[OTONEUROLOGY- A MULTIFACETED FIELD].

INTRODUCTION: Otoneurology is a broad, diverse and multidisciplinary field. On the one hand, it includes everything that relates to hearing: from complex surgery including life-changing implants to effective medical treatments and habilitation. On the other hand, it includes all that has to do with balance, from novel vestibular tests to complex medical treatments and recently, the development of a vestibular implant for patients suffering from bilateral peripheral vestibular loss. This special issue on otoneurology includes 8 original papers and 3 reviews. The first three articles deal with auditory implants. The first describes a series of children who underwent auditory brainstem implantation, including the first implantation in Israel 6 years ago. The second, presents patients with acoustic schwannomas undergoing cochlear implantation and the third relates to patients with Meniere's disease. Cochlear implants are one of the most significant developments in medicine in recent decades that enable most deaf individuals to hear, and develop normal language, heavily influencing all aspects of personal development and social integration.

[AUDITORY BRAINSTEM IMPLANTS (ABI) IN CHILDREN: CASE SERIES IN SHAARE ZEDEK MEDICAL CENTER].

BACKGROUND: Cochlear implants (CI) are the treatment of choice for individuals with severe to profound sensorineural hearing loss. A small group of patients, with pathology central to the cochlea, cannot benefit from CI. Examples in children include absence of the cochlear-nerve or cochlear aplasia. In these cases, implantation of an auditory brainstem implant (ABI), directly stimulating the cochlear nucleus, bypassing the inner-ear and auditory-nerve, may be beneficial. OBJECTIVES: Describe a series of children with ABI's treated in Shaare-Zedek, including the first ABI implantation in Israel (2017). METHODS: Of 9 patients with ABI's treated in Shaare Zedek Medical Center ,7 were children implanted between ages 2-8.6 years. Five boys and two girls. Surgeries were conducted in collaboration between neurosurgeons, neurotologists and audiologists (five implanted in Shaare-Zedek and two in New-York University). Follow-up was between 2-6 years. Hearing evaluation was conducted, mainly, with audiograms, categories of auditory performance (CAP), speech perception testing when possible and estimation of device use per day. RESULTS: Six of the seven children, who initially underwent unsuccessful CI, had deficient auditory-nerves. One child had cochlear-aplasia. In 3 children hearing loss was part of the CHARGE syndrome. CAP scores ranged from 0-7 (0,1,3,5,5,7). One child was able to achieve open-set speech perception. CONCLUSIONS: Although functional auditory outcomes for children with ABI are inferior to CI recipients and are highly variable, some children were able to obtain significant benefit. In these children, who are not candidates for CI, the ABI presents the only chance for auditory awareness and may be recommended. DISCUSSION: John Thomas Roland is a consultant and recipient of research support from Cochlear Americas.

Air, bone and soft tissue excitation of the cochlea in the presence of severe impediments to ossicle and window mobility.

Clinical conditions have been described in which one of the two cochlear windows is immobile (otosclerosis) or absent (round window atresia), but nevertheless bone conduction (BC) thresholds are relatively unaffected. To clarify this apparent paradox, experimental manipulations which would severely impede several of the classical osseous mechanisms of BC were induced in fat sand rats, including discontinuity or immobilization of the ossicular chain, coupled with window fixation. Effects of these manipulations were assessed by recording auditory nerve brainstem evoked response (ABR) thresholds to stimulation by air conduction (AC), by osseous BC and by non-osseous BC (also called soft tissue conduction-STC) in which the BC bone vibrator is applied to skin sites. Following the immobilization, discontinuity and window fixation, auditory stimulation was also delivered to cerebro-spinal fluid (CSF) and to saline applied to the middle ear cavity. While the manipulations (immobilization, discontinuity, window fixation) led to an elevation of AC thresholds, nevertheless, there was no change in osseous and non-osseous BC thresholds. On the other hand, ABR could be elicited in response to fluid pressure stimulation to CSF and middle ear saline, even in the presence of the severe restriction of ossicular chain and window mobility. The results of these experiments in which osseous and non-osseous BC thresholds remained unchanged in the presence of severe restriction of the classical middle ear mechanisms and in the absence of an efficient release window, while ABR could be recorded in response to fluid pressure auditory stimulation to fluid sites, indicate that it is possible that the inner ear may be activated at low sound intensities by fast fluid pressure stimulation. At higher sound intensities, a slower passive basilar membrane traveling wave may serve to excite the inner ear.

