Experimental paralysis of tensor veli palatini muscle

Epidemiology and pathogenesis of chronic suppurative otitis media: implications for prevention and treatment

Despite advances in public health and medical care, chronic suppurative otitis media is still prevalent around the world. It is most common in developing countries and in certain high risk populations in developed nations, as well as among children who have tympanostomy tubes inserted. Since this chronic infection is caused by persistent acute otorrhea, which in turn is usually secondary to acute otitis media, prevention should be directed toward prompt and appropriate treatment of the acute middle-ear infection. Repair of chronic perforations should prevent recurrence, since reinfection is due either to reflux of pathogenic organisms from the nasopharynx into the middle ear, or water contamination from the external canal. Information from epidemiological studies, which show that populations can be categorized into highest, high, low and lowest prevalence, can be helpful in setting national priorities for prevention and treatment.

Magnetic resonance imaging of the development of otitis media with effusion caused by functional obstruction of the eustachian tube

In this study, magnetic resonance imaging (MRI) was used to define in vivo the effect of experimental functional obstruction of the eustachian tube (ET) on vascular permeability and the development of middle ear (ME) effusion. After collection of baseline data for ME pressure and MRI, the right tensor veli palatini muscle of 10 cynomolgus monkeys was injected with botulinum toxin A to induce ET obstruction. The left tensor veli palatini muscle was injected with saline in 4 monkeys. Right and left ME pressures and compliances were measured twice daily over a follow-up period of 36 days, and MRI scanning sessions including administration of a contrast agent, gadopentetate dimeglumine, were repeated on days 3, 6, 11, 15, 21, 29, and 36 in 6 animals and on days 15, 21, 29, and 36 in 4 animals. Two right ears did not develop underpressures, 5 developed persistent underpressures, and 3 developed underpressures that resolved. No changes in MRI parameters were noted for the ears that did not develop underpressures, but a progressive brightening of the ME on T2-weighted images, indicative of the development of inflammation and effusion, was noted for the others. Also, an increasing rate of transfer of the contrast agent between the vascular and ME compartments, indicative of increasing vascular permeability, was observed to track the temporal changes in ME pressure. These results support a causal relationship between ET dysfunction, ME underpressures, increased vascular permeability, and otitis media with effusion

Pathogenesis of middle-ear effusion in nasopharyngeal carcinoma: a new perspective

The theory that middle-ear effusion (MEE) associated with nasopharyngeal carcinoma (NPC) is merely the result of tensor veli palatinus destruction is deficient because recent studies have shown that many patients with NPC have MEE but no tensor veli palatinus dysfunction. The present study evaluates the relationship between MEE and Eustachian cartilage erosion by NPC and examines the pathogenesis of NPC-associated MEE from a new perspective. Thirty-five patients with NPC were studied by magnetic resonance scans taken along the lengths of the Eustachian tubes. Twenty-four patients had tumour involvement of both sides of the nasopharynx so that 59 ears were available for study. Eighteen ears had MEE of which 12 had Eustachian cartilage erosion (p < 0.00001), Fischer's Exact Test). In ears with MEE, Eustachian cartilage erosion was frequently but not necessarily associated with tensor veli palatinus destruction. We postulate that altered Eustachian tubal compliance as a result of cartilage erosion by tumour is an important reason why middle-ear effusions develop in patients with NPC.

Role of Allergy in Eustachian Tube Blockage and Otitis Media with Effusion: A Review

Recent studies continue to support a role for allergy in the pathogenesis of otitis media with effusion. Although a variety of mechanisms have been proposed to relate these two disease conditions causally, none has been completely validated by experimental or clinical studies. This review suggests that the observed relationship between allergy and otitis media with effusion is caused by mediators of inflammation and cytokines and colony-stimulating factors released by mucosal mast cells and other inflammatory and epithelial cells in the nose and nasopharynx. These mediators produce blockage of the eustachian tube through a number of mechanisms, which may include local injury or vascular- or neural-mediated changes in the eustachian tube opening pressure and in middle ear perfusion. It is likely that the nasal allergic response in patients predisposes to eustachian tube blockage and, if prolonged, causes changes in gas absorption in the middle ear space. This gas exchange primarily involves nitrogen absorption, which may take several days to develop. This persistent underpressure will then lead to middle ear effusion. Irrespective of the theoretical mechanism, the relationship between allergy and otitis media with effusion will remain controversial until well-controlled clinical studies are conducted documenting that in select populations antiallergy therapy is efficacious in preventing or limiting the duration of otitis media with effusion.

