Vestibular Function In Patients Research Articles

Evaluation of the vestibulo-ocular reflex using sinusoidal off-vertical axis rotation in patients with canal paresis

The vestibulo-ocular reflex (VOR) was studied to determine the utility of off-vertical axis rotation (OVAR) in evaluating vestibular function in patients with canal paresis (CP). Our goal was to determine whether there is any correlation between caloric responses and sinusoidal rotatory responses. Subjects were rotated in a sinusoidal pattern with eyes open in complete darkness. Frequencies of 0.4 and 0.8Hz with a maximum angular velocity of 60°/s at either earth-vertical axis rotation (EVAR) or OVAR were used. Twenty-three control subjects and 21 patients with CP were investigated. Results showed that (1) the VOR gain difference between EVAR and OVAR in the CP patients was not significant at 0.4Hz and at 0.8Hz; (2) the gain during 0.4Hz EVAR was less in the bilateral CP patients compared to controls; and (3) the VOR gain of the affected side at 0.8Hz was significantly less during OVAR than during EVAR. We concluded that the absence or reduction of caloric responses does not indicate the absence of vestibular function. In addition, separation analysis of the VOR gain of affected and intact sides is useful for evaluating laterality of otolith function in patients with CP.

Cochlear Implantation Rarely Alters Horizontal Vestibulo-ocular Reflex in Motorized Head Impulse Test

Determine the change in vestibular function in patients receiving a unilateral cochlear implant, and to compare these results with other signs and symptoms. Prospective cohort study. Academic tertiary referral center. Forty-four adults (mean age, 55 yr; range, 30-76 yr) receiving their first cochlear implant. Cochlear implantation. Horizontal high-frequency vestibulo-ocular reflex (VOR) was measured using the motorized head impulse rotator preoperatively and twice (on average two and 19 months) postoperatively. VOR gain and asymmetry were calculated (mean ± standard deviation). Symptoms were assessed with a structured questionnaire. Gain on the operated side was 0.77 ± 0.26 preoperatively, 0.75 ± 0.30 in the early and 0.73 ± 0.33 in the late postoperative control, and did not change significantly. Mean asymmetry remained within 9% to 10% in all test occasions. Dizziness symptom score or dizziness-related quality of life score did not change significantly. General quality-of-life score improved significantly from that of preoperative 3.5 ± 1.2 to that of 2.6 ± 1.1 postoperatively (p = 0.01). Subjective hearing scores improved significantly from 4.9 ± 0.3 to 2.4 ± 1.0, respectively (p = 0.0000). Gain was decreased significantly in 4 patients (10%) in the early and in 2 patients (7%) in the late postoperative control. Late high-frequency loss of vestibular function or vestibular symptoms is rare but possible after cochlear implantation surgery. This should be taken into account in patient counseling especially when considering bilateral cochlear implant surgery.

Analysis of auditory and vestibular function in patients with unilateral Meniere's disease

Conclusion: The percentage of the unilateral weakness of the caloric response also reflects the clinical progress of Meniere's disease (MD), including clinical hearing loss. Objective: To evaluate the relationship between hearing status and vestibular function in patients with MD. Methods: Seventy-nine patients with unilateral definite MD underwent bithermal air caloric testing, vestibular evoked myogenic potential (VEMP) testing, and pure tone audiometry (PTA). The stages of the disease, clinical hearing level of the diseased ears, and dPTA (the difference in hearing level between ears in each patient) were compared with the percentage of the unilateral weakness of the caloric response and the interaural amplitude difference (IAD) ratio of the VEMP response. Results: Twenty ears (25.3%) revealed normal caloric responses and 59 ears (74.7%) showed reduced caloric responses. Testing revealed that the VEMPs were normal in 49 ears (62%), while 30 ears (38%) had abnormal VEMPs. The percentage of the unilateral weakness of the caloric response was positively correlated with the clinical hearing level of the diseased ears (p = 0.006) and the dPTA (p = 0.013).

