Refining the Video Head Impulse Test Diagnostic Accuracy: A Case-Control Study.

INTRODUCTION: Current clinical practice considers the vestibulo-ocular reflex (VOR) gain as registered by the video head impulse test (vHIT) as the primary measure for semicircular canal function, while the role of the re-fixation saccades (RSs) is still under evaluation. The goal of the study was to appraise the added benefit of RS towards the improvement of vHIT diagnostic accuracy in cases of suspected left horizontal semicircular canal dysfunction. METHODS: The vHIT recordings of 40 patients with left-sided horizontal VOR gains <0.8 were retrospectively evaluated for the presence of RS. The study groups included 20 patients with a final diagnosis of left horizontal semicircular canal dysfunction and 20 patients for whom vestibular dysfunction was ruled out. RESULTS: Gain values >0.72 were found in all patients with no vestibular disease and in 4 (20%) patients having vestibulopathy. Significantly higher average left-sided RS velocity and frequency were found among the vestibular patients. VOR gain <0.72 was found to be highly specific for the diagnosis of vestibular dysfunction. However, for gain values in the range of 0.72-0.79, the presence of RS with frequency >80% largely improved vHIT diagnostic accuracy. CONCLUSIONS: Although VOR gain <0.8 is considered to reflect dysfunction, a significant false-positive rate for left-sided horizontal vHIT was found for gains in the range of 0.72-0.79. The presence of RS with frequency >80% could improve vHIT diagnostic ability in these patients.

The Vestibular Time Constant and Clinical Response to Antimotion Sickness Medication.

OBJECTIVE: The therapeutic effects of antimotion sickness medications involve suppression of several components along the vestibular system. Scopolamine-based medications have proved to be the most effective anti-seasickness agents. However, there is high variability in individual responses. The vestibular nuclei, in which the vestibular time constant is modulated, contain acetylcholine receptors which are affected by scopolamine. The hypothesis of the study was that successful seasickness prevention by scopolamine requires vestibular suppression to be reflected by the shortening of the vestibular time constant. DESIGN: Subjects were 30 naval crew members suffering from severe seasickness and were treated with oral scopolamine. The study participants were defined as responsive or non-responsive to the anti-seasickness medication according to the clinical outcome: successful response to scopolamine was defined as a reduction of seasickness severity from the highest score of 7 according to the Wiker scale to 4 or less. Scopolamine and placebo were assigned to each subject in a crossover, double-blind design. The horizontal semicircular canal time constant was evaluated by a computerized rotatory chair before, 1 and 2 hours after drug or placebo administration. RESULTS: The vestibular time constant was significantly shortened from 16.01 ± 3.43 seconds to 12.55 ± 2.40 seconds ( p < 0.001) in the scopolamine-responsive group but not in the nonresponsive group. In contrast, vestibular time constant values were 13.73 ± 4.08 and 12.89 ± 4.48 for baseline and 2 hours measurements, respectively. This change was not statistically significant. CONCLUSIONS: Reduction in the vestibular time constant after scopolamine administration can be used to predict whether motion sickness alleviation will occur. This will enable the administration of appropriate pharmaceutical treatment without the need for prior exposure to sea conditions.

[THE VIDEO HEAD IMPULSE TEST (VHIT)].

INTRODUCTION: The video head impulse test (vHIT) is a new tool in the vestibular tests' arsenal. It is based on the clinical Head Impulse Test, where the integrity of the vestibulo-ocular reflex is tested by high frequency excitation of the semi-circular canals. The vHIT system is composed of an accelerometer measuring the head movements, and a high frequency infra-red camera for eye tracking mounted on a light-weighted goggles. The main measures obtained are the vestibulo-ocular reflex gain - the ratio between the head and eye velocities, and the recording of corrective saccades taking place during the head movement (covered saccades) or following it (overt saccades).

[THE VIDEO HEAD IMPULSE TEST (VHIT): CAN WE RELY ON THE GAIN PARAMETER ALONE?]

