Effects of Gaze Positions on Ocular Vestibular Evoked Myogenic Potentials / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Recent works have demonstrated the existence of ocular vestibular evoked myogenic potentials (OVEMPs), which reflects otolith-ocular reflex. The purpose of this study was to identify an appropriate gaze position to detect OVEMPs produced by air-conducted sound stimulation in healthy subjects. SUBJECTS AND METHOD: Twenty four healthy subjects (35 ears) were included in this study. Surface electromyographic activity was recorded from active electrodes placed inferior to each eye. Stimulation with 500 Hz short tone bursts was used to activate the vestibular end-organs. RESULTS: Sound stimulation evoked negative-positive biphasic responses on both ipsilateral and contralateral eyes, while responses were contralateral eye-dominant. Contralateral eye responses had higher response incidence and larger amplitudes. Altering the direction of gaze generally changed the incidence and size of the inter-peak amplitudes. The higher incidence and larger amplitudes were recorded when the eyes are directed to the superior and ipsilateral side to the sound stimulation. In that gaze position, the amplitude was 5.3 micronV, the first negative peak latency was 10.5 ms and the following positive peak latency was 15.4 ms on the average. CONCLUSION: OVEMPs can be evoked using an air-conducted 500 Hz tone burst and are best recorded contralaterally with a upward gaze towards the source of sound stimulation. Further changes of the test parameters are needed for higher and consistent responses.

Hearing Results of Tympanoplasties in 175 Patients with Chronic Otitis Media / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: To report the hearing results of tympanoplasty for chronic otitis media with or without cholesteatoma. SUBJECTS AND METHOD: One hundred and seventy-five patients presenting chronic otitis media with or without cholesteatoma were involved in a retrospective study. Tympanoplasties were performed by the same surgeon over a 30-month period. Audiometric results were reviewed. Audiometric results according to the following techniques were measured: tympanoplasty type 1 (T1), interposition (Si) and/or columella (Sc) over stapedial head, and interposition or columella (Fic) over footplate. The follow-up period ranged from 6 to 32 months. Audiological parameters using the average of four frequencies were assessed pre- and post-operatively. RESULTS: Overall hearing results showed postoperative air-bone gaps (ABG) < or =20 dB in 69% of cases. ABG was closed to within 20 dB in 89% for T1, 67% for Sc, 58% for Si, and 30% for Fic. ABG was closed to within 30 dB in 95% for T1, 67% for Sc, 83% for Si, and 70% for Fic. There was a significant improvement between preoperative and postoperative ABGs. The overall improvement of the air-bone gap was 8+/-13 dB. There was no significant functional difference between different surgical techniques. CONCLUSION: Our hearing results after tympanoplasties were similar to those from other studies. The hearing results observed in this study confirmed that successful results can be obtained by applying the current principles and approach to ossicular reconstruction.

Results of Air Caloric and Other Vestibular Tests in Patients with Chronic Otitis Media

OBJECTIVES: Air caloric results are supposed to be influenced by anatomic changes of the middle ear. The aims of our study were to evaluate the incidence and characteristics of abnormal air caloric results in patients with unilateral chronic otitis media and without any history of vertigo, and to compare caloric results with there of other vestibular function tests (VFTs). METHODS: Twenty five patients with unilateral chronic otitis media (COM) who were scheduled for surgery underwent VFTs preoperatively. Hearing was assessed using pure-tone audiometry and vestibular function was assessed using a set of VFTs: air caloric, head-shaking nystagmus (HSN), vibration-induced nystagmus (VIN), and subjective visual vertical (SVV) tests. RESULTS: Six patients (24%) showed pathologic canal paresis (CP) on COM-sided ears. Two patients showed pathologic CP on the contralateral side. However, both of the two showed inverted nystagmus to warm air stimulation on the COM-side and hyperactive nystagmus to cold air stimulation on the COM-side, which means that the COM-sided ear was stimulated too much. There was pathologic HSN in 12 patients (48%), pathologic VIN in 7 (28%), and pathologic SVV in 5 (20%). Overall, 20 (80%) patients showed abnormal findings through a set of VFTs. Patients with an interaural difference of bone-conduction hearing thresholds > or =10 dB tended to show more abnormal VFT results than those for whom the interaural difference of bone-conduction hearing thresholds was <10 dB. CONCLUSION: Our data show that one-fourth of patients with unilateral COM show abnormal caloric results on the COM side. However, subclinical latent vestibular imbalances were found to be common, which might be related to the gradual vestibular involvement in inflammatory processes, regardless of the caloric results. Results of a set of VFTs should be referred to when determining vestibular imbalance in patients with COM.

