The caloric irrigation test.

The test of caloric thermal irrigations is one of the first tests for sensitivity of the peripheral vestibular systems dating to the late 1800s. This chapter reviews the various protocols that have been developed over the years using thermal irrigations to the external auditory canals. The discussion covers the interpretations of the protocols and makes recommendations for those protocols that have the best performance and at the same time are practical to perform. The primary utility of the caloric test has remained the same since its origination - the comparison of the relative sensitivity of the right versus left peripheral vestibular function. This is now known to be applicable to the horizontal canals without any significant influence of the vertical canals. The hypothesized physiology behind the thermal caloric proposed in the early 1900s has now, with the help of experiments in microgravity, been partially verified. Until recently this was the only test that could investigate one peripheral end organ at a time. It is still the one test that emphasizes the low-frequency function of the horizontal canals individually.

Development of the Three-Clinic Hearing Aid Selection Profile (HASP).

The Three-Clinic Hearing Aid Selection Profile (HASP) was developed to assess a patient's beliefs about a number of basic considerations felt to be critical to the hearing aid selection (HAS) process. These characteristics are felt to be key to the acceptance of amplification and include motivation, expectations, cost of goods and services, appearance (cosmesis), attitudes about technology, physical function/limitations, communication needs, and lifestyle. The results of the first investigation suggest that we have been successful in developing a 40-item metric with adequate internal consistency reliability that assesses the aforementioned characteristics. Second, results of the administration of this tool to a large group of individuals indicated that (1) age impacted scores on the Technology, Physical Function, and Communicative Needs subscales; (2) gender impacted scores on the Motivation, Expectation, Technology, Communicative Needs, and Appearance subscales; (3) previous hearing aid use affected scores on the Motivation subscale; (4) level of education impacted scores on the Physical Function and Lifestyle subscales; and (5) self-perceived hearing handicap had an effect on Motivation and Communicative Needs subscale scores. Percentile data collected from this subject sample are presented as a benchmark against which to evaluate responses from individual patients. Case studies are presented to illustrate the potential clinical utility of this device.

A search for evidence of a direct relationship between tinnitus and suicide.

The purpose of this investigation was to determine whether there exists in the scientific literature support for a cause and effect relationship between tinnitus and suicide. MEDLINE and HealthStar databases were queried using the combined search terms "tinnitus" and "suicide" over the time period from 1966 to 2001 for MEDLINE and from 1975 to 2001 for HealthStar. Foreign-language reports were included if they had been translated into English or, at least, if they contained an English-language translation of the abstract. A total of three published reports pertinent to this topic were recovered. None of these reports showed a causal relationship between tinnitus and suicide. More often, patients who had attempted or committed suicide had significant preexisting psychiatric conditions, the most common being depression. Accordingly, it is our conclusion that nowhere in the existing literature is there any evidence supporting a cause and effect relationship between tinnitus and suicide.

Acquired bilateral peripheral vestibular system impairment: rehabilitative options and potential outcomes.

Acquired bilateral vestibular impairment can be a devastating disorder that is most frequently the result of aminoglycoside-induced toxicity. The presenting complaints are typically oscillopsia and gait and balance disturbances. These patients can be excellent candidates for vestibular rehabilitation therapy that focuses on facilitating maximal use of any remaining vestibular function, improving gaze and postural stability through the use of visual and somatosensory cues, and improving home and workplace safety. The prognosis for recovery is determined by the extent of the loss and the presence of other progressive disorders that may affect vision or somatosensation, coexisting illnesses, and the patient's compliance with the therapy program. Two cases are presented to illustrate the salient aspects of vestibular rehabilitation for patients with acquired bilateral vestibular system loss, including factors affecting patient progress and final outcome.

Self-perceived balance disability/handicap in the presence of bilateral peripheral vestibular system impairment.

The purpose of this report was to characterize the self-perceived balance disability/handicap of patients with bilateral reductions and bilateral complete losses of peripheral vestibular system function. Data from 72 patients whose electronystagmography and rotational examinations suggested normal, unilateral, or bilateral reductions in peripheral vestibular system function were used in the first investigation. Patients also completed a Dizziness Handicap Inventory (DHI). Results demonstrated significant group differences for DHI total and physical subscale scores. There were significant differences between normal and bilateral weakness groups for the total DHI score and between normal and unilateral and normal and bilateral weakness groups for the physical subscale score. In a second investigation, an item analysis of the DHI is presented for five patients with bilateral complete losses of peripheral vestibular system function. Results show that, predictably, these patients have difficulty engaging in activities requiring an intact vestibulocular reflex (e.g., physical activities such as sports, household chores).

A re-evaluation of tinnitus reliability testing.