In vivo observation with magnetic resonance imaging of middle ear effusion in response to experimental underpressures

In this study, magnetic resonance imaging (MRI) was used to define, in vivo, the effect of acute middle ear (ME) underpressures on vascular permeability and the development of effusion. The MEs of four cynomolgus monkeys were unilaterally inflated with oxygen and carbon dioxide on different occasions and followed for a period of approximately 4 hours by tympanometry and MRI scanning. Carbon dioxide inflations caused the rapid development of ME underpressures of less than -600 mm H2O by 10 minutes. The MRI scans showed a progressive brightening of the ME and all associated air cells, indicative of the accumulation of effusion in three of the four experiments. An MRI contrast agent was administered to the vascular compartment during the course of the experiment and was rapidly transferred to the ME space, indicating vascular permeability to the agent. The contralateral, control side did not develop significant underpressures, effusion, or increased vascular permeability. Inflation with oxygen caused lesser underpressures and no accompanying changes in the MRI scans. These data support the hydrops ex vacuo theory and confirm the usefulness of MRI for in vivo documentation of the development of ME effusions and changes in vascular permeability of the mucosa in the experimental setting.

Otologic and systemic manifestations of experimental influenza A virus infection in the ferret

In an effort to further validate an animal model and to better define the mechanisms relating viral upper respiratory tract infections and acute otitis media, we infected 10 ferrets intranasally with influenza A virus. Infection was monitored by cultures and antibody titers, illness was monitored by signs and temperatures, and otologic complications were monitored by otoscopy, tympanometry, and eustachian tube function testing. All animals became infected. Forced-response test results showed progressive increases in the passive function variables after inoculation. Inflation-deflation test results documented progressive impairment of active tubal function, which was accompanied by the development of middle ear underpressures. No otitis media was seen. The results suggest that influenza A virus infection results in progressive, subtotal occlusion of the eustachian tube lumen, which compromises the ventilatory function of the tube, thereby promoting the development of middle ear underpressures. These findings support the hypothesized pathophysiologic relationship between viral upper respiratory tract infections, eustachian tube dysfunction, middle ear underpressures, and acute otitis media. Given these pathophysiologic changes and previously documented physiologic similarities to the eustachian tube-middle ear system of human beings, we conclude that the ferret represents an appropriate animal model for studying the pathogenic processes related to viral upper respiratory tract infections, eustachian tube dysfunction, and otitis media and for testing of potential prophylactic and therapeutic regimens.

Functional-Anatomic Correlation of Eustachian Tube Obstruction Related to the Adenoid in a Patient with Otitis Media with Effusion: A Case Report

Prospective randomized clinical trials have shown modest but significant reductions in morbidity from otitis media with effusion following adenoidectomy. However, the precise role of the adenoid in the pathogenesis of otitis media with effusion remains unknown. Some authors have hypothesized that the adenoid may compress or obstruct the Eustachian tube lumen, thereby causing middle ear underpressures and subsequent effusion formation. Functional-anatomic correlation for this theory is lacking. Herein, we present a single case of a pediatric patient with otitis media with effusion and manometrically proven active and passive Eustachian tube obstruction which was relieved by adenoidectomy. Photographic anatomic correlation is presented.

