Nobuaki Tsuchihashi

Acoustic Neuromas Presenting as Sudden Hearing Loss

Progressive hearing loss is well known as a usually existing complaint in patients with acoustic neuromas. However, sudden hearing loss is also a relatively frequent condition in acoustic neuroma patients. In our review of 132 patients with surgically proven unilateral acoustic neuromas, 29 (22.0%) presented a history of sudden hearing loss. We investigated the clinical and audiological characteristics of these patients, and discuss the etiology of sudden hearing loss in patients with acoustic neuromas. The characteristics of patients with AN presenting sudden hearing loss were as follows: 1) a small tumor, 2) short duration after onset, 3) low incidences of vertigo, dizziness, facial and trigeminal nerve symptoms, 4) the trough type in the audiogram configuration, 5) normal caloric response. Based on the analysis of these results, we conclude that a conduction block of the cochlear nerve is likely to be the etiology of sudden hearing loss.

Steroid-Responsive Sensorineural Hearing Loss: Combination Therapy with Prednisolone and Sairei-to

We observed cases of hearing loss in which hearing deteriorated when steroid therapy was discontinued and improved upon re-administration. We identified these as cases of steroid-responsive sensorineural hearing loss (SNHL). The diagnostic criteria for determining steroid-responsive SNHL were stated, and 10 cases were examined. The 10 cases of steroid-responsive SNHL were divided into two groups: 3 cases associated with aortitis syndrome (systemic type) and 7 cases with no known systemic disease (localized type). Relatively satisfactory hearing was maintained in these cases by long-term oral administration of prednisolone (PSL). The combined use of Sairei-to made it possible to decrease the necessary maintenance dose of PSL. While the pathology of steroid-responsive SNHL is still unclear, it is suspected that immune complex disease or vasculitis may be involved.

Evaluation of Hearing Recovery in Patients with Sudden Deafness

It is still difficult to evaluate the efficacy of treatment of sudden deafness. Effective methods of therapy have been reported in some studies and other studies have reported spontaneous recovery. In the present study, we assessed the correlation between hearing recovery and various parameters measured during recovery. We used three parameters: hearing gain, relative hearing gain, and recovery rate. We found that the recovery rate during recovery and the parameters measured on the 7th treatment day demonstrated the greatest correlation. The recovery rate on the 7th day of treatment was found to be useful for predicting the final hearing recovery. Comparison of the recovery rate on the 7th day of treatment may be useful for the evaluation of the efficacy of treatment of sudden deafness.

Endoscopic diagnosis of idiopathic perilymphatic fistula

The usefulness of endoscopic examination for the diagnosis of idiopathic perilymphatic fistula (IPLF) was investigated. Eight patients presenting with unilateral sensorineural hearing loss and vertigo underwent endoscopic examination by the transtubal or transtympanic approach. In 5 out of the 8 patients, transtubal endoscopy was carried out using a superfine flexible endoscope. With this approach, no abnormal findings were visualized. A perilymphatic leak from the round window was observed in 2 patients by means of transtympanic examination using a needle scope. These findings were confirmed in both patients by microscopic observation during tympanotomy. In one patient who was finally diagnosed with IPLF, the transtympanic endoscopy failed to detect perilymphatic leakage. Although incision of the tympanic membrane is necessary for the examination, transtympanic endoscopy is useful for the diagnosis of IPLF. Further improvement of the superfine flexible fiberscope is necessary before transtubal observation of the tympanic cavity can be effectively conducted.