The purposes of these investigations were to (1) evaluate tinnitus loudness measures of unskilled normal listeners asked to imagine that they are experiencing a constant monaural tonal tinnitus and (2) compare the performance of these listeners to that of a sample of patients with tinnitus. Subgroups of 24 patients participated in two investigations. Results suggest that (1) normal subjects asked to imagine a high-pitched, tonal tinnitus show significantly greater tinnitus loudness matching levels (a) when they do not have an external reference, (b) after a 1-week interval, and (c) for low-frequency matching tones; (2) patients with high-pitched tinnitus did not demonstrate statistically significant differences in tinnitus loudness judgments within or between sessions or frequencies; (3) tinnitus patients do not differ significantly from normals feigning tinnitus in the variability of tinnitus loudness matching levels within a single session (two measures) or after a 1-week interval (one measure); and (4) normals feigning tinnitus tended to choose significantly greater loudness matching levels than did tinnitus subjects.

Test-retest stability and short-term habituation of the N1 and gamma band response.

The gamma band response (GBR) is an exogenous, cortically generated, event-related potential that occurs between 20- and 170-msec post-stimulus onset. The auditory GBR is superimposed on the transient evoked middle and long latency cortical auditory evoked potentials and demonstrates a peak spectral frequency between 30 and 40 Hz. The present investigations were conducted to evaluate the test-retest stability and short-term habituation of the GBR. Both the GBR and N1 were recorded from six normal-hearing, neurologically intact subjects (Investigation 1, test-retest stability) and two subjects with intractable epilepsy with implanted subdural electrode grid arrays (Investigation 2, short-term habituation characteristics). For Investigation 1, the test-retest interval was 1 month. For Investigation 2, 300 samples were acquired per stimulus block (a 10-minute interval) and then subaveraged in blocks of 25 to 50 samples each. Results suggest that (1) like N1, the GBR shows high repeatability (qualitative) and test-retest stability (quantitative) and (2) the GBR does not demonstrate evidence of short-term habituation.

A screening version of the Dizziness Handicap Inventory (DHI-S).

OBJECTIVE: This study aimed to develop a screening version of the Dizziness Handicap Inventory (DHI). STUDY DESIGN: Three separate prospective investigations are reported that assess: 1) the equivalency of the screening version of DHI (DHI-S) for the DHI; 2) the test-retest reliability of the DHI-S; and 3) whether abnormal performance on balance function testing is associated with greater scores on the DHI-S. SETTING: The investigation was conducted in the Balance Function Laboratory of the Division of Audiology at Henry Ford Hospital, which is a tertiary care setting. PATIENTS: There were 281 consecutive patients (for investigations 1 and 2) and 45 consecutive patients (for investigation 3) seen for balance function testing. INTERVENTIONS: There was a 1-week interval between test and retest administrations of the DHI-S. MAIN OUTCOME MEASURES: Comparability of the DHI-S for the DHI and the test-retest reliability of the DHI-S were assessed with a Pearson Product-Moment correlation coefficient. Scores on the DHI-S for patients with and without abnormal balance function tests were assessed with an analysis of variance. RESULTS: Results showed that scores on the DHI-S had high comparability for the total score on the DHI (r=0.86). The short-term, test-retest reliability for the DHI was high (r=0.95). Abnormal performance on the sensory organization subtest of computerized dynamic posturography was associated with significantly greater scores on the DHI-S. CONCLUSIONS: Results support the contention that DHI-S is a psychometrically robust screening measure of self-perceived dizziness disability-handicap.

Recovery nystagmus revisited.

Recovery nystagmus (RN) describes a spontaneous nystagmus with a fast-phase beating toward the ipsilesional ear. The mechanisms underlying RN implicate central vestibular system compensation processes. The presence of RN is significant because it implies that function has returned from the affected peripheral vestibular system. A case is described where RN was recorded. The processes underlying RN are described.

Intraoperative monitoring with stimulus-evoked electromyography during placement of iliosacral screws. An initial clinical study.

A consecutive series of twenty-seven patients who had thirty acute unstable (type-C) fractures of the pelvic ring was studied prospectively to evaluate the use of stimulus-evoked electromyography to decrease the risk of iatrogenic nerve-root injury during the insertion of iliosacral screws. A prerequisite for inclusion in the study was a normal neurological status preoperatively; somatosensory evoked potentials were monitored to further document the neurological status both before and after insertion of the screw or screws. A total of fifty-one iliosacral screws were inserted, and a current threshold of more than eight milliamperes was selected as the level that indicated that the drill-bit was a safe distance from the nerve root. Four of the fifty-one screws were redirected because of information obtained with stimulus-evoked electromyography. Postoperatively, all patients had a normal neurological status. Computerized tomography, although not accurate for detailed measurements, demonstrated that all of the screws were in a safe, intraosseous position. Monitoring with stimulus-evoked electromyography appears to provide reliable data and may decrease the risk of iatrogenic injury to the nerve roots during operations on the pelvic ring.

High resolution recording of late cortical surface potentials N1 and gamma band response (GBR).

The present investigation was conducted to help determine whether source activity of the direct recorded N1 response differed from that of the gamma band response (GBR). Auditory evoked cortical potential data from two patients with intractable epilepsy undergoing prolonged video EEG monitoring after implantation of subdural electrodes is reported in this investigation. Evoked responses were recorded to 1000-Hz tone bursts. The data were then filtered digitally to resolve the GBR. The voltage fields were subsequently viewed topographically. Although both responses originated in the supratemporal cortex, the N1 and GBR voltage field patterns differed. These results are consistent with the view that the sources of N1 and the GBR are different, suggesting that these components emanate from functionally distinct neuronal pools.