INTRODUCTION: While the bedside head impulse test evaluates the presence of refixation saccades (RS) as a measure of failing vestibulo-ocular reflex (VOR) the VOR gain calculated by the video head-impulse test (vHIT) is considered the primary measure for semicircular canal function while the role RS is still under evaluation. AIMS: To evaluate the benefit of various RS characteristics towards the diagnosis of the left horizontal semicircular function by vHIT. METHODS: The vHIT recordings of 40 patients with left sided horizontal VOR gains <0.8 were retrospectively evaluated for the presence of RS. The study groups included 20 patients with a final diagnosis of left horizontal semicircular canal dysfunction and 20 patients for whom vestibular dysfunction was ruled out. RESULTS: Gain values > 0.72 were found in all patients with no vestibular disease, and in 4 (20%) patients having vestibulopathy. Significantly higher average left-sided RS velocity and frequency were found among the vestibular patients. VOR gain < 0.72 was found to be highly specific for the diagnosis of vestibular dysfunction. However, for gain values in the range of 0.72-0.79 the presence of RS with frequency > 80% improved vHIT sensitivity. CONCLUSIONS: Although VOR gain<0.8 is considered to reflect dysfunction, a significant false positive rate for left-sided horizontal vHIT was found for gains in the range of 0.72-0.79. The presence of RS with frequency >80% could improve vHIT diagnostic accuracy in these patients.

[ACUTE OTITIS MEDIA BACTERIOLOGY IN CHILDREN YOUNGER THAN THREE MONTHS IN THE LAST 16 YEARS].

BACKGROUND: Only scant information is available regarding the bacteriology of acute otitis media (AOM) in neonates. OBJECTIVES: To investigate the bacteriology of AOM post the introduction of Pneumococcal Conjugate Vaccine (PCV13) in children younger than 3 months and its relation to the mode of delivery. METHODS: Retrospective bacteriological analysis of middle ear fluids taken from children younger than 60 months suffering from AOM. The effect of PCV13 and mode of delivery, caesarian section vs vaginal delivery, on AOM bacteriology was evaluated and compared between children younger than 3 months (group 1) and children aged 3-60 months (group 2). RESULTS: The prevalence of Streptococcus pneumoniae (S.pneumoniae) and Enterobacteriaceae (E.bact) was higher in group 1 compared to group 2, 47.1% vs 35.8% and 12.3% vs 4.3%, respectively (p<0.001), while that of Haemophilus influenza (H. influenzae) and Group A streptococcus (GAS) was higher in group 2 compared to group 1, 40.3% vs 30.1% and 17.5% vs 8.3% respectively (p<0.001). The mode of delivery did not affect AOM bacteriology. The introduction of PCV13 yielded in an increase in the prevalence of GAS (7% to 15%, P<0.001) in group 1. CONCLUSIONS: S. pneumoniae and E. bact are more common AOM pathogens in neonates. Also, the prevalence of GAS was increased in this age group following the introduction of PCV13. DISCUSSION: Our results are applicable towards the formulation AOM treatment guidelines in neonates. This study contributed additional information on a topic that has not been adequately researched so far - neonatal AOM.

Bone Mineral Density in Patients Suffering from Ménière's Disease.

