In 6 pairs of rat eyes there was no correlation in grade of laminar complexity between the two eyes of the same animal. The present study makes the rat eye a candidate for experiments where a possible influence of the lamina cribrosa as such is undesired.     

Management of frontal sinus fractures

LEARNING OBJECTIVES: After studying this article, the participant should be able to: 1. Understand the radiographic and clinical diagnosis of frontal sinus fractures. 2. Identify various management approaches to the frontal sinus fracture and the indications for each. 3. Understand the rationale behind the decision of sinus obliteration when needed. 4. Recognize the most common complications arising from frontal sinus fracture treatment and the methods of avoiding or managing these complications. SUMMARY: Frontal sinus fracture management is still controversial and involves preserving function when feasible or obliterating the sinus and duct, depending on the fracture pattern. There is no single algorithm for the choice of management, but appropriate treatment depends on an accurate diagnosis using physical examination, computed tomography data, and the findings of intraoperative exploration. The amount and location of fixation and the need for frontonasal duct and sinus obliteration or elimination of the entire sinus depend on the anatomy of the fracture in general and the extent of involvement of the anterior wall of the sinus, the frontonasal duct, and the posterior wall in particular. This article discusses an algorithm for frontal sinus fractures that was obtained from the literature and modified according to the authors' experience. The decision-making process presented by the authors has withstood the test of time over a period of more than 20 years in their practice and has been proven to be safe and efficacious in treating frontal sinus fractures of all types.     

Anterior Lamina Cribrosa Insertion in Primary Open-Angle Glaucoma Patients and Healthy Subjects

PurposeTo determine using swept-source optical coherence tomography (SS-OCT) whether there are differences in the location of the anterior lamina cribrosa insertion (ALI) in primary open-angle glaucoma (POAG) patients and healthy subjects.MethodsFifty three eyes from 53 patients with POAG, and 53 eyes from 53 age-matched healthy subjects were included prospectively in Seoul National University Bundang Hospital. Twelve radial line B-scans centered on the optic disc in every half-clock-hour meridian were acquired using SS-OCT. The ALI position was assessed by measuring two parameters: (1) ALI distance (ALID)—the distance from the anterior scleral canal opening (ASCO) to the ALI; and (2) marginal anterior lamina cribrosa surface depth (mALCSD)—the perpendicular distance from the ASCO plane to the anterior lamina cribrosa surface. These parameters were compared between the two groups for each meridian.ResultsBoth ALID (256±54 vs. 209±37 µm, mean ± SD, p<0.001) and mALCSD (232±63 vs. 187±40 µm, p<0.001) were significantly greater in the POAG group than in the normal group. The largest difference was observed at the 6.5 o′clock and 11.5 o′clock meridians for both ALID and mALCSD. Multiple regression analysis revealed a negative correlation between age and both ALID and mALCSD in the control group, and a negative correlation between mean deviation of the visual field test and both ALID and mALCSD in the POAG group.ConclusionsThe ALI was displaced posteriorly in eyes with POAG compared to those of healthy controls. This finding suggests that the posteriorly located lamina cribrosa insertion is an important component of glaucomatous optic nerve excavation.     

Ontogeny of the palatoquadrate and adjacent lateral cranial wall of the endocranium in prehatching Alligator mississippiensis (Archosauria: Crocodylia)

The purpose of this article is to gain insight into the ossification sequence of the palatoquadrate and the adjacent lateral cranial wall of prehatching Alligator mississippiensis, a process about which there is almost no published information. Results were obtained by studying serial histological sections of the series of ontogenetic stages and enlarged wax-plate models of several stages. The cartilage of the palatoquadrate starts to ossify endochondrally in the quadrate portion of the pars pterygoquadrata palatoquadrati in Stage 6A. In this stage, a bone, called the lamina palatoquadrati anterior here, appears at and close to the anteromedial wall of the cartilaginous pterygoid portion of the pars pterygoquadrata. The lamina palatoquadrati anterior ossifies in membrane. Later in ontogeny, the lamina palatoquadrati anterior spreads into the cavum epiptericum and sheathes the posterior portion of the trigeminal ganglion laterally. The jaw adductor muscles insert at the outer surface of the lamina palatoquadrati anterior. The lamina palatoquadrati anterior is a new structure not previously recorded in crocodylians or any other Recent reptile. The topology, mode of ossification, and functional anatomy of the lamina palatoquadrati anterior correspond to those of the membranous ossification of the alisphenoid of marsupials. Another bone, called the lamina prootici anterior here, spreads in membrane from the anterolateral wall of the prootic portion of the otic capsule into the prootic fenestra, above the trigeminal ganglion. The lamina prootici anterior represents a structure not recorded previously in crocodylians. It contributes to the orbitotemporal braincase wall.     

