Cholera toxin-stimulated adenylate cyclase activity was demonstrated cytochemically in the stria vascularis of the guinea pig inner ear by the cerium method of Rechardt and Hervonen, and it was compared with ALPase, Mg-ATPase, Ca-ATPase and Na, K-ATPase activity. Adenylate cyclase activity was observed in the marginal and basal cells. The reaction products were fine granular particles on the plasma membrane of the basal infoldings of the marginal cells, but not on that of the free surface facing the endolymphatic space. Enzyme activity was also observed in the large mitochondria;the reaction was intense in the outer chamber and weak in the cristae, was inhibited by 5 mM alloxan. The plasma membranes of adjacent basal cells showed a positive rea-ction. No enzyme activity was detected in the intermediate cells, the endothelial cells of the capillaries in the stria vascularis, fibrocytes in the spiral ligament, epithelial cells of the spiral prominence, Corti's organ or Reissner's membrane. In the marginal cells, the location of adenylate cyclase activity corresponded with that of Na, K-ATPase activity. Therefore, the adenylate cyclase activity of the stria vascularis may play a role in the regulation of the membrane permea-bility to water and electrolytes while Na, K-ATP-ase acts as an ion pump to maintain high potassium and low sodium ion concentrations in the endolymph.
Ca-ATPase activity, which is involved in the transport of Ca ions, was demonstrated cytochemically in Corti's organs of guinea pig inner ears and compared with Mg-ATPase, Na-K-ATPase and ALPase activities. The reaction products of Ca-ATPase ac-tivity were observed on the plasma membranes of hair cells, especially in the apical portion and in the hairlets. Moreover, the precipitate was also found in the basal portion and in the plasma membrane of the nerve endings. Both inner and outer pillar cells were completely devoid of reaction precipitate, as were the surface plasma membranes of the phalanges of the phalangeal cells. In the epithelial cells of the inner spiral sulcus, border cells, Hensen's cells and Claudius' cells, a strong reaction was observed in the surface plasma membrane facing the endolymphatic space. The location of Mg-ATPase activity was very similar to that of Ca-ATPase except that it was also found on the surface plasma membrane of the phalanges of the phalangeal cells facing the endolymph. ALPase activity was never observed in Corti's organ. Na-K-ATPase activity was detected only on the cytoplasmic side of the plasma membranes of the hairlets. The co-existence of Ca-ATPase and Na-K-ATP-ase, especially in the hair cells, may be important for the exchange of Ca and Na ions that initiates the excitation of these acoustic receptors.
The purpose of this experiment was to clarify the pattern of physiological change in the inner ear during the development of endolymphatic hydrops. Endolymphatic hydrops was experimentally induced in 67 guinea pigs by the introduction of silver nitrate into the endolymphatic sacs. The animals were sacrificed 1 day to 6 weeks later, and HE stained serial sections were made of their temporal bones. The endolymphatic spaces were examined under a light microscope and measured by computer to determine the pattern of size changes. The results were as follows : 1) The saccule displayed the greatest degree of hydrops, with the saccules of the treated guinea pigs dilating to 7 times the size of the saccules in the control group. 2) Cochlear hydrops developed principally in the upper turns during the first 3 weeks, and in the lower turns during the second 3 weeks. The final result was an even degree of dilation throughout the cochlea to a size 2.5 times normal. 3) The utricle, which had been thought to display minimal dilatation, showed nearly the same degree of bulging as the cochlea : 2.5 times normal at 6 weeks.