INTRODUCTION: Previous studies have reported an association between reduced bone mineral density and the occurrence of benign paroxysmal positional vertigo, balance impairment, and saccular dysfunction. Furthermore, the results of recent animal studies have raised the possibility that vestibular dysfunction could affect bone remodeling and bone mass. The goal of the study was to compare bone mineral density of patients suffering from definite Ménière's disease to that of a matched control group. METHODS: We conducted a case-control cross-sectional study in a tertiary referral center. The study group included 23 patients suffering from definite Ménière's disease, and the control group was comprised of 23 patients matched in their race, gender, and age parameters in whom no vestibular pathology could be found. Dual energy X-ray absorptiometry of the femoral head was used for the assessment of bone mineral density. The T and Z scores of the femoral heads' bone mineral density were compared. RESULTS: The average T scores were -1.53 ± 1.08 in the study and -0.39 ± 0.72 (p = 0.016) in the control groups, and the Z scores were -0.4 ± 0.63 and 0.33 ± 0.31 (p = 0.018), respectively. Seventeen patients (74%) of the study group and 9 (39%) of the control group had T scores less than -1.0, indicating osteopenia/osteoporosis (p = 0.036). CONCLUSIONS: The results showed a significant association between Ménière's disease and reduced bone mineral density of the femoral head. Bone mineral density studies of the weight-bearing bones are warranted in Ménière's disease for the early diagnosis and treatment of osteopenia/osteoporosis on the one hand and possible benefit of this treatment for the evolution of Ménière's disease on the other hand.

Evidence for the initiation of decompression sickness by exposure to intense underwater sound.

Mass stranding of cetaceans (whales and dolphins), in close association with the activity of naval sonar systems, has been reported on numerous occasions. Necropsy showed bubble-associated lesions similar to those described in human decompression sickness (DCS). We examined the hypothesis that exposure to underwater sound may potentiate DCS. Rats were subjected to immersion and simulated dives with and without simultaneous acoustic transmissions at pressure levels and frequencies of 204 dB/8 kHz and 183.3 dB/15 kHz. DCS severity was assessed using the rotating wheel method. Recording of somatosensory evoked potentials (SSEPs) was employed under general anesthesia as an electrophysiological measure of neurologic insult. A significantly higher rate of decompression sickness was found among animals exposed to the 204-dB/8-kHz sound field. Significantly higher pathological SSEPs scores were noted for both underwater sound protocols. Pathological SSEPs scores in animals immersed during the acoustic transmissions, but without changes in ambient pressure, were comparable to those observed in animals exposed to the dive profile. The results demonstrate induction of neurological damage by intense underwater sound during immersion, with a further deleterious effect when this was combined with decompression stress. The study outcome has potential implications for human diving safety and may provide an explanation for the mass stranding of cetaceans purportedly associated with sonar activity.

Barotrauma-Induced Perilymph Fistula: Video Head Impulse Test and High-Resolution Temporal Bones Computed Tomography Role in Evaluation and FollowUp.

We report a case of a woman presenting with unilateral right profound hearing loss accompanied by vertigo secondary to barotrauma-induced perilymph fistula during recreational skydiving. Video head impulse test demonstrated a reduced gain in both the right horizontal and right anterior semicircular canals accompanied by frequently gathered overt corrective saccades. High-resolution computed tomography revealed an enlarged vestibular aqueduct on the affected side, a predisposing factor for the development of perilymph fistula. An exploratory tympanotomy was performed during which a perilymph leak was visualized at the round window niche. Temporal fascia patches enforced by absorbable gelatin sponges were applied to both round and oval windows. During post-surgery follow-up, the patient remained free of vestibular symptoms. An audiogram displayed mild improvement in the right ear speech reception threshold, although her hearing remained non-serviceable. The video head impulse test showed a favorable dynamic with a stepwise return to normal gain values in all semicircular canals and the disappearance of overt corrective saccades. This is the first case in which video head impulse test was employed as a valuable diagnostic tool for the evaluation and post-surgery follow-up of vestibular function in a barotrauma-induced perilymph fistula. The demonstration of an enlarged vestibular aqueduct on high-resolution computed tomography and the risk of perilymph fistula recurrence are discussed.

Vertigo in children and adolescents: characteristics and outcome.

