[Clinical experiences and postoperative results with partially implantable middle ear implant].

A partially implantable middle ear implant using an ossicular vibrator of a piezoelectric ceramic bimorph has recently been developed in Japan as a new rehabilitative method for hearing. Four patients at the Miyazaki Medical College Hospital were implanted with this device between September 1994 and October 1996. Implantation of the internal component was performed under local anesthesia after confirmation of sufficient sensitivity to the ossicular vibrator in an intraoperative vibratory hearing test. All patients regained socially useful hearing with the middle ear implant without any foreign body reactions or recurrence of otitis media. None of the cases showed any elevations of bone conduction thresholds 2 to 4 years postoperatively. Natural and clear sounds without interference noise and howling due to acoustic feedback were highly satisfactory in all patients. However, the first case, who had an implant in an ear following cholesteatoma surgery using the intact canal wall technique, experienced about a 10dB deterioration of the average hearing level with the implant 2 years after implantation. Gradual deterioration appeared to be caused by the retracted tympanic membrane interfering with the mobility of the ossicular vibrator. The following three cases were implanted in ears previously operated on by radical mastoidectomy, showing stable or improving hearing results with the implant. Closure of the external canal skin at the cartilaginous portion at the time of implantation seemed appropriate to maintain a sufficient middle ear space for the ossicular vibrator to work properly. Our case study confirms that the partially implantable middle ear implant is a safe and useful tool for patients with mixed deafness which cannot be satisfactorily rehabilitated by tympanoplasty and/or a conventional hearing aid.

Expression of the Vax family homeobox genes suggests multiple roles in eye development.

BACKGROUND: Homeobox gene products are thought to regulate target genes involved in the regional specification of tissues and organs. Several genes play roles in eye development. RESULTS: We isolated two new mouse homeobox genes, Vax1 and Vax2, expressed in retina primordium. The two genes share the same gene organization, consisting of three exons with predicted amino acid sequences identical in the homeodomain but diversified in other regions. At 9. 5 days post coitum, both Vax genes were expressed in optic vesicles. At 11.5-14.5 dpc, Vax1 became restricted to the optic stalk, while Vax2 was expressed in the ventral half of the neural retina. Mapping of Vax2 between D6Mit3 and D6Mit8 on chromosome 6 indicated a possible linkage with Emx1. CONCLUSIONS: The expression patterns of Vax genes suggest separate and specific involvement in eye development. Vax1 may contribute to differentiation of the neuroretina, pigmented epithelium and optic stalk, while Vax2 could function in the establishment of the dorso-ventral axis of the retina and the visual system. The chromosomal location of Vax2 suggests that Vax2-Emx1 and Vax1-Emx2 arose by chromosome duplication of the same ancestral gene.

Prussak's space: chronological development and routes of aeration.

Investigation of Prussak's space and its relationship to adjacent spaces is important in elucidating the cause of retraction pocket and cholesteatoma formation in this space. This study was designed to quantitatively characterize the chronological development of Prussak's space and its relationship to adjacent spaces in temporal bones. One-hundred and forty-nine human temporal bone slides (115 normal, 28 with otitis media with effusion, three with retraction pockets and three with attic type cholesteatoma) including specimens ranging from fetal to adult bones were studied. Prussak's space was formed and sufficient aeration routes established by 4 years of age in normal temporal bones. In temporal bones with otitis media with effusion, however, the growth of Prussak's space was suppressed and few routes for aeration established until 10 years of age. In normal temporal bones, Prussak's space developed with aeration routes sufficient to avert the negative pressure which can result in retraction pocket formation in the pars flaccida of the tympanic membrane.

Utilization of nickel-titanium shape memory alloy for stapes prosthesis.

A new type of stapes prosthesis made of nickel-titanium shape memory alloy wire was developed and its biocompatibility was examined in 24 ears of 12 cats. The prosthesis was implanted at the long crus of the incus. The incus was examined 27-355 days after operation. In 23 ears, the prosthesis was found macroscopically well implanted at the aimed position. In one ear the prosthesis was found to be dislocated and in another the prosthesis was slightly loosened. The incudes were removed and five specimens were prepared for scanning electron microscopy and the other specimens were observed under light microscopy. Histological studies revealed severe bone resorption of the long crus in the dislocated case and moderate bone resorption in the slightly loosened case. These bone resorptions were found to be caused by the inadvertent removal of the mucosal membrane during the implant operations. In seven ears under a light microscope and in one ear under a scanning electron microscope, slight bone resorption as bone erosion was seen at the contact area of the prosthesis. This bone resorption was induced by the mechanical pressure of the prosthesis and was not progressive due to fading of the pressure of the prosthesis. With the exception of pressure induced bone erosions, there was no progressive bone resorption which was prosthesis induced. The biocompatibility of the nickel-titanium alloy stapes prosthesis with the long crus of the incus was proved. The prosthesis should be implanted loosely at the long crus of the incus without removal of the mucosal membrane.

Iodine-123 metaiodobenzylguanidine myocardial imaging in patients with pulmonary hypertension.