A tension test was performed on the semicircular canals of fish, frogs and guinea pigs, with a tension testing machine capable of measuring microloads (the "microtension tester"). The mechanical properties of the semicircular canals were examined. The semicircular canals of guinea pigs were so fine that no exact data could be obtained. The elongation, elastic modulus and tensile strength of fresh semicircular canals was 115.9%, 2.23 kgf/mm2 and 0.88 kgf/ mm2, respectively, in fish and 83.7%, 1.25 kgf/mm2 and 0.46 kgf/mm2, respectively, in frogs. The thickness of the semicircular canals was compared. The frog's semicircular canals were the thickest, followed by those of fish, and the guinea pig's were the thinnest. The comparison of strength considering membranous thickness of the semicircular canals was performed. The frog's semicircular canals were the strongest, followed by those of fish, and the guinea pig's were the weakest. There was a good correlation between the thickness and the strength of the semicircular canals. These findings suggest that the increase of the endolymph volume takes place throughout the entire labyrinth in Meniere's disease, and because of the thick membranes of the semicircular canals and the utricle, endolympatic hydrops is seen only in the cochlea and the saccule.
The temporal bones and/or vestibular nerve nuclei were studied in 7 aged cadavers. In 5 cases there was a history of "vertigo". Distension of Reissner's membrane was present in the 6 out of 8 cochleae of those with "vertigo" and in 2 out of 3 cochleae of the controls. In addition, distension of Reissner's membrane was found in 2 turns of the cochleae in 2 cases with "vertigo". In one of them, remarkable atherosclerosis was present in the labyrinthine artery. Pigmentation granules were found in the stria vascularis of all cases, and they were not decolorized by treatment with H2O2, suggesting that they were not melanin. Many degenerating nerve cells were observed in the vestibular nuclei of 2 of the cases with "vertigo".
A 65-year-old woman with chronic renal failure had been treated with homodialysis. Five years after the start of homodialysis, she developed partial hearing loss in both ears, and 21 months later her hearing loss suddenly increased and vertigo developed. The right temporal bone showed moderate collapse of Reissner's membrane and flattening of the organ of Corti in all turns of the cochlea. The tectorial membrane in the basal turn of the cochlea was tightly adherent to Reissner's membrane. The saccular wall was partially collapsed on its macula. The copula of the semicircular canals showed concentrated changes. However, the sensory epithelium of the vestibules and semicircular canals appeared normal. The left temporal bone abnormalities were almost the same. These changes were similar to those found in viral infections.
In this series of reports, further information has substantiated the existence of immunoglobulins (IgG, IgA, IgM) in the lateral walls of endolymphatic sacs, obtained during endolymphatic sac surgery from 19 patients with Meniere's disease. In an immunohistochemical procedure using the PAP method (peroxidase-anti-peroxidase method), IgG was recognized in the epithelium and the subepithelial layer of the endolymphatic sacs of 12 of the 19 (63 %) patients with Meniere's disease, while IgA and IgM were absent in all of the patients. It is still impossible to determine the exact site of some active immunological reactions and the resultant products in the sac, but this finding suggests that some immunological disorders might exist in the endolymphatic space, including the sac and that they might be closely related to one of the causes of endolymphatic hydrops.
The effect of perilymphatic pressure on the CM threshold was examined in 30 guinea pigs with endolymphatic hydrops. When a pressure of 300 mmH2O was applied to the scala tympani of the basal turn, the 500 Hz CM threshold shift in hydropic ears was significantly smaller in the early stage than in normal ears, and it returned gradually to normal. The findings in the present study may be similar to the time course of the scala media pressure in hydropic ears; i.e. an initial increase, followed by a gradual decline towards normal.
Endolymphatic and perilymphatic pressures were measured simultaneously with two sets of a servo-nulling system in guinea pigs. This method seems to reveal pressure relationships between the perilymph and the endolymph in excellent detail, because the servo-nulling system is the most suitable equipment for studying the pressure of inner ear fluid and both pressures can be measured simultaneously with the same precision. The results were different from those of our previous study in which endolymphatic and perilymphatic pressures were measured by different systems. (1) Under physiological conditions there was no significant pressure difference between perilymph and endolymph. (2) Anoxia or oral administration of glycerol caused no pressure difference between the endolymph and the perilymph. (3) When the perilymphatic space was opened to the atmosphere, no significant pressure change was seen in either the endolymph or the perilymph. The boundaries between the perilymph and the endolymph, especially Reissner's membrane, may be too weak to sustain pressure differences between them.
