Examination of dynamic body balance using the body tracking test in cases of vestibular neuronitis

Body Tracking Test (BTT) is a testing method of the dynamic body balance function wherein movement of the center of gravity in accordance with a moving visual target stimulus is examined to evaluate the tracking function of the body. The objects were the patients who were diagnosed as having vestibular neuronitis at the Department of Otolaryngology in Toho University medical center Sakura hospital, and were undergoing hospital treatment. Lateral BTT was performed in 31 subjects, and antero-posterior (A-P) BTT in 45 subjects. Although gaze nystagmus was noted, inspection was enforced when a standing position posture was possible. In lateral BTT, the average (cm/second) horizontal direction body sway speed was compared, however, no clear lateral difference was noted. In the antero-posterior (A-P) BTT, it inquired using the direction body sway average center displacement (cm) of X. Deviation was seen by the affected side in stabilometry. Deviation was seen by the unaffected side in the antero-posterior (A-P) BTT. This phenomenon differs from the deviation pattern until now and is considered to involve participation of the higher centers.     

Postural control in the elderly]

In order to investigate postural control in the elderly, a stabilometric investigation including fast Fourier Transform (FFT) analysis was conducted in three different age groups. The oldest group was composed of 16 subjects who ranged in age from 75 to 86 years: another group consisted of eight 65 to 74 year olds; the control group was composed of 21 young students. The subject was instructed to stand and look for 30 seconds at a spot in a CRT 50 cm ahead of his eyes, and to control body sway as indicated by the gravitational spot in the CRT. The subject was then told to stand with eyes closed for 30 seconds. Next, a 100 Hz vibratory stimulation was applied to the bilateral Achilles tendon in each trial. The data was filtered with a 10 Hz high cut filter and digitized at 25 Hz, and subsequently analyzed by a microcomputer (PC9801 VM 2). Thus, statistical analysis was performed in terms of area, length, and total frequency spectra from 0.10 Hz to 10.0 Hz in both lateral and antero-posterior directions. Sixteen power spectra of 0.249 Hz step from 0.10 to 3.96 Hz were demonstrated in the CRT and were also compared with those of the young group. When standing naturally, significant increases in body sway were found in terms of area, length, and total frequency spectra in the most elderly group as compared with the other two groups. There was no significant change in Romberg ratio between the elderly and the young groups. However, FFT analysis confirmed the influence of visual cues. When vibration was applied, no increases in body sway with regard to these parameters were demonstrated in the elderly, whereas significant increases were found in the young control group. This was especially evident in the eyes-closed trials, as previously reported. There were few increased frequency ranges in either lateral or antero-posterior sway in the elderly. This might suggest that proprioceptive afferent information play a less important role in elderly than in young subjects. When the subject was requested to minimize his own sway by utilizing visual feedback, no difference was found in this parameter between the elderly and young groups. However, FFT analysis of the elderly group revealed an increase of the power spectra close to 1.0 Hz in both lateral and antero-posterior sway, whereas increases of approximately 1.0 and 2.0 Hz in the power spectra and a decrease in the power spectrum from 0.10 to 0.29 Hz were found in both directions in young subjects.(ABSTRACT TRUNCATED AT 400 WORDS)     

The deviation of the body's sway center with galvanic stimulation

We investigated galvanic body sway of ten healthy adults and eight patients by using the averaging program for measuring T1 and T2, which were latencies at the onset and at the cutoff of galvanic stimulation, respectively, and the plotting program, which adopted 1.73 sec as T1 and 0.39 sec as T2, for calculating the coordinates of the body's sway center. We estimated galvanic body sway with the difference between the coordinate of the body's sway center during stimulation and that during no stimulation. The deviation in lateral direction on the healthy subjects ranged from 0.7 or 0.9 to 2.1 cm at right- or left-side stimulation. One of the patients with peripheral disorders revealed differences between right- and left-side stimulation. The other patients did not reveal any differences. In antero-posterior direction six of the healthy subjects deviated backward at right-side stimulation and nine subjects deviated backward at left-side stimulation. The patients with peripheral disorders did not reveal any differences. The other patients revealed some differences. Waves computed by the averaging program do not always show the quantity of galvanic body sway. The deviation of the body's sway center shows the quantity of body sway consistently. The body's sway center is considered to be a suitable parameter in the galvanic body sway test for statistical analysis.     