OBJECTIVES: To describe the characteristics and outcome of vertigo in a pediatric population. PATIENTS: All children and adolescents presenting with vertigo to a tertiary otoneurology clinic between the years 2003-2010 were included in the study. RESULTS: Thirty-seven patients with a mean age of 14 years were evaluated. The most common etiology was migraine-associated vertigo (MAV) followed by acute labyrinthitis/neuritis and psychogenic dizziness. Ten patients (27%) had pathological findings on the otoneurological examination. Abnormal findings were documented in sixteen of the twenty-three (70%) completed electronystagmography evaluations. Twenty patients (54%) were referred to treatment by other disciplines than otology/otoneurology. A follow-up questionnaire was filled by twenty six (70%) of the study participants. While all patients diagnosed with MAV had continuous symptoms, most other patients had complete resolution. CONCLUSIONS: Various etiologies of vertigo may present with similar symptoms and signs in the pediatric patient. Yet, variable clinical courses should be anticipated, depending on the specific etiology. This is the reason why treatment and follow up should be specifically tailored for each case according to the diagnosis. Close collaboration with other medical disciplines is often required to reach the correct diagnosis and treatment while avoiding unnecessary laboratory examinations.

Two decades of otitis media in northern Israel: Changing trends in the offending bacteria and antibiotic susceptibility.

OBJECTIVE: Bacteriology and antibiotic resistance trends changed considerably following introduction of the pneumococcal conjugate vaccines (PCV) 7 and 13, with differences between geographic regions. The objective of this study was to evaluate changes in acute otitis media (AOM) bacteriology and antibiotic susceptibility from the pre-vaccination period (2002-2008) to after the introduction of PCV13 (2010-2019) in northern Israel. METHODS: Data were collected from 3277 middle ear fluid (MEF) cultures and 4822 common AOM-generating pathogens of children aged <5 years with otitis media, taken during 2002-2019. Age of the child, bacteriology, and antibiotic resistance were compared between 2002 and 2008, the pre-vaccination period when no vaccination was available and 2010-2019 when PCV13 was introduced. RESULTS: The mean age of the children in the pre-vaccination and the vaccination periods was 18.7 ± 13.7 and 15.7 ± 12.5 months, respectively (p < 0.001); the mean age of those with group A streptococcus (GAS) positive cultures was older, p < 0.001.The prevalence of Streptococcus pneumoniae (S. pneumoniae) decreased between those periods, from 47% to 25.8%, p < 0.001, Haemophilus influenzae (H. influenza) increased from 38.4% to 47.1%, p < 0.001, GAS increased from 12.9% to 23.8%, p < 0.001, and Moraxella catarrhalis (M. cat) increased but not statistically significant from 1.7% to 3.1%. The yearly number of positive MEF cultures decreased from 395.1 to 205.6, p < 0.001. The antibiotic sensitivity rate of almost all antibiotics increased between the two study periods. CONCLUSION: The most common MEF bacteria in northern Israel today is H. influenzae. Comparing the pre-vaccination to the vaccination period, the incidence of S. pneumonia-positive cultures decreased while GAS and H. influenza cultures increased. The age of children with positive cultures increased, and the antibiotic sensitivity rate increased. Key This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Medical waiver for flying after microvascular decompression for hemifacial spasm.

BACKGROUND: Microvascular decompression has become the treatment of choice for hemifacial spasm. Post-surgical symptoms of vestibular dysfunction may appear, but are mostly transient. The unique occupational demands of military aviators necessitate complete otoneurological evaluation after vestibular insults to allow safe return to flying duties. CASE REPORT: We present a case of a military jet-fighter pilot who developed transient vertigo and disequilibrium after microvascular decompression for hemifacial spasm. Resolution of symptoms and complete recovery as documented by vestibular bedside and laboratory tests allowed us to grant the pilot full solo flying privileges.

Monothermal caloric testing in the screening of vestibular function.