Harmonic scalpel assisted superficial parotidectomy.

OBJECTIVE: The Harmonic Scalpel (HS) has been recently widely used to perform a variety of surgical procedures. We reviewed our experience with the use of HS in superficial parotidectomy to determine the safety and efficacy of this procedure, with regard to operative time, postoperative facial nerve function, and drainage output. STUDY DESIGN: Nonrandomized retrospective review. MATERIALS AND METHODS: The medical records of all patients who underwent superficial parotidectomy for benign pathology at Shaare Zedek Medical Center from January 2006 to July 2009 were retrospectively reviewed. Patients with prior facial nerve weakness or prior parotid surgery or who had undergone concurrent neck dissection or total parotidectomy were excluded. RESULTS: Fifty-eight patients were reviewed; 26 patients underwent HS parotidectomy and 32 patients underwent conventional (cold knife) parotidectomy (control group). Harmonic Scalpel assisted parotidectomy was associated with significantly decreased length of surgery from 163.12 ± 21.8 minutes for controls to 137.3 ± 18.6 minutes in the HS assisted group (P < .05). The incidence of temporary postoperative facial nerve paresis was significantly reduced from 43% in the controls to 23% in the HS group (P < .05). No permanent facial nerve paralysis was reported. There were differences in the overall postoperative drain output between the HS and control groups, 68 ± 22.3 mL and 73.5 ± 38.2 mL, respectively, but these differences did not achieve significance. CONCLUSION: This study shows that HS assisted superficial parotidectomy for benign pathology is a safe technique and associated with reduced surgical time and incidence of temporary postoperative facial nerve paresis compared with conventional techniques.

[Fluoroscopic assisted cochlear implantation in children with inner ear malformations].

BACKGROUND: Cochlear implants are the treatment of choice for individuals with severe to profound sensorineural hearing loss. In most cases, the anatomy is normal and the insertion of the electrode-array is straightforward, complete and in the correct position. In the presence of inner-ear malformations, the risk of an intra or extra-cochlear malpositioned electrode-array increases. OBJECTIVES: To describe the technique of fluoroscopic assisted cochlear implantation in children with severe inner-ear malformations and present the results with respect to the number of active electrodes and function. METHODS: Fifteen fluoroscopy assisted implantations in 9 children were conducted at the Shaare Zedek Cochlear Implant Center between 2009-1014. All implanted ears had severe anatomic malformations. Mean implantation age was 3.5 years (range 1-11). Six children underwent sequential bilateral implantation. Two children underwent revision surgery due to a malpositioned electrode initially implanted without fluoroscopy at other centers. RESULTS: There was no radiologic or electro-physiologic evidence of kinking, bending or electrode damage in all 15 implantations. Complete insertion was achieved in all ears except one with partial insertion. There were no extra-cochlear or intrameatal placements. In 9 ears, all electrodes were active at switch-on and in the remaining, 15-20 were active. In all ears the Ling-6 sounds were detected and in 13 they were also identified. CONCLUSION: Fluoroscopy is an effective tool in complex cochlear implant surgeries and its use is simple and safe. As demonstrated in this study, with fluoroscopy assistance, good results are achieved in children with inner-ear malformations.

Effect on auditory threshold of air and water pockets bordering the pathway between soft tissue stimulation sites and the cochlea.