Effects of eye tracking stimulation on movement of body's center of gravity and head in elderly subjects]

This study was designed to investigate the effects of eye tracking stimulation on the movement of the body's center of gravity (CG) and the head in aged persons 60 years old and above. Twenty-three healthy aged subjects ranging from 60 to 79 years old and 10 healthy young subjects were asked to pursue a pendulously moving horizontal target when standing with the feet together. The frequencies of target movement were 0, 0.1, 0.25, 0.5, 0.75, 1.0 and 1.5 Hz. The results were as follows: 1) The body sway locus patterns increased significantly up to around 0.5 Hz of target movement. 2) The total lengths of the locus traced by CG movement and the head movement were larger than that of control subjects throughout the test runs. The aged subjects were also affected by eye tracking stimulation, and showed individual variations. 3) The ratio of the anteroposterior component to the lateral component of CG movement was higher in the elderly subjects than in the control subjects, while head movement was characteristically different. 4) The averaged divisional frequencies were calculated in the range between 0.0195 and 1 Hz. In the anteroposterior component, the averaged divisional frequencies of CG movement and head movement were significantly larger while watching the moving target than when watching a stationary target.     

Quantitative evaluation of the upper airway during nasopharyngoscopy with the Müller maneuver.

OBJECTIVE: To quantitatively examine changes in the upper airway caliber of normal subjects at graded negative inspiratory pressures generated during nasopharyngoscopy with a Müller maneuver. STUDY DESIGN: Eighteen normal subjects prospectively underwent nasopharyngoscopy with Müller maneuvers. Subjects performed graded and maximal effort Müller maneuvers while sitting upright, and maximal-effort Müller maneuvers in the supine position. Two regions of the upper airway--the retropalatal and retroglossal--were examined. METHODS: Images from the endoscopic examination were objectively analyzed by adjusting manually traced airway contours using full-width, half-maximum edge detection algorithm software. The adjusted tracings' area and dimensions through the airway centroid were measured. RESULTS: Müller maneuvers performed at -40 cm H2O resulted in a 64%+/-17% (P = .0001) reduction in upper airway area that consisted of a 51%+/-20% (P = .0001) reduction in the lateral dimension and a 21%+/-24% (P = .0026) reduction in antero-posterior dimension. Müller maneuvers in the retroglossal region did not significantly reduce airway area (P = .575), but demonstrated an altered airway conformation that consisted of lateral narrowing and an increase in antero-posterior dimension. Changes in body position did not result in significant differences in either airway caliber or airway dimension. CONCLUSIONS: Airway caliber during forced inspiration is mediated primarily through changes in the lateral pharyngeal walls. This study has also shown that antero-posterior and lateral airway structures are largely independent in their response to Müller maneuvers. Similarly, the retropalatal and retroglossal regions of the upper airway respond differently to forced negative intraluminal pressure.     

Accuracy of cochlear implant recipients on pitch perception, melody recognition, and speech reception in noise

OBJECTIVE: The purposes of this study were to (a) examine the accuracy of cochlear implant recipients who use different types of devices and signal processing strategies on pitch ranking as a function of size of interval and frequency range and (b) to examine the relations between this pitch perception measure and demographic variables, melody recognition, and speech reception in background noise. DESIGN: One hundred fourteen cochlear implant users and 21 normal-hearing adults were tested on a pitch discrimination task (pitch ranking) that required them to determine direction of pitch change as a function of base frequency and interval size. Three groups were tested: (a) long electrode cochlear implant users (N = 101); (b) short electrode users that received acoustic plus electrical stimulation (A+E) (N = 13); and (c) a normal-hearing (NH) comparison group (N = 21). Pitch ranking was tested at standard frequencies of 131 to 1048 Hz, and the size of the pitch-change intervals ranged from 1 to 4 semitones. A generalized linear mixed model (GLMM) was fit to predict pitch ranking and to determine if group differences exist as a function of base frequency and interval size. Overall significance effects were measured with Chi-square tests and individual effects were measured with t-tests. Pitch ranking accuracy was correlated with demographic measures (age at time of testing, length of profound deafness, months of implant use), frequency difference limens, familiar melody recognition, and two measures of speech reception in noise. RESULTS: The long electrode recipients performed significantly poorer on pitch discrimination than the NH and A+E group. The A+E users performed similarly to the NH listeners as a function of interval size in the lower base frequency range, but their pitch discrimination scores deteriorated slightly in the higher frequency range. The long electrode recipients, although less accurate than participants in the NH and A+E groups, tended to perform with greater accuracy within the higher frequency range. There were statistically significant correlations between pitch ranking and familiar melody recognition as well as with pure-tone frequency difference limens at 200 and 400 Hz. CONCLUSIONS: Low-frequency acoustic hearing improves pitch discrimination as compared with traditional, electric-only cochlear implants. These findings have implications for musical tasks such as familiar melody recognition.     

