Cochlear blood flow volume has been measured by injecting microspheres intracardially and simultaneously withdrawing reference blood at a constant suction rate from the femoral artery in experimental animals. When non-radioactive microspheres were used, the number of microspheres in the cochlea and reference blood was counted directly. However, the non-radioactive microspheres enabled us to investigate the distribution of blood flow inside the cochlea if the number of microspheres was counted following soft surface preparation or the serial section technique. By using radioactive microspheres, total cochlear blood flow volume can be determined after the radioactivity of the cochlea and reference blood is measured. However, it is not possible to investigate the regional distribution of microspheres in the cochlea by the measurement of radioactivity for technical and statistical reasons. In this paper, the results of cochlear blood flow determined by the microsphere method were reviewed.
Cochlear blood flow (CoBF), systemic blood pressure (BP) and endocochlear DC potential (EP) were simultaneously measured to study pharmacologic actions of vasodilating agents, which were given intravenously and to the round window membrane in normal guinea pigs. CoBF was assessed using a laser Doppler flowmeter by placing the probe on the basal cochlear turn. Sodium nitroprusside (4% solution), hydralazine hydrochloride (4% solution) and beraprost sodium (0. 1% solution) induced increase of CoBF substantially by the window application. CoBF by intravenous injection of these drugs were changed more complexly due to substantial decrease of BP which also modified the CoBF increases. It is confirmed that topical application has the advantage of delivering the agents solely to the inner ear, avoiding the BP alteration. However, decrease of EP was observed in topical application of sodium nitroprusside and hydralazine hydrochloride. In contrast, topically applied beraprost sodium showed no significant EP reduction, suggesting possible clinical use for acute inner ear disease.
Local blood flow is determined by perfusion pressure in the tissue, radius of the blood capillary and blood viscosity. Cochlear blood flow changes during and after the infusion of following various drugs were recorded by the use of a laser Doppler flowmeter. In the experiments to change perfusion pressure, we observed the effects of Epinephrine, Angiotensin II, Trimetaphan camsylate (depressor) and several osmotic diuretics. Since 76% Urografin is a solution of a higher osmolarity in the contrast media for vasography and known to produce vasodilation in the legs when infused in the abdominal aorta. The effect of Urografin was compared with that of glycerol in regard to the effect on cochlear blood flow and systemic blood pressure. For the experiment on the effects of vasoactive agents, we measured the changes of cochlear blood flow during and after the infusion of Prostaglandin E1, Prostaglandin E2, and Dihydroergotamin. To evaluate the influence of viscosity factor on cochlear blood flow, we used Batroxobin for defibrinogenation, Erythropoetin to produce polycythemic condition, normal saline for hemodilution and Pentoxyfilline to facilitate erythrocyte deformability. Pentoxyfilline was found to exert the increasing effect in cochlear blood flow, especially in the animal with a higher hematocrit value. These findings may imply the significance for understanding the physiology of cochlear blood flow as well as pharmacoclogy of above mentioned agents in the cochlear microcirculation.
We reported 12 cases of patients with traumatic ossicular disruption. In 11 cases, disruption was caused by indirect force. Audiograms of these cases showed conductive and mixed hearing impairment, and air-bone gap was ranged from 25 to 60dB. On X-ray studies, ossicular disruption could not be detected in all cases. On tympanogram, Ad type in 5 cases showed, B type in 4, and As type in 3. In those 11 cases, stapedialreflexes were negative. In one case, there was rupture of the tympanic membrane with perilymph fistula caused by direct injury. Eleven cases with indirect injury had a temporal bone fracture, and 7 cases showed facial paralysis. The ossicular disruption was observed at incudo-stapedial joint in 7 cases and malleo-incudial joint in 3. Two cases had stapedial dislocation. In 5 cases, replacement and reconstruction of the disrupted ossicles were performed, and in 7 cases, adhesive glue was used to secure the ossicular chain continuity. After surgery, postoperative hearing improvement was achieved in 7 cases (58%). The success rate of postoperative hearing improvement was higher in cases with adhestive glue fixation (71%) than those without adhesive glue fixation (40%). Those findings suggested that although postoperative hearing improvement was not influenced by the location of ossicular chain disruption, by using adhesive glue, the reconstuction of the ossicularchain was firmly fixed, and postoperative hearing was improved.