INTRODUCTION: The alternate binaural bithermal caloric test (ABBT) is the standard test for evaluation of the dizzy patient. Monothermal caloric testing (MT) has the potential benefits of reducing the administration time and patient discomfort. The goal of the present study was to investigate the role of MT screening in the prediction of ABBT results. METHODS: ABBT results of 218 patients having normal otoneurological examination, normal hearing, and normal electronystagmography (ENG) were retrospectively analyzed to generate norms for all subtests. These norms were then employed to calculate the sensitivity and specificity of MT for predicting normal ABBT in a group of 197 consecutive dizzy patients who were referred for vestibular testing. RESULTS: The best predictions of ABBT by MT results were achieved when ENG testing showed oculomotor integrity and no spontaneous, positional, or positioning nystagmus. Under these conditions, warm MT lateralization < 32% had 90% sensitivity and 92% specificity for the prediction of normal ABBT. DISCUSSION: When no pathology is detected in the other parts of the ENG, warm MT lateralization < 32% can indicate normal ABBT with a 10% probability for a false-negative result. This false negative rate precludes the routine use of warm MT in the clinical realm and its application as a screening tool for possible vestibular deficits in a generally healthy population like aviation or diving candidates. Higher sensitivity may be achieved by lowering the cut-off point of the response asymmetry required for the diagnosis of MT screening failure and the omission of directional preponderance diagnosis from the goals of the screening.

Vestibular evoked myogenic potentials and saccular plasticity in divers.

INTRODUCTION: Otolith function, which is dependent on linear velocity and acceleration, may be expected to change in underwater divers, who are submerged in a medium that is denser than air. The purpose of the present study was to examine possible changes in the sacculocollic reflex of professional divers and to investigate whether there might be diving-induced adaptation of the saccular response. METHODS: We used the vestibular evoked myogenic potential (VEMP) response to evaluate saccular function in 12 professional divers shortly after a dive and after an interval of at least 24 h. The control group consisted of 12 matched non-divers. Wave latencies and amplitudes, asymmetry ratio, and the response threshold were compared between the groups. RESULTS: Statistically significant shortening of N23-wave latency was found in the divers compared with the control group. The mean +/- SE were 22 +/- 0.1 and 22.1 +/- 0.7 ms early and late after a dive in the divers group vs. 24.5 +/- 0.5 ms in the control group. No significant differences were found in any of theVEMP parameters between the early and late post-dive recordings. DISCUSSION: We suggest that the reduction in N23 latency reflects long-term adaptation of the sacculocollic reflex to underwater conditions. Increased sensitivity of the reflex is required to compensate for the decrease in linear velocity and acceleration, resulting in reduced stimulation of the otolith organ.

Functional Integrity of the Inferior Vestibular Nerve and Posterior Canal BPPV.

The functional integrity of the inferior vestibular nerve (IVN) may be evaluated by the cervical vestibular evoked myogenic potential (cVEMP) response, which requires signal transmission via the nerve. As functional integrity of the IVN innervating the posterior semicircular canal is required to produce the typical positioning vertigo and nystagmus characterizing posterior canal benign paroxysmal positional vertigo (PCBPPV), we hypothesized that normal cVEMPs would be found in most PCBPPV patients. Twenty-four PCBPPV patients participated in a prospective cohort study. All were treated by canal repositioning maneuver and had air-conduction cVEMP and videonystagmography (VNG). Follow-up evaluations including history and otoneurological bedside examination were carried out 1, 3, 6, and 12 months after the initial treatment. At the last follow-up, the patients filled the Dizziness Handicap Inventory (DHI) questionnaire. Normal cVEMPs were recorded in 19 (79%) and were absent in 5 (21%) of the subjects. The average DHI in the patients with normal cVEMP was 16.42 ± 17.99 vs. 0.4 ± 0.89 among those with pathological cVEMP (p < 0.04, Mann-Whitney test). Thirteen (54%) patients experienced recurrent PCBPPV (rPCBPPV). The average DHI score was significantly higher among patients having recurrence (22.15 ± 18.61) when compared to those with complete cure (2.36 ± 5.98; p < 0.003, Mann-Whitney test). Ten (77%) of the subjects with rPCBPPV had normal and 3 (23%) had pathological cVEMP as compared to 9 (82%) and 2 (18%) subjects in the non-recurrent (nrPCBPPV) group (Fisher's exact test-not significant). cVEMP p13 and n23 wave latencies and amplitudes, inter-aural differences in p13-n23 peak-to-peak amplitudes, and response thresholds did not differ between the groups. No differences were found between the rPCBBPV and nrPCBBPV groups in VNG caloric lateralization and directional preponderance values. We have found that in most cases, PCBPPV symptoms and signs are associated with normal cVEMP response supporting the role of IVN functional integrity. The absent cVEMPs in the minority of patients, although having similar clinical presentation, raise the possibility that the ipsilateral saccule is affected by the same pathology causing degeneration of the utricle macula. Alternatively, lacking inhibitory stimuli from the involved ipsilateral utricle or partial degeneration of the IVN and ganglion could explain the diminished cVEMP response. Clinical Trial Registration: The study was registered in ClinicalTrials.gov Internet site (study ID-NCT01004913; https://clinicaltrials.gov/ct2/show/NCT01004913?cond=BPPV&cntry=IL&draw=2&rank=3).

