Eustachian tube communicating with sphenoid sinus: report of a novel anatomical variant.

Reports of congenital anomalies of the Eustachian Tube (ET) are scarce, and often associated with chromosomal abnormalities. We report a unique case of a completely bony left Eustachian tube which communicated with the sphenoid sinus. This report details these findings and discusses the potential embryological basis and implications of such an unusual anatomy, in the context of a comprehensive literature review.

Pressure changes in the human middle ear without opening the eustachian tube.

CONCLUSION: By means of a direct, though non-invasive experiment on healthy humans we could demonstrate that middle ear (ME) pressure decreases when the eustachian tube (ET) does not open. Thus with a very simple method the basic theory of continuous gas loss from the ME into the circulation and the replenishment of the loss through the ET could be validated. OBJECTIVES: To record changes in ME pressure over a period of time in normal human ears, while the ET is kept closed. SUBJECTS AND METHODS: On-line tympanometry was carried out in three subjects, who refrained from swallowing for 20-120 min. RESULTS: During the time when the ET was kept closed by refraining from swallowing, tympanometric monotonous pressure decrease was recorded. Once the tested subject could not refrain from swallowing any longer and swallowed again, ME pressure equalized immediately.

Patulous Eustachian tube in spontaneous intracranial hypotension syndrome.

A 48-year-old slender woman presented with a rare case of spontaneous intracranial hypotension syndrome manifesting as patulous Eustachian tube. The patient complained of sudden onset of ear fullness and nasal voice as well as typical orthostatic headache. Patulous Eustachian tube was identified by observation of synchronous movement of the tympanic membrane with respiration and swallowing. The diagnosis of spontaneous intracranial hypotension was confirmed by negative cerebrospinal fluid pressure, and typical magnetic resonance imaging and radioisotope cisternography findings. All symptoms completely resolved within a few days after epidural blood patch treatment. Changes in the venous blood distribution led by collapse of the dural sac of the cervical spine in the standing position presumably caused decreased size of the pterygoid venous plexus around the Eustachian tube.

Nasopharyngeal extension of glomus tympanicum: an unusual clinical and imaging manifestation.

Nasopharyngeal extension of the glomus tympanicum is rare. Only 2 cases have been reported in the literature to date. We present a reported case of a large nasopharyngeal extension of recurrent glomus tympanicum, with various kinds of imaging and histopathology and a review of the literature.

On morphometric measurement of oxygen diffusing capacity in middle ear gas exchange.

An accurate mathematical model of transmucosal gas exchange is prerequisite to understanding middle ear (ME) physiology. Current models require experimentally measured gas species time constants for all extant conditions as input parameters. However, studies on pulmonary gas exchange have shown that a morphometric model that incorporates more fundamental physiochemical and anatomic parameters accurately simulates transport from which the species time constants can be derived for all extant conditions. Here, we implemented a variant of that model for ME gas exchange that requires the measurement of diffusional length (tau) for the ME mucosa. That measure contributes to the mucosal diffusing capacity and reflects the resistance to gas flow between air space and capillary. Two methods for measuring tau have been proposed: linear distance between the air-mucosal boundary and capillary and the harmonic mean of all contributing pathway lengths. Oxygen diffusing capacity was calculated for different ME mucosal geometries by using the two tau measures, and the results were compared with those predicted by a detailed, two-dimensional finite element analysis. Predictive accuracy was improved by incorporating the harmonic tau measure, which captures important information regarding variations in capillary shape and distribution. However, compared with the oxygen diffusing capacity derived from the finite element analysis, both measures yielded nonlinear, positively biased estimates. The morphometric techniques underestimate diffusion length by failing to account for the curvilinear gas flow pathways predicted by the finite element model.

Diseases of the guttural pouches.

Guttural pouches are unique anatomic structures in Equidae. Conditions affecting the guttural pouches present with clinical signs that are not observed in other domestic species, and treatment of some of these conditions can be challenging. This article describes the anatomy and examination of the guttural pouches and reviews the presenting signs and treatment of the more common conditions affecting them, including empyema, tympany, mycosis, and stylohyoid arthropathy.

Regional blood flow volume in the eustachian tube.

Measurements of regional blood flow around the pharyngeal orifice of the Eustachian tube were carried out after topical administration of various inflammatory mediators in 14 mongrel dogs by the hydrogen clearance method. Histamine and platelet-activating factor (PAF) resulted in a significant alteration of blood flow volume. Histamine was found to induce a dose-response related increase, whereas blood flow volume tended to decrease in each concentration range in the series of PAF administration. There was no significant difference in blood flow between topical application of leukotriene C4 and leukotriene D4. It is likely that in upper respiratory tract inflammation, such as in otitis media and in nasal allergy, activated histamine and PAF affect the microcirculation of the tubal orifice. These results suggest that disturbance of the microcirculatory system in the Eustachian tube mucosa could be involved in the pathogenesis of chronic otitis media with effusion.

The permeability of capillaries in the eustachian tube mucosa.

The transendothelial passage of horseradish peroxidase (HRP) and diffusion of HRP into the pericapillary space, injected intravenously into cats, was studied at the light and electron microscopic level in the mucosa of the eustachian tube. The permeability of capillaries in the pharyngeal two-thirds of the tube was higher than in the tympanic one-third though all the subepithelial capillaries were of the continuous type. In the lamina propria of the subepithelium in the pharyngeal two-thirds much HRP was found 10 min after its intravenous injection, but in the tympanic one-third, it was absent in the perivascular spaces. The capillaries of the pharyngeal two-thirds had many projections and marginal folds inside the capillary lumen and large pinocytotic vacuoles containing HRP as well as many micropinocytotic vesicles. On the other hand, the capillaries in the tympanic one-third had many micropinocytotic vesicles too, but only a few large pinocytotic vacuoles.

Electron-microscopic observation of adrenergic innervation in guinea pig Eustachian tube.

The precise locations of adrenergic nerve terminals in the Eustachian tube of guinea pigs have, for the first time, been demonstrated by electron microscopy, with application of a false transmitter (5-OHDA). Adrenergic nerve terminals were found in abundance near the arteries in each area of the Eustachian tube. In particular, these terminals were observed just beneath the smooth muscle layer of the arteries. The exact locations of adrenergic nerve terminals in the submucous and gland region are also discussed.

The vascular anatomy of the eustachian tube in the guinea pig.

Vascular anatomy of the eustachian tube has received little attention in the world's medical literature. Forty guinea pigs were perfused with Berlin Blue as a contrast medium and the eustachian tube microvascular architecture visualized through surface preparations. A diffuse, dense two-layered capillary network was found which followed the distribution of mucous glands. Five animals suffering from suppurative otitis media showed marked capillary congestion with increased vessel to tissue density. Relationships to gross arterial and venous supply as found in the human are discussed.

Eustachian tube lymphatics.

Serous otitis media is the most common cause of hearing impairment. The role of lymphatic obstruction in the pathogeneis of serous otitis media is significant. A method for removeal of the human Eustachian tube specimen and two techniques for identification of Eustachian tube lymphatic capillaries are described. One involves the antemorten intratympanic installation of Berlin blue. The other utilizes electron microscopy. Lymphatic capillaries cannot be reliably differentiated from blood capillaries with the light microscope. With electron microscopy, lymphatic capillaries can be differentiated from blood capillaries by differences in the basement membrane. The lymphatic capillary has gaps in the basement membrane with large nuclei in the wall. A blood capillary has a continuous basement membrane and sometimes red blood cells be be identified in the lumen. Using these methods, Eustachian tube lymphatic capillaries in the human are described for the first time in this report.