Iodine-123-metaiodobenzylguanidine [123I-MIBG] has been used to evaluate the cardiac sympathetic nervous system. We evaluated the effect of pulmonary hypertension on the sympathetic neuronal function of the left ventricle in patients with pulmonary hypertension. We studied 20 patients with either chronic lung disease or pulmonary vascular disease. The patients were divided into a pulmonary hypertensive group and a control group. Single photon emission tomography was performed in the resting state 15 min and 4 h after administration of 123I-MIBG. Regions of interest (ROI) were set in the left ventricular (LV) free wall, the interventricular septum (IVS) and outside the LV free wall on short-axis images. The washout rate and the ROI/LV uptake ratio were calculated in each ROI. The IVS:LV uptake ratio was significantly lower in the pulmonary hypertensive group than in the control group. Our results suggest that left heart sympathetic neuronal dysfunction initially occurs in the IVS before it involves the LV free wall subsequently.

Iodine-123-metaiodobenzylguanidine myocardial imaging in patients with right ventricular pressure overload.

UNLABELLED: Iodine-123-metaiodobenzylguanidine ([123I]MIBG) has been used to evaluate the cardiac sympathetic nervous system, particularly that of the left heart. To clarify whether the right ventricular (RV) sympathetic neuronal function could be evaluated by [123I]MIBG myocardial imaging, we applied the technique in patients with pulmonary hypertension that was associated with either chronic pulmonary diseases or pulmonary vascular diseases. METHODS: All patients underwent right heart catheterization, and right heart hemodynamics were determined during a clinically stable state. SPECT was performed in the resting state 15 min (early imaging) and 4 hr (delayed imaging) postadministration of [123I]MIBG. Seven regions of interest (ROI) were selected on the delayed short-axis images on the RV free wall, left ventricular (LV) free wall and interventricular septum (IVS). We calculated the IVS-to-LV uptake ratio from the scintillation counts of the ROI. Thallium-201 myocardial imaging was also performed within 1 wk after [123I]MIBG imaging. RESULTS: Images obtained with these techniques were analyzed for the RV-to-LV uptake ratio. The IVS-to-LV ratio on [123I]MIBG correlated negatively and significantly with the mean pulmonary arterial pressure (PAm). The RV-to-LV uptake ratio on 201Tl images correlated significantly with PAm. CONCLUSION: Our results suggest that the uptake ratio of [123I]MIBG in the IVS is a useful index for evaluating the severity of pulmonary hypertension, and that chronic RV pressure overload contributes to disturbances of the cardiac sympathetic nervous system.

[Tympanic electrocochleography with disposable electrode].

Extratympanic recording of electrocochleography (ECochG) has played an important role in the differential diagnosis of inner ear diseases. We used a special electrode, which was wrapped in a cotton ball at the tip and covered with a silicon sheath over the entire length, and recorded ECochG from the tympanic membrane (tympanic ECochG). Our method was found to be more convenient and less traumatic than recording with an ear canal electrode. Tympanic ECochG records from 10 normal volunteers showed no influence of iontophoretic anesthesia on the tympanic membrane. The effects on the conductive hearing mechanism were negligible. The input-output curve of the action potential (AP) by click stimuli was fairly stable and comparable to that obtained with transtympanic recording. We performed tympanic ECochG in patients with Meniere's disease or other sensory hearing loss, and compared the amplitude ratios of the summating potential (SP) and AP (SP/AP ratio) with those in normal hearing subjects. The SP/AP ratios in patients with Meniere's disease were significantly increased, an observation consistent with the results of other studies. The SP/AP ratio was also elevated in patients with autoimmune sensory hearing loss or perilymphatic fistula. Based on the results of the present study, we speculate that it is possible to diagnose an inner ear disorder by comparing the tympanic ECochG findings with not only records from normal subjects, but also the contralateral record of tympanic ECochG from the same subject. We conclude that tympanic ECochG using disposable electrodes can provide useful information on inner ear function, because of its convenience, non invasiveness and safety in clinical use. We found tympanic ECochG to be useful in the glycerol dehydration test and for monitoring inner ear function during acoustic neurinoma surgery.

Cochlear implantation in an intralabyrinthine acoustic neuroma patient after resection of an intracanalicular tumour.

This case study describes a therapeutic strategy using a cochlear implant for a bilateral acoustic neuroma deafened patient. The cochlear nerve had previously been sacrificed on one side during tumour removal, but on the remaining side a functioning cochlear nerve was assessed by electric promontory stimulation in spite of a neuroma extending into the vestibular labyrinth. The patient was successfully stimulated with a Nucleus 22-channel implant after removal of the intracanalicular portion of the neuroma via a middle fossa approach.

[Middle ear cholesteatoma caused by cannonball foreign bodies impacted in the bony eustachian tube: a case report].