Observations on conduction of caloric stimulation to the middle ear cavity by thermoscanning

OBJECTIVE: To elucidate the ways in which caloric stimulation conducts and the temperature recovers on the temporal bone by the caloric stimulation test. METHODS: Four cases examined temperature changes of the bony lateral semicircular canal eminence with thermal images by caloric stimulation tests. Changes in the heat distribution were observed by means of a Thermoscan (Nihondenki Sanei Thermotracer 6T67R, Tokyo, Japan). RESULTS: The temperature began to decrease from the external canal and the decrease reached the posterior cranial fossa plate through the middle ear cavity while the stimulation continued. After the end of stimulation, the stimulation advanced in the direction opposite to the order in which it was transmitted and recovered in a manner resembling a mirror image despite the difference in speed. CONCLUSIONS: The way in which the caloric stimulation was conducted and the way in which the temperature recovered were in the opposite direction.     

Interaural cross correlation of event-related potentials and diffusion tensor imaging in the evaluation of auditory processing disorder: a case study

In a previous publication (Jerger et al, 2002), we presented event-related potential (ERP) data on a pair of 10-year-old twin girls (Twins C and E), one of whom (Twin E) showed strong evidence of auditory processing disorder. For the present paper, we analyzed cross-correlation functions of ERP waveforms generated in response to the presentation of target stimuli to either the right or left ears in a dichotic paradigm. There were four conditions; three involved the processing of real words for either phonemic, semantic, or spectral targets; one involved the processing of a nonword acoustic signal. Marked differences in the cross-correlation functions were observed. In the case of Twin C, cross-correlation functions were uniformly normal across both hemispheres. The functions for Twin E, however, suggest poorly correlated neural activity over the left parietal region during the three word processing conditions, and over the right parietal area in the nonword acoustic condition. Differences between the twins' brains were evaluated using diffusion tensor magnetic resonance imaging (DTI). For Twin E, results showed reduced anisotropy over the length of the midline corpus callosum and adjacent lateral structures, implying reduced myelin integrity. Taken together, these findings suggest that failure to achieve appropriate temporally correlated bihemispheric brain activity in response to auditory stimulation, perhaps as a result of faulty interhemispheric communication via corpus callosum, may be a factor in at least some children with auditory processing disorder.     

Effects of optokinetic stimulation on head movement and body sway of children

We evaluated the effects of horizontal and vertical optokinetic stimulation on head movement (HM) and body sway (BS) in children and adults, using a Jung type optokinetic stimulator, a strain gauge-platform, and a encephalography. Twenty healthy children aged 7 to 9 years and twenty healthy adults aged 20 to 26 years were instructed to stand with feet close together on the platform with eyes open with and without optokinetic stimulation for 60 seconds. In all subjects, optokinetic stimulation significantly increased the total lengths of HM and BS. In addition, optokinetic stimulation significantly increased the areas of HM and BS in children, but not in adults. Although the ratio of the anteroposterior component to the lateral component in BS was significantly higher in children than in adults, the value of HM was not. Children exhibited a characteristic BS in which the anteroposterior swaying velocity was larger than the lateral swaying velocity. In the anteroposterior component, averaged divisional frequencies of BS were significantly larger in children than in adults. However, averaged divisional frequencies in the lateral component of BS and those in the anteroposterior and lateral components of HM did not differ between the two age groups. The ratio of the total length of HM to that of BS was significantly higher in children than in adults. These results suggest that HM and BS of children are readily affected by optokinetic stimulation, and that in children, the BS velocity in the anteroposterior direction is higher than that in the lateral direction.     

