Achieving Mild Therapeutic Hypothermia in the Human Cochlea.

OBJECTIVE: To determine temperature and duration of cooling necessary for achieving cochlear mild therapeutic hypothermia (MTH) via ear canal cooling using cool water and earmold attached to a Peltier device. STUDY DESIGN AND SETTING: Human temporal bone lab study performed at the University of Mississippi Medical Center. INTERVENTIONS: Cochlear cooling via the ear canal using water irrigation and an earmold attached to a Peltier device. Temperature analysis through implanted thermal probes within the cochlea. MAIN OUTCOME MEASURES: Temperature changes in the cochlea. RESULTS: Irrigation of the ear canal with water resulted in achieving MTH in approximately 4 minutes using cool water (30°C) and in approximately 2 minutes using ice-chilled water. After 20 minutes, irrigation of the ear canal using cool water plateaued at a ∆2°C while cooling with ice-chilled water results in an average ∆4.5°C. We observed MTH using a medium-length earmold attached to a Peltier device after approximately 22 minutes of cooling and achieved a maximal average ∆ of 2.3°C after 60 minutes of cooling. Finally, we observed that a longer earmold (C2L) with greater proximity to the eardrum resulted in more efficient intracochlear temperature change, achieving MTH in approximately 16 minutes. CONCLUSIONS: MTH of the cochlea can be achieved with water-based ear canal irrigation and via a Peltier device connected to an aluminum earmold.

Otologic and Audiologic Considerations for COVID-19.

The COVID-19 pandemic has created a number of considerations for otolaryngology; anosmia and ageusia in particular have gained significant attention. Here we present considerations in regard to treatment with quinine-derived drugs and the influence of masks on communication.

The Cervical Vestibular-Evoked Myogenic Potentials (cVEMPs) Recorded Along the Sternocleidomastoid Muscles During Head Rotation and Flexion in Normal Human Subjects.

Tone burst-evoked myogenic potentials recorded from tonically contracted sternocleidomastoid muscles (SCM) (cervical VEMP or cVEMP) are widely used to assess the vestibular function. Since the cVEMP response is mediated by the vestibulo-collic reflex (VCR) pathways, it is important to understand how the cVEMPs are determined by factors related to either the sensory components (vestibular end organs) or the motor components (SCM) of the VCR pathways. Compared to the numerous studies that have investigated effects of sound parameters on the cVEMPs, there are few studies that have examined effects of SCM-related factors on the cVEMPs. The goal of the present study is to fill this knowledge gap by testing three SCM-related hypotheses. The first hypothesis is that contrary to the current view, the cVEMP response is only present in the SCM ipsilateral to the stimulated ear. The second hypothesis is that the cVEMP response is not only dependent on tonic level of the SCM, but also on how the tonic level is achieved, i.e., by head rotation or head flexion. The third hypothesis is that the SCM is compartmented and the polarity of the cVEMP response is dependent on the recording site. Seven surface electrodes were positioned along the left SCMs in 12 healthy adult subjects, and tone bursts were delivered to the ipsilateral or contralateral ear (8 ms plateau, 1 ms rise/fall, 130 dB SPL, 50-4000 Hz) while subjects activated their SCMs by head rotation (HR condition) or chin downward head flexion (CD condition). The first hypothesis was confirmed by the finding that the contralateral cVEMPs were minimal at all recording sites for all the tested tones during both HR and CD conditions. The second hypothesis was confirmed by the finding that the ipsilateral cVEMPs were larger in HR condition than in CD condition at recording sites above and below the SCM midpoint. Finally, the third hypothesis was confirmed by the finding that the cVEMPs exhibit reversed polarities at the sites near the mastoid and the sternal head. These results improve understanding of the cVEMP generation and suggest that the SCM-related factors should be taken into consideration when developing standardized clinical cVEMP testing protocols.

Cochrane Corner: Amplification with Hearing Aids for Patients with Tinnitus and Co-existing Hearing Loss.

The "Cochrane Corner" is a section in the journal that highlights systematic reviews relevant to otolaryngology-head and neck surgery, with invited commentary to aid clinical decision making. This installment features a Cochrane review, "Amplification with Hearing Aids for Patients with Tinnitus and Co-existing Hearing Loss," which identified only 1 randomized controlled trial and concluded that current evidence for use of hearing aids is limited.