The ultrastructure of the swimbladder of the toadfish,Opsanus tau L.

Summary The anterior chamber of the swimbladder of the toadfish Opsanus tau L. is lined by a single layer of columnar gas gland cells, cuboidal cells that resemble gas gland cells but are located outside of the gas gland region, and squamous cells. Multilamellar bodies are numerous in the gas gland cells and the cuboidal cells and are present in smaller numbers in the squamous cells. Capillaries lie in the lamina propria directly below the epithelial lining. A thick continuous muscularis mucosae and a submucosa consisting of tightly packed cells, cell processes, and connective tissue may contribute to the impermeability to gases of the wall of the anterior chamber.The posterior chamber of the swimbladder is lined by a single type of squamous epithelial cell. Multilamellar bodies were occasionally observed in these cells also. Other types of cells frequently form a partial second layer between the epithelial lining and the basement lamina. A thin muscularis mucosae lies directly below the basement lamina and the capillaries of the posterior chamber are located in the submucosa. The tunica externa is a layer of dense connective tissue that surrounds both the anterior and posterior chambers. Collagen fibrils in the form of tactoids are present in this layer.Part of this work was submitted by S.M.M. in partial fulfillment of the requirements for the degree of Doctor of Philosophy, Biology Department, Boston University. S.M.M. is grateful for a National Science Foundation Traineeship.     

Scleral thickness in human eyes

Purpose

To obtain information about scleral thickness in different ocular regions and its associations.

Methods

The histomorphometric study included 238 human globes which had been enucleated because of choroidal melanomas or due to secondary angle-closure glaucoma. Using light microscopy, anterior-posterior pupil-optic nerve sections were measured.

Results

In the non-axially elongated group (axial length ≤26 mm), scleral thickness decreased from the limbus (0.50±0.11 mm) to the ora serrata (0.43±0.14 mm) and the equator (0.42±0.15 mm), and then increased to the midpoint between posterior pole and equator (0.65±0.15 mm) and to the posterior pole (0.94±0.18 mm), from where it decreased to the peri-optic nerve region (0.86±0.21 mm) and finally the peripapillary scleral flange (0.39±0.09 mm). Scleral thickness was significantly lower in the axially elongated group (axial length >26 mm) than in the non-axially elongated group for measurements taken at and posterior to the equator. Scleral thickness measurements of the posterior pole and of the peripapillary scleral flange were correlated with lamina cribrosa thickness measurements. Scleral thickness measurements at any location of examination were not significantly (all P>0.10) correlated with corneal thickness measurements. Scleral thickness was statistically independent of age, gender and presence of glaucoma.

Conclusions

In non-axially elongated eyes, the sclera was thickest at the posterior pole, followed by the peri-optic nerve region, the midpoint between posterior pole and equator, the limbus, the ora serrata, the equator and finally the peripapillary scleral flange. In axially elongated eyes, scleral thinning occurred at and posterior to the equator, being more marked closer to the posterior pole and the longer the axial length was. Within the anterior and posterior segment respectively, scleral thickness measurements were correlated with each other. Posterior scleral thickness was correlated with lamina cribrosa thickness. Scleral thickness measurements at any location of examination were not significantly correlated with corneal thickness or with age, gender and presence of absolute secondary angler-closure glaucoma.     

