Takuji Okitsu

MR imaging findings of parotid tumors with pathologic diagnostic clues:A pictorial essay

This pictorial essay depicts MR features of benign and malignant parotid tumors. Increased T2 signal intensity is suggestive of pleomorphic adenoma. Tumors with relatively low signal intensity on T2-weighted images are more likely to be malignant even when they are well-demarcated. Fat suppression technique improves the ability to define the boundaries of neoplatic or inflammatory lesions.

Positive intratympanic pressure in the morning and its etiology.

Intratympanic pressures were measured by tympanometer in forty ears free from disease. In the recumbent position, the first tympanogram was obtained in the morning at awakening, before swallowing. The second pressure measurement was performed in the upright position after swallowing and chewing. Twenty-two ears showed positive pressure in the middle ear before swallowing and decreased pressure after swallowing. The present results revealed no evidence of continuous gas absorption from the middle ear during sleep. The other experiment demonstrated that raising of the PCO2 level by hypoventilation increased the pressure in the middle ear. The results suggested indirectly a diffusion of carbon dioxide to the middle ear cavity from its surrounding tissue. The intratympanic pressure seems limited in part to the partial pressure gradient of gases between the middle ear cavity and its surrounding tissue when ventilation through the Eustachian tube is impaired.

Forward-backward tracing tympanometry

Two tympanograms were routinely recorded from each ear by altering the pressure in the external auditory meatus (EAM), first in the decreasing direction (Forward Tracing: TG-F) and next in the increasing direction (Backward Tracing: TG-B). In a normal ear the TG-F peak tended to be in the negative pressure area and that of the TG-B in the positive area. When the middle ear pressure was adjusted to the atmospheric pressure in a model, the TG-F peak always indicated a negative pressure and that of TG-B always showed a positive pressure value. As long as the same model was used, the magnitude of the difference of the two peaks was identical irrespective of the middle ear pressure, but it was influenced by the speed of EAM pressure change, and a linear increase was observed up to the speed of 70 mmH2O/s, both in the normal ear and in the model. In ears with pathology, considerable variation was noted in the magnitude of the peak shift. These findings seem to suggest that the peak location of a unidirectionally drawn tympanogram cannot be regarded as indicating the precise middle ear pressure. The middle ear pressure can be estimated more accurately by averaging the peak pressures of TG-F and TG-B of Forward-Backward Tracing Tympanogram.

Prevalence of acoustic neuroma associated with each configuration of pure tone audiogram in patients with asymmetric sensorineural hearing loss.

Objectives The criteria have not yet been established for identifying the configuration of a pure tone audiogram constituting abnormal results that warrant further investigation. The purpose of this study was to determine the prevalence of acoustic neuroma associated with each configuration of the pure tone audiogram in patients with asymmetric sensorineural hearing loss (SNHL). Methods We performed a retrospective chart review of 500 patients 15 years of age or older who had asymmetric SNHL and had undergone magnetic resonance imaging. Results The prevalence of acoustic neuroma in these patients was 2.6% (13 of 500). The prevalence of acoustic neuroma in each audiometric configuration was as follows: 7.1% (3 of 42) for a basin-shaped loss (odds ratio [OR] versus overall prevalence, 2.88; p =0.23; 95% confidence interval [CI], 0.79 to 10.54),4.7% (5 of 107) for a flat loss, 3.4% (2 of 58) for total deafness, 2.9% (l of 34) for a high-frequency sloping audiogram, and 2.5% (2 of 81) for a high-frequency steep audiogram. The prevalence in patients with nonimproving idiopathic sudden deafness was 8.1% (OR, 3.29; p = 0.06; 95% CI, 1.13 to 9.55). Conclusions In conclusion, 2.9% to 8.1% of patients with a characteristic configuration of the pure tone audiogram and symptoms of nonimproving or progressive idiopathic sudden deafness may have acoustic neuroma.

ABR Audiometry in the Diagnosis of Cerebellopontine Angle Tumors

Auditory brain-stem responses (ABR) examination with simultaneous lobe-vertex (L-V) and membrane-vertex cm-v) recording was performed in 34 ears with cerebellopontine angle tumors. The detectability of wave I was better in M-V recording than in L-V recording, whereas L-V recording exhibited better detectability of wave V. ABR waveforms were classified into three groups, and the relations between the waveforms and the size of tumor or the degree of hearing loss were analyzed. Positive finding in ABR were obtained in 25 out of 34 ears in the present study. It was stressed that this dual recording in ABR was extremely useful in the diagnosis of cerebellopontine angle tumors.