OBJECTIVES: Auditory sensation can be elicited by applying a bone conduction vibrator to skin sites on the head, neck, and thorax over soft tissues. This is called soft tissue conduction (STC). We hypothesized that introducing substances with acoustic impedances that sharply deviate from those of soft tissues, such as air pockets, into the soft tissues beneath soft tissue stimulation sites would have an effect on the auditory threshold to stimulation at skin sites over soft tissue. METHODS: In human subjects, we assessed the auditory threshold with a bone vibrator applied to several STC sites, especially the cheek, and to several bone conduction sites on the skull. The subjects were equipped with bilateral earplugs. The subject then filled his or her cheek with either air or water, and the auditory threshold was again determined. We also recorded the auditory brain stem response to STC stimulation under the chin in fat sand rats in the absence and presence of subcutaneous air or saline solution pockets (0.4 mL) under the chin. RESULTS: In humans, the threshold to stimulation on the cheek was elevated (13 to 18 dB) in the presence of an air-inflated cheek, but not with a water-filled cheek. In animals, in the presence of an air pocket, the auditory brain stem response threshold was elevated by 10 to 20 dB; no threshold change occurred with a saline solution pocket. CONCLUSIONS: The introduction of air (but not water) into the soft tissues beneath the soft tissue stimulation sites led to a threshold elevation in both humans and animals. This was not the case when an identical volume of water was introduced, which would also have interrupted a possible parallel bone conduction pathway. These results provide evidence that soft tissue stimulation at low intensities induces tissue vibrations that are transmitted to the cochlea along a series of soft tissues with similar acoustic impedances.

Time from sudden sensory neural hearing loss to treatment as a prognostic factor.

Introduction: The widely accepted treatment for sudden sensorineural hearing loss (SSNHL) is corticosteroid treatment (oral or intratympanic). The main goal of this work is to define the significance of the time between symptom onset and treatment initiation, as well as other prognostic factors, for hearing improvement. Methods: This retrospective study included 666 patients treated for SSNHL. Demographic data, audiometry, treatment method, time since symptom onset, and associated symptoms were recorded for each patient. The patients were divided into five groups according to the treatment initiation time-half a week, one week, 2 weeks, 3 weeks, or 4 weeks and over-after symptom onset. The degree of improvement was assessed by comparing the audiometry at the beginning and the end of the treatment. Results: The average period of hearing loss from symptom onset to treatment initiation was 10.8 days. Significant differences were found between the groups of half a week, one week, and 2 weeks and the groups of 3 weeks and 4 weeks and over (each separately, p < 0.001). No difference was found between the half-week, one-week, and two-week groups, nor was there a difference between the three-week and four-week-and-over groups. A correlation was found between the treatment initiation time in days and the degree of improvement in hearing for both speech recognition threshold (SRT) and discrimination, R = 0.26 p < 0.001 and R = 0.17 p < 0.001, respectively. No correlation was found for gender, age of the patients, comorbidities, or associated symptoms. Conclusion: The threshold for treatment initiation time is up to 2 weeks, after which the amplitude of hearing improvement decreases significantly. The other prognostic factors measured were not found to be statistically significant predictors.

Experimental exploration of the soft tissue conduction pathway from skin stimulation site to inner ear.

OBJECTIVES: Auditory sensation can be elicited by air conduction (AC) and by bone conduction (BC). It is also possible to elicit such responses by applying the standard clinical bone vibrator to the skin over soft tissue sites on the head, neck, or thorax of humans and animals. This mode of auditory stimulation has been called soft tissue conduction (STC). This study was designed to investigate the pathway between soft tissue sites and the ear. METHODS: The air in the middle ear was replaced with saline solution in an animal with unique anatomy--the fat sand rat, in which about 70% of a thin-walled inner ear bulges into the middle ear bulla cavity--while we recorded the auditory brain stem responses (ABRs) to AC, BC, and STC stimulation. RESULTS: This replacement of air with saline solution led to a significant improvement in STC threshold. With AC stimulation, the ABR threshold was elevated and the latency of the first ABR wave was prolonged. Consistent changes were not seen with BC stimulation. CONCLUSIONS: When the air (which has a very low acoustic impedance) that normally surrounds most of the inner ear is replaced with saline solution (which has an acoustic impedance similar to that of soft tissues), the STC threshold is improved. This improvement may be due to improved transmission of acoustic energy from the soft tissues to the inner ear.

