Surgical approach through middle cranial fossa (MCF) for acoustic neuroma might be a special category among the various types of temporal bone surgery, because the surgical team works with a nerosurgeon. However this approach has significant merit looking down the temporal bone from superior portion and this technique could be applied to control other pathologies of the temporal bone. This approach might have several merits for acoustic neuroma surgery from the viewpoint of functional preservation as has been developed for that purpose by W. House in the middle of last century. Based upon my experience of 57 cases with acoustic neuroma removed by MCF during the past 15 years, the technique and its results were reviewed. This approach was basically employed for functional preservation, and most of the cases were tried to preserve the function regardless to the degree of the hearing impairments. To attain this goal, intra-operative monitoring of facial nerve function and hearing by ABR is mandatory. In most of the cases visual observation to identify the facial nerve from the tumor has its limitations, and an operator is obliged to rely upon a facial nerve stimulator.This could provide the best results for facial nerve preservation. However it could become harder when the tumor becomes larger. Regarding our results on the facial nerve, anatomical preservation was attained in 93% of the cases and 86 % were grouped in Class I, II of House-Blackmann's grading system. On the other hand, measurable hearing preservation rate among cases which has a hearing level belonging to class A & B preoperatively was 64%(14/22). Among these, 8 cases (57%) had more than 50-50 (8/14). Three cases which had a hearing level in Class D preoperatively recovered quite well to Class Bafter the surgery. This may present some evidence to reconsider the validity of the so called 50-50 rule. Recent development of diagnostic tools, especially MRI, have made it possible to find small tumors which had mild or nearly normal hearing loss. Also, some of the tumors may not grow in size, in other words, doubling time of the tumor should have considerable individual variation. Thus early diagnosis is important, and when it is small, one should confirm its growing tendency before functional reservation surgery is determined, otherwise to wait and scan could be better.
Surgery for cholesteatoma in the petrous apex were reviewed. There are two main approaches reported up to now; middle cranial fossa approach and transmastoid approach. The latter involves translabyrinthine and extralabyrinthine approaches.Selection of them depends on whether or not cochlear function or facial nerve function is preserved. The extralabyrinthine approach is devided into five categories; supralabyrinthine, infralabyrinthine, precochlear, infracochlear, taranscanal-infrapetrosal approaches, which can be applied to other cystic lesions like cholesterol granuloma as well as cholesteatoma. Combind approaches with trans-and extra-labyrinthine approaches would be recommended in most of cases.How to deal with the lesion of cholesteatoma at surgery is another important surgical point in the treatment. Basic technique is to exteriorize the petrous lesion to the external auditory canal or mastoid.Alternative technique is to obliterate the lesion with fat or muscle, which should not be recommended because of high potential of recurrence inside the lesion.We have been trying to pneumatize inside the lesion after surgery by the method that the spaces after removal of cholesteatoma are obliterated with a small piece of muscle, and the other spaces only with fibrin glue. It was recognized that this maneuver facilitates aeration of the operative lesion including petrous apex, mastoids, middle ear space. Aerated lesion can have two important benefits; one is an early detection of recurrence of cholesteatoma on CT and MRI during follow up. Another is easy access to the petrous apex lesion because of an absence of barriers in the approach to the recurrent lesion if it could occur.
Surgical treatment for vertigo is indicated when conservative management fails.Before surgery, it is necessary to confirm that the vertigo is of peripheral origin, and the diseased ear needs to be identified. In this symposium, I reviewed our experience on vestibular neurectomy for intractable vertigo attacks due to Meniere's disease and obliteration of vestibular aqueduct and encolymphatic sac for persistent positional vertigo in patients with large vestibular aqueduct syndrome (LVAS). Surgical procedures for vertigo are classified into two types;ablative and preservative procedures. Vestibular neurectomy is a typical ablative surgery for Meniere's disease, and vestibular aqueduct and endolymphatic sac obliteration surgery is a preservative procedure which we newly introduced to treat intractable positional vertigo in LVAS patients. Our results on vestibular neurectomy are satisfactory with excellent control of vertigo attacks and no patient with total hearing loss. Positional vertigo in LVAS patients disappeared with thetreated ear up head position, which improved the quality of life in our patients significantly. With appropriate indications and accurate surgical procedures, surgical treatment efficiently relieves vertigo and improve the patients' quality of life.