A 49-year-old woman complained of dizziness, and CT scans and MRI revealed an enlargement of the vestibule with deformity of the lateral semicircular canal in the right side. A highly situated enlarged jugular bulb was found in the same side. An audiogram showed normal hearing in the both ears. During right exploratory tympanotomy, a perilymphatic leakage from the round window was noted. The malformation of the lateral semicircular canal might be caused by a space-occupying effect of the high jugular bulb in the temporal bone. It should be cautioned that congenital inner ear deformities are sometimes associated with perilympatic leakage.
Using high-resolution computed tomography (CT), we measured the area of mastoid air cells and the shortest length between the posterior wall of the external auditory canal and the anterior edge of the sigmoid sinus, and then compared the right-left difference in sixty cases of unilateral chronic otitis media and in twenty normal cases. In the case of unilateral chronic otitis media the shortest length between the external auditory canal and the sigmoid sinus was significantly short where there was poor mastoid pneumatization, regardless of whether it was the right or left ear. Mastoid pneumatization was found to be prohibited by chronic inflammantion, and as a result, the relative positions of the external auditory canal and the sigmoid sinus were affected.
A 64-year-old female was presented with idiopathetic temporal meningoencephalocele. This patient had been repeatedly treated with myringotomy and ventilation tube insertion because of otitis media with effusion on the right side during past 2 years. She was referred to our clinic on suspicion of CSF otorrhea or perilymph fistula because of massive and watery effusion and its high level of glucose (97 mg/dl). CT and MRI examinations revealed a presence of the effusion in the right mastoid air cells without any mass. In 111In cisternography, an accumulation of the isotope was not detected in both middle ear, while the radioactivity of the effusion from the right ear extremly elevated, 200-times higher than that of blood. Mastoidectomy was performed under general anesthesia, and a soft mass protruding from the middle cranial fossa through a bony defect of the tegmen antri into the antrum with CSF leakage was found. Histopathological examination of the mass revealed brain tissue with gliosis. After resection, a dural defect was patched with a fascia graft, and the mastoid cavity was obliterated with fatty tissues. Clinical signs and sympotoms, differential diagnosis and surgical treatments of this disease were discussed.
Only 34 cases of chondroblastoma of the temporal bone, including our one case, have been reported since in 1950. We presented a 54-year-old female with chondroblastoma of the left temporal bone and discussed rentogenographical differential diagnosis and surgical treatments of this tumor. The patient developed left hearing impairment. The left external ear canal was completely almost obstructed with a bulging of the superior canal wall. Audiogram showed left conductive hearing impairment, and tympanogram showed A-type on both sides. Rentogenograms of the temporal bone revealed a large radio-luscent area without marginal osteoscrelosis from the mastoid to the zygomatic process over the temporo-mandibular joint. She had received mastoidectomy under suspicion of cholesteatoma of the middle ear. A large tumor occupying the temporal lesion, compatible with a radio-lucent area on x-ray, was completely resected, and the postoperative cavity of the temporal region was obliterated with a pedicled temporal muscle flap. Four years after surgery, no recurrence of the tumor was recognized.