Several mechanical manipulations of the wall of the inner ear do not affect air and bone conduction auditory thresholds.

OBJECTIVES: According to classic theories, auditory stimulation, whether air- or bone-conducted, has been thought to begin with sound-induced relative motion between the cochlear shell and the stapes footplate, producing a passive mechanical traveling wave along the basilar membrane. This study was designed to assess the effect of experimental mechanical manipulations of the cochlea on the auditory thresholds to air-conducted and bone-conducted stimulation. METHODS: The left ear of Psammomys obesus (highest auditory sensitivity between 0.5 and 5.0 kHz) was initially ablated in all animals studied. After baseline recording of auditory nerve-brain stem evoked response (ABR) thresholds to air- and bone-conducted broadband click stimulation from the right ear, a hole was drilled in the vestibule of that ear in 3 animals. In 2 other animals, the round window of the animals was immobilized. In 3 additional animals, the round window was widely perforated. Repeat ABR thresholds were then determined. RESULTS: There was no change in ABR thresholds to both air- and bone-conducted stimulation following these manipulations. The ABR wave latency also did not change. CONCLUSIONS: It is likely that an alternative mode of cochlear excitation is possible.

Experimental confirmation that vibrations at soft tissue conduction sites induce hearing by way of a new mode of auditory stimulation.

BACKGROUND: A new mode of auditory stimulation has been demonstrated which is through soft tissue conduction (STC). It involves evoking auditory sensations by applying the clinical bone vibrator to the skin over soft tissue (not over bone) sites on the head and neck. METHODS: This study was designed to show that stimulation by STC excites the cochlea in a way similar to that of air conduction (AC) and bone conduction (BC). RESULTS: It is shown here that auditory nerve brainstem evoked response (ABR) thresholds in mice and in the fat sand rat to AC, to BC and to STC stimulation are all elevated following administration of drugs (salicylic acid and furosemide) which depress the cochlear amplifier. In addition, the present study brings evidence that STC stimulation is not a variant of BC since the sound pressures recorded in the occluded external auditory canal (the occlusion effect) in response to STC are significantly smaller than that to BC stimulation, though both are of equal loudness. CONCLUSIONS: This new mode, STC, therefore appears to bypass the middle ear mechanisms and consequently may contribute to auditory diagnosis.

The Effect of Soft Tissue Stimulation on Skull Vibrations and Hearing Thresholds in Humans.

HYPOTHESIS: Hearing via soft tissue stimulation involves an osseous pathway. BACKGROUND: A recent study that measured both hearing thresholds and skull vibrations found that vibratory stimulation of soft tissue led to hearing sensation that correlated with skull vibrations, supporting the hypothesis of an osseous pathway. It is possible, however, that a lower application force of the vibrator on the stimulated soft tissue would not be sufficient to elicit skull vibration suggesting hearing via a nonosseous pathway. The purpose of the present study was to confirm the osseous pathway by measuring skull vibrations and behavioral thresholds using a low application force on a layer of ultrasound gel. Gel was used to mimic soft tissue because of its similar acoustic impedance and to control for variability between participants. METHODS: Hearing thresholds and the skull vibrations of five patients who were implanted with bone-anchored implants were assessed in two conditions when the bone vibrator was applied on the forehead: 1) direct application with 5N force; 2) through a layer of ultrasound gel with minimal application force. Skull vibrations were measured in both conditions by a laser Doppler vibrometer focused on the bone-anchored implant. RESULTS: Skull vibrations were present even when minimal application force was applied on soft tissue. The difference in skull vibrations when the vibrator was directly on the forehead compared with the gel condition was consistent with the variability in hearing thresholds between the two conditions. CONCLUSION: These results reinforce the hypothesis that skull vibrations are involved in hearing when sound is transmitted via either soft tissue or bone.