Insufficient Evidence for the Effect of Corticosteroid Treatment on Recovery of Vestibular Neuritis

The authors studied the effect of corticosteroid treatment on clinical recovery and recovery of vestibular function in patients with vestibular neuritis. The comprehensive search (March 29, 2012) yielded 496 original papers, of which 5 (including 199 patients) during full-text screening satisfied our eligibility criteria. Methods assessment showed that 1 study (30 patients) provided direct evidence and carried low risk of bias. Two studies properly reported on their random and concealed allocation of treatment. In 1 study, patients were not randomly allocated to treatment. Blinding of outcomes was lacking in 2 studies, whereas outcome data were clearly incomplete for 2 studies. Given the wide variety in outcome measures and scales and follow-up duration, the meaning of the size of reported effects is not clear. Therefore, the reported effects cannot simply be compared between studies, and this precludes pooling of study results. Still, there are large differences between studies in the size of the reported absolute effects after the placebo treatment. Moreover, the difference in effects between treatments is rather small and does not always favor corticosteroids. The moderate to high risk of bias of studies precludes firm conclusions, whereas the reported short-term effects on symptom recovery and improvement of peripheral vestibular function are too small to be clinically important. No long-term effect on symptom recovery has been shown. Recommendations or decisions for corticosteroid treatment in patients with vestibular neuritis cannot be based on current best evidence and therefore should be discussed with the patient.

In Vivo Visualized Endolymphatic Hydrops and Inner Ear Functions in Patients With Electrocochleographically Confirmed Ménière’s Disease

To study the correlation between the degree of endolymphatic hydrops as detected in vivo by magnetic resonance (MR) imaging and the auditory and vestibular function in patients with definite Ménière's disease. Prospective observational study. Tertiary referral center for balance disorders. In this prospective study, 41 patients who fulfilled the criteria for definite unilateral Ménière's disease according to the American Association of Otolaryngology-Head and Neck Surgery and who showed a summating potential-to-action potential ratio of greater than 0.4 on electrocochleography were included. Intratympanic contrast-enhanced 3 Tesla MR imaging of the inner ear was performed using a 3D Inversion Recovery Turbo Spin Echo sequence. The degree of endolymphatic hydrops was graded on a Likert scale (0-3) in the cochlea and by vestibular endolymph space ratio in the vestibulum. The degree of hydrops was then analyzed with respect to its correlation with audiometric hearing levels, interaural amplitude ratios of vestibular evoked myogenic potentials, degree of horizontal semicircular canal paresis on caloric irrigation, and disease duration. The degree of hearing loss and the disease duration correlated significantly with cochlear hydrops (r = 0.85; r = 0.34). Sacculus dysfunction was significantly correlated with vestibular hydrops (r = -0.47). There was no significant correlation between horizontal semicircular canal paresis and vestibular hydrops. In patients with clinically and electrocochleographically confirmed definite Ménière's disease, the degree of MR morphological hydrops severity correlates significantly with impairment of hearing function and sacculus function.

The mitochondrial A3243G mutation involves the peripheral vestibule as well as the cochlea

To evaluate vestibular function in patients with the mitochondrial A3243G mutation. Data from patients with the A3243G mutation attending an academic tertiary referral center were prospectively recorded. The clinical histories of 13 unrelated patients with the mitochondrial A3243G mutation (six mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes; and seven maternally inherited diabetes and deafness) were recorded, in particular their history of vestibular symptoms. Vestibular examinations including caloric testing and vestibular evoked myogenic potentials in response to air-conducted sound (ACS-VEMPs) were performed. In seven patients who showed abnormal ACS-VEMP, VEMP in response to galvanic stimuli (galvanic-VEMP) were also recorded. Eleven of the 13 patients had vestibular symptoms. The age of onset of vestibular symptoms was significantly later than the ages of onset of hearing loss and diabetes mellitus (P < .05). Ten of the 13 patients showed abnormal caloric responses, whereas 12 patients showed abnormal ACS-VEMPs on one or both sides. All of the seven patients who underwent galvanic-VEMP testing showed normal responses. The A3243G mutation is associated with vestibular dysfunction involving both the superior and inferior vestibular nerve systems. Furthermore, our results from galvanic-VEMP testing suggests that a labyrinthine lesion is primarily responsible for the symptoms of vestibular dysfunction.

