Journal of Vestibular Research - Volume 16, issue 4-5

Authors: Shinder, Michael E. | Ramanathan Jr., Murugappan | Kaufman, Galen D.

Article Type: Research Article

Abstract: Commercial microarrays were used to identify transcriptome expression within vestibular related brain regions (vestibular brainstem and cerebellum, and caudotemporal cortical regions) during the acute period of recovery following unilateral surgical vestibular labyrinth ablation in the gerbil. As a representative model of vestibular compensation, vestibular lesions in the gerbil produced activation in a common set of genes related to vestibular compensation. The total RNA was prepared and amplified using Affymetrix Gene Chip™ probes from the Rat U34 Neurobiology and R230, and Mouse M430 gene sets, resulting in GCRMA summarized data from S+AA software. Matched rat and mouse genes from gerbil hybridization …produced good interspecies synteny. Multiple gene target trends supported global increases in neuron excitability throughout the vestibular brainstem and cerebellum. We focused further on gene expression with anatomically asymmetric activation relative to the lesion, indicative of involvement in rebalancing central vestibular tone during the vestibular compensation process. Cluster analysis revealed distinct spatial (regional and ipsi-contra) and temporal patterns. The asymmetric genes were part of well-defined neuron-related networks and included multiple members of the glutamate and GABA neurotransmitter systems. Transcripts for D3 dopamine, glycine, and some GABA receptor signals increased quickly in the ipsilesional vestibular complex and then increased gradually in the contralateral region, restoring the expression symmetry. Alternatively, the NMDA binding subunit decreased gradually over the acute compensation period in the contralateral vestibular complex. There was evidence for numerous associations between signaling systems with PKC as one possible mediator between early changes in GABA and progressive changes in NMDA signaling. These data begin to define the compensatory response at the level of molecular cascades. Show more

Keywords: Plasticity, labyrinthectomy, flocculus, gene expression, cerebellum, vestibular

DOI: 10.3233/VES-2006-164-501

Citation: Journal of Vestibular Research, vol. 16, no. 4-5, pp. 147-169, 2006

Authors: Lozada, Adrian | Karlstedt, Kaj | Panula, Pertti | Aarnisalo, Antti A.

Article Type: Research Article

Abstract: In the auditory periphery, GDNF has been shown to have a trophic effect to spiral ganglion neurons, both during development and in adult animals. We have studied the effect of unilateral labyrinthectomy (UL) on protein levels and expression of GDNF multicomponent receptor complex: the ret tyrosine kinase and coreceptor GFRα-1 in the medial vestibular nucleus of the adult rat. GFRα-1 protein levels display an increasing trend in ipsilateral medial vestibular nucleus culminating at 48 h post UL. On the other hand, GFRα-1 mRNA expression levels in ipsi- and contralateral medial vestibular nucleus show a steadily decreasing trend that is significant …at 1 week post-lesion. Protein levels for c-Ret isoforms also show an initial bilateral decreasing trend that ceases at 48 h in ipsilateral medial vestibular nucleus but persists on the contralateral side. c-Ret mRNA expression levels show a significant decrease at 4 h post UL followed by another significant decrease 1 week post UL. Our data would suggest that neurotrophins belonging to the GDNF family are involved in this model of post-lesional CNS plasticity. Show more

Keywords: GDNF, rat, c-ret, GFRα-1, vestibular compensation

DOI: 10.3233/VES-2006-164-502

Citation: Journal of Vestibular Research, vol. 16, no. 4-5, pp. 171-177, 2006

Authors: Van Cleave, S. | Shall, M.S.

Article Type: Research Article

Abstract: Children with hearing deficits and hypofunctioning vestibular receptors frequently have delayed motor development. This study focuses on when the vestibular system needs to be active for normal motor behavior development and the maturation of the soleus muscle in the ferret. Both vestibular labyrinths were removed from ferrets at Postnatal day 10 (P10), P21, or P45 and the resulting data were compared with ferrets that had undergone a sham surgery at the same ages. The animals were sacrificed at P120 (young adult ferret). The resulting data from these ferrets revealed that standing and walking balance was significantly affected when the vestibular …system was eliminated at or before P21. The soleus of P10 and P21 animals generally had smaller diameter muscle fibers and proportionally less type I Myosin Heavy Chain (MHC) and more type IIX MHC. The twitch contraction time of the soleus of the P21 group was significantly slower than the other groups. It appears that the vestibular system is important to motor and muscle fiber development in the ferret during the period before P21. The eyes are still closed at that age and all of the vestibular receptors are not fully mature. These findings imply a "critical period" for vestibular sensation and the development of a muscle that is important to standing balance. Show more