Vascular Anomaly in the Fallopian Canal Encountered Unexpectedly During Cochlear Implantation.

A 68-year-old male with progressive sensorineural hearing loss underwent left cochlear implant surgery. While developing the posterior tympanotomy and identifying the facial nerve mastoid segment, gentle stimulation by the nerve stimulator resulted in unexpected profuse venous bleeding. After achieving hemostasis with Surgicel and Spongostan, the posterior tympanotomy was extended exposing a large aberrant vein running parallel to the tympanic and mastoid segments of the facial nerve in the fallopian canal. Good exposure and careful palpation of the vein assisted in ruling out facial nerve hemangioma. An intraoperative decision to proceed with implantation, taking into account limited benefit from future magnetic resonance imaging, was taken. The patient had a temporary 3-month post-operative facial nerve weakness, probably from pressure applied during hemostasis. Auditory cochlear implant function was excellent. A larger than normal diameter of the tympanic and mastoid segments of the facial nerve was seen in re-reviews of the preoperative computed tomography. We believe drawing the readers' attention to this anomaly, which to the best of our knowledge has not been previously described, can assist in the choice of preoperative imaging and increase awareness of deviation from the norm of facial nerve diameter. In addition, knowledge of possible venous anomalies may aid surgeons in such intraoperative decisions.

Furosemide administered before noise exposure can protect the ear.

OBJECTIVES: We assessed the effect of furosemide administration on noise-induced hearing loss. This drug reversibly elevates the auditory threshold by inducing a temporary reduction of the endocochlear potential and thereby suppresses the cochlear amplifier and active cochlear mechanics. METHODS: Mice were given a single injection of furosemide 30 minutes before exposure to 113 dB sound pressure level broadband noise. Control animals received saline solution. Furosemide was administered in other mice after the noise exposure. Auditory threshold shifts were assessed by recording auditory nerve brain stem evoked response (ABR) thresholds to broadband clicks. RESULTS: The mean ABR threshold in the group injected with furosemide and exposed to temporary threshold shift (TTS)-producing noise was elevated by 20.4 +/- 12.3 dB, and that in the saline control group was elevated by 35.4 +/- 18.3 dB (p < 0.02). The mean threshold elevations in the group injected with furosemide and exposed to permanent threshold shift (PTS)-producing noise and in the PTS saline control group were 15.0 +/- 10.3 dB and 27.0 +/- 12.7 dB, respectively (p < 0.01). Similar results were obtained when the PTS was assessed with an 8-kHz tone burst ABR. There was no significant difference in the PTS between mice given a single injection of furosemide and those given saline solution after the noise; this finding shows that furosemide is not acting as an antioxidant. CONCLUSIONS: It appears that reversible hearing threshold elevation as a result of furosemide administration before noise exposure can reduce the TTS and PTS. This finding provides insight into the mechanism of noise-induced hearing loss.

Shifting trends: mastoiditis from a surgical to a medical disease.

OBJECTIVE: The aim of this study is to review the outcome of pediatric patients suffering from acute mastoiditis treated conservatively and to correlate this to the evolution of our understanding of the shift in which mastoiditis has been transformed from a surgical to a medial disease. METHODS: We performed a retrospective review patient files hospitalized in our tertiary-care center between 2005-2008. We examined the data concerning the infection which included: presenting signs/symptoms, prior otologic history, treatment (including both surgical and conservative) prior to hospitalization and during hospitalization, computed tomography (CT), hospital duration, complications and overall outcome. This data was analyzed and compared between different patients who underwent different treatment strategies. RESULTS: Fifty-one patients were included in this retrospective review. Initially, forty-nine patients admitted to our hospital were treated conservatively. This treatment included intra-venous antibiotics, myringtomy and if needed subperiosteal abscess incision and drainage. Only 2 patients underwent CT scanning on admission. Further on, during hospitalization 4 additional patients underwent CT scanning due to continued fever or progression of local disease. All four CT scans showed no intra-cerebral complications, and so all continued with conservative treatment. CONCLUSION: Most cases of acute mastoidits may be treated with a conservative therapy regime. This regime, in our opinion, should include three branches: the first intravenous antibiotic therapy using a broad spectrum antibiotic. The second is myringotomy and the third branch is incision and drainage of subperiosteal abscess when needed.