A Case of Superior Canal Dehiscence Syndrome as a Cause of Step-Synchronous Tinnitus / 대한이비인후과학회지

The superior canal dehiscence syndrome (SCDS) is a rare disorder caused by the dehiscence of the temporal bone overlying the superior semicircular canal. It has become apparent that SCDS can lead to a variety of clinical manifestations, vestibular and/or auditory, in contrast to the typical symptoms, as initially described. We recently examined a 54-year-old woman with unilateral stepsynchronous tinnitus without any vestibular symptoms. Tinnitus is a quite unremarkable finding among variable symptoms of the syndrome; however, it can be one of the clues to identify SCDS when it is accompanied by low-frequency conductive hearing loss. Therefore, in diagnosing SCDS, attention must be also paid to those patients with nonspecific complaints, for example, stepsynchronous tinnitus.

Effects of Changes of Plateau and Rise/Fall Times on Ocular Vestibular Evoked Myogenic Potentials

BACKGROUND AND OBJECTIVES: The ocular vestibular evoked myogenic potential (OVEMP) is a recently discovered test of labyrinthine function, analogous to the cervical VEMP. Recent works have demonstrated the existence of OVEMPs, which likely reflect otolith-ocular reflex. The purpose of this study was to identify the optimal plateau and rise/fall times of short tone bursts to detect OVEMPs in healthy subjects. MATERIALS AND METHODS: Thirteen healthy subjects (26 ears) were included in this study. Surface electromyographic activity was recorded from active electrodes placed inferior to each eye. Stimulation with 500 Hz short tone bursts was used. We used a variety of plateau and rise/fall times. Three different plateau times (1, 2, and 3 ms) and rise/fall times (0.5, 1, and 2 ms) were used. The incidence, amplitudes and latencies were compared. RESULTS: VEMP responses were clearly observed in all 26 ears at the plateau time of 2 ms and two rise/fall times (0.5 and 1 ms). The amplitudes in the individual ears tested were lower at the rise/fall time of 2 ms than at the other conditions. The amplitudes were lower at the plateau time of 3 ms compared to the other conditions. When the rise/fall time was prolonged from 0.5 to 2 ms, the n1 and p1 latencies were prolonged in parallel. However, there was no such change in latencies according to the plateau times. CONCLUSIONS: Our findings show that the ideal stimulation pattern for evoking OVEMP is at the rise/fall times of 0.5 or 1 ms and the plateau time of 2 ms. The waveform morphology of the VEMP responses observed with this stimulation pattern was simultaneously the most constant and marked.

Tympanometry and CT Measurement of Middle Ear Volumes in Patients with Unilateral Chronic Otitis Media

OBJECTIVES: The goals of the study were to compare the middle ear (ME) volumes from both normal and lesioned ears, and these ME volumes were measured by a digital image processing computed tomography (CT) program in patients with unilateral chronic otitis media, and we wanted to compare the ME volumes of the lesioned ears by comparing the ME volumes obtained by tympanometry with those ME volumes measured by the digital image processing CT program. METHODS: Forty-four patients who had unilateral chronic otitis media (COM) and contralateral normal tympanic membranes (TM) and 100 subjects with normal TMs were included in the study. The normal volumes of the external auditory canal (EAC) were measured in the normal group. The tympanometric ME volumes in the ears with a perforated TM were calculated as the difference of the tympanometric volumes measured from the both ears in patients with unilateral COM. The CT ME volumes were measured by a digital image processing program. RESULTS: The tympanometric volumes of the EACs in the ears with normal TMs were 1.4+/-0.3 mL. There were no significant differences according to gender, age and the side of the face the ear was on. The tympanometric volumes of the EAC in the normal-side ear of the patients with unilateral COM showed no significant differences when compared with those from the normal group. The ME volumes of the intact ears, as measured by CT, showed significantly higher values than those ME volumes of the lesioned ears. The ME volumes of the lesioned ears, as measured by tympanometry, showed a strong, significant linear correlation with those ME volumes calculated by CT; however, the ME volumes of the lesioned ears, as measured by tympanometry (1.5+/-1.4 mL), were significantly larger than those ME volumes measured by CT (1.1+/-0.8 mL). CONCLUSION: Our results show that chronic otitis media causes reduced ME volumes compared to those ME volumes of the contralateral normal ears. Tympanometry can provide a valuable estimation of the ME volumes in chronic ears, although it tends to overestimate the ME volumes, and especially for the ears with a larger ME volume.