CO2 Laser-assisted fenestration of the tympanic membrane for acute otitis media was performed in 12 patients (18 ears) for drainage from the middle ear space, and for ventilation. Using OtoLAMTM (ESC/Sharplan, Yokneam, Israel), fenestration of the tympanic membrane of 1.8mm in diameter was created and remained patent for an average of 10.2 days (range, 4-14 days). All fenestration healed without noticeable scarring or persistent perforation. During the follow-up period (about 2months), only 1 patient (2ears) had recurrence of acute otitis media but this case had a very short period of fenestration (4days). The other patients, all of whom were infected with antibiotics-resistant bacteria, had no recurrence of acute otitis media during the follow-up period. Oto LAMTM appears to be a safe, cost-effective procedure, which can easily be used to perform fenestration of the tympanic membrane and obtain a longer persisting perforation than that by the usual myringotomy. With this procedure, there is a possibility of a good result in the treatment of acute otitis media. In spite of such good points, there are the following problems 1) The fenestration persisting period was shorter than that with fenestration of the tympanic membrane for otitis media with effusion. 2) It is difficult to fenestrate a large perforation in children, whose ear canals are very small. Japanese children's ear canals are smaller than those of American and European children. 3) There are not enough examples in Japan of the use of OtoLAMTM, so we must determine the appropriate diameter and power of the CO2 Laser for fenestration of the tympanic membrane for acute otitis media in Japanese patients. 4) It is difficult to hit CO2 Laser at right angle to the tympanic membrane for acute otitis media because the tympanic membrane expands to the outside.
Sixty three tympanoplasties in children 3 to 15 years of age were reviewed. The success rate in hearing was calculated based on the following criteria: 1) A-B gap: not more than 15 dB, 2) Hearing gain: more than 15 dB, and 3) Hearing level: not more than 30 dB. The results were considered to be satisfactory if one of the three was successfully achieved.(Otology Japan 2000) Success rate of closing perforation was 95% and improvement of hearing was 90% in all age groups. Success rate of closing perforation and improvement of hearing was 100% in preschool children (3-6 years old) and almost that in the other all age groups. Tympanoplasty can be recommended in children of all ages, including preschool age. The rate of failure was higher for bilateral otitis media.
Between January 1995 and March 2003, 52 children (under 15 years old) with middle ear diseases, including 15 cases of chronic otitis media, 6 cases (7 ears) of ossicular malformations and 31 cases of cholesteatomas were operated on by tympanoplasty in Mie University Hospital. Success rates of hearing improvement, according to the criteria of Otological Society of Japan (2000) were 100% of patients with chronic otitis media and ossicular malformations. Success rates of patients with cholesteatoma were 100% of type I, 100% of type III, and 72. 7% of type N tympanoplasty. Twenty four cases (77. 4%) with cholesteatoma were operated on by canal wall down tympanoplasty with canal reconstruction, and 7 cases by canal wall up tympanoplasty. Staged operation was performed in 17 of 31 cases (54. 8%). Of the 17 ears, 9 (52. 9%) had residual cholesteatoma detected at second stage operation. Residual cholesteatoma was observed at follow-up in 3 of 31 ears (9. 7%): 2 of 14 ears (14.3%) with one-stage group, and 1 of 17 ears (5.9%) with staged operation group. For the canal reconstruction, cortical bone was used for attic reconstruction in 4 cases, and auricular cartilage was used in 20 cases. Retraction cholesteatoma was found in 4 of 31 ears (12. 8%): 2 of 4 ears (50.0%) with cortical bone reconstruction, and 2 of 20 ears (10.0%) with auricular cartilage reconstruction. These results indicate the usefulness of staged tympanoplasty and auricular cartilage reconstruction for prevention of residual cholesteatoma and retraction cholesteatoma.
A 65-year-old man underwent radical middle ear operation fifty years ago and has suffered retroauricular fistula since then. He requested us to close the fistula. His skin around the fistula had scar and lost elasticity. Operation was performed using auricular transposition flap and the fistula was successfully closed. The usefulness of the auricular transposition flap was discussed.
Since the 1990's, endoscopes assisted ear surgery has been employed because of its excellent view of surgical field. Two cases of idiopathic perilymphatic fistulas were treated using endoscopes. A 52-year-old woman presented with dizziness and deterioration of the right hearing. The neurotological examination revealed the right sensorineural hearing loss with an average of 63 dB and spontaneous nystagmus toward the right side. Exploratory tympanotomy was performed and middle ear observation using a 30 degree angled endscopy revealed perilymphatic leakage from the round window. Both the round window and the vestibular window were covered with fascia. Case 2 was a 69-year-old woman who presented with dizziness after she was singing. In the outpatient clinic, audiometry showed sensorineural hearing loss with an average of 40 dB and spontaneous nystagmus toward the left was noted. In the operation, after tympanomeatal flap was elevated through the left external ear canal, the middle ear was observed by an endoscopy. Perilymph leakage was observed through the mucous membrane of the round window niche. Both window were covered with fascia. Endoscopic repair of perilymphatic fistula is useful especially for idiopathic perilymphatic fistulas in terms of the minimal invasive surgery.