Implications from cochlear implant insertion for cochlear mechanics.

It is usually thought that the displacements of the two inner ear windows induced by sound stimuli lead to pressure differences across the basilar membrane and to a passive mechanical traveling wave progressing along the membrane. However, opening a hole in the sealed inner ear wall in experimental animals is surprisingly not accompanied by auditory threshold elevations. It has also been shown that even in patients undergoing cochlear implantation, elevation of threshold to low-frequency acoustic stimulation is often not seen accompanying the making of a hole in the wall of the cochlea for insertion of the implant. Such threshold elevations would be expected to result from opening the cochlea, reducing cochlear impedance, altering hydrodynamics. These considerations can be taken as additional evidence that it may not be the passive basilar membrane traveling wave which elicits hearing at low sound intensities, but rather factors connected with cochlear fluid pressures and fluid mechanics.

Is it Beneficial to Treat Patients Presenting Three Weeks or Longer after the Onset of Sudden Sensorineural Hearing Loss?

OBJECTIVES: The accepted treatment for idiopathic sudden sensorineural hearing loss (ISSNHL) consists of oral or intratympanic steroids. The time from onset to treatment is considered as an important prognostic factor, although there is no clear cutoff point when treatment is no longer beneficial. This study aimed to assess the efficacy of treatment with oral or intratympanic steroids and carbogen, in patients presenting 21 days or later after the onset of hearing loss. MATERIALS AND METHODS: A total of 895 patients with ISSNHL was seen in our center between 2010 and 2018. The study cohort included 103 patients treated with oral or intratympanic steroids or both with carbogen 21 days or longer after experiencing hearing loss. Retrospective analysis of files and audiometry was conducted, and pre- and post-treatment audiograms were compared. Improvement was defined by SRT (≥15 dB improvement), discrimination (≥15% improvement), or 15 dB improvement at specific frequencies (250-500, 4000-6000 Hz). RESULTS: Hearing improvement, according to the study definition, was seen in 22.3% (23/103) of patients within the time period of the treatment. All the 23 patients had functional hearing after treatment and 16 of them returned to their baseline or normal hearing. While the time from onset of ISSNHL to treatment varied, most patients demonstrating improvement were treated 21-30 days after onset. CONCLUSION: In this patient cohort treated late for sudden sensorineural hearing loss (SSNHL), a small but significant number of patients improved during the time of treatment. Although the lack of a control group makes it difficult to prove that the improvement resulted from the treatment, we recommend not to rule out treatment systematically in patients presenting late after ISSNHL. Additional prospective studies are warranted.

Revision cochlear implantation using a double array device in the post-meningitis ossified cochlea.

PURPOSE: To describe the surgical technique and outcome in a series of patients who underwent revision cochlear implantation using a double array or split electrode device. All patients developed ossified cochleae due to meningitis and were functioning poorly with the previous implant. METHODS: Four patients between the ages of 4-15 years underwent revision with five double-array cochlear implant devices. One patient underwent bilateral revision surgery. All patients had previous meningitis with CT and MRI imaging studies that demonstrated completely ossified cochleae. The time interval range between the disease and the initial cochlear implantation and was 4 months to 3 years. The patient's data were retrospectively analyzed with emphasis on the surgical technique, the number of electrodes inserted, and the number of active electrodes at follow-up. In addition, pre and post-revision surgery function was compared. RESULTS: The revision surgery was carried out 2-11 years after the initial surgery. Two tunnels, basal and apical, were drilled in the ossified cochlea. In each of the tunnels, 5 to 11 electrodes were inserted. While the number of active electrodes before revision was 0-5, after revision with the double array, it was increased to 8-12, resulting in improved auditory and speech function. CONCLUSION: Revision cochlear implantation with a double array implant using the two tunnel technique can increase the number of active electrodes. This leads to a better outcome in post-meningitis children with completely ossified cochleae and a poor functioning previous device.