The effects of 6-hydroxydopamine (6-OHDA) and amphetamine on baroreflex sensitivity (BRS), blood pressure (BP) and brain stem PO2 tension were studied in conscious rabbits. 6-OHDA, which produces chronic degeneration of catecholamine (CA) nerve terminals was injected into a lateral ventricle of the brain. The facilitation of CNS CA release was produced by intravenous injection of amphetamine.BRS was calculated from changes in the BP after the injection of norepinephrine (NE) or nitroglycerine. Following 6-OHDA administration, BRS became significantly higher and BP fluctuation was minimum for one hour in loosely restrained rabbits. On the other hand, amphetamine inhibited the BRS and caused large fluctuations of BP, as has been shown in other reports. Furthermore, decreases of BP and brain stem PO2 were observed when passive head up tilt (45 degrees) was performed quickly in rabbits with lower BRS. These findings suggest that brain stem blood flow is hampered by disturbances of BRS caused by prolonged exposure to stressfull conditions.
The effect of glycerol on oxygen tension was studied in the cochlear perilymph of guinea pigs with a polarographic technique. Following a transient fall immediately after the intravenous administration of glycerol, the oxygen tension increased to reach a peak 10 minutes later, and then decreased gradually. These changes suggest alterations of the cochlear blood flow due to the local vasodilating effect of glycerol. The increase of oxygen tension and blood flow in the cochlea is considered to be one of the possible contributory factors in the improvement of hearing in patients with Meniere's disease after glycerol administration.
Glycerol is known to improve hearing acuity in Meniere's disease. Experimentally induced endolymphatic hydrops in guinea pigs was used as a model of Ménière's disease, and the effect of glycerol on the cochlear potentials was measured. In 7 albino guinea pigs the endolymphatic sac of one ear was obliterated surgically to produce endolymphatic hydrops. In the 6th postoperative month, glycerol (50 % W/V, 6 ml/kg BW) was injected intravenously, and the electrocochleogram was recorded before, and 1 and 2 hours after the injection. Glycerol did not improve the thresholds of the cochlear microphonics (CM) and compound action potentials (AP). The same dose of glycerol was administered to 5 normal guinea pigs. The elevation in AP threshold for the click and the diminution in the AP amplitude for the click and the tone bursts of the middle and high frequencies were slightly greater in the hydropic ears than in the normal ears. Glycerol caused almost no change in CM thresholds and made the CM amplitudes slightly smaller for the tone bursts of the low and middle frequencies in both of the hydrops and control groups. These findings were contrary to the improvement of hearing in patients treated with glycerol. Furthermore, the amplitudes of +SP for the click were decreased at 1 hour in 4 animals and recovered by 2 hours after the injection in 2 of the 4. This finding was also quite different from that reported in papers describing the diminution of -SP in patients with Méenière's disease.
The negative summating potential (-SP) and action potential (AP) were recorded by extratympanic electrocochleography in patients with Meniere's disease. The -SP amplitude and the ratio of -SP amplitude to AP amplitude (-SP/AP ratio) were significantly larger in Meniere ears than in normal ears or ears with hair cells damaged by streptomycin or kanamycin or by noise. An increased -SP/AP ratio was observed more often in ears with endolymphatic hydrops, as in Meniere's disease (58 of 94 ears, 62%) or sensorineural hearing loss due to syphilis (4 of 7 ears, 57%) than in ears with hearing loss of other origins. The results demonstrate the usefulness of electrocochleography [in the diagnosis of Meniere's disease. An increased -SP/AP ratio and a positive glycerol test was recorded in 32 of 51 ears (63%) and 26 of 51 ears (51%), respectively. In 15 of 51 ears (29%) both tests were positive, and in 43 of 51 ears (84%) one of tests was positive. The incidence of an increased -SP/AP ratio was higher in ears with a moderate to severe hearing loss at high frequencies, whereas the glycerol test was more often positive in ears with a moderate to severe hearing loss at low frequencies. The difference in selectivity by the method makes the combination of both tests useful in the diagnosis of Meniere's disease.