Ondansetron for the prevention of seasickness in susceptible sailors: an evaluation at sea.

BACKGROUND: Seasickness is a common problem, causing a significant decrement in performance among naval crew. In about 20-60% of crewmembers, symptoms appear with varying intensity depending on the sea state and the duration of the voyage. Recent studies have suggested antiemetic 5HT3 blockers as a possible treatment for motion sickness, emphasizing their minor clinical and cognitive side effects. The purpose of the present study was to evaluate the 5HT3 blocker ondansetron in the prevention of seasickness. METHODS: There were 16 volunteers with a normal otoneurologic examination and no previous medical history of inner ear disease or vertigo who took part in a double blind, randomized, crossover study. During an initial learning phase, the participants practiced on a battery of computerized performance tests until their results stabilized. Ondansetron 8 mg or placebo was administered 2 h before sailing aboard a 500-ton naval vessel in mild sea conditions. Participants did the performance tests and completed a questionnaire evaluating their seasickness symptoms 4 h into the voyage. RESULTS: No statistically significant reduction of seasickness symptoms was demonstrated between ondansetron treatment and placebo (a Wiker score of 2.69 +/- 1.78 and 2.81 +/- 1.97, respectively). There was no statistically significant difference in side effects or the results of the performance tests. CONCLUSION: In this study, ondansetron was not found to be beneficial in the treatment of seasickness. It could be speculated that the mechanism of nausea in seasickness is different from that of toxin-induced nausea.

Prednisone treatment for vestibular neuritis.

OBJECTIVE: To evaluate the value of corticosteroids in the treatment of vestibular neuritis (VN). DESIGN: Prospective controlled randomized. METHODS: Thirty VN patients, 15 in the study and 15 in the control group, were the subjects of the study. The study group was treated by 1 mg/kg prednisone for 5 days, followed by gradually reduced doses of prednisone for an additional 15 days, and vestibular sedatives for symptomatic relief during the first 5 days after presentation. The control group received a placebo and similar vestibular sedatives. The patients had a baseline evaluation and follow-up examinations after 1, 3, 6, and 12 months. The groups were compared for the presence of symptoms and signs, caloric lateralization on the electronystagmography (ENG), the presence of other pathologic findings in the ENG, and Dizziness Handicap Inventory scores. RESULTS: No differences were found between the groups in the occurrence of symptoms and signs, degree of caloric lateralization, presence of other ENG pathologic findings, and Dizziness Handicap Inventory scores at the end of the study. Complete resolution was observed in 64% of the study and in 80% of the control group. The study group showed earlier recovery of ENG lateralization at the 1- and 3-month follow-up evaluations and higher rates of complete resolution at the 3- and 6-month follow-up points. CONCLUSION: Prednisone therapy might enhance earlier recovery but does not improve the long-term prognosis of VN. The clinical and laboratory parameters in VN are not correlated, and both are required for complete patient evaluation.

The head impulse test as a predictor of videonystagmography caloric test lateralization according to the level of examiner experience: A prospective open-label study.