To evaluate the effects of therapy, hearing recovery rates were analyzed in 86 patients with sudden deafness. As for the drugs to the patients, Steroids, Urokinase, ATP were administered together or independently. Changes of drugs were made in 26 patients during the treatment period (drug change group). Another 60 patients were treated without changes of drugs (same drug group). The recovery rates were compared between the hearing at the 7th day after administration of the drugs and at a fixed stage. The recovery rates at the 7th day in the drug change group were lower than those in the same drug group. At the fixed stage, no statistical difference was observed between the two groups. Although no clear effect of drug change was established in this study, drug changes according to the recovery rate at the 7th day might be feasible. The present results suggest that a randomized prospective study on the treatment of patients with sudden deafness is needed in order to evaluate the detailed effects of the various treatments.
An 8-year-old female patient presented with a hearing loss of 7 months' duration in her left ear. Audiometry revealed left moderate hearing loss with poor speech discrimination. CT and MRI demonstrated a CP angle tumor with a diameter of about 3 cm. There were no findings suggesting neurofibromatosis 2. The tumor was removed via the extended middle cranial fossa approach type II. Although hearing preservation surgery was not indicated in this case because her speech discrimination was 12%, the facial nerve was preserved anatomically and functionally. Clinical features of the acoustic neuroma developing in a child are discussed with a review of the literature.
In order to investigate whether the long-term prognosis of postoperative facial nerve function might be predicted by the analysis of facial nerve function in the early stage after the operation, we conducted sequential evaluations of facial nerve function in 51 cases of unilateral acoustic neuroma. The operation was conducted through the extended middle cranial fossa approach, and facial nerve function was evaluated by the modified Yanagihara's grading system (40 points Japanese grading system) at 6 points of postoperative time course, 5 days, 15 days, 1 month, 3 months, 6 months and over 1 year. Based upon the facial score in the 40 point Japanese grading system, facial nerve function was classified into 5 degrees, such as normal (40 points), excellent (over 30 points, below 40 points), moderate (over 20 points, below 30 points), poor (over 10 points, below 20 points) and severe (below 10 points). And the time course of degree of postoperative facial nerve function was analyzed. The results obtained were as follows; 1) Eight cases, whose function was evaluated to be normal immediately (5 days) after the operation showed no subsequent facial palsy. 2) Six cases whose function was evaluated as excellent immediately after the operation, recovered to normal function at 3 months after tumor removal. 3) Seven of Eight cases whose function was evaluated as moderate immediately after the operation, recovered to normal function at 6 months after tumor removal. 4) Seven of fourteen cases in the excellent or moderate groups immediately after the operation showed a temporary deterioration of facial function 15 days after the operation, however, its function improved to normal except one case during the follow-up period. 5) The recovery of facial palsy was delayed in twenty-eight of twenty-nine cases whose function was evaluated as poor or severe immediately after the operation and did not recover to normal function during the follow-up period. 6) These results conclude that the facial nerve function immediately after tumor removal enables us to differentiate cases with an excellent long-term prognosis from others, and furthermore, it could be helpful in predicting the required time for the recovery to the normal function in the cases of excellent long-term prognosis.
Lidocaine is well known to be capable of releaving tinnitus. In the present study, we introduced an intravenous continuous lidocaine infusion therapy, and compared the therapeutic results of this method to those of an intravenous bolus injection of lidocaine. Twelve patients with tinnitus associated with idiopathic cochlear hearing loss, 6 patients with tinnitus caused by sudden deafness and 2 patients suffering from tinnitus without hearing loss underwent an intravenous bolus injection of lidocaine (60mg) followed by an intravenous continuous lidocaine infusion therapy (120mg over 30-60min). In 30% of the patients, tinnitus intensity was reduced by more than 50% after an intravenous bolus injection of lidocaine, while tinnitus intensity in 65% of the patients decreased more than 50% with an intravenous continuous lidocaine infusion therapy. In addition, the duration of tinnitus suppression was significantly prolonged by an intravenous continuous lidocaine infusion therapy. No noxious side effect was observed in this method. These results indicated that an intravenous continuous lidocaine infusion therapy might be useful for tinnitus management. An underlying mechanism of the effect of lidocaine on tinnitus was discussed with a review of the literature.