Endolymphatic sac enhancement. Principles of diagnosis and treatment

Principles of diagnosing and treating Meniere's disease using endolymphatic sac enhancement are described. Based on a current understanding of the natural history and pathogenesis of this disease, the terminology, diagnosis, and thereby are discussed. Techniques (methods) and surgical objectives of endolymphatic sac enhancement are designed to counteract the pathogenesis (endolymph malabsorption). Current surgical methods and results are presented for 100 patients selected at random from a larger group. Discussion of this method of treatment and reporting criteria follow.

Thickness of the human round window membrane in different forms of otitis media

The thickness and morphologic characteristics of the round window membrane were evaluated in temporal bones from normal subjects as well as those with serous otitis media, purulent otitis media, and chronic otitis media. Temporal bones were studied in chronological order in six age ranges to determine the possibility of age-related differences. No significant difference in the mean thickness of the round window membrane was observed in terms of age groups in normal temporal bones or temporal bones from patients with otitis media; however, a significant difference in the mean thickness was observed in the various forms of otitis media compared with the normal round window membrane in all age groups. The membrane was thickest in patients with chronic otitis media when compared with that in normal subjects or those with serous or purulent otitis media. The epithelial layer (including the subepithelial space) and the fibrous layer were measured individually to determine in which layer the change in mean thickness occurred. These measurements showed an involvement of all layers of the round window membrane in those groups with otitis media, with maximal involvement of the combined epithelial layer and subepithelial space.

The permeability of the round window membrane during otitis media

Studies of the permeability of the round window membrane (RWM) during otitis media are important because toxins and cellular components that occur in otitis media as well as pharmacologic agents used in treating the disease have the potential to cross the RWM and pass into the inner ear. Twenty-five cats were evaluated electron microscopically as to the passage of a tracer, horseradish peroxidase, through normal RWMs and RWMs three days, one week, and two weeks following eustachian tube obstruction. Passage at three days following obstruction was similar to passage through the normal RWM. Following one to two weeks of obstruction, the permeability of the membrane was drastically reduced. The reduction in permeability was probably due to the presence of residual effusion overlying the membrane, the presence of granulation tissue within the niche, and a thickening of the RWM.

Cochleovestibular nerve sections in labyrinthectomized patients

Labyrinthectomy is indicated for a patient who has unilateral peripheral labyrinthine disease with unserviceable hearing loss. For most patients, labyrinthectomy provides complete relief from intractable vertigo. Some patients continue to have persistent vertigo, however, even after a complete destructive labyrinthectomy. Only after cochleovestibular nerve sections were these patients relieved of intractable vertigo. Representative cases of cochleovestibular nerve sections in labyrinthectomized patients are presented. The reason why the cochleovestibular nerve section relieves the symptom of vertigo in labyrinthectomized patients is not clear. Labyrinthectomy destroys vestibular sense organs, while cochleovestibular nerve section eliminates spontaneous activity and prevents the possibility of nerve regeneration by excision of the ganglion. For those patients who required vestibular nerve sections, there may have been abnormal excitation of vestibular nerve fibers. This might be explained by incomplete labyrinthectomy, regeneration of vestibular nerve fibers, contribution from vestibular ganglia or nonfunctioning cochlea, and vascular loop syndrome.

Primary and secondary tumors of the facial nerve. A temporal bone study

Of 1400 temporal bones in the collection at the University of Minnesota, Minneapolis, 17 temporal bones from 15 patients were found to have tumors involving the facial nerve. The findings were as follows: one case of facial nerve schwannoma; two cases of invasion of the facial nerve by contiguous tumor; and 14 cases of metastatic tumors involving the facial nerve. Facial nerve paralysis was present in half of the cases (nine of 17). Facial nerve paralysis was present in the case of facial nerve schwannoma, in both cases of invasion of the facial nerve by contiguous tumor, and in six of 14 cases of metastatic tumors involving the facial nerve. The presence of the facial nerve paralysis correlated well with the degree of tumor infiltration into the nerve fibers and the segment of the tumor involvement in the facial nerve. In the patients with metastatic tumors, facial nerve paralysis was a sign of extensive intracranial tumor involvement and was usually accompanied by other cranial nerve palsies, most commonly involving the fifth nerve.