Harmonic acceleration tests in yaw plane were performed in 14 normal subjects, with the head centered or in an eccentric position 90 cm from the axis of rotation in an investigation of the influence of additional linear acceleration on the canal-ocular reflex. Pendular rotation in the eccentric position produces the same angular stimulation and, in addition, involves linear centrifugal and tangential acceleration vectors which act on the otolith organs. In the eccentric position, all subjects showed an in crease in gain of slow phase eye movements at 0.32 Hz and 0.64 Hz, when compared with the results in the head centered position. For the high frequency range in eccentric pendular rotation, the value of tangential acceleration was larger than that of centrifugal acceleration. In the eccentric position, tangential acceleration is sensed mainly by the utriculus. Therefore it appeares that gain enhancement at high frequencies in eccentric pendular rotation is derived from tangential acceleration acting on the utriculus.
The furosemide test is effective in the detection of endolymphatic hydrops (Futaki & Kitahara, 1971). However, this test is not easily performed because patients sometimes have nausea and vomiting. Instead of the caloric test, we used a furosemide VOR test, in which the pendular rotation test is performed before and after an i. v. injection of 20 mg of furosemide. Thirteen of 24 patients with Meniere's disease, four of six with delayed endolymphatic hydrops and one of two with syphilitic labyrinthitis had positive tests. These data suggest that endolymphatic hydrops may be easy to detect by the furosemide VOR test.
The trapezoid rotation test with Contraves' computerized rotary chair system was carried out 108 times in 23 patients with Meniere's disease, and the results were analyzed in an attempt to find predictors for the next episode of vertigo. 1) Four types of results were observed during the course of Meniere's disease : labyrinthine preponderance ispilateralis (LPi), labyrinthine preponderance contralateralis (LPc), recruitment (Rec) and normal. 2) The LPi type appeared to precede an attack of vertigo, and the LPc type to follow it. 3) Rec and normal types were observed during stable periodes far from the time of an attack. 4) The ncidience of the LPi type increased as the episode of vertigo approached. Therefore, the appearance of the LPi type was thought to be a very important sign predicting the next episode, and it suggested the development of endolymphatic hydrops, which was supported by the glycerol test in patients and by animal experiments. It should be possible to prevent the next episode of vertigo by adequate therapy when the LPi type of response is observed.
The influence of middle ear pressure changes on the otolith organs was investigated in cats. The activits of both the primary and secondary vestibular neurons were influenced by middle ear pressure changes. More otolith neurons were influenced by middle ear pressures than semicircular canal neurons. Among the otolith neurons, those which were activated by lateral tilt were more sensitive to middle ear pressure than those which were activated by the nose up or the nose down position.
This study investigated the influence of relative pressure changes in the middle ear on the stepping test in 59 normal subjects. The pressure in the middle ear was altered by exposure of the external auditory canal to positive or negative pressures. Six pressure loading conditions (-300, -200, -100, + 100, +200, +300 mmH2O) were maintained constantly in the stepping test. The angle of rotation, the angle of transition, the distance of transition were determined. 1) There were significant deviations in the angle of rotation towards ipsilateral side at +300 mmH2O of pressure, and towards the contralateral side at -300 mmH2O. 2) There was a significant deviation in the angle of transition towards the ipsilateral side at +300 mm H2O of pressure. 3) There was no significant change in the distance of transition at any pressure. This test will be used to investigate vestibulospinal reactions in patients with Meniere's disease.