Probing Residual Vestibular Function With Galvanic Stimulation in Vestibular Loss Patients

Galvanic vestibular stimulation (GVS) was used to probe the residual vestibular function in unilateral vestibular loss. 39 control subjects, 60 patients areflexic to caloric tests, 21 patients with pre-operative acoustic neurinoma, and 26 patients with surgical deafferentation were tested with 4mA trapezoidal GVS. Horizontal slow phase velocity and vertical slow phase velocity components of the slow phase of induced nystagmus were recorded with videonystagmography. All patients had lower horizontal slow phase velocity compared with intact subject. In caloric areflexic patients, the intact ear responded similarly to controls. The lesioned ear was less excitable but could be inhibited as in controls. In patients with acoustic neurinoma, the intact ear was normally excitable but less sensitive to inhibition. The lesioned ear, although not excitable, could be inhibited. In patients with surgical deafferentation, the intact ear could be barely excited and not inhibited. The lesioned ear could not be excited but slightly inhibited. These results fit well with previous data in animal models after unilateral vestibular loss. Unilateral vestibular patients exhibit a progressive deterioration of the horizontal canal function, corresponding to 4 different patterns of GVS response. This study confirms that GVS is useful to probe evolution of the residual vestibular function in patients.

Poster 240: The Study of Vestibular Function in Patients With Multiple Sclerosis

Poster 240: The Study of Vestibular Function in Patients With Multiple Sclerosis

Vestibular function of patients with profound deafness related to GJB2 mutation

Conclusion: GJB2 mutations are responsible not only for deafness but also for the occurrence of vestibular dysfunction. However, vestibular dysfunction tends to be unilateral and less severe in comparison with that of bilateral deafness. Objectives: The correlation between the cochlear and vestibular end-organs suggests that some children with congenital deafness may have vestibular impairments. On the other hand, GJB2 gene mutations are the most common cause of nonsyndromic deafness. The vestibular function of patients with congenital deafness (CD), which is related to GJB2 gene mutation, remains to be elucidated. The purpose of this study was to analyze the relationship between GJB2 gene mutation and vestibular dysfunction in adults with CD. Methods: A total of 31 subjects, including 10 healthy volunteers and 21 patients with CD, were enrolled in the study. A hearing test and genetic analysis were performed. The vestibular evoked myogenic potentials (VEMPs) were measured and a caloric test was performed to assess the vestibular function. The percentage of vestibular dysfunction was then statistically analyzed. Results: The hearing level of all CD patients demonstrated a severe to profound impairment. In seven CD patients, their hearing impairment was related to GJB2 mutation. Five of the seven patients with CD related to GJB2 mutation demonstrated abnormalities in one or both of the two tests. The percentage of vestibular dysfunction of the patients with CD related to GJB2 mutation was statistically higher than in patients with CD unrelated to GJB2 mutation and in healthy controls.

Ocular Vestibular Evoked Myogenic Potentials to Bone-Conducted Vibration in Vestibular Schwannomas