Comparative study of the lamina cribrosa and the pial septa in the vertebrate optic nerve and their relationship to the myelinated axons

The optic nerve contains the connective tissues, i.e. the lamina cribrosa and pial septa. This report presents a histological comparison of the lamina cribrosa and pial septa in the five classes (mammals, birds, reptiles, amphibians and teleosts) of vertebrates. Furthermore, the distribution of myelinated fibers was observed from the optic nerve through the retina in the same animals. The lamina cribrosa is found in mammals except for mice, and in birds. Structural complexity of the lamina was different in animals but generally dependent of the optic nerve thickness. The pial septa were present in the optic nerve proper of the mammals except for the mice, in birds and in a part of teleosts. Fasciculation of the optic nerve by the pial septa tended to be more prominent as the optic nerve become thicker. The optic nerve consisted of largely myelinated fibers in vertebrates. The retina contained some myelinated fibers in submammals but was thoroughly devoid of myelinated fibers in mammals. The borderline between myelinated and unmyelinated portions in the optic nerve of different species did not related to the lamina cribrosa. Amphibians had exceptionally only a few myelinated fibers in the optic nerve and no myelinated fibers in the retina.     

Differences in distensibility between the anterior and posterior walls of the left ventricle in dogs

Nonuniformity of myocardial systolic and diastolic performance in the normal left ventricle has been recognized by a number of investigators. Lack of homogeneity in diastolic properties might be caused by or related to differences in the distensibility of different regions of the left ventricular (LV) wall. Thus, we compared the end-diastolic transmural pressure-strain relations in both the anterior and posterior LV walls in seven anesthetized dogs during two interventions (pulmonary artery constriction and aortic constriction). Transmural pressure was defined as the difference between LV intracavitary pressure and local pericardial pressure. LV pressure was measured using a micromanometer; pericardial pressures over the LV anterior and posterior walls were measured with balloon transducers. Circumferentially oriented pairs of sonomicrometer crystals were implanted in the midwall of the anterior and posterior walls of the LV to measure segment lengths. Strains were calculated as (L-L0)/L0, where L was the instantaneous segment length and L0 was the segment length when transmural pressure was zero. The pattern of end-diastolic transmural pressure--strain relations was similar in all dogs. The change in strain in the posterior wall was always greater than that in the anterior wall. Opening the pericardium did not affect the difference in distensibility of the anterior and posterior walls. The results suggest that the posterior wall is more compliant than the anterior wall (that is, for a given difference in transmural pressure, the local segment length change of the posterior wall was greater). This seems consistent with other observations, which suggest that the posterior wall might make a greater contribution to diastolic filling.     

Acoustic rhinometry in humans: accuracy of nasal passage area estimates, and ability to quantify paranasal sinus volume and ostium size.

A comprehensive study that compared acoustic rhinometry (AR) data to computed tomography (CT) data was performed to evaluate the accuracy of AR measurements in estimating nasal passage area and to assess its ability of quantifying paranasal sinus volume and ostium size in live humans. Twenty nasal passages of 10 healthy adults were examined by using AR and CT. Actual cross-sectional areas of the nasal cavity, sinus ostia sizes, and maxillary and frontal sinus volumes were determined from CT sections perpendicular to the curved acoustic axis of the nasal passage. Nasal cavity volume (from nostril to choana) calculated from the AR-derived area-distance curve was compared with that from the CT-derived area-distance curve. AR measurements were also done on pipe models that featured a side branch (Helmholtz resonator of constant volume but two different neck diameters) simulating a paranasal sinus. In the anterior nasal cavity, there was good agreement between the cross-sectional areas determined by AR and CT. However, posterior to the sinus ostia, AR overestimated cross-sectional area. The difference between AR nasal volume and CT nasal volume was much smaller than the combined volume of the maxillary and frontal sinuses. The results suggest that AR measurements of the healthy adult nasal cavity are reasonably accurate to the level of the paranasal sinus ostia. Beyond this point, AR overestimates cross-sectional area and provides no quantitative data for sinus volume or ostium size. The effects of paranasal sinuses and acoustic resonances in the nasal cavity are not accounted for in the present AR algorithms.     