We conducted a study to compare how well the head impulse test (HIT), without and with eye-movement recordings, would predict videonystagmographic (VNG) caloric test lateralization when performed by a resident and an experienced otoneurologist. This prospective, open-label, blinded study was conducted in an ambulatory tertiary care referral center. Our study population was made up of 60 patients-29 men and 31 women, aged 20 to 82 years (mean: 56.4 ± 11.4)-with peripheral vestibulopathy who underwent HIT and VNG caloric testing. The HIT was conducted in two protocols: HIT0 and HIT1. The HIT0 was performed with passive brisk movements of the patient's head from the 0° null position to 20° sideways, and the HIT1 was performed toward the center while the null position was a 20° head rotation to the right and to the left. Each protocol was carried out without video eye-movement recordings (HIT0 and HIT1) and with such recordings (rHIT0 and rHIT1). The primary outcome measures were (1) a comparison of the HIT's sensitivity and specificity when performed by the resident and by the experienced otoneurologist and (2) the ability of video-recorded HIT to predict VNG caloric test lateralization. The sensitivity and specificity obtained by the resident were 41 and 81%, respectively, for HIT0 and 41 and 90% for HIT1. The sensitivity and specificity obtained by the experienced otoneurologist were 18 and 89% for HIT0 and 32 and 85% for HIT1. Analysis of the recorded eye-movement clips of the HIT0 and HIT1 obtained by a second experienced otoneurologist found a sensitivity and specificity of 32 and 63% for rHIT0 and 33 and 82% for rHIT1. We conclude that the HIT yields high false-negative rates in predicting significant caloric lateralization. Analysis of the eye-movement recordings was no better than normal testing alone for detecting saccades. The experience of the examining physician had no impact on test performance characteristics.

Otoacoustic emissions in early noise-induced hearing loss.

OBJECTIVE: To follow changes in transient evoked and distortion product otoacoustic emissions (TEOAEs, DPOAEs) as they relate to pure-tone audiometry (PTaud) thresholds during the first 2 years of occupational noise exposure. DESIGN: Prospective controlled. METHODS: Pure-tone audiometry thresholds, TEOAE and DPOAE amplitudes, and contralateral medial olivocochlear reflex strength were repeatedly evaluated during 2 years and compared between and within a cohort of 135 ship engine room recruits and a control group of 100 subjects with no noise exposure. RESULTS: Pure-tone audiometry thresholds for 2,000, 3,000 and 4,000 Hz in both ears were significantly elevated in the study group after 2 years of noise exposure. Significantly lower TEOAE amplitudes were found at 2,000 Hz in the right ear and 2,000 and 4,000 Hz in the left ear. Longitudinal intrasubject analysis of the study group revealed significant reductions of TEOAE amplitudes at 2,000 to 4,000 Hz in both ears and reduced DPOAE amplitudes for 5,957 Hz in the right ear and 3,809, 4,736, and 5,957 Hz in the left ear in the second follow-up evaluation. Baseline medial olivocochlear reflex strength showed no correlation to PTaud thresholds after 2 years of noise exposure. Poor to moderate negative linear correlations (r = -0.07 to -0.37) were found between the DPOAE-averaged amplitudes at 2,979 to 5,957 Hz and PTaud threshold means at 3,000 to 6,000 Hz. Abnormal TEOAE parameters after the first year of noise exposure had high sensitivity (86-88%) and low specificity (33-35%) for the prediction of noise-induced hearing loss (NIHL) after 2 years. CONCLUSION: The DP-gram is not significantly correlated with PTaud and cannot be used as an objective measure of pure-tone thresholds in early NIHL. Medial olivocochlear reflex strength before the beginning of chronic exposure to occupational noise has no relation to individual vulnerability to NIHL. Although TEOAEs changes after 1 year showed high sensitivity in predicting NIHL after 2 years of exposure, they cannot be recommended as an efficient screening tool due to high false-positive rates.