Diet-induced hyperlipidemia and auditory dysfunction

Chinchillas rendered hyperlipidemic by a 1% cholesterol diet or maintained on a normal diet were either exposed to a 2-octave bandpass noise (700-2,800 Hz for 220 min at 105 or 114 dB) or else not exposed to noise. The animals were assessed with tone-burst (2-16 kHz) elicited compound action potentials (CAP). Compared with normal diet animals, the hyperlipidemic animals: not exposed to noise exhibited elevated thresholds at 8 kHz and higher frequencies; exposed to 105-dB noise exhibited elevated thresholds at 16 kHz; and exposed to 114-dB noise exhibited elevated thresholds at 2-16 kH. Surface preparations were made of the left cochleae of all noise-exposed animals. There was essentially no difference in hair cell counts between hyperlipidemic animals exposed to the 105-dB noise and normal animals similarly exposed. The hyperlipidemic animals exposed to the 114-dB noise exhibited a greater hair cell loss in the first turn of the cochlea than did similarly exposed normal animals. We conclude that maintenance on a high-cholesterol diet can cause a high-frequency hearing loss, probably due to vascular pathology resulting from a hyperlipidemic state. Furthermore, maintenance on a high-cholesterol diet can increase susceptibility to noise-induced hearing losses.

Silent otitis media: clinical applications

Silent (masked) otitis media refers to usually chronic pathological conditions behind an intact tympanic membrane which may be clinically "undetected" or "undetectable." Correlations are described for pathological changes in temporal bones and clinical considerations for silent otitis media associated with Hemophilus influenzae meningitis in infants, silent otitis media--the continuum, silent otitis media--sequelae, and chronic silent otitis media.

Sensorineural hearing loss in experimental purulent otitis media due to Streptococcus pneumoniae

Sensorineural hearing loss (SNHL) has been described clinically following chronic otitis media with effusion, but to the best of our knowledge, no studies have demonstrated SNHL in an animal model of otitis media. Using the chinchilla model of pneumococcal otitis media, significant SNHL was demonstrated after purulent otitis media, especially at higher frequencies. Animals with otitis media received penicillin G procaine treatment for five days after otitis media with effusion (OME) was first documented; resolution of middle ear infection was confirmed by middle ear effusion culture in all animals. Both the inoculated and uninoculated ears were examined by tone burst-elicited compound action potential at threshold. The inoculated ear showed a marked hearing loss of 13 to 36 dB three to four days after OME was first documented; a hearing loss up to 24 dB persisted two to five weeks after inoculation. The change in the compound action potential was highly significant at all frequencies studied. Conductive losses were largely ruled out because there was no middle ear effusion at death and the tympanogram was normal. Purulent labyrinthitis was ruled out by histopathological study. These results indicate that purulent pneumococcal otitis media in the chinchilla model causes significant SNHL and suggest that the pathogenesis of SNHL associated with chronic OME in humans may be studied in this model.

Hyperlipidemia and noise in the chinchilla

Chinchillas were maintained on a 1% cholesterol diet for 6 months. Auditory Brainstem Response (ABR) measurements were obtained before and at 1, 3, 5, and 6 months after initiation of diet. Compound Action Potential (AP) measurements were obtained at sacrifice at 6 months. A significant reduction in ABR was seen at 5 months-on-diet. At 5 months, the animals were exposed to a 2 octave bandpass noise centered at 1 kHz at 105 dB for 220 min. One month following noise exposure, the cholesterol-fed animals exhibited a greater ABR latency shift at low intensities, and an elevated AP threshold at higher frequencies, vis-à-vis a control group.

Subepithelial space in otitis media

The role of the subepithelial space (SES) has not received sufficient attention in assessing pathogenesis, pathology, and therefore, clinical diagnosis and treatment of the various forms of otitis media (OM). Temporal bones from patients with OM were classified as cases of acute purulent (POM), serous (SOM), mucoid or secretory (MOM), or chronic otitis media (COM). Controlled morphometric studies were made of cellular components of the SES, along with studies of the epithelium and middle ear space. Corollary studies of biochemistry, cellular components, and prostaglandins (PGs) were done on fluid from the human middle ear. Middle ear effusions (MEE) from animal models of SOM, MOM, and POM were analyzed biochemically. Findings are surprising in that the SES was more actively involved in all forms of OM than had been thought, especially in MOM and COM. Implications are discussed.