Frequency tuning of the cervical vestibular-evoked myogenic potential (cVEMP) recorded from multiple sites along the sternocleidomastoid muscle in normal human subjects.

Frequency tuning of tone burst-evoked myogenic potentials recorded from the sternocleidomastoid muscle (cervical VEMP or cVEMP) is used clinically to assess vestibular function. Understanding the characteristics of cVEMP is important for improving the specificity of cVEMP testing in diagnosing vestibular deficits. In the present study, we analyzed the frequency tuning properties of the cVEMPs by constructing detailed tuning curves and examining their morphology and dependence on SCM tonic level, sound intensity, and recording site along the SCM. Here we report two main findings. First, by employing nine tone frequencies between 125 and 4,000 Hz, some tuning curves exhibited two distinct peaks, which cannot be modeled by a single mass spring system as previously suggested. Instead, the observed tuning is better modeled as linear summation of two mass spring systems, with resonance frequencies at ~300 and ~1,000 Hz. Peak frequency of cVEMP tuning curves was not affected by SCM tonic level, sound intensity, and location of recording site on the SCM. However, sharpness of cVEMP tuning was increased at lower sound intensities. Second, polarity of cVEMP responses recorded from the lower quarter of the SCM was reversed as compared to that at the two upper sites. While more studies are needed, these results suggest that cVEMP tuning is mediated through multiple generators with different resonance frequencies. Future studies are needed to explore implications of these results on development of selective VEMP tests and determine the nature of polarity inversion at the lower quarter of SCM.

Extracts from the Cochrane Library: modifications of the Epley (canalith repositioning) maneuver for posterior canal benign paroxysmal positional vertigo.

The "Cochrane Corner" is a quarterly section in the Journal that highlights systematic reviews relevant to otolaryngology-head and neck surgery, with invited commentary to aid clinical decision making. This installment features a Cochrane review "Modifications of the Epley (Canalith Repositioning) Manoeuvre for Posterior Canal Benign Paroxysmal Positional Vertigo (BPPV)" that finds no evidence of benefit for mastoid oscillation applied during the Epley maneuver nor any clinically important benefit for post-Epley postural restrictions in comparison with the Epley maneuver alone.

Safety and efficacy of high-intensity focused ultrasound atop coronary arteries during epicardial catheter ablation.

BACKGROUND: Coronary arterial injury continues to be a limitation of epicardial catheter ablation using currently available energy sources. Application of high intensity focused ultrasound (HIFU) energy may avoid such injury due to its theoretical ability to focus energy beyond the ablation element and create lesions at depth. OBJECTIVE: This study evaluated the safety of HIFU applications delivered directly over the left anterior descending (LAD) artery in an open-chest swine model. METHODS: Ten swine underwent median sternotomy. A prototype HIFU probe was placed atop the LAD. Forty-three therapies along the LAD (60-seconds/6 watt) were analyzed. Three, 3, and 4 swine were studied at 2, 4, and 8 weeks and subsequently sacrificed. Lesions were scored (0-4) depending on the percent circumferential involvement of arteries. RESULTS: Lesion area increased minimally from 54.5 ± 18.0 mm(2) at 2 weeks to 56.9 ± 20.6 mm(2) at 8 weeks, and depth increased moderately from 13.2 ± 2.5 mm to 15.5 ± 3.4 mm. At 2, 4, and 8 weeks, the mean injury score of the LAD was 0.8 ± 0.3, 1.5 ± 0.9, and 2.0 ± 0.7. No/minimal arterial injury was seen in 64% of all sections. However, a progressive increase in injury resulted in 89% of all sections showing any injury at 8 weeks. One animal developed occlusion of the distal LAD. CONCLUSIONS: HIFU has the potential to create deep ventricular lesions with relative sparing of the LAD. The incremental arterial damage noted over time warrants further evaluation to support the viability of focusing ultrasound energy beyond vulnerable critical structures to ablate deeper targets.

Assessment of air quality during mastoidectomy.

