Toshihiko Chiba

Measurement of Endocochlear DC Potentials in Ears with Acoustic Neuromas: A Preliminary Report

The pathogenesis of hearing loss in acoustic neuromas remains to be elucidated. To obtain more detailed information about inner ear damage in this disease, especially that dealing with the possibility of ischemia of the inner ear due to compression of the blood supply in the internal auditory canal by acoustic neuromas, measurement of endocochlear DC potential (EP) was attempted in three ears with acoustic neuromas during surgical removal of the tumors by the translabyrinthine approach. The size of each tumor was 3.0, 0.8, and 1.8 cm, respectively. An EP with a positive value was recorded in each of the three ears, i.e., 54, 57, and 38 mV, respectively, although the first and third patients were profoundly deaf on the side with a tumor. These findings were interpreted as being evidence of retention of function by the stria vascularis and the existence of blood supply to the inner ear in spite of the presence of tumors. Measurement of the EP seems to provide a new tool with which to analyze the causes of hearing loss in acoustic neuromas. Relatively low EP values may suggest mild dysfunction of the stria vascularis with acoustic neuromas.

Ototoxic effect of erythromycin on cochlear potentials in the guinea pig

The mechanism of hearing loss due to the administration of intravenous erythromycin was investigated in the albino guinea pig, and it was found for the first time that this drug causes cochlear dysfunction. The endocochlear potential (EP) and the cochlear microphonics (CM) recorded at the first cochlear turn transiently decreased when erythromycin was administered intravenously at dosages of 100 and 150 mg/kg. The averaged maximum decrease in EP was 16 mV (n = 5) and 33 mV (n = 5) for 100 and 150 mg/kg, respectively. The maximum decrease in the CM was about 25% when the EP reached its lowest value with the injection of 150 mg/kg. A complete recovery of the EP and CM ensued within 20 minutes after each erythromycin dose. The perilymphatic perfusion of 3 mmol/L of erythromycin decreased the EP and CM; however, in contrast to the intravenous administration, the decrease of the CM was nearly complete and both the EP and CM were irreversible. Hearing loss due to intravenously administered erythromycin could likely be attributable to the transient dysfunction of the stria vascularis, although concomitant dysfunction of the central auditory pathway cannot be excluded.

Upper airway obstruction by epiglottis and arytenoids hematoma in a patient treated with warfarin sodium.

With the increase in the number of patients undergoing warfarin therapy, reports of complications due to such therapy have become frequent. Although upper airway obstruction secondary to bleeding resulting from warfarin therapy is rare, it is a life-threatening complication because of the risk of airway obstruction. Only one previous case of hematoma of the epiglottis and arytenoids has been reported. We here in report a case of an 83-year-old woman on warfarin therapy who presented with a sore throat. On flexible nasoendoscopy, edema of the epiglottis and bilateral arytenoids with a red and purple hue were observed. The left true vocal cord was erythematous, but the airway was adequately maintained. The PT-INR of the patient was 10. She was managed conservatively and had a good course.

S159 – Inter-capsular Resection of Cervical Schwannomas

Objectives To present a new concept of surgical procedure for total removal of cervical schwannomas with neural function preservation, and the outcomes of this procedure in a series of tumors, with special reference to postoperative function of the nerve of origin. Methods A retrospective case study of consecutive 18 patients seen from January 2003 to December 2007 who underwent inter-capsular resection of cervical schwanomas derived from the nerve of vagus, hypoglossus, sympathetic trunk, accesorius, etc. was performed. During the procedure, motor fibers were confirmed and located on the surface of the tumor using nerve stimulator. Avoiding motor fibers, nerve sheath (epineurium and perineurium) is cut with a scalpel and the true capsule of the tumor is recognized. By the dissection between nerve sheath and true capsule, tumor is completely removed. The senior author named this procedure “Inter-capsular resection.” Results All tumors were resected completely, being proven by pathological study. No motor function deficit resulted, but mild Horners symptom was experienced in a case with the tumor of superior cervical ganglion origin. In a case of cervical plexus schwannoma, nerve fibers were seen in the tumor pathologically. Conclusions Cervical schwannoma can be totally removed by inter-capsular resection without postoperative motor function deficit.

A Case of Psoas Abscess due to Methicillin Resistant Staphylococcus Aureus after Total Laryngectomy.

A 78-year-old Japanese man was admitted to Iwaki Kyoritsu General Hospital for treatment of laryngeal cancer (T2N2aM0). Total laryngectomy with bilateral modified neck dissection was performed, and the patient initially showed good recovery. On the 12th postoperative day, the patient suddenly obtained a high-grade fever. Sustained lumbago followed two days later. Broad spectrum antibiotics were administered under suspicion of a bacterial infection. However, the antibiotics were not effective. Hemoptosis from gastric ulcer appeared on the 19th post-operative day, causing anemia and deterioration of his general condition. Since computed tomography revealed bilateral psoas abscess on the 20th postoperative day, open drainage under general anesthesia was performed. At the end of the operation, cardiac arrest of unknown origin occurred. Bacteriological examination of the abscess and blood after surgery proved Methicillin resistant staphylococcus aureus. Consciousness of the patient was never recovered, and the patient died on the 44th day after the initial surgery. This is the first case of psoas abscess reported as a postoperative complication after head and neck surgery in Japan. The pathogenesis of psoas abscess in this patient was discussed.

The Effect of Erythromycin on Cochlear Potentials.

The mechanism of hearing loss following administration of intravenous erythromycin lactobionate was investigated using the albino guinea pig. This hearing loss was found, for the first time, to be due to cochlear dysfunction caused by erythromycin administration.The endocochlear potential (EP) and the cochlear microphonics (CM), recorded at the first or second cochlear turn, transiently decreased when erythromycin was administered intravenously at dosages of 100 and 150 mg/kg. The decrease in EP and CM was clearly related to dose. A complete recovery of EP and CM ensued after each erythromycin application. However, perilymphatic perfusion with 3 mM of erythromycin caused an immediate and drastic decrease in CM, while it caused a mild decrease in EP following its initial elevation. The magnitude of the negativity of EP in response to anoxia was small after perilymphatic perfusion, while it remained within the normal range with intravenous application.These findings suggest that intravenously applied erythromycin has a direct effect upon the stria vascularis, while erythromycin applied via the perilymph exerts its potent action predominantly on the hair cells.

Is facial nerve decompression surgery effective

Since steroid therapy has been proven to be effective on facial nerve palsy, many doctors have abandoned facial nerve decompression surgery (FND), and it is usually used only for traumatic facial palsy. However, there are still a few cases which cannot be cured by steroid therapy. With such cases or the cases which were not properly treated, we have used FND in the late period. In this paper, the results of this surgery are reported and its effectiveness is discussed.