Psychometric adequacy of the Tinnitus Handicap Inventory (THI) for evaluating treatment outcome.

This study assessed the test-retest reliability/repeatability and 95 percent confidence intervals (CIs) of the Tinnitus Handicap Inventory (THI) and developed categories for classifying self-perceived tinnitus handicap severity. Twenty-nine adults with tinnitus as their primary auditory complaint served as subjects. The THI was administered on two occasions (mean interval 20 days) using a paper-pencil format. Results support the contention that the THI is psychometrically robust. Specifically, the test-retest reliability/repeatability was high. Additionally, the 95 percent CI for the THI was 20-points, indicating that a 20-point or greater change had to occur from test to retest for a change to be considered statistically significant at the 5 percent confidence level. Quartiles calculated from raw scores were used to create a matrix of values representing tinnitus severity. We conclude that the THI is a brief, easily administered, and psychometrically robust measure that evaluates the impact of tinnitus on daily living.

Intraoperative stimulus-evoked electromyographic monitoring for placement of iliosacral implants: an animal model.

OBJECTIVE: A canine model was designed to evaluate the feasibility of stimulus-evoked electromyographic (EMG) monitoring of the lumbosacral nerve roots during the insertion of iliosacral implants. STUDY DESIGN/METHODS: Four 2.5-millimeter Kirschner wires (K-wires) were percutaneously inserted under general anesthesia into the S1 body of each of five dog hemipelves using C-arm fluoroscopy image-intensifier control in an actual attempt to compromise the S1 canal and the S1 nerve root. A searching current of twenty milliamperes was initially applied to the K-wire with monitoring electrodes placed in the gastrocnemius muscle. Current thresholds required to evoke an EMG response were recorded for each K-wire. Actual K-wire location was determined by anatomical dissection. RESULTS: Evaluation of these twenty wires revealed that current threshold was directly related to the proximity of the K-wire to the nerve root, with a correlation coefficient of 0.94 (p < 0.001). CONCLUSIONS: Stimulus-evoked EMG monitoring provided reliable data indicating the proximity of the iliosacral implants to the sacral nerve root. This method of intraoperative nerve monitoring could potentially decrease the risk of iatrogenic nerve root injury during pelvic ring surgery. Further study is warranted.

Self-focused and somatic attention in patients with tinnitus.

Self-focused and somatic attention were examined in a sample of 51 patients with tinnitus using the Self-Focus Sentence Completion Test, Private Self-Consciousness Subscale of the Self-Consciousness Scale, Modified Somatic Perception Questionnaire, and the Somatization Subscale of the Symptoms Checklist-90-Revised. Two subgroups of patients emerged following a cluster analysis of the attentional tasks. One group scored lower on both self-attention and somatic attention measures ("low self-attenders"), whereas a second group was more internally directed and scored higher on the attention measures ("high self-attenders"). Between-group comparisons showed that the high self-attenders were, on average, more depressed, had greater emotional distress due to tinnitus, and had greater perceived tinnitus handicap. In contrast, no differences were observed for pitch and loudness measures using either psychophysical or rating scale techniques. Results of this investigation support the belief that attentional mechanisms play an important role in patients' perception of tinnitus and should be considered when planning management strategies.

Factors affecting the recordability of auditory evoked response component Pb (P1).

The auditory middle latency response (AMLR) is characterized by two positive peaks (Pa, Pb) and two negative peaks (Na, Nb). The unpredictable nature of the second positive peak, Pb or P1, has made its diagnostic use problematic. Our purpose was to determine an appropriate combination of stimulating and recording variables that evoked a repeatable Pb in adults and children. Three experiments were designed to evaluate systematically the amplitude and latency of the Pb as a function of duration, stimulus type (500- and 4000-Hz tone bursts and clicks), repetition rate (0.5, 0.7, 1.1, 2.1, and 5.1/sec), and electrode array. Results showed that a longer duration (60 msec), low-frequency (500-Hz) tone burst consistently evoked the Pb in all subjects. Results also showed that a longer interstimulus interval (1.1/sec) is more likely to evoke the Pb component. Additionally, results showed that Pb is generally largest when recorded from a noninverting electrode at Fz with a noncephalic reference. Finally, results showed that Pb latency is significantly longer and amplitude larger in children than in adults.

Perceived hearing handicap of patients with unilateral or mild hearing loss.

Using the Hearing Handicap Inventory for Adults (HHIA), we assessed self-perceived hearing handicap in a sample of 63 patients having either unilaterally normal hearing or a mild hearing loss (pure tone average < or = 40 dB hearing level). Large intersubject variability in responses to the HHIA confirmed observations that reactions to minimal hearing impairment vary greatly among patients. The individual differences in responses highlight the importance of quantifying the perceived communication and psychosocial handicap, which cannot be determined from the audiogram alone. An item examination of responses to the HHIA revealed a number of emotional and social-situational problems encountered by patients with minimal hearing loss.