Yasuya Nomura

Effect of single-drug treatment on idiopathic sudden sensorineural hearing loss

OBJECTIVES In order to evaluate the effect of a medical administration for the sudden deafness patients, single-drug treatment for idiopathic sudden sensorineural hearing loss (ISSHL) was assessed at multi-centers participating in the Acute Severe Hearing Loss Study Group sponsored by the Ministry of Health, Labor and Welfare of Japan. METHODS The subjects consisted of ISSHL patients who were (1) 20 years of age or older, (2) diagnosed within 2 weeks after the onset of hearing loss, (3) showing a mean hearing level of 40-90 dB at five frequencies from 250 to 4000 Hz, (4) previously untreated, and (5) with normal for age in hearing of the opposite ear. The drugs used in this study were ATP, alprostadil, hydrocortisone and amidotrizoate, which were administered intravenously, and beraprost sodium and betamethasone, which were given orally. Two drugs were assigned to each center, one of which was selected according to the code hidden in envelopes and administered for 1 week. The treatment after the single-drug administration was conducted at the discretion of each center. The hearing gain and recovery rate at 1 week after the initiation of single-drug treatment and at 1 month or over when the hearing level was fixed, were evaluated based on the criteria for hearing recovery prepared by the Acute Severe Hearing Loss Study Group. RESULTS There was no statistically significant difference in the recovery rate among drugs either at 1 week after the initiation of single-drug treatment or at the time of fixed hearing level. At the time when the hearing level was fixed, a statistically significant difference in the complete recovery rate was detected only between amidotrizoate and beraprost sodium. CONCLUSION From these results, we could not find any specific drugs recommended for ISSNHL. In evaluating the effect of the drugs, however, several problems in the clinical trial for ISSHL should be considered.

Influence of Changed Blood pH on Anionic Sites in the Labyrinth

Using polyethyleneimine as a cationic probe, changes in the anionic sites of the labyrinthine basal laminae occurred during acidosis and alkalosis. Hartley-strain guinea pigs (200-300 g) with normal Preyers reflex were injected i.v. with 0.5% polyethyleneimine (PEI, mol. wt 1800) solution adjusted to pH 7.3 with HCI via an axillary vein. The animals were divided into three groups: control, acidosis, and alkalosis. Acidosis was produced by inducing hypoxia, and alkalosis by injecting 7% NaHCO3. In controls, anionic sites were demonstrated on the basal laminae in the labyrinth. During both acidosis and alkalosis, a decreased number of anionic sites were observed on the basal laminae of the capillary walls in both stria vascularis and subepithelial layer of the vestibular sensory epithelium. However, an increase in anionic sites was observed on the basal lamina in Reissners membrane during both acidosis and alkalosis.

Argon laser irradiation of the semicircular canal in two patients with benign paroxysmal positional vertigo

The results of long-term follow-up after surgical treatment of two patients with intractable benign paroxysmal positional vertigo are reported. Argon laser irradiation of the blue-lined posterior and lateral semicircular canals in one patient, and of only the posterior canal in the other was performed seven and six years ago, respectively. Argon laser irradiation was carried out 10 times in succession three mm along the canal to occlude it. The power applied each time was 1.5 W on the dial of the laser device for 0.5 sec. Relief of vertigo was noted on the second post-irradiation day. There has been no recurrence of vertigo in these patients.

Regeneration of olfactory mucosa in mice after inhalation exposure to perchloroethylene.

An experimental group of 20 male pure-bred mice was exposed to perchloroethylene gas at 300 ppm for 6 h daily for 5 days. Histopathological study of the nasal mucosa, particularly the olfactory mucosa, was performed sequentially 2 weeks to 3 months after exposure, to clarify the process of regeneration. The tissue damage due to perchloroethylene gas was more persistent in the nasal mucosa of the olfactory region than in the respiratory region. Two weeks after exposure, ciliated epithelial cells, as well as normal pseudostratified nonciliated columnar epithelium, began to appear in the area previously covered by olfactory epithelium and remained for up to 3 months after exposure. A basement membrane was present under the ciliated epithelium, suggesting a possible persistence of basal cells. The olfactory epithelium may thus be replaced by ciliated epithelium. The lamina propria of the olfactory mucosa, however, lost its normal structure with atrophy of the olfactory nerves and Bowmans glands.

Treatment of Vertigo Using Laser Labyrinthectomy

Benign paroxysmal positional vertigo developed in a patient with perilymph fistula 3 years after closure of the fistula which was in the lower margin of the annular ligament. The patients symptoms were long-lasting and intractable. The macula utriculi and utriculoampullary nerve were irradiated by argon laser beams through the stapedectomized oval window. Singular neurectomy was performed using Argon laser, although the nerve could not be identified. After surgery, the patients symptoms disappeared. Pure tone average of the operated side was 50 dB which remained unchanged after surgery. The macula utriculi may have been completely destroyed. Ocular counter-rolling was indicative of hypofunction of the irradiated utricle. The singular nerve may or may not have been sectioned. The ampullary nerves to the lateral canal and probably the anterior canal were intact, judging from the normal caloric reaction.