Clinical-histopathological correlations in experimental otitis media: implications for silent otitis media in humans

Clinical-histopathological correlations were sought in an experimental animal model of otitis media. Among 20 chinchillas inoculated intranasally with wildtype influenza A/Alaska virus (H3N2) and type 7F Streptococcus pneumoniae, 15 animals (18 ears) developed otoscopic and tympanometric signs of otitis media with middle ear effusion. Middle ear inflammation was most intense 10 days after virus inoculation. Twenty-two days after virus inoculation, eight ears showed diffuse middle ear histopathology and contained effusion, which cultured pneumococcus, five ears showed focal histopathology, and four of the five contained no effusion. Clinical manifestations of otitis media had disappeared in four of the 13 ears with pathology at sacrifice; otoscopy was normal in all four ears, tympanometry was normal in three ears, and both otoscopy and tympanometry were normal in one ear. All four of these ears with clinically "silent" middle ear histopathology had shown abnormalities of ear drum appearance or tympanometry between 7 and 14 days after inoculation. Discordance between histopathology and the clinical examination performed at sacrifice was greatest for ears with focal pathology.

Vestibular Meniere's disease

The clinical entity of vestibular Meniere's disease (VMD) is assessed and described. Twenty percent of cases eventuating in typical Meniere's disease presented with VMD first. In other patients VMD alone persisted for many years (30 or more). VMD, usually unilateral, is characterized by recurrent episodes of vertigo typical of classical Meniere's disease. Positional vertigo can occur between or during episodes. Aural pressure is second to vertigo in importance, and electronystagmographic findings are third. Although hearing is normal, tinnitus or loudness intolerance may be present. Concepts of pathogenesis are discussed.

The cause (multifactorial inheritance) and pathogenesis (endolymphatic malabsorption) of Meniere's disease and its symptoms (mechanical and chemical)

A clinical classification separates Meniere's disease (MD) of known cause (e.g. infection, trauma, otosclerosis, syphilis, genetic and others) from MD, idiopathic. Atypical forms of MD include vestibular MD and cochlear MD. Temporal bone studies from our laboratory and as reviewed in the literature reveal hydrops of the pars inferior, sometimes with ruptures, most often seen in Reissner's membrane, and sometimes without ruptures, to be the most important pathological correlate. Gross anatomical pathological findings include decreased mastoid and periaqueductal pneumatization and anterior displacement of the lateral sinus which reduces Trautmann's triangle. Such developmental changes most probably influence the endolymphatic absorptive system. Any explanation for the mechanisms of pathogenesis of clinical symptoms must encompass all aspects of the natural history, including vestibular symptoms, auditory symptoms, and aural pressure. Both mechanical and chemical factors best explain the clinical symptoms, and both may be traceable to multifactorial inheritance.

Sensorineural hearing loss in otitis media

Additional evidence is presented to support the hypothesis that both acute purulent otitis media (POM) and chronic suppurative otitis media (COM) can cause high frequency sensorineural hearing loss. In selected patients and in animals (chinchillas) in a pilot study using electrophysiological methods, both temporary threshold shifts and permanent threshold shifts of basal cochlear turn involvement were demonstrated in POM. Data of cochlear involvement in 475 ears with bilateral COM, 607 ears with unilateral COM, and 607 ears serving as controls were obtained from six centers in five countries. In group 1 (15 dB or greater), 43% of ears with unilateral COM and 42% of ears with bilateral COM showed losses, for a combined odds ratio eight times that in controls. In group 2 (30 dB or greater), 16% of ears with unilateral COM and 17% of ears with bilateral COM demonstrated, respectively, seven and ten times that in controls. These statistically significant findings influence clinical considerations.

