Hisashi Kohno

A new tool for testing ossicular mobility during middle ear surgery: preliminary report of four cases.

Objective: We developed an ossicular vibration tester for the objective and quantitative assessment of ossicular mobility, which is one of the most critical factors affecting postoperative hearing after tympanoplasty. Methods: Our device consists of three components: a probe shaft with a curved tip to be attached to the target ossicle, a vibration exciter to activate the probe, and a piezoelectric sensor to detect vibrations of the probe. These components are encased in a stainless steel holder, allowing easy hand manipulation during ear surgery. The probe is activated with an electric signal at around 1,600 Hz. The system is controlled with a laptop computer, and the results are presented as the ratio of the ossicular resistance (ROR) to a reference value as a percentage. One measurement takes 10 ms. The device was applied in four selected patients during ear surgery. Results: Several measurements in two of the cochlear implantees showed a greater difference in the RORs of the stapes (15-20% in Case 1 and 35-45% in Case 2), whereas the RORs of the malleus and incus were within the same range. This was thought to correspond to the partial cochlear calcification noted in Case 2. In Case 3, who underwent surgery because of otosclerosis, the ROR of the stapes was high, ranging from 70 to 80%. When measured for the malleus-incus fixation anomaly (Case 4), the ROR of the malleus and incus was in the range of 60 to 70%. Owing to the limited surgical view, the ROR of the stapes could not be measured. No problems related to the measurements with this device were noted. Conclusion: The design, principles, measuring procedures, and preliminary results of our new tool for testing ossicular mobility are reported. Measuring the ossicular mobility during surgery may provide important information for deciding the surgical procedures.

Pathogenesis of facial nerve synkinesis in guinea pig

Abstract Problem: The facial nerve synkinesis is one of the common complaints after facial palsy. However, the precise mechanism of synkinesis is still unknown. In this study we tried to establish an animal model of synkinesis. Methods: Extratemporal portion of the facial nerve (group 1, n = 6) and the intratemporal portion (group 2, n = 6) were compressed by using a micro needle holder. After the compression, the grade of facial nerve injury was evaluated by electroneurography. The existence of synkinesis was judged by the presence of R1 in the orbicularis oris muscle by the electrophysiolgical blink reflex. For evaluating the misdirection of nerve fibers, double labeling was performed by injecting retrograde fluorescence tracer in the orbicularis oculi muscle and the orbicularis oris muscle, and then facial nucleus was investigated for the presence of the neurons with aberrant fluorescence. Results: In both groups, all animals showed the ENoG threshold under 10%. In group 1, none of animals developed synkinesis. On the other hand, in group 2, all animal developed synkinesis. Furthermore, disrupted neurons in the facial nucleus, representing the existence of misdirection, were observed in all animals of group 2. Conclusion: In this study we succeeded in making a synkinesis model only in group 2 and reported the existence of misdirection in these animals. Sunderland found that the facial nerve consisted of a single bundle in the intratemporal portion, even though it had a mulitifuniculated plexiform structure in the extratemporal portion. Because of this anatomical feature, when the facial nerve was injured in the intra- and extra-temporal portions, the misdirection may occur only in the intra-temporal portion. This is thought as a reason for the appearance of synkinesis only in group 2. Significance: It is important to know the pathogenesis of synkinesis for diagnosing and treating facial nerve disorders. Support: None reported.

Origin Unknown Neck Lymphnode Metastasis, after Six Years, That Primary Site was Considered Maxillary Sinus.

A rare case of unknown origin neck metastasis is reported, in which the primary site was revealed to be the maxillary sinus six years later.A 18-year-old man was admitted to our hospital with a right cervical mass in 1993.The histological diagnosis was metastatic squamous cell carcinoma. Further examinations including the paranasal sinus did not reveal the primary lesion. After preoperative irradiation including the epipharynx, right neck dissection was performed with postoperative adjuvant chemotherapy.Four years after first admission the patient exhibited left cervical lymphadenopathy. Left neck dissection was carried out but the primary site was still unknown.Two years after the second surgery the patient exhibited right nasal obstruction and rhinorrhea, and CT scan revealed right maxillary tumor. Total maxillectomy was performed after preoperative radiation therapy and the patient has shown an uneventful good clinical course to date.In conclusion, in cases of unknown origin neck lymphnode metastasis it may be important to examine the paranasal sinus.