Vestibular schwannoma (VS) arises from either the superior or the inferior vestibular nerve and causes vestibular dysfunction to various degrees. Recently, ocular vestibular evoked myogenic potentials to bone-conducted vibration (oVEMPs to BCV) have attracted much interest as a new clinical test for otolith-ocular pathway function. Because it is unclear whether the oVEMPs to BCV primarily originate from activation of the superior or the inferior vestibular nerve, the results in patients with VS might enlighten us concerning the origin of oVEMPs to BCV. To compare the results of 3 clinical tests for vestibular function in patients with VS: 1) oVEMPs to BCV; 2) cervical vestibular evoked myogenic potentials to air-conducted sound (cVEMPs to ACS), which reflect the function of inferior vestibular nerve; and 3) caloric test, which reflect the function of superior vestibular nerve. Thirty-six patients with unilateral VS who underwent vestibular tests, including oVEMPs to BCV, cVEMPs to ACS, and caloric tests, were enrolled. The asymmetry ratios of the amplitudes of the oVEMPs to BCV and cVEMPs to ACS and canal paresis on the caloric test were measured. Among the 36 patients with VS, 31 (86%) showed reduced or absent oVEMPs to BCV. Twenty-eight patients (78%) showed abnormal cVEMPs to ACS, and 31 (86%) showed abnormal caloric responses. The consistency of the results between oVEMPs to BCV and the caloric test was significantly higher than that between oVEMPs to BCV and cVEMPs to ACS (p < 0.02). Ocular vestibular evoked myogenic potentials to bone-conducted vibration mainly reflect the function of the superior vestibular nerve.

Evaluation of Vestibular Function in Idiopathic Sudden Sensorineural Hearing Loss

Background and Objectives : It is very important to evaluate vestibular function in patients with sudden sensorineural hearing loss (SNHL) because vertigo combined with sudden SNHL is well known as an important prognostic factor. However, the vestibular function test is not usually performed in sudden SNHL patients without vertigo. We investigated whether different vestibular function tests such as the results of vestibular evoked myogenic potential (VEMP) testing or caloric testing were correlated to prognosis in not only sudden SNHL patients with vertigo but also in sudden SNHL patients without vertigo. Subjects and Method : We enrolled in our study 47 patients with idiopathic sudden SNHL with vertigo or without vertigo. The degree of initial hearing loss was categorized as mild, moderate, moderate-severe, severe, and profound group. Types of initial audiograms were categorized as high tone loss, low tone loss, flat and scale out type. We analyzed the association of the VEMP and caloric test with degree of hearing loss, type of audiogram, and hearing recovery in two month. Results : The more sever the hearing loss was, the more increased was the rate of abnormal VEMP response (p=0.003). The rate VEMP and caloric abnormality was higher in hearing loss types with high tone loss than in the types with only low tone loss. The rate of accompanying vertigo was high (p=0.017), when the hearing loss was more severe. There was significant correlation between the hearing recovery and vestibular dysfunction (p=0.000, r=0.563). Conclusion : VEMP and caloric test are useful in evaluating vestibular function and prognosis of sudden SNHL patients.

The evaluation of vestibular functions in patients with pseudoexfoliation syndrome

The main objective of the study is to evaluate vestibular system of the inner ear with postural tests in the patients with pseudoexfoliation syndrome (PEX). It is clinical case-control study. The study group included 34 patients with PEX and 40 controls without PEX. The patients and controls underwent complete ophthalmic and otorhinolaryngologic examinations. Vestibular functions were done by Fitzgerald and Dix-Hallpike, caloric tests, Romberg test, tandem Gait test, Quiks test in both control and study groups. Pur-tone and high-frequency audiography were also performed in all cases. The mean patient age was 63 years (+/-11.80) (range 47-74 years) in the PEX group and 65 years (+/-8.70) (range 61-68 years) in the control group with no differences among the two groups (P > 0.05). Although none of the 34 patients with PEX had clinical history of balance disturbance, 21 (61.76%) had significant pathologic sign in vestibular function tests (P < or = 0.05), while only 3 (7.5%) of 40 cases in the control group had pathologic sign in vestibular function tests. The scales from pure tone and high-frequency audiogram in the PEX group were similar to those of the control group. In conclusion, the patients with PEX, there may be a vestibular involvement in the pathological level in the inner ear. Larger clinical studies, experimental animal studies, and post mortem studies in humans are needed to disclose the pathology in the vestibulocochlear system in the patients with PEX.