Keywords: Vestibular system, ferret, development, balance, soleus

DOI: 10.3233/VES-2006-164-503

Citation: Journal of Vestibular Research, vol. 16, no. 4-5, pp. 179-186, 2006

Authors: Isaacson, Brandon | Murphy, Emily | Cohen, Helen

Article Type: Research Article

Abstract: The objective of this study was to assess the effects of different methods of sternocleidomastoid muscle (SCM) activation on vestibular evoked myogenic potentials (VEMP). Forty normal volunteers were tested using three different methods of SCM activation: sitting with the head turned away from the test ear (SIT), supine with the head held straight up (SHU), and supine with the head held up and turned away from the test ear (SHT). Dependent measures were latency, and amplitude. Head and body position significantly affected the amplitude of the VEMP, but had no significant effect on latency. Testing subjects in the supine position …with the head up and turned toward the non-test ear yielded the most robust amplitude response and sternocleidomastoid EMG activity. When amplitude measures where corrected according to tonic electromyographic (EMG) activity no significant difference was noted between the three different test positions. The increased amplitude in the supine with head turned position can be directly attributed to increased tonic SCM EMG activity. Show more

Keywords: Vestibular evoked myogenic potentials, otoliths, saccule

DOI: 10.3233/VES-2006-164-504

Citation: Journal of Vestibular Research, vol. 16, no. 4-5, pp. 187-191, 2006

Authors: Markham, Charles H. | Diamond, Shirley G.

Article Type: Research Article

Abstract: Nineteen normal subjects underwent two naso-occipital rotations to 90° right and left ear down in our standard ocular counterrolling (OCR) protocol. Both eyes were videotaped. Following two rotations, subjects drank 90~ml vodka in 180 ml orange juice; and in about 20 min, when blood alcohol levels reached 0.04–0.09%, the protocol was repeated. An SMI videooculography system provided measurements. Results showed that amplitude of OCR was significantly decreased after alcohol ingestion; smoothness was significantly increased after alcohol, similar to alcohol's effect on essential tremor. Although disconjugacy was not significantly different in the two conditions when the entire trials were examined, the …latter portions of the post-alcohol trials did show significant disconjugacy, similar to earlier findings in vestibular-defective patients whose OCR deficits were apparent only in the final segments of the rotation trials. We postulate the results are due to alcohol's action on cerebellar GABAergic Purkinje cells projecting to vestibular nuclei. Show more

Keywords: Ocular counterrolling, alcohol, otolith, vestibular

DOI: 10.3233/VES-2006-164-505

Citation: Journal of Vestibular Research, vol. 16, no. 4-5, pp. 193-199, 2006

Authors: Ferraresi, Aldo | Azzena, Gian Battista | Troiani, Diana

Article Type: Research Article

Abstract: Sinusoidal vestibular stimulation induces in the intact rabbit in prone position a periodic alternating drift (PAD), evident in the earth horizontal plane when the animal is rotated about the vertical axis but weak in the vertical one when the animal is rotated about the longitudinal axis. It has been hypothesized that these oscillations are related to an intrinsic instability of the velocity storage, due to the length of its time constant. The velocity storage has the longest time constant aligned with the vertical axis, and it changes its orientation with the gravity vector. The present research examined the spatial orientation …of PAD in relation to changes of the animal position with respect to gravity. Normal pigmented rabbits were sinusoidally oscillated about their longitudinal axes to evoke vertical eye responses. The stimulation was carried out with the animal in prone position and with the animal in nose-up condition. With the animal in prone position, PAD had a weak vertical component, but an evident horizontal component was visible. When the animal was in nose-up position, the horizontal component of PAD was clearly visible, while the vertical component was negligible. In both stimulation conditions PAD period and peak velocity were not modulated by the stimulus characteristics. These results are consistent with a model of PAD based on an interaction between velocity storage and the cerebellar adaptation-habituation circuit. Show more

Keywords: Vestibulo-ocular reflex, rabbit, velocity storage, gravity, cerebellum

DOI: 10.3233/VES-2006-164-506

Citation: Journal of Vestibular Research, vol. 16, no. 4-5, pp. 201-207, 2006

Authors: Furman, Joseph M. | Redfern, Mark S. | Jacob, Rolf G.