Changes in middle ear pressure in daily life

The present study was performed to estimate changes of middle ear pressure (ME‐P) during actions of daily life such as nose blowing and sniffing. ME‐P was measured in 18 patients with perforation of the eardrum. They were asked to perform actions which included nose blowing and sniffing. Eustachian catheterization and politzerization were also applied. Change of ME‐P before and after these actions was recorded using a pressure monitor. Results showed that changes of ME‐P after nose blowing with both nostrils closed were large and rapid. The mean value of ME‐P after nose blowing was 252 mmH2O. In our previous study, the mean value of cerebrospinal fluid pressure (CSF‐P) after nose blowing was 388 mmH2O.1 Therefore, the pressure gradient across the cochlear windows is about 130 mmH2O during nose blowing. The cochlear windows may have been pressed toward the middle ear side. After sniffing, ME‐P was unchanged. These results suggest that nose blowing may be an important cause of perilymphatic fistula (PLF) via the “explosive route,”2 while sniffing is not likely to cause PLF.

Argon Laser Irradiation to the Semicircular Canal

In order to elucidate the effects of argon laser irradiation on the lateral semicircular canal of the guinea pig, the vestibular labyrinth was histologically studied after irradiation, using the conventional celloidin method. Irrigation of the external meatus with ice water was used to evaluate the function of the semicircular canal by recording caloricnystagmus. When irradiation was performed, a laser probe was approximated to the lateral canal, 0.5 to 1 mm away from the surface of the canal. Each time, power applied was 1.0 W on the dial of the laser machine. The duration of irradiation was 0.5 s. The lateral canal was irradiated one to 15 times. Twenty‐five to 87 days after irradiation, the temporal bones were fixed in Heidenhein‐Susa solution, removed, and subjected to celloidin processing. The irradiated bony wall of the lateral canal demonstrated charring. Lucent areas were observed around and under the charred area. The semicircular duct showed shrinkage with disappearance of the trabecular mesh. New bone formation was observed along the endosteum of the irradiated area. The lateral canal was completely occluded by ossification with or without fibrosis when sufficient energy was applied. The anterior and posterior canals were normal. Caloric tests using 5 mL of ice water for 5 s failed to elicit nystagmus on the irradiated side.

The Vestibular Nerve: Its Course to the Anterior and Lateral Ampullae

The course of the ampullary nerve to the anterior and lateral ampullae was studied using 25 human temporal bones. Sudan Black B staining was applied to decalcified temporal bones in order to stain nerve fibers. After removing the external and middle ear, each temporal bone was divided into four blocks by three parallel planes, making an angle of 45 degrees to the long axis of the stapes footplate or a line along the stapedial tendon. Two planes were in contact with the anterior and posterior margin of the oval window, respectively. The third plane passed through the capitulum of the stapes. Distances from the upper margin of the oval window, to the distal and proximal part of the ampullary nerve, to the facial nerve, and to the utricular macula were measured in the third plane. The thickness of the thinnest part of the wall of the facial canal facing the stapes was also measured. A new surgical approach to the ampullary nerve is discussed.

Vestibular Changes after Guinea Pig Cytomegalovirus Infection

A guinea pig model of viral labyrinthitis was established by inoculating guinea pig cytomegalovirus into the inner ear and then determine its effect on vestibular function. Neither spontaneous nor positional nystagmus could be detected postoperatively. Nine out of 18 (50%) animals had caloric hyperfunction in the virus-inoculated ear at 1 to 3 weeks postoperatively. Five of these 9 animals also had caloric hyperfunction in the control ear. A morphological study in animals with caloric hyperfunction showed no change in the peripheral vestibular apparatus by light microscopy. It is thus assumed that caloric hyperfunction in experimental viral labyrinthitis is transient and functional.

Laser irradiation of the semicircular canal: Occlusion of the canal or duct

Abstract The aim of this study was to evaluate the effects of argon laser irradiation of the semicircular canals using computed tomography (CT) images and to examine the basis for laser treatment for benign paroxysmal positional vertigo (BPPV). CT images of the posterior canal were evaluated postoperatively in a patient with intractable BPPV, in whom the unilateral posterior and lateral semicircular canals were irradiated with an argon laser. In addition, bootstrap analysis of 20 patients with normal CT findings of the temporal bone was performed and previous experimentally obtained histologic findings were compared. Cross-sections of the posterior canals of 20 patients were found to show no difference in size between the right and left sides. The laser-irradiated posterior canal became narrower than that on the non-irradiated healthy side in our patient. There was a discrepancy between the CT images and experimentally obtained histologic findings that showed complete occlusion of the canal. CT images of a patient with severe vertigo demonstrated that argon laser irradiation to the blue-lined semicircular canals did not occlude the canal of the corresponding areas, while the canal of the guinea pig histologically showed complete obstruction with new bone after irradiation with the same energy (1.5 W, 0.5 s, spot size: around 200 μm in diameter). The patient has been free from vertigo for 16 years. Marked constriction of the semicircular duct corresponding to the irradiated area appeared to be effective in treating intractable BPPV.