Evaluation of the vestibulo-ocular reflex using sinusoidal off-vertical axis rotation in patients with acoustic neurinoma

The vestibulo-ocular reflex (VOR) was studied to examine the utility of off-vertical axis rotation (OVAR) in the diagnosis of acoustic neurinoma. Subjects were sinusoidally rotated with eyes open in complete darkness at frequencies of 0.4 and 0.8 Hz with a maximum angular velocity of 60°/s at either earth-vertical axis rotation (EVAR) or OVAR. Thirteen patients with acoustic neurinomas were investigated. Results showed that VOR gain during OVAR at 0.8 Hz and in a 30° nose-up position in patients with internal auditory canal tumors was significantly less than the gain measured during EVAR. The VOR gain measured from all patients (including those with tumors extending to the cerebellopontine angle) was not significantly different when the patients were subjected to EVAR and OVAR. These observations were possibly due to superior vestibular nerve dysfunction. We concluded that certain stimulating parameters—patient's nose tilted up 30°; sinusoidal OVAR at 0.8 Hz and 60°/s maximum angular head velocity—were useful for evaluating vestibular function in patients suffering from an acoustic neurinoma located within the internal auditory canal.

Vestibular evoked myogenic potentials in patients with the mitochondrial A1555G mutation

To evaluate the vestibular function in patients with the mitochondrial DNA A1555G mutation. Data from patients with the mutation at an academic tertiary referral center were prospectively recorded. The histories of five unrelated patients with bilateral moderate to profound sensorineural hearing loss (SNHL) carrying the A1555G (A to G substitution at 1555 nucleotide) mutation were recorded, especially their history of vestibular symptoms. Thereafter, vestibular examinations, including positional, positioning and spontaneous nystagmus testing; caloric response testing; and vestibular evoked myogenic potential (VEMP) testing were performed. In the cases where the VEMP activity presented, the amplitudes of the first positive-negative peak (p13-n23) of the mutation group were compared to a healthy volunteer group and to a sudden SNHL group. Four of the five patients suffered from repetitive vestibular symptoms. Positioning, positional, and spontaneous nystagmus were not observed except in one patient. Three of the five patients had normal caloric responses, but all the patients had abnormal VEMPs. The interpeak amplitudes in the mutation group were significantly lower at the intensities of 95 and 105 dB normal hearing level (nHL) in comparison to the healthy volunteer group. In addition, the amplitudes in the mutation group were significantly lower at the intensity of 95 dB nHL in comparison to the sudden SNHL groups. These results indicated that the A1555G mutation can cause vestibular dysfunction, especially saccular dysfunction and cochlear dysfunction. Further studies are necessary to elucidate the pathophysiological nature of the inner ear dysfunction in patients with the A1555G mutation.

Meniere's disease and middle ear pressure – vestibular function after transtympanic tube placement

Conclusion: Selected patients with Meniere's disease (MD) show an improvement of disability from vertigo after transtympanic ventilation tube insertion, although an effect on vestibular function is not seen if ipsilateral middle ear pressure lower than –50 daPa is used as a selection criterion. Objectives: Transtympanic ventilation tube insertion as a treatment option for MD has been reported but its results have been controversial. So far, no investigations on vestibular function in patients with MD after tube insertion have been carried out. Subjects and methods: Twenty-two patients with unilateral MD who were intractable to medical treatment and who had an ipsilateral middle ear pressure lower than –50 daPa received a transtympanic ventilation tube. Vestibular evoked myogenic potentials (VEMPs) and sinusoidal harmonic acceleration (SHA) testing were recorded pre- and postoperatively and were compared. Results: Most patients (68.2%) reported an improvement of vertigo. Before surgery 63.6% of patients did not show VEMPs, whereas vestibulo-collic reflexes were measured in 36.4% of all cases compared with 68.2% of patients without and 31.8% with recorded VEMPs after surgery. No statistically different findings in gain and phase lag of SHA testing were seen postoperatively compared to preoperative findings.