We analyzed the bilateral oculo-cardiac reflex in patients with Meniere's disease and evaluated their parasympathetic nervous function. Although the oculo-cardiac responses of patients with Meniere's disease were not different from those of healthy controls, the incidence of difference in laterality of each eye response was significantly increased in the patients. In addition, the patients with Meniere's disease exhibited weaker oculo-cardiac responses of the affec-ted side than on the unaffected side. These findings suggest asymmetry of parasympathetic nervous function in patients with Meniere's disease.
HLA-A, -B, -C, -DR and -DQ typing was done in 21 patients (12 males and 9 females) with bilateral Meniere's disease. Their ages ranged from 39 to 74 years (average, 54.3 years). None of them had a family history of Meniere's disease. HLA-Bw56 antigen was found in 14% (3/21) of the patients. The frequency of the HLA-Bw56 antigen was higher than in healthy control (1/120, p=0.010), but the difference was not significant after corrections were done for the number of antigens tested.
β-thromboglobulin (β-TG) and platelet factor 4 (PF-4), which are indexes of intravascular platelet activation, were measured in patients with Meniere's disease. Serum concentrations of p-TG and PF-4 were elevated in 15% of the patients. Ticlopidine, a platelet aggregation inhibitor, decreased the serum levels of β-TG and PF-4, and was effective clinically in 69% of the cases. These findings suggest that platelet aggregation is one of the causes of vertigo in Meniere's disease.
Serial horizontal sections of 15 temporal bones from 13 patients were examined. Four patients had simple chronic otitis media with central perforation of the tympanic .membrane and 11 had cholesteatoma or adhesive otitis media. 1) The ears with cholesteatoma or adhesive otitis media had greater histological changes than those with simple chronic otitis media. 2) The histological changes in the cochlea were greater than those in the vestibule. 3) In the cochlea, histological changes consisted of collapse or distention of Reissner's membrane, compression of the organ of Corti, fibrous tissue proliferation in the scala tympani near the round window and atrophy of the stria vascularis. 4) In the vestibule, the histological changes consisted of eosinophilic precipitation and distention of the saccular membranous labyrinth.
In this investigation of the relationship between endolymphatic hydrops and otitis media, 25 patients with chronic otitis media received the glycerol test for endolymphatic hydrops before middle ear surgery. 1) The incidence of positive reactions to the glycerol test was higher in the following patients with otitis media: a) those with a long duration of disease b) those with vertigo and tinnitus c) those with severe otorrhea. 2) Patients with positive glycerol test before surgery were retested after the operation, and all had negative test after the elimination of middle ear inflammation. 3) Some of the patients with chronic otitis media also seemed to have endolymphatic hydrops due to the spread of inflammation from the middle ear to the inner ear.
After middle ear infection, the inner ear has been shown to be affected in various ways, such as by endolymphatic hydrops. We studied this relationship biochemically and morphologically in guinea pigs after lipopolysaccharide (LPS) or Staphylococcus aureus was injected into the middle ear. 1. LPS in the inner ear fluids was calculated by the toxicolor test after LPS had been injected into the middle ear. Immediately and 25 minutes later, no statistically significant change of LPS concentration was observed in the inner ear fluids, but in a few cases the concentration was high. 2. One, 3 and 5 days after the middle ear injection of LPS or Staphylococcus aureus, light microscopic studies were performed. The cochleae showed precipitations in the scala tympani and scala vestibuli, but no other outstanding changes were observed in these cochleae and vestibula except that in a few cases after 3 days, there were distended membranes of the sacculus. After being dipped in cold water, two other guinea pigs were injected in the middle ear with LPS. After 3 days, distended membranes were observed in the sacculi. 3. These results indicate no statietically significa cant changes of LPS concentration in the inner ear after middle ear injection of LPS, but in a few cases the LPS concentration was high and the inner ear seemed to be affected with endolymphatic hydrops.