We present a 76-year-old male patient with adhesive-type cholesteatoma and with metal foreign bodies which were shown to be located in the bony eustachian tube by computed tomography. He sustained a burn injury of the left tympanic membrane when he was struck by a bomb 52 years ago, during World War II. The cannonball fragments that entered the tympanic cavity were apparently transported to and stuck in the eustachian tube isthmus by mucociliary action after spontaneous closure of the tympanic membrane perforation. Persistent tubal obstruction due to the impacted foreign bodies and surrounding granulation tissue seems to have caused chronic adhesive otitis, leading to cholesteatoma which developed in the attic and mastoid antrum. No foreign bodies became visible after cholesteatoma removal by an intact canal wall technique in conjunction with anterior tympanotomy for wide exposure of the supratubal recess and the tympanic osteum of the eustachian tube. Therefore, anterior tympanotomy was further extended anteriorly to open the enlarged bony eustachian tube, allowing visualization and safe removal of two cannonball-fragments firmly impacted within it. We call this surgical approach to the bony eustachian tube "extended anterior tympanotomy". The transmastoidal accessibility of the bony eustachian tube produced by this technique should be assessed by preoperative computed tomography.

Tl-201 SPECT in Kimura's disease involving the parotid glands and cervical nodes.

Kimura's disease is a chronic inflammatory condition producing subcutaneous tumor-like nodules, mainly in the head and neck region. Most patients have involvement of regional lymph nodes and major salivary glands. The authors present two cases of Kimura's disease with parotid gland and postauricular lymph node involvement. With Tl-201 SPECT, elevated uptake was noted on early and delayed images. Kimura's disease should be included in the differential diagnosis when increased Tl-201 uptake in head and neck mass lesions is noted.

Noninvasive assessment of right heart function by 81mKr equilibrium radionuclide ventriculography in chronic pulmonary diseases.

Noninvasive multigated equilibrium radionuclide ventriculography with krypton-81m (81mKr) was used to assess right heart relaxation in patients with chronic pulmonary diseases (CPD). The subjects consisted of 30 patients with CPD and 8 patients free of cardiopulmonary diseases admitted to our department. A region of interest (ROI) was selected on both the right atrium (RA) and right ventricle (RV). A time activity curve was obtained for each ROI. As a diastolic index of the right heart performance, the right atrial early emptying rate (RAER) was obtained from the right atrial time activity curve, while the right ventricular rapid filling rate (RVRFR) was obtained from the right ventricular time activity curve. The mean RAER was significantly lower in CPD patients compared with the control (CPD, 9.5 +/- 4.5; control, 16 +/- 3.4%/100 ms). Similarly, the mean RVRFR was significantly lower in CPD patients compared with the control (CPD, 27.3 +/- 9.9; control, 34 +/- 8.5%/100 ms). A strong negative correlation was noted between the mean pulmonary arterial pressure (mPAP) and RAER (r = -0.77; p < 0.001) and between the mPAP and the RVRFR (r = -0.63; p < 0.001). Our results suggest that RAER and RVRFR measured by 81mKr are clinically useful in the noninvasive assessment of right heart relaxation in patients with CPD.

Developmental anatomy of the supratubal recess in temporal bones from fetuses and children.

The supratubal recess (STR), located superior to the bony eustachian tube and anterior to the attic and often the site of disease, is clearly separated from the attic by the presence of a bony partition. Its anatomic development in childhood, however, remains nuclear. We reviewed serial horizontal sections of fetal and children's temporal bones from the collection of the Otopathology Laboratory, University of Minnesota. Apparently, upward expansion of the bony eustachian tube begins at a late fetal stage and continues throughout childhood, thus forming the STR. Our finding that the STR had already developed in temporal bones without pneumatization of petrous bone suggests that its formation is independent of the air-cell system. Absorption of mesenchymal tissue in the STR tends to be slower than elsewhere in the temporal bone. Surrounded solely by petrous bone, the STR seems, both developmentally and anatomically, a distinctive compartment of the middle ear.

[Hearing results after anterior tympanotomy in cholesteatoma surgery].

Between 1987 and 1993, 71 ears of attic type cholesteatoma and 20 ears of adhesive type were operated on using the intact canal wall technique combined with anterior tympanotomy. Pre- and postoperative pure tone hearing after the surgery were analyzed, especially to determine whether anterior tympanotomy is harmful to the inner ear. Mean values of 500, 1000 and 2000Hz of air conduction threshold immediately, before and about 1 year after the operation were compared. In attic cholesteatoma, type 1, type 3, and type 4 of ossiculoplasty revealed significant improvement of 8.4dB, 9.3dB, and 8.0dB respectively. In adhesive cholesteatoma, results obtained were 8.4dB, 0.8dB, and -3.0dB. Differences between pre- and postoperative bone conduction threshold at 4000Hz were 1.5dB in type 1, 1.3dB in type 3, and 5.0dB in type 4 in attic cholesteatoma. Those in adhesive cholesteatoma were -2.5dB, -0.2dB, and -10.0dB respectively. From the results obtained, we concluded that (1) our results were satisfactory with regards to hearing ability following all types of ossiculoplasty in attic cholesteatoma and in type 1 in adhesive cholesteatoma, (2) anterior tympanotomy itself is not a harmful procedure to the inner ear in both types of cholesteatoma, (3) an increase in bone threshold in adhesive cholesteatoma is due to the surgical procedure at the stapes and/or the oval window.