Effect of Intratympanic Application of Aminoglycosides on Click-Evoked Myogenic Potentials in Guinea Pigs

Although numerous studies have identified damage to the cochlear and vestibular end organs as the primary site of aminoglycoside-induced ototoxicity, the effect on the saccule remains poorly understood, possibly due to lack of monitoring saccular function in experimental animals. Therefore, this study applied three kinds of aminoglycosides into the tympanic space of guinea pigs to examine their toxic impact on the saccule by way of click-evoked myogenic potential test coupled with morphologic assessment. Albino guinea pigs were treated with saline, gentamicin, tobramycin, or amikacin, with 10 animals assigned to each group. Each compound was injected directly overlying but not through the round window membrane on the left ear, with the right ear serving as a control. One week after injection, each animal underwent auditory brain stem response, caloric test, and click-evoked myogenic potential test. Animals were then killed for morphologic assessment through the use of light and electron microscopic examinations. The animals treated with saline, gentamicin, tobramycin, or amikacin exhibited abnormal auditory brain stem response in 0%, 30%, 100%, and 30% of cases; abnormal caloric responses were found in 0%, 100%, 40%, and 40% of cases; absent click-evoked myogenic potentials were found in 0%, 100%, 30%, and 40% of cases, respectively. Gentamicin and other groups differed significantly in abnormal rates of caloric responses and click-evoked myogenic potentials. Morphologic study of the gentamicin-treated animals confirmed that the absence of click-evoked myogenic potential originated from the lesion in the saccular macula. Gentamicin represents the dominant susceptibility of aminoglycoside-induced vestibulotoxicity for eliminating both semicircular canal and saccular functions. This study further confirms the findings of human studies in which the caloric and vestibular evoked myogenic potentials responses were monitored to assess the abolition of vestibular function in patients treated with intratympanic gentamicin injection.

Hearing Loss in Patients With Vestibulotoxic Reactions to Gentamicin Therapy

To determine whether patients with vestibulotoxic reactions to gentamicin have hearing thresholds worse than predicted by distributions of better-ear hearing thresholds in people of the same age and sex in the general population, and, if so, to measure the severity and audiometric pattern of that hearing loss. Retrospective case series from previously published prospective and retrospective studies of vestibular function in patients receiving gentamicin. Tertiary neurotological practice. Convenience sample of 33 consecutive patients seen for objective evidence of vestibulotoxic reactions after systemic gentamicin therapy. Twenty-five of 33 patients underwent valid and complete audiometry. Age- and sex-corrected better-ear pure tone thresholds, 0.5 to 6.0 kHz. The better-ear audiogram was defined in 2 ways: primarily, the audiogram of the ear with the better average threshold at 0.5, 1.0, and 2.0 kHz; secondarily, the composite audiogram taking the better threshold for each frequency. Patients exhibiting vestibulotoxic reactions to gentamicin therapy had hearing thresholds that were similar to those seen in the general population at 0.5, 3.0, and 6.0 kHz. Median thresholds were 6 to 7 dB worse than expected at 1.0 and 2.0 kHz (95% confidence intervals, 2-13 dB and 3-12 dB, respectively). The largest median difference was 15 dB at 4.0 kHz (95% confidence interval, 3-23 dB), but this difference was not significant for the more conservative composite definition of the better ear. Patients with vestibulotoxic reactions to gentamicin therapy have little additional hearing loss compared with the general population. Physicians should monitor both auditory and vestibular function when aminoglycosides, especially gentamicin, must be used.

Transtympanic Gentamicin and Fibrin Tissue Adhesive for Treatment of Unilateral Menière’s Disease: Effects on Vestibular Function