Listening in Noise Remains a Significant Challenge for Cochlear Implant Users: Evidence from Early Deafened and Those with Progressive Hearing Loss Compared to Peers with Normal Hearing.

Cochlear implants (CIs) are the state-of-the-art therapy for individuals with severe to profound hearing loss, providing them with good functional hearing. Nevertheless, speech understanding in background noise remains a significant challenge. The purposes of this study were to: (1) conduct a novel within-study comparison of speech-in-noise performance across ages in different populations of CI and normal hearing (NH) listeners using an adaptive sentence-in-noise test, and (2) examine the relative contribution of sensory information and cognitive-linguistic factors to performance. Forty CI users (mean age 20 years) were divided into "early-implanted" <4 years (n = 16) and "late-implanted" >6 years (n = 11), all prelingually deafened, and "progressively deafened" (n = 13). The control group comprised 136 NH subjects (80 children, 56 adults). Testing included the Hebrew Matrix test, word recognition in quiet, and linguistic and cognitive tests. Results show poorer performance in noise for CI users across populations and ages compared to NH peers, and age at implantation and word recognition in quiet were found to be contributing factors. For those recognizing 50% or more of the words in quiet (n = 27), non-verbal intelligence and receptive vocabulary explained 63% of the variance in noise. This information helps delineate the relative contribution of top-down and bottom-up skills for speech recognition in noise and can help set expectations in CI counseling.

Acute mastoiditis in children: is computed tomography always necessary?

OBJECTIVES: Acute mastoiditis (AM) is the most common intratemporal complication of acute otitis media in children. In the past decade, reports have indicated a rise in the incidence of AM in the pediatric population. A parallel rise in the use of computed tomography (CT) imaging has occurred. The rise in the use of CT scanning in the pediatric population, entraining with it a rise in pediatric brain irradiation, has led us to question the necessity of using CT for pediatric patients with AM. METHODS: We reviewed the medical files of pediatric patients who had AM in the years 2005 through 2007. RESULTS: Fifty patients were identified. The gender distribution was equal, and the ages ranged from 4 months to 12 years. Of the 46 patients who were admitted to our institution "de novo," only 2 underwent CT scanning on admission, and 4 other patients had CT performed during hospitalization. The majority of patients (92%) with AM did not have a CT scan performed and were treated conservatively with no complications. CONCLUSIONS: In most pediatric patients, CT does not seem to be indispensable in the diagnosis of AM. Conservative therapy and close follow-up seem to suffice for most.

Occluding the round window causes no change in threshold, but an increase in hearing loss following noise exposure.

AIM: To assess the effects of occluding the round window on the degree of hearing loss following exposure to broad band noise. DESIGN: Following opening of the middle ear bulla in both ears of ten sand rats, auditory nerve-brainstem evoked response (ABR) thresholds were determined in each ear separately using an insert earphone. The round window of one ear was then occluded with super-glue. The opposite ear was sham-operated. ABR thresholds were again assessed immediately. The animals were then exposed to 113 dB SPL broad band noise for 12 hours. 24 hours after the round window was occluded, which was 8-10 hours after the end of the noise exposure, ABR thresholds were again determined in each ear. In four control animals, the round window was blocked, but they were not exposed to noise. RESULTS: Following the noise exposure, the mean ABR threshold elevation in the round window blocked ears (54.5 +/- 5.5 dB) was significantly (p < 0.004) greater than that in the sham-operated ear (40.5 +/- 8.6 dB). In the four control ears, there was no change in ABR threshold 24 hours after the round window was occluded. CONCLUSION: Occluding the round window was not accompanied by a threshold elevation, but following noise exposure, the noise induced hearing loss was increased, probably by reducing the efficacy of an inherent protective mechanical mechanism.