Is the presence of transient evoked otoacoustic emmissions in ears with acoustic neuroma significant?

One hundred sixty-eight patients admitted for acoustic neuroma removal were involved in this study. In all cases, the size of the tumor and the presence or absence of tinnitus and vertigo or dizziness were evaluated. Investigated functional procedures included bilateral measures of pure-tone audiometry (PTA), auditory brainstem response (ABR), electronystagmography (ENG), and transient evoked otoacoustic emissions (TEOAEs). Thirty-five patients (21%) had normal preoperative TEOAEs in the affected ear, whereas 133 patients (79%) failed to show reproducible responses. The aims of this study were 1. to evaluate what distinguishes patients with preoperative TEOAEs in the pathological ear (group A) from those who had no TEOAE (group B); and 2. to determine in cases of attempted hearing preservation whether preoperative TEOAE presence in the neuroma ear (group C) was predictive of postoperative hearing preservation compared with the group of patients without TEOAEs (group D). The presence of vertigo or dizziness was significantly less frequent, the age was lower, and preoperative mean PTA loss in both ears was lower in group A compared with group B. Frequency of the other studied parameters and ABR threshold were similar in both groups. When hearing preservation was attempted, the mean preoperative PTA loss of group C patients was lower in both ears compared with group D. However, postoperative mean PTA loss did not significantly differ in the two groups. In group C, the percentage of hearing preservation (66.6%) was significantly higher than the percentage of deafness (33.4%), whereas in group D the percentage of postoperative preserved audition and deafness did not significantly differ (respectively 44.4% and 55.6%). The findings suggest that 1. TEOAEs in ears with acoustic neuromas are found in younger patients with a lower preoperative mean PTA loss and are accompanied by fewer functional complaints, perhaps because preserved TEOAEs indicate a better preservation of inner ear vasculature; and, 2. along with radiological and electrophysiological investigations, TEOAE presence in the pathological ear could provide an additional criterion or predictive factor for the successful outcome of attempted hearing-conservation surgery in ears with acoustic neuromas.

Myogenic vestibular-evoked potentials in normal subjects: a comparison between responses obtained from sternomastoid and trapezius muscles.

Brief intense clicks cause short latency microcontraction of cervical muscles. Several studies have supported the hypothesis that these microcontractions are of vestibular origin. Averaging these muscular responses enables us to obtain myogenic vestibular evoked potential (MVEP). The receptor of these responses is thought to be the saccule, afferent pathways being the vestibular nerve and efferent pathways the vestibulospinal tract. However, discrepancies are reported with regard to results obtained in healthy subjects: some authors obtained symmetrical response to monaural clicks whereas others obtained responses of greater amplitude on the muscle ispilateral to stimulation. These discrepancies may be due to the presence of different recording sites (inion, sternomastoid or trapezius muscles). The aim of this study was to clarify MVEP results in healthy subjects, using a simple non-traumatic method, and to compare the results obtained on sternomastoid (SM) and trapezius muscles (TRP). Sixteen normal hearing healthy subjects were involved. Latencies and amplitude of both SM and TRP muscle were reproducible in the same subject. Patterns of response were similar to those obtained in previous studies. Following binaural and monaural stimulations, latencies of MVEP were symmetrical on both muscles and amplitudes tended to be greater on muscles contralateral to stimulation, which conflicts with previous results in the literature. Whatever the type of stimulation, latencies of responses obtained on SM were significantly shorter (mean = -3.8 ms), and amplitudes lower (mean = -7.1 microV), than those obtained on TRP. Binaural stimulation resulted in responses of greater amplitude compared to monaural (mean = 0.45 microV). Given the intrasubject reproducibility of the responses, these methods allow MEVP to be recorded in a standardized and reproducible way.

Transient evoked otoacoustic emissions in nonsurgical ear.

Several studies have reported contralateral hearing deficits following ear surgery. This study aimed to evaluate changes in micromechanical cochlear properties which could occur in the contralateral ear following ear surgery, using transient evoked otoacoustic emission (TEOAE) recording. Surgery involved tympanic membrane surgery in 13 cases and middle ear surgery in 16 cases. TEOAEs were recorded and compared for contralateral ears before (day 1: D1) and after (day 2: D2) ear surgery. Two patients failed to show a TEOAE reproductibility > 75%, and were excluded from the study, thus reducing the number of patients to 27. Results were compared to those of a control group of 12 normal hearing subjects, recorded in similar conditions also on day one (D1) and day two (D2). The difference between D1 and D2 was not significant in either group. Pre/postsurgery variations in TEOAE amplitude for the patient group were negatively and significantly correlated with the corresponding preoperative levels in that the greater the presurgical TEOAE level, the larger the decrease in postoperative level. Compared to the variation confidence intervals in the control group, TEOAE amplitude remained stable in 15 patients, increased in four and decreased in eight. These three groups of patients differed only regarding preoperative TEOAE amplitude values, which were significantly greater in the group which presented a decrease in TEOAE amplitude than in the others. Increase in TEOAE amplitude was more frequent after tympanic membrane surgery. On the other hand, TEOAE amplitude decrease was more frequent after middle ear surgery, and is significant compared to the tympanic membrane surgery results. The results show that cochlear micromechanical properties may be reduced in the ear contralateral to surgery and that this decrease depends on the severity of the surgical procedures in the operated ear, such as drilling or opening of the oval window.

[Malignant external otitis. Apropos of 7 recent cases]. / Les otites malignes externes. A propos de sept cas récents.

Seven recent malignant external otitis are described. The authors report criteria of both etiology, bacteriologic, radionuclide scanning computed tomography. Now, for the positive diagnosis, the radionuclide scanning is essential. The computed tomographic scan provided the best anatomic imaging of the infection process. The treatment of choice is systemic antibiotic therapy as fluoroquinolones antibiotic. This antibiotic is active against P. Aeruginosa and has an excellent bone penetration. Only one patient died and another suffered from osteomyelitis of the base of the skull. The radionuclide scanning is very important for criteria of healing, particularly about stoppage of systemic antibiotic therapy.