The effect of stimulus predictability and age on human tracking eye movements

Human tracking eye movements were recorded in healthy volunteers of varying age. The target motion was either predictable (pure sinusoids or sinusoidal frequency sweep) or unpredictable (pseudorandomized). Gain and phase values for the tracking and the smooth pursuit eye movement signal were calculated as a function of target frequency from 0.2 to 2 Hz. Max. target velocity was 20 or 40 deg/sec. In the low frequency area the smooth pursuit gain for predictable stimulation was higher than the gain elicited by the pseudorandomized stimulation. In the high-frequency area, gain values did not differ significantly. For the predictable stimulation, the phase of the smooth component was always a lag, increasing with increasing frequency. At low frequencies of the pseudorandomized signal a phase lead was observed. At higher frequencies the lead turned into a lag that was greater than for the predictable stimulation. The young and old groups showed reduced smooth pursuit gain values, compared with the main group specially when the target waveform was pseudorandomized. The reduced smooth pursuit ability was mostly compensated for by an increased amount of saccades.     

Optokinetic and vestibular interactions with smooth pursuit: psychophysical responses.

The effect was evaluated in normal subjects of the subjective perception of motion of a small visual target (VT) when combined with the effect of vestibular stimulation produced by different magnitudes of constant angular accelerations in the dark or the effect of optokinetic stimulation produced by different constant velocities of rotation. The visual target appeared to the subject to travel more slowly and for a shorter duration when it moved in the direction of the body's angular acceleration or against that of the optokinetic drum. The perceived error in motion was: (i) in the same direction as the subject's motion sensation produced by either of the two stimuli, and (ii) quantitatively related, although differently, to the magnitude of each of the two stimulus modalities; an heuristic model is proposed to account for these observations.     

Effect of retroauricular galvanic stimulation on the central vestibular system--immunohistochemical evaluation of GABA

The changes of the neurotransmitter (GABA) distribution in the brain stem of the rats by retroauricular galvanic stimulation were investigated using immunohistochemical method. Twenty-one rats were divided into two groups: the control group which received no galvanic stimulation, and the galvanically stimulated group which received anodal galvanic stimulation (unipolar monoauricular, 5 mA in intensity, 500 msec of duration, 1 Hz in frequency) for 30 minutes. The specimens obtained as usual strict procedure for histological investigation were stained immunohistochemically using antisera against GABA. The results were as follows: 1. In the control group, GABA-like immunoreactivity was observed in all four main vestibular nuclei. In the superior, medial, and descending vestibular nuclei GABA-like immunoreactivity was found in the small cells and the terminals. Giant cells in the lateral vestibular nucleus were surrounded by GABA immunoreactive terminals. 2. In the galvanically stimulated group GABA-like immunoreactivity showed recognizable laterality in the lateral vestibular nucleus where GABA-like immunoreactivity surrounding giant cells showed more intensive on the side ipsilateral to the stimulation compared with the opposite side. On the other hand GABA-like immunoreactivity showed no laterality in the superior, medial, and descending vestibular nuclei. 3. It can be concluded that the retroauricular galvanic stimulation cause some changes in the inhibitory activity of the lateral vestibulo-spinal tract and of the spinal motor neuron.     

Pitch ranking with deeply inserted electrode arrays

OBJECTIVE: Electrode pitch ranking was assessed as a function of cochlear region, electrode spacing, and stimulation rate in eight subjects implanted with the MED-EL COMBI 40+ implant. The MED-EL COMBI 40+ electrode array allows deep insertion of the electrode up to the apex of the cochlea and provides a wide electrode spacing of 2.4 mm. DESIGN: The pitch of a reference electrode was compared with the pitch of two apical and two basal probe electrodes using a two-alternative forced-choice procedure. The reference electrodes were placed in the apical region, in the middle region, and in the basal region of the cochlea. Each condition was tested at pulse rates of 1515 pps, 500 pps, and 250 pps. RESULTS: Electrode pitch ranking did not depend on electrode spacing, the position of the reference electrode in the cochlea, or stimulation rate. CONCLUSIONS: These results indicate that a spacing of 2.4 mm seems sufficient to allow good electrode pitch ranking performance for the average user and that electrode pitch ranking is similar in the apical, middle, and basal region of the cochlea, irrespective of the stimulation rate. Most importantly, the results of this study indicate that residual neural structures in the apical region of the cochlea are sensitive to pitch changes provided by different places of electrical stimulation.     