A 6-year-old girl was detected hearing loss without subjective complaints by screening audiometry before entering elementary school. The audiogram showed bilateral conductive hearing loss, and repeated pure tone audiometry indicated that right conductive hearing loss was due to ossicular chain abnormality and that left fluctuating conductive hearing loss was due to functional deafness. When she was 11 years old, the audiogram showed bilateral mixed hearing loss, and she was referred to our outpatient clinic due to progressive hearing loss. Bekesy audiometry revealed type V in the right ear. And there was unexplainable discrepancy between the threshold of pure tone audiometry and response threshold of auditory brainstem response. It was considered that the deterioration of the right hearing loss was due to ossicular chain abnormality and functional deafness, and that of the left hearing loss was due to deteriorated functional deafness. Type III-itympanoplasty was performed on the right ear. After operation, bilateral hearing loss was improved. These observations suggested that a diagnosis of functional deafness with ossicular chain abnormality is difficult, and that various kinds of objective hearing tests are useful for diagnosis of such pathologies.
The current study was intended to evaluate the efficacy of calcium chelator (EGTA) and calcium free artificial perilymph (AP) administered directly into the inner ear, to attenuate noise-induced trauma in the guinea pig, as assessed electrophysiologically amd and morphologically. Animals were administered AP, calcium free AP or calcium chelator (EGTA) via a mini-osmotic pump directly into scala tympani. On the fourth day after pump implantation, animals were exposed to 120dB SPL octave band noise, centered at 4 kHz, for 24 hours. Noise-induced auditory brainstem response (ABR) threshold shifts outer hair cell survival, observed 7 days following exposure, were significantly attenuated in the group receiving EGTA compared to the AP treated group. These physiological and morphological results indicate that direct infusion of EGTA and calcium free AP into the perilymphatic space has protective effects against noise-induced trauma in the guinea pig cochlea.
Epidemical studies demonstrated that Bell's palsy is highly associated with diabetes mellitus. On the other hand, evidence of herpes simplex virus type 1 (HSV-1) as an etiological cause of Bell's palsy has been increasing in recent years. Then, following questions arise. Why diabetes mellitus is so highly associated with Bell's palsy and how to manage Bell's palsy associated with diabetes mellitus. To clarify above questions, we made animal model of facial nerve paralysis induced by HSV-1 in diabetic mice induced by streptozotocin. Facial nerve paralysis did not develop in mice treated with streptozotocin alone. However, when HSV-1 was inoculated in 4 and 8-week-old mice, facial nerve paralysis developed more frequently in mice with diabetic mice than in healthy mice. Severity and recovery of the facial nerve paralysis tended to be more profound in diabetic mice, however, no statistical significance was seen between the diabetic mice and the healthy mice. Electrophysiological test and histopathological findings of the affected nerve showed mixed nerve degeneration with severe demyelination and mild axonotomy in both the diabetic and healthy mice. HSV-1 proliferation in the nerve cell was more prominent in the diabetic mice compared to that of the healthy mice. These results suggest that diabetic condition does not cause facial nerve paralysis by itself but enhance the infection of HSV-1 in nerve tissue, leading to develop the facial nerve paralysis.
The hearing organ is a sensory apparatus that converts the mechanical stimulation of sound into electrical energy in the cochlea, and then into a neural code in the central auditory pathway. Electrical phenomena in the cochlea include the endocochlear potential (EP), receptor potential of the sensory hair cells, outer hair cell motility, and neurotransmission, all of which involve the maintenance of the intra-and extracellular chemical and electrical environment. Namely, the fundamental and substantial cellular responses of the cochlear cells are based upon an ion transport system responsible for the electrochemical properties, resulting in the efficient energy-yielding processes of acoustic transduction. I focus on functional, molecular biological, and genetic analyses of carrier transporters, ion channels and receptors localized in the cochlea, mainly from the viewpoint of my own works, to clarify the cellular and molecular bases of pathophysiological events and responsible genes for deafness, with the hope that this will in the future contribute to the screening, diagnosis, treatment and prevention of deafness. Tremendous progress in auditory research has been carried out by approaching the genetic basis of deafness. An increasing amount of hereditary deafness is found to be caused by defects of the carrier transporters, ion channels and receptors in the cochlea. Clarifying the physiology, and the structural and molecular framework of the ion transport systems encoded by deafness genes and resolving the underlying mechanisms of deafness could make it possible to develop fundamentally new methods of diagnosis, therapy, and prevention for millions of patients suffering from unknown origins of deafness.
Animal models have contributed to our understanding of cochlear injuries. In this report, generation mechanisms of the cochlear ischemia-reperfusion injury were examined using animal models. Increase in the extracellular concentration of glutamate is one of key components in the sequence of the cochlear ischemia injury. In addition, enhanced generation of free radicals and nitric oxide following reperfusion contributed to the further injury of outer hair cells. The present findings are important in the light of an attenuation of the cochlear ischemia-reperfusion injury.