Middle ear gas exchange in rhesus monkeys

The mechanism of gas exchange between the middle ear and tissue is fundamental to understanding middle ear physiology and pathophysiology. In this study, the middle ears of six rhesus monkeys were inflated on separate occasions with nitrogen (N2), carbon dioxide (CO2), and oxygen (O2), and middle ear pressures were recorded at defined times postinflation for up to 4 hours. From these data, rate constants governing the exchange of these gases were estimated and compared to those predicted under both diffusion and perfusion limitations. The results show that the rate constants for middle ear to tissue exchange of O2 and CO2 are consistent with a diffusion-limited process. In contrast, middle ear pressure did not decrease over the study period following introduction of N2 into the middle ear. This is interpretable as a much slower rate of N2 exchange than that predicted by either perfusion or diffusion-limited models calibrated to the O2 and CO2 rate constants. These results have significant implications for middle ear gas exchange and suggest that for relatively short observation periods, the behavior of middle ear pressure is controlled by experimentally established O2 and CO2 gradients.

Immunohistochemical quantitation of collagen types I, II, IV and V in the ventilated and non-ventilated rabbit middle ear with otitis media with effusion

Morphometric quantitation of the area fractions of collagen types I, II, IV and V was determined in the normal rabbit middle ear mucosa and in relation to otitis media with effusion (OME) using a three-layered peroxidase-antiperoxidase technique. The effects of substituting normal low-oxygen middle ear gas (non-ventilated) with atmospheric air (ventilated) were studied in both healthy ears and ears with OME. Based upon previous histological examinations in rabbits, only ears with OME for more than 8 weeks were included to ensure the presence of chronic inflammation (COME). Atmospheric air was introduced into the middle ears by insertion of ventilation tubes or by an enlarged myringotomy. Collagen type I was predominant in all groups studied. The area fractions of collagen types I, II and IV were increased significantly in COME, with collagen type II elevated in particular. Ventilation of the normal ears resulted in a significantly increased area fraction of cells, while the area fractions and distributions of the collagen types were unaffected. None of the ventilated ears in COME improved or healed spontaneously. The total fraction of collagen in COME was not changed significantly by the introduction of atmospheric air. However, the individual distribution of the collagen types was altered, with significantly larger area fractions of types II and V found in ventilated ears with COME. Possible explanations for the differences found are discussed, including the role of oxygen-derived free radicals.

The nasopharynx, eustachian tube and otitis media

It has been classically hypothesized that a mass in the nasopharynx causes an obstacle to air flow through the eustachian tube, thereby creating a negative pressure in the middle ear followed by an effusion. However, examination of the relevant data concerning the supposed obstruction of the eustachian tube by nasopharyngeal carcinomas, choanal polyps and adenoids does not seem to support this cause and effect relationship. Evidence points to other more sophisticated mechanisms which cause negative pressure and an effusion in pathological middle ear conditions. While the hypothesis of a nasopharyngeal mass as the usual obstructive cause of middle ear effusion is hard to maintain, evidence does exist to support the origin of middle ear infection, as seen in acute and secretory otitis media, as being associated, at times, with an ascending infection from the nasopharynx.

Nasal and otologic effects of experimental influenza A virus infection

Past studies showed that experimental rhinovirus colds in adults resulted in eustachian tube dysfunction and abnormal middle ear pressures. In the present study, the symptoms and pathophysiologic findings accompanying experimental influenza viral infection were documented. A total of 33 healthy adult volunteers were intranasally challenged with an influenza A/Kawasaki/86 (H1N1) virus and cloistered over a 9-day postchallenge period to monitor for evidence of infection, signs and symptoms of illness, and the extent and frequency of pathophysiologic responses of the nose, eustachian tube, and middle ear. Results showed a protective effect of high (> or = 16) prechallenge specific hemagglutination-inhibition antibody titer on the rate of infection and the magnitude and extent of provoked symptoms and pathophysiologic findings. Infected subjects with low (< 16) prechallenge serum antibody titers (n = 21) developed significant respiratory illness. These subjects also had objectively measurable increases in nasal secretion production, and decreased nasal patency and mucociliary clearance rates. More than 80% of the infected subjects developed eustachian tube dysfunction, and approximately 80% had middle ear underpressures of less than -100 mm H2O on study days 4 and 5. Five of 21 infected subjects with low prechallenge antibody titers had otoscopic evidence of otitis media with effusion. These results support a causal role for viral upper respiratory tract infection in the pathogenesis of otitis media, possibly mediated by the early development of eustachian tube dysfunction and abnormal middle ear pressure.