Contribution of eye position to movement perception

OBJECTIVE: To investigate the influence of gaze eccentricity on movement perception during asymmetric vestibular stimulation. MATERIAL AND METHODS: Subjects (n = 10) were placed on a rotating platform and oscillated asymmetrically in the dark. Subjects were asked to reproduce with a pointer the location in space of a light spot that was turned off at the beginning of the oscillation. The target was presented in centric and eccentric (0 degrees, 20 degrees and 40 degrees) positions. RESULTS: In the centric position a large shift from the real position of the target was observed in the opposite direction to that of the faster vestibular stimulation. The shift increased when the target was placed eccentrically toward the slower vestibular stimulation side and decreased when it was placed in the opposite direction. CONCLUSION: The dependence of rotation perception on the target position suggests that the eye deviation, imposed by the eccentricity of the target, is able to influence the perception of body movement and may modulate the internal reference frame.     

Postural behaviour responses to visual stimulation in patients with vestibular disorders

Patients with different vestibular disorders exhibit changes in postural behaviour when they receive visual stimuli, reproducing environmental stimulation. Postural control was studied using an AMTI Accusway platform, measuring the confidential ellipse (CE) and sway velocity (SV). Postural responses were recorded according to the following stimulation paradigm: i) without specific stimuli; ii) smooth pursuit with pure sinusoids of 0.2 Hz (foveal stimulation); and iii) optokinetic stimulation (retinal stimuli). Patients with central vestibular disorders (CVD), cerebellar damage and unilateral peripheral vestibular lesions (UPVL) in asymptomatic periods were studied. A group of normal subjects was studied as control. Signal processing was done with a scalogram by wavelets in order to observe the relation between time and frequency in postural control. While patients with CVD and cerebellar disease showed a significant increase in CE and SV in the three conditions of the paradigm compared to the normal group, the patients with UPVL showed no change. Wavelets processing showed that the main sway occurs in the Y axis (antero-posterior) and below at 0.4 Hz in normal subjects, while the CVD and cerebellar patients showed sway frequencies in both the X and Y axes. The clinical implications of these findings are discussed.     

Dehiscence of the greater palatine nerve. A risk factor in inferior turbinectomy?

Inferior turbinectomy, often combined with septal surgery, is frequently performed in the surgical treatment of nasal obstruction. A patient with post-operative greater palatine anaesthesia occurring after this procedure prompted a study of the anatomy of the greater palatine nerve in the region of the inferior turbinate. Sixty-four lateral nasal walls were examined in cadavers. A dehiscence rate of 22% was noted, and in an additional 55% there was only a minimal bony covering to the nerve. Dehiscences occurred exclusively in the inferior meatus, anterior to the posterior bony end of the inferior turbinate. The narrow antero-posterior extent of the dehiscence, the hard dense lateral nasal wall bone and the lateral position of the nerve in the canal help to protect the nerve from surgical trauma during turbinate surgery.     

Postural Behaviour Responses to Visual Stimulation in Patients with Vestibular Disorders

Patients with different vestibular disorders exhibit changes in postural behaviour when they receive visual stimuli, reproducing environmental stimulation. Postural control was studied using an AMTI Accusway platform, measuring the confidential ellipse (CE) and sway velocity (SV). Postural responses were recorded according to the following stimulation paradigm: i) without specific stimuli; ii) smooth pursuit with pure sinusoids of 0.2 Hz (foveal stimulation); and iii) optokinetic stimulation (retinal stimuli). Patients with central vestibular disorders (CVD), cerebellar damage and unilateral peripheral vestibular lesions (UPVL) in asymptomatic periods were studied. A group of normal subjects was studied as control. Signal processing was done with a scalogram by wavelets in order to observe the relation between time and frequency in postural control. While patients with CVD and cerebellar disease showed a significant increase in CE and SV in the three conditions of the paradigm compared to the normal group, the patients with UPVL showed no change. Wavelets processing showed that the main sway occurs in the Y axis (antero-posterior) and below at 0.4 Hz in normal subjects, while the CVD and cerebellar patients showed sway frequencies in both the X and Y axes. The clinical implications of these findings are discussed.     