Middle ear inflation as a treatment for secretory otitis media in children

Clinical evaluations of middle ear inflation for secretory otitis media (SOM) were performed with special emphasis on the influence of seasonal and aging factors. One hundred and forty-nine children between the ages of 3 and 9 years (227 ears) were all diagnosed as SOM by pneumatic-otoscopic findings, and type B tympanogram (TG) at 3 weeks or more after the onset of acute SOM or the initial observation of SOM. Middle ears were inflated by Politzers method or by our modified method once or twice each week for 2 months. After inflation, TG displayed two different time sequences: one group changed to the A or C type immediately after inflating the ear one or more times, but usually returned gradually to the B type (TG-improved group): and the other group remained without any changes (TG-unchanged group) for the duration of this study. The healing rate in the TG-improved group was significantly higher than in the TG-unchanged group at the 2-month endpoint. The cure rate of SOM was significantly higher in spring than in autumn in the TG-unchanged group but not in the TG-improved group. There were almost no differences between the healing rates in the 3-5 and 6-9 year-old children. When a TG-unchanged ear is found in autumn during the 2-month inflation treatment, more careful and forcible treatments should be introduced later, especially to children between the ages of 3 and 9 years.

Study of a simultaneous lobe-vertex and membrane-vertex recording technique in auditory brainstem response.

The study of a simultaneous lobe-vertex and membrane-vertex recording in auditory brainstem response was performed in normal adults and in patients suffering from brainstem disorders. It was demonstrated that in normal subjects the detectability of waves I and V depends on the site of the recording electrodes and there is no statistical difference between the two recording methods in the latencies of the two waves. We reported 3 typical cases that illustrate the value of this recording method in the detection of the cochlear nerve or the brainstem disorders.

Auditory evoked magnetic fields in children with functional hearing loss

OBJECTIVES Abnormal cortical responses in patients with functional hearing loss were evaluated by magnetoencephalography, which can better separate bihemispherical activity than electroencephalography. METHODS Auditory evoked fields in response to 1 kHz or 2 kHz tone bursts at 80 dB sound pressure level were measured by a helmet-shaped magnetoencephalography system in 22 patients with functional hearing loss (18 females, mean age 13.2 years) as well as 5 control subjects under 10 years old. Waveform, latency, and equivalent current dipole of N100m responses were used to evaluate activity in the bilateral auditory cortices. RESULTS Abnormal N100m of the contralateral response to the stimulated ear, either absence or delayed latency in comparison to normal adult subjects, was found in 6 of the 7 patients with functional hearing loss aged 9 years or younger, but in only 3 of the 15 patients aged 10 years or older. However, such abnormalities were also observed in younger control subjects. CONCLUSION Auditory evoked field may be applied to objectively evaluate cortical auditory function in patients with functional hearing loss, but the normal findings for young children have not yet been established.

Investigation of Three-Dimensional CT Images in Facial Bone Fractures.

Recently, excellent three-dimensional (3-D) images can be quickly and easily obtained using helical scan CT, a procedure of continuous scanning CT to acquire volume data. 3-D CT imaging was applied to 66 surgical cases of facial fractures and it was helpful not only to evaluate facial fractures, but also to plan operations except for in cases of blowout fractures.The quality of 3-D CT image depended on the slice thickness and on the slice interval at CT scanning, and we also found that the threshold value of CT number at which 3-D images were reconstructed influenced the quality of the 3-D imaging.However, 3-D imaging does not necessarily provide additional new information if two-dimensional (2-D) CT scans have been performed, and 2-D CT images also provide superior fracture details. Thus, based on our clinical experiences we suggest that 2-D CT image and 3-D image reconstructions are complementary procedures.

Effect of oxygen-flooding to the round window membrane on the inner ear function of the anoxic cochlea.

The effect of pure oxygen-flooding towards the round window membrane of the anoxic cochlea was studied in guinea pigs, with the CM and EP as indicators of inner ear function. No recovery was observed in the CM or EP recorded from either the first or second cochlear turns.This study indicates that oxygen-flooding towards the round window membrane is far from effective in maintaining the cochlear function of animals with systemic ischemia.The usefulness of this technique in the treatment of sudden deafness is discussed.