Article Type: Research Article

Abstract: Previous studies of vestibulo-ocular function in patients with anxiety disorders have suggested a higher prevalence of peripheral vestibular dysfunction compared to control populations, especially in panic disorder with agoraphobia. Also, our recent companion studies have indicated abnormalities in postural control in patients with anxiety disorders who report a high degree of space and motion discomfort. The aim of the present study was to assess the VOR, including the semicircular canal-ocular reflex, the otolith-ocular reflex, and semicircular canal-otolith interaction, in a well-defined group of patients with anxiety disorders. The study included 72 patients with anxiety disorders (age 30.6 +/− 10.6 yrs; …60 (83.3% F) and 29 psychiatrically normal controls (age 35.0 +/minus; 11.6 yrs; 24 (82.8% F). 25 patients had panic disorder; 47 patients had non-panic anxiety. Patients were further categorized based on the presence (45 of 72) or absence (27 of 72) of height phobia and the presence (27 of 72) or absence (45 of 72) of excessive space and motion discomfort (SMD). Sinusoidal and constant velocity earth-vertical axis rotation (EVAR) was used to assess the semicircular canal-ocular reflex. Constant velocity off-vertical axis rotation (OVAR) was used to assess both the otolith-ocular reflex and static semicircular canal-otolith interaction. Sinusoidal OVAR was used to assess dynamic semicircular canal-otolith interaction. The eye movement response to rotation was measured using bitemporal electro-oculography. Results showed a significantly higher VOR gain and a significantly shorter VOR time constant in anxiety patients. The effect of anxiety on VOR gain was significantly greater in patients without SMD as compared to those with SMD. Anxiety patients without height phobia had a larger OVAR modulation. We postulate that in patients with anxiety, there is increased vestibular sensitivity and impaired velocity storage. Excessive SMD and height phobia seem to have a mitigating effect on abnormal vestibular sensitivity, possibly via a down-weighting of central vestibular pathways. Show more

Keywords: Space and motion discomfort, off-vertical axis rotation, height phobia

DOI: 10.3233/VES-2006-164-507

Citation: Journal of Vestibular Research, vol. 16, no. 4-5, pp. 209-215, 2006

Authors: Ozeki, Hidenori | Iwasaki, Shinichi | Ushio, Munetaka | Takeuchi, Naonobu | Murofushi, Toshihisa

Article Type: Research Article

Abstract: Ramsay Hunt syndrome (RHS) is characterized by vestibulocochlear dysfunction in addition to facial paralysis and auricular vesicles. The present study investigated the lesion site of vestibular dysfunction in a group of 10 RHS patients. Caloric testing, vestibular evoked myogenic potentials by click sound (cVEMP) and by galvanic stimulation (gVEMP) were used to assess the function of the lateral semicircular canal, saccule, and their afferents. The results of caloric testing (all 10 cases showed canal paresis) mean the existence of lesion sites in lateral semicircular canal and/or superior vestibular nerve (SVN). Abnormal cVEMPs in 7 patients mean the existence of lesions …in saccule and/or inferior vestibular nerve (IVN). Four of the 6 patients with absent cVEMP also underwent gVEMP. The results of gVEMP (2 absent and 2 normal) mean that the former 2 have lesions of the vestibular nerve, and the latter 2 have only saccular lesions concerning the pathway of VEMPs. Thus, our study suggested that lesion sites of vestibular symptoms in RHS could be in the vestibular nerve and/or labyrinth, and in SVN and/or IVN. In other words, in the light of vestibular symptoms, there is the diversity of lesion sites. Show more

Keywords: Vestibular nerve, otolith, saccule, vestibular neuritis, labyrinthitis, varicella-zoster virus

DOI: 10.3233/VES-2006-164-508

Citation: Journal of Vestibular Research, vol. 16, no. 4-5, pp. 217-222, 2006

Authors: Pavlou, Marousa | Davies, Rosalyn A. | Bronstein, Adolfo M.