Otolith Function Tests in Patient with Meniere's Disease

BACKGROUND AND OBJECTIVES: The aims of this study were to measure otolith function using subjective visual vertical (SVV) test and vestibular evoked myogenic potential (VEMP) test in patients with unilateral Meniere's disease, and to see the relationship of the otolithic impairment with caloric and audiologic results. MATERIALS AND METHODS:Twenty two patients with unilateral Meniere's disease who received treatment and also had been tested for pure tone, caloric, SVV and VEMP tests were enrolled. All the tests were done simultaneously. RESULTS: Five of 22 (23%) patients showed abnormal tilt to the lesion side in SVV test, and 13 of 22 (59%) patients showed abnormal VEMP results on the affected side. There was no correlation between SVV tilts and unilateral weakness (UW) in caloric tests or pure-tone average. There was also no difference of UW in patients with or without VEMP abnormalities. Two patients showed abnormal finding in both SVV & VEMP tests. One patient showed UW (47%) and SVV tilt (3.08degrees) to the lesion side, and the other showed normal UW and SVV tilt (3.22degrees) to the lesion side. CONCLUSION: Our results demonstrate that the otolith system was implicated in 16 out of 22 (73%) patients with Meniere's disease. However, there was no correlation between the abnormal results of the three tests and these findings suggest that impairment of the otolithic function is depending on the extent and/or the localization of Meniere's disease, suggesting vestibular rehabilitation for the specific lesion might be helpful.

Comparison of Air Caloric Test and Vibration-Induced Nystagmus Test in Patients with Unilateral Chronic Otitis Media without Vertigo

BACKGROUND AND OBJECTIVES: The aims of the study were to characterize the vibration-induced nystagmus (VIN) and air caloric test in patients with unilateral chronic otitis media, and to clarify the clinical availability of VIN by comparing the results of VIN test with those of air caloric test. MATERIALS AND METHODS: Nineteen patients with unilateral chronic otitis media who had had no vestibular symptoms in past history were investigated. Pure tone audiometry (PTA), air caloric, VIN and subjective visual vertical (SVV) tests were done and the results were analyzed to estimate the utility for investigating vestibular imbalance. RESULTS: If we consider a patient with abnormal results from two or more tests as a patient with latent vestibular imbalance, because they had no previous vestibular symptoms, 3 patients was considered to have latent asymmetric vestibular function. False positive rate were 32% in air caloric test, 5% in VIN test and 0% in SVV test. CONCLUSION: Our findings show that vestibular imbalance in patients with chronic otitis media should be determined through various tests and vibration-induced nystagmus test can be more useful than air caloric test in estimating the vestibular imbalance.

Follow-up Examination of Vibration-Induced Nystagmus in Patients with Unilateral Vestibular Neuritis

BACKGROUND AND OBJECTIVES: The aim of this study was to verify if vibration-induced nystagmus in patients with vestibular neuritis changed over time and to compare the results of vibration-induced nystagmus (VIN) test to those of caloric test. MATERIALS AND METHOD: We compared VIN results with those of caloric testing in 23 patients (M:F = 11:12, 15~67 years old) with unilateral vestibular neuritis seen at onset and in follow-up for around 2 months. The eye movement recordings were made and the maximum slow-phase eye velocities (SPV) were calculated during vibration. If spontaneous nystagmus was present, it was subtracted from the slow-phase eye velocities of VIN. RESULTS: In acute stage, VIN of which SPV was directed towards the lesioned side was observed in 21 (91%). In follow-up, VIN of which SPV was directed towards the lesioned side was observed in 19 (83%). There was a significant decrease of the SPV of VIN over time. Significant correlations were observed in between canal paresis & SPV of VIN in both acute and follow-up stages. CONCLUSION: Our findings show that VIN test can predict the severity of vestibular asymmetry not only in acute stage but also in follow-up stage. Our results suggest that vibration-induced nystagmus might represent the peripheral vestibular asymmetry in patients with vestibular neuritis.