Peritonsillar abscess as a cause of transient velopharyngeal insufficiency

"Hot potato voice" is a characteristic sign of peritonsillar abscess and peritonsillitis. Our findings show that the hot potato voice is the result of an underlying transient velopharyngeal insufficiency combined with muffled oral resonance. The hot potato voice should be distinguished from the muffled oral voice which can be occasionally encountered in cases of severe tonsillitis. The velopharyngeal insufficiency is the result of transient dysfunction of the palatal muscles on the affected side. Transient negative middle-ear pressure indicating eustachian tube dysfunction was found in few of the patients in whom concomitant sinusitis was also present. The clinical, nasendoscopic, and radiologic findings are analyzed and discussed. We believe that this phenomenon is valuable as a research tool for the investigation of the anatomy and physiology of the velopharyngeal valve.

Animal model of otitis media with effusion

A rat model of otitis media with effusion (OME) was developed by intratympanic injection of E. coli endotoxin and section of the third branch of the trigeminal nerve (V3). The period of fluid retention induced by the endotoxin was prolonged for 5 days or longer, in cases when tubal function was impaired by cutting of V3. Three Eustachian tube function tests (patency test of inflation-deflation tests, forced response test and negative pressure test) were carried out before and after the endotoxin inoculation and V3 sectioning. At 4 days after these procedures, passive opening pressure (Po), closing pressure (Pc) and tubal resistance (R2) were significantly lowered. The negative pressure test showed impaired capacity of active opening. This model of Eustachian tube dysfunction is considered to reveal functional obstruction, a condition similar to that of clinical cases of OME. The study shows that both inflammation in the middle ear and tubal dysfunction, such as functional obstruction, are factors in the development and prolongation of OME.

Histological examination of the rabbit middle ear in secretory otitis media with and without a ventilation tube

To study the time-related histopathological lesions in secretory otitis media as it develops into the chronic stage, including the influence of ventilation of the middle ear, we examined the middle ear mucosa in a rabbit model. The observation period was from two weeks until 18 months. The histological method applied included haematoxylin-eosin and Sirius red staining for morphometric quantification of the goblet cells, the thickness of the connective tissue layer, the area fractions of blood vessels, inflammatory cells, fibroblasts and collagen fibres. In conclusion, the middle ear mucosa in secretory otitis media exhibited inflammatory changes correlating with the duration of the disease. Ventilation of the middle ear in secretory otitis media did not improve the changes.

Serous otitis media and paranasopharyngeal extension of nasopharyngeal carcinoma

Two hundred thirty-two patients with nasopharyngeal carcinoma were evaluated for serous otitis media (SOM) at diagnosis. The diagnosis of SOM required the detection of effusion behind the tympanic membrane in association of air-bone gap of 10 dB or more in pure tone audiogram. These patients were also evaluated by computed tomography for the degree of tumor extension. By stepwise logistic regression analysis, the degree of paranasopharyngeal extension of tumor, erosion of petrous temporal bone, and the obliteration of pharyngeal recess were significantly related to the development of SOM, but sex and age were not. The findings of computed tomography may influence the plan of management for SOM in patients with nasopharyngeal carcinoma at diagnosis.

Age-related morphologic differences in the components of the eustachian tube/middle ear system

The current study utilized a three-dimensional computer graphics technique to analyze the size, shape, and positional associations of the eustachian tube (ET) cartilage and lumen, the levator veli palatini (LVP) muscle, and the tensor veli palatini (TVP) muscle. Older specimens 7 years and above (n = 13) were compared to young specimens less than 7 years (n = 4). Our results suggest that changes in ET function associated with age could result from size and shape differences in the ET cartilage and changes in the position of the LVP and TVP muscles.