Article Type: Research Article

Abstract: Patients with chronic vestibular dysfunction often experience visually-induced aggravation of dizzy symptoms (visual vertigo; VV). The Situational Characteristics Questionnaire (SCQ), Computerized Dynamic Posturography or Rod and Frame Test (RFT) are used to assess VV symptoms. This study evaluates whether correlations exist between these three tests, their ability to identify patients with VV and whether emotional state correlates with VV symptoms. Tests were completed by 20 normal controls (Group NC), 20 patients with vestibular dysfunction plus VV (Group VV) and 13 without VV (Group NVV). Additionally, the Vertigo Symptom Scale (VSS-V) was applied to quantify general, non-visually induced vertigo (dizziness, lightheadedness …and/or spinning) and imbalance. Autonomic (VSS-A) and psychological symptoms (Hospital Anxiety and Depression questionnaire; HAD) were also assessed. With the SCQ 100% of Group VV scored outside normal ranges and scores differed significantly between Group VV and both Groups NC and NVV. RFT values were not significantly different between groups; only 15% of patients scored outside normal ranges. Posturography scores were abnormal for 50% of patients; significant differences were noted between Groups NC and VV for composite scores and ratios 3/1, 4/1, 5/1 and 6/1 (indicative of abnormal sensory re-weighting). There were no correlations between the three data sets in patients. Anxiety and depression scores significantly differed between Groups NC and VV but not between patient groups; this indicates that psychological symptoms may be present in either patient group. The SCQ can be used to corroborate an initial clinical diagnosis of VV and quantify its severity in patients with vestibular dysfunction. Posturography data suggested patients with VV have a sensory re-weighting abnormality. The rod and frame test results and posturography findings agree less with the clinical diagnosis of VV. Psychological symptoms may need to be addressed. Show more

Keywords: Visual vertigo, posturography, rod and frame, vestibular rehabilitation

DOI: 10.3233/VES-2006-164-509

Citation: Journal of Vestibular Research, vol. 16, no. 4-5, pp. 223-231, 2006

Authors: Meretta, Bridget M. | Whitney, Susan L. | Marchetti, Gregory F. | Sparto, Patrick J. | Muirhead, Robb J.

Article Type: Research Article

Abstract: Objective: The purpose of this study was to determine if patients with balance and vestibular disorders would demonstrate clinically meaningful improvement in the Five Times Sit to Stand Test (FTSST) score as a result of vestibular rehabilitation and to determine the concurrent validity of the FTSST. Design: Retrospective chart review of 351 people who underwent individualized outpatient vestibular rehabilitation programs. Setting: Outpatient tertiary balance and vestibular clinic. Subjects: One hundred and seventeen patients (45 men, 72 women), mean age 62.7 years, with peripheral, central or mixed vestibular dysfunction. Main outcome measures: FTSST, gait speed, Timed Up …and Go Test (TUG), Dynamic Gait Index (DGI), Dizziness Handicap Inventory (DHI), and Activities-Specific Balance Confidence Scale (ABC). Results: The mean change in FTSST score was 2.7 seconds. Subjects demonstrated statistically significant improvements in the FTSST, gait speed, ABC, DHI, DGI and TUG after vestibular rehabilitation (p < 0.01). The responsiveness-treatment coefficient (RT) was calculated as 0.58 for the FTSST indicating moderate responsiveness. Logistic regression showed that an improvement in the FTSST of greater than 2.3 seconds resulted in an odds ratio of 4.67 for demonstrating clinical improvement in DHI, compared with a change less than 2.3 seconds. The univariate linear regression model for baseline FTSST predicting FTSST change was significant (p < 0.01) and predicted 49% of the change variance. The FTSST scores demonstrated a moderate correlation with gait speed and the TUG (p< 0.01). FTSST improvement subsequent to vestibular rehabilitation was moderately correlated with improvements in the DGI and the TUG scores (p< 0.01). Conclusions: The FTSST was moderately responsive to change over time and was moderately related to measures of gait and dynamic balance. Show more

Keywords: Sit to stand, sensitivity, physical therapy, dizziness, measurement

DOI: 10.3233/VES-2006-164-510

Citation: Journal of Vestibular Research, vol. 16, no. 4-5, pp. 233-243, 2006