OBJECTIVES: The Occupational Health and Safety Administration (OSHA) outlines specific requirements governing the use of respiratory protection for workers dealing with dust or other aerosolized compounds. Health care workers may be exposed to bone dust produced during otologic procedures, creating an occupational hazard. The purpose of this research was to quantify the total suspended particulate matter (TSPM) and respirable particulate matter (PM(5)) created during cortical mastoidectomy and investigate whether the concentration of aerosolized dust during mastoidectomy would require the use of a particulate respirator. STUDY DESIGN: Cadaveric study to assess air quality during cortical mastoidectomy. SETTING: Temporal bone laboratory. METHODS: A simple mastoidectomy was performed on 3 cadaveric temporal bones. Suspended particulate concentration was measured using gravimetric filter methodology for TSPM and PM(5). Concentration of particulate exposure was compared between mannequins positioned near the surgical field with a standard surgical mask, surgical respirator, or controls. RESULTS: The average total particulate matter concentration during cortical mastoidectomy was 1.89 mg/m(3). The average quantity of respirable particles was below detection levels. The calculated particulate exposure concentrations for TSPM and PM(5) did not exceed OSHA's requirement for respirator use. The particulate respirator prevented exposure to bone particulates compared with controls (P = .028). CONCLUSION: The concentration of bone dust produced during cortical mastoidectomy is below regulatory guidelines for use of particulate respirators. However, experimental studies show the use of a surgical respirator may decrease particulate exposure.

Frequency tuning of bone-conducted tone burst-evoked myogenic potentials recorded from extraocular muscles (BOVEMP) in normal human subjects.

OBJECTIVES: In this study, we characterized the frequency tuning of bone-conducted sound-evoked myogenic potentials recorded from extraocular muscles (BOVEMP) in normal human subjects. STUDY DESIGN: Experimental design. METHODS: In a sample of nine subjects, acoustic tone bursts (57 dB nHL, 8 ms plateau, 1 ms rise/fall, alternating polarity) with frequencies from 250 Hz to 2,000 Hz were delivered by a bone oscillator (Radioear B-71) placed on the left mastoid processes. Subjects were required to sit upright and maintain a straight gaze. The BOVEMPs were recorded from surface electrodes placed at four locations around the right eye (superior, inferior, nasal, and temporal) and referenced to an electrode placed at the nape of the neck over cervical vertebrate C7. Signals from electrodes were amplified (10,000 gain) and sampled at 10 kHz and were averaged over 500 repetitions. RESULTS: Short latency biphasic potential were present at each of the four recording sites around the eye. The average latency of the first peak (negative) and the second peak (positive) was 15.7 ± 0.3 ms and 23.3 ± 0.5 ms, respectively. The tuning curve of the BOVEMP was similar at each recording site with largest N1 amplitude following stimulation at 383 Hz (± 17 Hz) and largest P1 amplitude following stimulation at 440 Hz (± 22 Hz). CONCLUSIONS: Since the frequency tuning for the bone-conducted sound-evoked OVEMP (BOVEMP) was different from that of the air-conducted sound-evoked OVEMP (AOVEMP), we hypothesize that the BOVEMP and AOVEMP are generated by activation of different vestibular end organs.

Frequency tuning in the tone burst-evoked myogenic potentials in extraocular muscles in normal human subjects.

OBJECTIVE: In this cross-sectional study, we investigated the frequency tuning properties of sound-evoked vestibular myogenic potentials in extraocular muscles (OVEMPs) in normal human subjects. METHODS: Acoustic tone bursts (130 dB pSPL, 10 ms plateau, 1 ms rise/fall) with nine frequencies from 125 to 4000 Hz were presented monoaurally to 12 normal subjects while they sat upright and maintained centre gaze. Using surface electrodes, the OVEMPs were recorded at four locations surrounding the contralateral eye (superior, inferior, nasal, and temporal) and were referenced to an electrode placed at the nape of the neck over C7. To measure the amplitudes of the OVEMP, signals from the electrodes were amplified and sampled at 10 kHz and were averaged over 250 repetitions. RESULTS: We found that the OVEMPs recorded at the four sites exhibited similar well-defined frequency tuning with peak amplitude at ≈ 1000 Hz. CONCLUSION: Although several studies have examined the frequency tuning of the vestibular evoked myogenic potential measured from the sternocleidomastoid muscles (SVEMP), the reported results are quite variable as regards frequency, which produces peak amplitude. The well-defined OVEMP frequency tuning provides an alternative to the SVEMP for assessing vestibular function via acoustic stimulation. Further studies are needed to identify the extent to which each of the five vestibular end-organs is activated by sound and their contribution to the sound-evoked vestibular myogenic potentials.