Dual electrode stimulation using the nucleus CI24RE cochlear implant: electrode impedance and pitch ranking studies

OBJECTIVE: The first aim of the study was to determine the reduction in electrode impedances using dual electrode stimulation compared with single electrode stimulation in the new Nucleus CI24RE receiver-stimulator. The CI24RE is connected to the Nucleus 22-electrode intracochlear array. Dual electrode stimulation is produced by electrically coupling two adjacent single electrodes. The second aim was to determine whether dual electrode stimulation produced pitch percepts that were intermediate to the pitch of the two adjacent single electrodes. DESIGN: Eight postlingually hearing-impaired adults with severe to profound loss, implanted with the CI24RE, participated in the study. Electrode impedances were measured by using the standard telemetry function of the system. A pitch ranking task was used to measure pitch for dual and single electrodes. Seven sets of three electrodes along the electrode array were tested. Each set of electrodes consisted of a dual electrode and the two adjacent single electrodes. Pitch ranking was measured using a two-alternative forced choice procedure, with the three electrodes in each set paired with each other as AB and BA pairs. The subject indicated which of the two stimuli had the higher pitch. Random variation in current level was used to remove any loudness cues. RESULTS: The average electrode impedance was 38.6% lower for dual electrodes compared with single electrodes. Three subjects were able to successfully rank the three electrodes in each set in the expected tonotopic order for all seven sets of electrodes along the array. Three other subjects were able to rank sets of electrodes in the tonotopic order for most of the tested positions on the array. The remaining two subjects gave more variable pitch ranking across positions along the array, although successful tonotopic ranking was demonstrated for several sets of electrodes. CONCLUSIONS: Dual electrode stimulation with the CI24RE receiver-stimulator produced systematically lower electrode impedances and was capable of producing pitch percepts that were intermediate to those produced by the corresponding adjacent single electrodes. This makes available up to 43 channels of stimulation from 22 single electrodes.     

Simple assessment of olfaction in patients with chronic rhinosinusitis

Conclusion: The brief-smell identification test (B-SIT) can substitute for the butanol threshold test (BTT) in screening of anosmia and postoperative assessment of olfactory outcomes in patients with chronic rhinosinusitis (CRS). A time-effective test battery composed of B-SIT and the visual analog scale (VAS) can be implemented for simple olfactory assessment in any otolaryngology clinic. Objectives: Anosmia is a distinct clinical entity requiring special attention. Unpredictable olfactory outcomes after surgery make preoperative assessment more important. We compared the results of the BTT, B-SIT, and VAS to investigate whether B-SIT or VAS can substitute for BTT in screening of anosmia and postoperative follow-up. Methods: We collected data on 68 CRS patients who had bilateral CRS and underwent endoscopic sinus surgery. Olfactory performance was graded using the BTT: normosmia, hyposmia, or anosmia. VAS and B-SIT were also performed. All tests were repeated 6 months after surgery. Postoperative improvement was defined by an increase of the BTT score ≥ 2. Results: The B-SIT and VAS scores of the anomics were significantly lower than those of the normosmics. B-SIT discriminated anosmia with high specificity. Within the improvement group, postoperative increase of B-SIT/VAS score showed significance. However, neither the B-SIT nor the VAS differentiated between no change and deterioration of olfaction.     

The effects of distraction on smooth pursuit in normal subjects

Smooth pursuit eye movements made in response to 5 and 20% targets were studied in young and old subjects. Tracking of a target was carried out both with no competing stimuli and while auditory and visual distractions were presented. Only tracking the target against a projected background significantly impaired pursuit. It did so in both age groups, by reducing pursuit gain and also by eliciting 'anticipatory saccades', which took the eyes ahead of the target to a new fixation point for 0.5 s or longer. Elderly subjects showed a significantly greater number of such interruptions, however, suggesting that continuous performance of the tracking task could be more readily disrupted in this group. These findings may arise from changes in the way in which elderly individuals process incoming sensory information.