A new reconstruction of the Le Moustier 1 skull and investigation of internal structures using 3-D-μCT data

Using the non-destructive technique of 3-D micro computed tomography (3-D-μCT), we present a new, virtual reconstruction of the Le Moustier 1 Neandertal skull. This new reconstruction corrects defects found in earlier reconstruction attempts by repositioning misaligned cranial fragments, addressing the problem of asymmetry caused by pressure during the fossilization process, and placing the basioccipital in its proper anatomical position. Metric comparisons between Le Moustier 1 and juvenile and adult Neandertals demonstrate that facial height proceeded at a faster rate of growth than facial prognathism at the beginning of the adolescent period. They also confirm the anterior placement of the basioccipital. A compound painted to match the colour of the fossilized bone was used in previous reconstruction attempts and the aim of this analysis was to remove the false material to reveal to what extent the fossilized bone was preserved. The areas with the most artificial material and glue include the palate, areas around the mandibular teeth, the left frontal, and parts of the right parietal and temporal bones. The μCT data were also used to examine internal structures of the skull including the frontal sinus and the labyrinth of the inner ear. An investigation of the frontal sinus reveals morphology similar to that found in adult Neandertals, although the structure does not extend to mid-orbit. The dimension of the radius of curvature of the lateral semicircular canal falls within one standard deviation, and the anterior and posterior canals within two standard deviations, of the published Neandertal mean. As in other Neandertals, the posterior semicircular canal is in an inferior position relative to the plane of the lateral canal.     

Clinical anatomy of the blood spaces and blood vessels surrounding the siphon of the internal carotid artery

The anterior blood space of the cavernous sinus is situated anterolateral to the carotid siphon in 70%, anterior to it in 15%, and lateral to it in 15%. Its height, depth, and mediolateral breadth were measured. The mean distance between the carotid siphon and the skin at the supraorbital foramen was measured with 63 (52.4-71.4) mm. The drainage of the orbital veins was studied and described as well as the area of origin and first course of the ophthalmic artery and its clinical importance.     

A biomathematical model for pressure-dependent lamina cribrosa behavior.

Investigating the relationship between intraocular pressure and the behavior of the lamina cribrosa (the primary site of the optic nerve damage in glaucoma) is important to insight into the pathogenesis of glaucomatous optic neuropathy. In most previous studies, unsuitable approaches were used since the lamina cribrosa was not taken as the main target. In the present study, a linear model of elastic mechanics theory on the bending of thin circular plate was developed for this purpose. The structural features of the lamina cribrosa and the forces acting on the lamina cribrosa were analyzed, and the constitutive equation was formulated. The general solution on a class of Kármán Equation and the analytic solution on fixed boundary conditions were obtained, and from them, the morphological changes and the mechanical properties such as retrodisplacement and force distributions of the lamina cribrosa under pressure were derived. Some of the clinical phenomena occurring in glaucoma damage were explained with the results. Theoretical values were compared with the experimental data obtained by other investigators. The effects of structural parameters on susceptibilities to glaucoma damage were discussed. The biomathematical model, serving as formalistic expressions of the well-known hypothesis of pressure-dependent optic nerve damage in glaucoma, should make it possible for us to further understand and manage this disease.     

The arterial and venous blood supply of the septum pellucidum in the rat.

The arterial and venous systems of the rat's septum pellucidum has been studied by means of the perfusion technique. The arteries may be classified into three groups. The branches of each of the three groups originate from the a. hemispherica and enter the septum from the frontal direction. The veins may be divided into an anterior and a posterior group. The anterior veins flow through the v. subcallosa into the sinus cavernosus, the posterior veins into v. cerebri magna. The arterial and venous blood supply of the individual nuclei of the septum are compar independent.     

Immunolocalization of allatostatin-like neuropeptides and their putative receptor in eyestalks of the tiger prawn, Penaeus monodon

Allatostatin (AST)-like immunoreactivity (IR) was localized in the eyestalk of Penaeus monodon by immunohistochemistry using four anti-AST antibodies. Depending on the antisera, AST-like immunoreactivity was detected in neuronal bodies of the lamina ganglionalis, cell bodies anterior to the medulla externa and cell bodies on the anterior and posterior of the medulla terminalis. Neuronal processes in neuropiles of the medulla externa, medulla terminalis, sinus gland and nerve fibers in the optic nerve were also recognized. No IR in cell bodies or in nerve fibers was found in the medulla interna. Strong AST-like immunoreactivity was found in hundreds of cells of the X organ. The localization of AST-like peptides suggests that they function as neurotransmitters and/or neuromodulators. Antiserum to the Drosophila AST receptor (Dar-2) recognized a single protein in P. monodon eyestalk protein extracts that was identical in size to that found in Drosophila protein extracts. Using this antiserum the putative P. monodon AST receptor was localized to the sinus gland in both juvenile and adult eyestalks. To our knowledge this is the first demonstration of a neuropeptide receptor localized to the crustacean sinus gland. This suggests that ASTs may function directly on the sinus gland as a neuromodulator. In juvenile eyestalks, the putative AST receptor was also localized to neuronal X organ cells of the medulla terminalis in males but not in females. The significance of this sex-specific receptor localization is unclear but emphasizes that ASTs function within the nervous system of the eyestalk.     