The current status of audiologic rehabilitation for profound unilateral sensorineural hearing loss.

OBJECTIVES/HYPOTHESIS: Audiologic rehabilitation of individuals with profound unilateral sensorineural hearing loss (USNHL) has traditionally been limited to the use of air-conduction contralateral routing of sound (CROS) hearing aids. Treatment for these individuals has expanded with new applications of the bone-anchored hearing aid (BAHA), transcranial hearing aid (t-CROS), and the cochlear implant. In this article, the authors review the literature that addresses these various treatment options. STUDY DESIGN: Contemporary review RESULTS: Historical information is available that describes the limited efficacy of air-conduction CROS hearing aids in lifting hearing handicap associated with USNHL. Current investigations on providing cross hearing are generally focused on use of the BAHA. Little is known at present whether new developments in hearing aid technology can improve on conventional air-conduction CROS or t-CROS approaches. Interestingly, the cochlear implant seems to be a viable option for individuals with USNHL and tinnitus who also have intact auditory nerve pathways. CONCLUSIONS: There is indication in the literature that BAHA provides greater relief of hearing handicap associated with USNHL than CROS hearing aids; however, both have been found to provide limited patient satisfaction and seemingly fall short of restoring true sound localization. Adequate trials have not been performed comparing BAHA with the best CROS hearing aid technology. Transcranial hearing aids and cochlear implants are experimental methods to treat USNHL and hold promise, although there remains a lack of studies available to fully support this.

Postoperative carotid spasm in the setting of head and neck surgery.

Delayed arterial spasm is a clinical and angiographic condition frequently observed after subarachnoid hemorrhage. It has long been associated with a local myogenic reaction to prolonged arterial contact with fresh blood. Carotid spasm from direct manipulation of the petrous carotid during skull base procedures is also a rare but known response to longitudinal arterial traction. Uncomplicated cervical cases, although subject to similar conditions of arterial manipulation, have less commonly been associated with arterial spasm. Two cases of severe internal carotid spasm leading to stroke in patients undergoing removal of glomus tumors are presented to emphasize carotid spasm as a potential complication in head and neck surgery. The perioperative guidelines to prevent, recognize, and treat this complication are also reviewed as outlined in the literature.

Use of intradermal dilutional testing and skin prick testing: clinical relevance and cost efficiency.

OBJECTIVES/HYPOTHESIS: The objective was to determine the agreement of the positive results from a multiple skin prick test (SPT) device with the ability to determine a definable endpoint through intradermal dilutional testing (IDT) to compare semiquantitatively the degree of positivity of SPT results with quantitative results from IDT and to analyze the cost of immunotherapy based on SPT compared with IDT guided by SPT. STUDY DESIGN: Retrospective review of clinical data (random accrual). METHODS: One hundred thirty-four patients underwent allergy screening using a multiple SPT device. Antigens testing positive by skin prick device were tested using IDT on a separate day. Antigens testing negative by SPT were not evaluated by IDT. Regional allergy testing practice patterns were determined, and a cost analysis using Medicare rates was performed RESULTS: There was good agreement between an antigen testing positive by SPT and the determination of a definable endpoint (93.33%, n = 1,334 antigens). The degree of positivity from the SPT correlated poorly with the final endpoint concentration (r = 0.40, P < .0001). Blended testing techniques were similar in cost when compared with several commonly used allergy testing protocols. CONCLUSIONS: Antigens which show reactivity to a multiple SPT device usually have a treatable endpoint that is independent of the degree of positivity of the SPT result. IDT is an important step in the determination of the strongest starting dose of immunotherapy that may be safely administered. Initiating immunotherapy in this manner may potentially create significant health care savings by shortening the time required for a patient to reach their individual maximally tolerated dose. The use of a relatively large screening panel is cost effective and does not increase the average number of antigens treated by immunotherapy. Blended allergy testing techniques that include IDT in their protocol are comparable in cost with commonly used allergy testing protocols.