Otosclerosis and Meniere's syndrome: diagnosis and treatment

Occasionally a patient with otosclerosis and a conductive hearing loss will develop typical findings of Meniere's syndrome in the involved ear, years later. A review of clinical and pathological studies in the literature and in our laboratory and clinic indicates a likely cause-and-effect relationship for these cases. The pathology and pathogenesis of the syndrome of otosclerosis and Meniere's syndrome is discussed. A stapedectomy/sacculotomy was used to treat 17 patients, 13 of whom acquired a satisfactory result in terms of improvement of hearing and control of vertigo. This technique and findings are described and discussed.

Otosclerosis and endolymphatic hydrops

It has been postulated that otosclerosis may produce vertigo by several mechanisms. One mechanism is by causing endolymphatic hydrops. We present six temporal bones in which otosclerosis and endolymphatic hydrops coexist. We consider that there is a spectrum-like interrelationship between these two entities. At one end of the spectrum the relationship is coincidental, while at the other end of the spectrum we consider the massive amount of active otosclerosis to be a causative factor in the development of the endolymphatic hydrops.

Pathology of Meniere's disease

From review of recent findings, the pathology of Meniere's disease is described and correlated with clinical signs. Since Meniere's disease can be seen only in humans, assessing its natural history is important. A recent survey of 500 patients demonstrated the three major symptoms to be vestibular, auditory, and aural pressure. Meniere's disease (idiopathic) is distinguished from Meniere's syndrome (symptoms with likely cause), which accounted for approximately one fourth of the patients. Atypical forms include vestibular and cochlear Meniere's disease. A recent review of our temporal bone collection and detailed study of the pathological conditions of 134 temporal bones described in the literature revealed characteristic pathological findings. Patients with clear-cut histories of Meniere's disease may demonstrate little or no endolymphatic hydrops at death. Nevertheless, hydrops of the pars inferior remains the most significant pathological correlate of Meniere's disease. On the basis of these findings, the pathogenesis of the disease (malabsorption of endolymph) and the pathophysiology of the symptoms (physical and chemical) are discussed.

Intact-bridge tympanomastoidectomy

In recent years closed-cavity (intact wall) tympanomastoidectomy has been described and recommended by many. The pendulum now is swinging back to open-cavity tympanomastoidectomy. The literature in this regard is reviewed. In all patients with chronic otitis media and mastoiditis with intractable tissue pathology, the primary objective is total eradication of disease with a dry, safe ear; a concomitant but secondary objective is hearing retention and restoration with tympanoplasty techniques. Over a 3-year period we have used a one-stage procedure called intact-bridge tympanomastoidectomy (IBM) that fulfills the desirable objectives of both open- and closed-cavity tympanomastoidectomy. The salient features include good exposure as in open-cavity tympanomastoidectomy, maintenance and widening of the middle ear space by bony bridge retention and facial buttress sculpturing to enhance grafting and ossiculoplasty such as TORP or PORP as in canal-up tympanomastoidectomy, and enhancement of mastoid obliteration for large cavities by blocking the aditus with bone paté or cartilage and by providing a separation between middle ear and mastoid. Specific methods, techniques, and results will be presented and discussed.

Bilaterality of Meniere's disease

The audiometric configurations of a randomly selected group of 360 patients with clinical Meniere's disease were analysed in conjunction with their clinical manifestations. Although 78.6% of the patients had an abnormal pure-tone audiogram in the opposite ear from that which was initially diagnosed as Meniere's disease, based on the entire clinical picture, the disease was found to be definitely bilateral in 32% of the patients. A peaking audiogram type was found to be most common, occurring in about half of the involved ears. In approximately half of those with bilateral disease the second ear became involved within two years of onset of involvement of the first ear, and in another 27% the second ear became involved after a period of 5 years or more. These observations stress the importance of conservation in managing Meniere's disease, especially when considering surgical intervention for intractable disease, with the hope of retaining or restoring labyrinthine function.

A metastatic glomus jugulare tumor. A temporal bone report

The clinicopathologic findings in the temporal bone of a patient with a highly malignant metastasizing glomus jugulare tumor are reported. The patient exhibited all the symptoms of primary malignant tumors of the ear, including facial paralysis, otorrhea, pain, hearing loss, tinnitus, dizziness, and vertigo. He was treated with cobalt irradiation followed by radium implant in the ear canal for a residual tumor; then a left-sided radical mastoidectomy was performed.