Manabu Maeta

Evaluation of facial palsy by moiré topography index.

We investigated the usefulness of moiré topography for evaluating facial nerve function in 51 patients with facial palsy and 10 normal volunteers. This method visualizes the shape of objects in three dimensions. We devised three moiré indexes as a simple method of quantifying the severity of facial palsy: the nasolabial groove moiré index, the oral angle moiré index, and the inner canthus moiré index. We compared the results obtained by the moiré indexes with findings obtained using the House-Brackmann grading system and found that they were highly correlated. These three moiré indexes included all the standard factors of the House-Brackmann grading system, allowing us to develop the total moiré index.

Quantification of TECTA and DFNA5 expression in the developing mouse cochlea.

TECTA and DFNA5 are the mouse orthologues of the human deafness-associated genes TECTA and DFNA5. To determine how expression of these genes is regulated during development, relative mRNA abundance was examined in mice by non-radioactive RT-PCR. TECTA mRNA was detected on embryonic day 15 (E15), increased to its highest level on postnatal day 3 (P3) and then dramatically decreased by P15. Low levels persisted (adulthood, P45 to 67) with mean mRNA abundance after P15 less than 25% of P3 levels. DFNA5 mRNA expression was constant throughout these time points. These results imply that TECTA is transcribed at a particularly high level during tectorial membrane morphogenesis. In contrast, DFNA5 is present in both the developing and mature cochlea.

False-positive magnetic resonance image in the diagnosis of small acoustic neuroma

A patient presented with sudden hearing loss on her first visit to our department. Gadolinium-DTPA-enhanced magnetic resonance imaging (MRI) of the posterior cranial fossa portrayed an intracanalicular tumour image (2-3 mm), and the pure tone average (PTA) and speech discrimination score (SDS) values were 65 dB and 60 per cent, respectively. Surgical intervention to remove the suspected tumour was scheduled by the translabyrinthine approach. Intracanalicular observations by the retrolabyrinthine approach revealed limited oedema on the inferior vestibular nerve with vascular dilation. The tumour image disappeared two years after the operation. Surgical findings and the post-operative course advocate that gadolinium-DTPA-enriched MRI image of an intracanalicular lesion such as arachnoiditis might produce a false-positive result.

Evaluation of facial palsy by Moiré topography.

To evalute facial nerve function, several visual assessment methods have proposed by May, Yanagihara, Stennert, House, Brackman, among others, and the score method is widely accepted as a simple and useful method for examination to evaluate roughly the degree of facial palsy. However, it is difficult to capture fine changes with the score method when precise evaluation is required, and it is limited as a form of objective and reporducible assessment. Therefore, it is not a very suitable method to follow up the process of the recovery in facial nerve palsy.

Protective effect of brain-derived neurotrophic factor against the ototoxicity of Pseudomonas aeruginosa exotoxin A.

Objective--The protective effect of brain-derived neurotrophic factor (BDNF) against the ototoxicity resulting from exposure of Pseudomonas aeruginosa exotoxin A (PaExoA) to the middle ear was analyzed. The combined effect of BDNF and NG-nitro-L-arginine methyl ester (L-NAME) was also investigated. Material and methods--Six groups of albino rats were instilled through the tympanic membrane into the round window niche with the following solutions: saline; PaExoA; BDNF; L-NAME; PaExoA + BDNF; and PaExoA + BDNF + L-NAME. Frequency-specific (2-31.5 kHz) auditory brainstem responses were used to obtain the hearing thresholds before and 2, 5 and 15 days after instillation. Results--PaExoA penetrated from the middle ear into the cochlea, causing initially mixed hearing loss, followed by persistent sensorineural hearing loss. This impairment was blocked by BDNF at 6, 8 and 10 kHz on Day 2 and at 8 kHz on Day 5. L-NAME given in combination with BDNF did not show any additional protective effect. There were no significant differences in the thickness of the round window membrane between control ears and those in each instillation group. Conclusion--Our results suggest that BDNF may protect against cochlear damage caused by PaExoA in the middle turns of the ear.

Surgical intervention in middle-ear cholesterol granuloma

Eleven patients who had been surgically treated from 1988 to 1999 were retrospectively reviewed in order to evaluate the efficacy of ventilation tube insertion and mastoidectomy with, or without, mastoid obliteration for intractable middle-ear cholesterol granuloma. The mean age registered was 17.2 years at the time of surgical treatment. All cases were unilaterally affected. Five ears were treated with simple mastoidectomy coupled with the insertion of a ventilation tube, while six others had additional mastoid obliteration. The hearing prognosis was excellent with an improved post-operative hearing level of 16.5 dB (cf. pre-operative 37.7 dB). However, morphological prognosis revealed two ears had a residual perforated tympanic membrane without otorrhoea after displacement of the ventilation tube. Of the remaining nine ears with intact placement of the ventilation tube, five had dry ears while four had occasional otorrhoea. Although the morphological prognosis was incomplete, treatments involving at least an insertion of a ventilation tube with thorough mastoidectomy were thought to be necessary.

Visualization of Human Vestibular Aqueduct with Computeraided Serial Section Reconstruction System

The computer-aided serial section reconstruction system (SERSERS) was employed to elucidate the entire configuration of the vestibular aqueduct in the human temporal bone. The advantages and the disadvantages of this system are discussed in comparison with several conventional methods such as X-ray visualization, plastic casting and graphic reconstruction. In spite of some limitations encountered, such as difficulty in placing a marker on each section or time consumption in data input, SERSERS can be useful in the study of the vestibular aqueduct, since a three-dimensional structure which can be observed from multidirectional aspects is reconstructed.

The potential of a plastination specimen for temporal bone surgery.

OBJECTIVE The benefits of plastination specimens in temporal bone surgery (TBS) were evaluated. METHODS A formalin-preserved human temporal bone was drilled and dissected with the middle cranial fossa approach or the translabyrinthine (or transcochlear) approach. The specimen was thereafter subjected to silicon impregnation. RESULTS The flexibility of the dura mater after plastination was maintained, and not only bony structures such as the auditory ossicles and semicircular canals but also soft tissues such as the facial nerve, internal carotid artery and the sinus attached to the dura mater were easily discriminated. CONCLUSION The technique furnishes a persistently dry, odorless and durable specimen that allows handling and may serve as the most ideal specimen for anatomical learning of various approaches of TBS.

Dynamic observation of facial movements by moire topography video

The moire topography video visualizes the facial movement dynamically in three dimensions. By using the digital video, we analyze facial movements in expression more precisely, because we can handle dynamic images as the series of static images with time axis. This technique reveals several special features on the facial expression.

Dynamic evaluation of facial palsy by moire topography video: second report

By using moire topography video, the feature of facial expression can be well analyzed. The dynamic change of moire strips pattern enables the observation of facial movement in three dimensions and contributes to the better evaluation of patients with facial palsy. Using this method, several special features on the facial expression of patients with facial palsy were demonstrated.