Some patients with otitis media probably have endolymphatic hydrops, because it has been confirmed pathologically that otitis media is sometimes accompanied by endolymphatic hydrops. In this study, treatment with steroid, Isosorbide (hyperosmotic diuretic) and antibiotics was used for patients with otitis media who seemed to have endolymphatic hydrops on the basis of clinical symptoms of inner ear disturbances and positive glycerol test. This combined treatment was significantly more effective than in the controls. It is concluded that decompression treatment should be tried in patients with otitis media and endolymphatic hydrops.
A long-term follow-up of 15 patients with Meniere's disease was carried out, and the changes in hearing were examined. 1) A decrease in hearing was noted within three years after the first medical examination in 13 of the 15 patients. Thereafter hearing dropped progressively in the 13 patients. 2) A bilateral decrease in hearing was observed in five of the 15 patients. Of the five, two had bilateral Meniere's disease. An unphysiologic dec-rease in hearing of the healthy ear was noted in the remaining three patients. 3) Vertigo disappeared or was improved in 12 pa-tients, was unchanged in two and because worse in one.
Many patients with Meniere's disease (53.1%) also have other underlying diseases. Our previous study showed that the stage of healing in Meniere's disease could be evaluated from the improvement of such background factors through a 5-year study of attacks of vertigo in 15 patients by correlating the changes in the background factors with the treatment. In this recent study, we re-examined the justifiability of our previous findings by a secound 5-year observation of the same patients-a total of 10 years. The recurrence of Meniere's disease triggered by new background factors we called "new pathopoiesis" and recurrences triggered by the same background factors "recidivation". The results of this study justified our healing stage evaluation standard mearly perfectly. Further research to clarify the highly related back-ground factors in this disease is needed.
In an attempt to reduce endolymphatic hydrops, Isosorbide (ISO) has been adminstered to patients with definite Meniere's disease since the beginning of the 1980s in our departments. Follow-up studies of two years or longer on 19 patients were available for analysis according to the 1985 AAO-HNS evaluation criteria. 1) Vertigo: Complete control of definite attacks was achieved in seven patients (37%), substantial control in five (26%) and limited control in four (21%). 2) Hearing loss: The three frequency pure-tone average at 500 Hz, 1 KHz and 2 KHz was utilized for the assessment of the hearing level. Hearing improved in five patients (26%), was unchanged in seven and deteriorated in seven. 3) Disability: 14 patients (74%) were improved, while five (26%) were unchanged. These findings suggest that ISO is one of the most appropriate conservative treatment for disabling Meniere's disease.
The efficacy of transdermal scopolamine (TTS-scopolamine) was evaluated in 21 patients, 10 females and 11 males, with confirmed Meniere's disease. Twelve patients in the acute phase who could recognize relatively definite prodromal symptoms, such as a sensation of ear fullness and/or tinnitus, etc., several hours before the onset of intractable vertigo accompanied by severe autonomic nerve disturbances and nine patients in the intermittent phase were included in this study. For the acute phase patients, one sheet of TTS scopolamine (TTS 1.5) (7 μg/h release) was prescribed for application to the postauricular skin to be left for three days when the prodromal symptoms occurred. In the intermittent phase patients, one sheet of TTS scopolamine was applied as indicated. TTS scopolamine significantly reduced vertigo and autonomic nervous symptoms (nausea, vomiting) in 10 of the 12 acute phase patients. In the intermittent phase patients, tinnitus and hearing loss were vertually unchanged by TTS-scopolamine application. TTS-scopolamine, with scopolamine released for up to 3 days, generally did not cause scopolamine's usual side effects, such as drowsiness and sedation, but minor reactions of blurred vision and dry mouth were observed. In conclusion, our objective in the present study was to evaluate TTS-scopolamine efficacy and its side effects in the treatment of attacks of Meniere's disease. In acute phase patients, TTS provided satisfactory relief and the side effects were minor and tolerable.