Electrocochleography during experimental cochlear ischemia of the guinea pig

It has been postulated that impairment of cochlear blood flow (CoBF) is one of the most important causes of hearing loss occurring during acoustic neuroma (AN) surgery. However, it remains unclear how the degree of cochlear ischemia influences the evoked responses in electrocochleography. (ECochG) which has been used for monitoring cochlear functions. In the present study, we investigated alterations in ECochG during cochlear ischemia of varying degree in the guinea pig. In order to induce cochlear ischemia, the anterior inferior cerebellar artery (AICA) was mechanically compressed via the transclival approach. The compression of AICA resulted in the reduction of CoBF in 55 out of 70 guinea pigs. A constant reduction of CoBF was maintained during the compression of AICA in 44 (63%) guinea pigs. CoBF abruptly decreased upon compressing AICA, and promptly recovered after releasing the compression. N1 and N2 in ECochG were also altered by compression. During 3-min ischemia, N1 and N2 disappeared in 36% and 41% of the cases, respectively. The residual CoBF in cases whose N1 and N2 disappeared was significantly lower than that in other cases whose N1 and N2 were sustained during 3-min ischemia. In addition, there was a tendency that the lower the residual CoBF was, the shorter the survival time of N1 and N2. In cases whose N1 and N2 did not disappear, the prolongation of N1 and N2 latencies after 3-min ischemia was positively correlated to the residual CoBF. On the basis of these results, we discuss the mechanisms underlying the changes in CoBF and ECochG during cochlear ischemia, and conclude that the degree of cochlear ischemia during AN surgery can be estimated with ECochG.

Postoperative complications in acoustic neuroma surgery by the extended middle cranial fossa approach

The complications of acoustic neuroma (AN) surgery by the extended middle cranial fossa approach were studied in 160 cases. Death during surgery occurred in 3 cases (1.9%); 2 of these involved large tumors and the third was a case of recurrence. Transient temporal lobe symptoms were seen in 24 cases (15.3%); the average tumor diameter in these cases was 36.0 mm. Beside symptoms of 7th and 8th nerve disturbance, hemiparesis was seen 7.6%; 3rd, 4th, and 6th cranial nerve symptoms in 7.0%; and cerebellar symptoms in 7.6% of the patients. The incidence of these disturbances increased with tumor size. Cerebrospinal fluid (CSF) leakage occurred in 20.4% of the cases and this necessitated surgical treatment in 5% of the cases.

Progression of hearing loss in acoustic neuromas.

The progression of hearing loss and the factors influencing it are not well understood in patients with acoustic neuroma (AN). We investigated the relationships between the progression of hearing loss and the clinical findings in 42 patients with unilateral AN whose hearing could be examined for a period of 6 months or more. There was a tendency for hearing to deteriorate progressively in the patients with retrocochlear hearing loss, or with a small tumor. Based on these results, we conclude that an operation for hearing preservation should be performed as early as possible in these patients.

Acoustic neuromas with normal hearing

We report on 10 patients with surgically proven acoustic neuroma (AN) who have normal hearing, and their clinical features have been investigated. The results obtained in this study were as follows: The clinical features of AN patients with normal hearing involved 1) predominance in younger adults, 2) predominance in small tumors with short duration after onset, 3) subjective hearing loss accompanied with tinnitus was the most common symptom, and 4) vertigo or dizziness without any cochlear symptoms was also a frequently seen symptom. We conclude that in order not to overlook AN among patients with normal hearing, transorbital X-ray and ABR tests should be performed on these patients for the screening purpose.

Clinical Analysis of Steroid-Responsive Sensorineural Hearing Loss

In order to clarify general clinical features, characteristics of hearing level fluctuation, and therapeutic strategy in steroid-responsive sensorineural hearing loss, we conducted clinical analysis in the cases which were registered based upon the diagnostic criteria proposed by Kanzaki in 1981. The results obtained were as follows: (1) Disregarding steroid-responsiveness, both ears were impaired in all cases. (2) Female predominance and middle aged onset were found. (3) The underlying immunological abnormality could exist even in the cases without systemic autoimmune disease. (4) The mean incidence in acute hearing change was about once a year in low-frequency area and once 2 years in mid- and high-frequency areas. (5) The mean value of maximum hearing level fluctuation during follow-up period was about 35 dB. (6) The final prognosis of hearing was relatively excellent. (7) By the supplemental administration of Sairei-to for more than 2 years, the maintenance dose of prednisolone was reduced in 80% of the subjects without any significant deterioration of hearing.

Management of acute otitis media. Assessment of therapeutic strategy in Japan today.

Currently, myringotomy is widely used in the routine initial treatment of acute otitis media in Japan. In an attempt to evaluate the validity of this strategy, a number of issues that demand reassessment or clarification have been identified. These issues and factors contributing to the persisting uncertainty about myringotomy are examined.