To determine the effects of transtympanic injections, with a mixture composed of gentamicin and fibrin tissue adhesive (FTA), on vestibular function of patients with intractable unilateral Menière's disease. This was an open, prospective study. The study was performed at 2 tertiary referral centers. Twenty-six patients affected by "definite" unilateral Menière's disease, unresponsive to medical therapy for at least 6 months, were enrolled. A buffered gentamicin solution mixed with FTA was injected in the middle ear until the development of bedside vestibular hypofunction signs and/or caloric weakness in the treated ear. Vestibular function was evaluated by 3 bedside vestibular tests (observation of spontaneous nystagmus, head shaking test, and head thrust test) and by a caloric test. Tests were performed on days 10 and 30 after completion of treatment. Tests were also performed 3, 6, and 12 months from completion of the gentamicin-FTA protocol. The effects of treatment were also assessed in terms of hearing levels, control of vertigo, and disability status. In 22 of the 26 patients, only 1 gentamicin-FTA injection was necessary to obtain 1 or more signs indicating a reduction of the vestibular function in the treated ear. Four patients needed another treatment because of the persistence of their incapacitating symptoms during the follow-up. Four patients needed more than 1 injection to obtain a vestibular hypofunction. None of the patients who received 1 or 2 injections presented hearing loss in direct temporal relationship to the treatment. A mixture of gentamicin and fibrin glue makes it possible to considerably reduce the number of administrations in patients with intractable unilateral Menière's disease. Spontaneous nystagmus, post head shaking nystagmus, and a head thrust sign are the clinical signs that indicate onset or progression of unilateral vestibular hypofunction. These signs were obtained with only 1 injection in 81% of patients.

Prognosis of Inner Ear Periphery and Central Vestibular Plasticity in Sudden Deafness with Vertigo

We sought to elucidate the clinical problems and otopathology of patients with sudden deafness with vertigo (SDV). In 24 patients with SDV who had significant canal paresis (CP) at their first visit to our hospital between 1997 and 2001, we examined pure tone audiograms, caloric tests, and several questionnaires twice, at the first visit within 5 days after the onset and around 2 years after steroid therapy. These examinations revealed that improvements of auditory and vestibular function in patients with SDV tended to be correlated with one another. Sixteen of the 24 patients (66.7%) still had CP. This rate in SDV was significantly worse than that reported previously for vestibular neuritis (VN). On the other hand, patients with SDV with long-lasting CP had a faster reduction of head-shaking afternystagmus and of handicaps in their everyday life due to dizziness than did patients with VN and CP. These findings suggest that SDV may deteriorate the inner ear function more severely but accelerate the central vestibular compensation more effectively than VN after the lesion. It is well known that vestibular neurectomy causes much more severe motion-induced dizziness after surgery than does labyrinthectomy. Taken together, these findings suggest different regions of damage in SDV (mainly the labyrinth, as in labyrinthectomy) and VN (mainly the ganglion, as in vestibular neurectomy).

VEMPs and dynamic posturography after intratympanic gentamycin in Menière's disease

In this study, we investigated whether vestibular evoked myogenic potentials (VEMPs) and dynamic posturography (DP) are useful in the evaluation of the vestibular function in patients affected by active monoaural Menière's disease (MD) treated with intratympanic gentamycin. Twelve subjects affected by monoaural MD were treated with weekly intratympanic injections of 0.5 ml of gentamycin at a concentration of 20 mg/ml. VEMPs were used to test saccular function, while postural control was analyzed by DP. The results obtained with these two techniques were compared with those obtained by using bithermal caloric test. The mean follow-up was 15.3 months (6--28 months). Therapy resulted in complete absence of the caloric response in six subjects (50) and in caloric test-induced asymmetry in the remaining individuals, ranging from 83 to 27. At follow-up, eleven patients (91.6%) were free of vertigo, while one patient had two vertigo spells 9 months after treatment. Before treatment, VEMPs were present in the affected ear of eleven patients. After treatment VEMPs were absent in all the patients. At the end of follow-up, reappearance of VEMPs was observed in two patients, with no changes in latency values and amplitude ratio. DP demonstrated a reduction of the Composite Score (CS) one week after therapy, with a prevalent reduction of the vestibular component. After 6 months, there was an improvement of the CS and, in particular, of the vestibular component. The present study demonstrates that bithermal caloric test and VEMPs allow for the functional evaluation of both the horizontal semicircular canal and the sacculus, suggesting that these techniques might be used together to monitor the efficacy of intratympanic gentamycin therapy. In addition, our data indicate that DP might provide important information on compensation phenomena and show that intratympanic gentamycin can improve postural control in MD patients.