Measurements of the tympanic cavity

The angle between the annulus fibrocartilaginous and the superior crest of the petrous bone was measured with 14 (10 to 19) degrees. The height of the annulus was in our material 10.04 mm, the width 9.45 mm. Measured were also the length of the plicae malleares and the height of the recessus membrane tympani anterior, posterior et superior with (2.5, 3.0 and 1.5 mm). In about 74%, the chorda tympani was imbedded in different zones of the plicae malleares. Its entrance and exit areas, the length of its intratympanal course and its width were measured. Included are also values of the ligaments of the otic ossicles, measurements of the ostium tympanicum tubae auditivae, of the epitympanic recess, the aditus ad antrum, and the antrum mastoideum. The eminentia pyramidalis, the sinus posterior and the sinus tympani, ponticuli and subicula, the fossula fenestrae cochleae and the fenestra cochleae, the fenestra vestibuli and prominences of the facial canal in the lateral semicircular canal have been researched and measured. Also the tympanic nerve and its course on the promontorium have been estimated.     

Dental lamina develops even within the mouse diastema

In embryos of albino mice of ICR strain, collected between days 13 and 15, the epithelial lining within the future upper maxillary diastema was studied using frontal histological sections stained with hematoxylin-eosin and PAS methods. In embryos harvested on the 12th hr of day 13 (stage 13/12), a continuous epithelial rudiment of dentition was found in the anterior extension of the epithelial anlage of the first upper molar, up to the level of the lower anterior margin of the primary choana. In this stage the rudiment acquired, in the most anterior region of the future diastema, an arrangement typical for the dental lamina. In its dorsal extension there was found a distinct tooth anlage at the transitory stage lamina bud, which further (at stage 13/24) disintegrated into several segments. Starting with the day 14 (stage 14/12), the epithelial rudiment of dentition within the future upper diastema began to regress. From the stage 14/24 on, the anlage persisted only in its posterior terminal part where it merged with the epithelial lamina extending anteriorly from the anlage of the first upper molar. The existence of the dentition rudiment within the future mouse diastema constitutes the ontogenetic evidence that the diastema originates only secondarily--by regression. In some mutant strains of mice (tabby, crooked, sleek), the regression appears incomplete. The odontogenic potency of mouse diastema tissues should be considered when interpreting the results of in vitro experiments investigating the odontogenic inductive tissue interactions in mouse.     

Comparison of the Deep Optic Nerve Head Structure between Normal-Tension Glaucoma and Nonarteritic Anterior Ischemic Optic Neuropathy

PurposeTo compare the deep optic nerve head (ONH) structure between normal-tension glaucoma (NTG) and nonarteritic anterior ischemic optic neuropathy (NAION) and also in healthy subjects as a control using enhanced depth imaging (EDI) spectral-domain optical coherence tomography (SD-OCT).MethodsThis prospective cross-sectional study included 21 NAION patients who had been diagnosed as NAION at least 6 months prior to study entry, and 42 NTG patients and 42 healthy controls who were matched with NAION patients in terms of age, intraocular pressure (IOP), and optic disc area. The retinal nerve fiber layer (RNFL) thickness in the affected sector was also matched between NAION and NTG patients. The ONH was imaged using SD-OCT with the EDI technique. The anterior lamina cribrosa surface depth (LCD) and average prelaminar tissue (PT) thickness were measured in a sector of interest in each eye and compared among the three groups.ResultsIn the sector-matched comparison, LCD was largest in NTG patients, followed by NAION patients, while PT was thinner in NTG patients than in NAION patients (all P < 0.001). NAION patients had a comparable LCD and a thinner PT relative to normal controls (P = 0.170 and < 0.001, respectively).ConclusionThe deep ONH configuration is strikingly different between NTG and NAION. The differing features provide comparative insight into the pathophysiology of the two diseases, and may be useful for differential diagnosis.