Changes of Vibration-Induced Nystagmus by Age in Normal Subjects

BACKGROUND AND OBJECTIVES: It has been reported that vibration applied either on the mastoid or on the sternocleidomastoid (SCM) muscles induces nystagmus in normal subjects. The aims of the study were to characterize the direction and velocity of slow-phase eye movement which is induced by vibration in normal subjects and to propose the mechanism of vibration-induced nystagmus (VIN) in normal subjects. MATERIALS AND METHOD: We recorded eye movements during unilateral 100-Hz vibration on the mastoid bone and SCM muscles in 56 normal subjects. The subjects were divided into 4 groups in ages (20s, 30s, 40s, 50~60s). The directions of VIN, the degree of maximal slow-phase eye velocities were analyzed according to age. Positive value means slow-phase velocity (SPV) to the right side. RESULTS: In 20s, vibration on right/left mastoids induced SPV of 1.2+/-2.0degrees/sec, 0+/-2.1degrees/sec and on right/left SCM muscles, 1.1+/-1.9degrees/sec, -1.2+/-2.5degrees/sec. In 30s, vibration on right/left mastoids induced SPV of 3.3+/-3.8degrees/sec, -0.3+/-1.4degrees/sec and on right/left SCM muscles, 2.8+/-4.2degrees/sec, -1.0+/-1.5degrees/sec. In 40s, vibration on right/left mastoids induced SPV of 0+/-1.7degrees/sec, -0.2+/-1.2degrees/sec and on right/left SCM muscles, 0+/-1.8degrees/sec, 0+/-1.0degrees/sec. In 50~60s, vibration on the right/left mastoids induced SPV of -1.3+/-1.3degrees/sec, 1.2+/-1.3degrees/sec and on right/left SCM muscles, -0.6+/-0.9degrees/sec, 0.9 +/-1.5degrees/sec. The directional preponderance of the slow-phase eye movement to the vibrated side was statistically significant in 20s and 30s, however, the preponderance of the slow-phase eye movement changed into the non-vibrated side in 50~60s. CONCLUSION: The proprioceptive input, changing major rotator from the inferior oblique muscle to the sternocleidomastoid muscles might explain the change of the directional preponderance of the slow-phase eye movements in normal subjects according to ages. Although this directional preponderance is not consistent in all age groups, it is still important in discriminating normal responses from abnormal responses which can be induced by vibration.

Vibration-Induced Nystagmus in Patients with Vestibular Disorders

BACKGROUND AND OBJECTIVES: It has been reported that vibration applied either on the mastoid or the sternocleidomastoid (SCM) muscles induces nystagmus in patients after unilateral vestibular neuritis. The aims of the study were to characterize the vibration-induced nystagmus (VIN) in patients with various vestibular disorders and to compare the results of VIN to unilateral weakness in caloric test. MATERIALS AND METHODS:Fifthy-four patients with Meniere's disease, 58 patients with unilateral vestibular neuritis, 170 patients with migraine-associated dizziness, and 78 patients with chronic recurrent vestibulopathy were included. We recorded eye movements during unilateral 100-Hz vibration on the mastoids and SCM muscles. The bithermal caloric test was also performed. Abnormal criteria of VIN were slow-phase slow-phase velocity (SPV) at 4 all different conditions > or = 2degrees/s with the same directions or mean of SPV at vibration on both mastoids or both SCM muscles > or = 5degrees/s with the same directions. RESULTS: In Meniere's disease, 28 of 57 (49.1%) of patients show pathologic VIN, 21 of 57 (36.8%) show pathologic canal paresis. 14 of 57 (24.6%) show abnormalities in both tests, and 35 of 57 (61.4%) show any abnormalities in either test. In unilateral vestibular neuritis, 43 of 58 (77.6%) showed pathologic VIN, 58 of 58 (100%) show canal paresis. In migraine-associated dizziness, 48 of 170 (28.2%) showed pathologic VIN, 58 of 170 (18.8%) show canal paresis. 15 of 170 (8.8%) showed abnormalities in both tests, and 65 of 170 (38.2%) show any abnormalities in either test. In chronic recurrent vestibulopathy, 23 of 78 (29.5%) of patients show pathologic VIN and 17 of 78 (21.8%) show pathologic canal paresis. Seven of 78 (9.0%) showed abnormalities in both tests, and 33 of 78 (42.3%) show any abnormalities in either test. CONCLUSION: VIN test can increase the sensitivity in detecting vestibular imbalance in vestibular disorders when combined with caloric test.

Clinical Study on Blowout Fractures of the Medial Orbital Wall Reconstructed by Bulla Ethmoidalis Osteomucosal Flap / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Various surgical approaches have been employed to treat fractures of the medial orbital wall. Among them, the transnasal endoscopic approach provides the chance to avoid external scars and to observe the fracture site clearly. These approaches mostly require the use of grafts or splints. Authors carried out a retrospective study on the blowout fractures repaired by bulla ethmoidalis osteomucosal flap (BOMF) and compared them with the groups that were treated with silastic sheet only and with Med-pore(R) registered to investigate the merits of BOMF with respect to results and complications. SUBJECTS AND METHOD: We reviewed 62 cases (64 sides) of medial wall fractures that were treated surgically. They were diagnosed with 3 mm facial CT scans and treated according to the authors' indications from February 1998 to March 2004 at Namgwang Hospital, Seonam University. The surgical treatment consisted of the reconstruction of the fractures and the repair of the remaining bone defects by graft and splint, and the type of graft was selected according to the size of the defect. For minor defects, silastic sheet was used alone, whereas major defects were repaired with BOMF or Med-pore(R) registered. All patients were evaluated regularly for at least six months postoperatively. RESULTS: There were no differences in the aspects of the final treatment results of diplopia and enopthalmos. But in the aspects of postoperative crust formation and granulation, the cases that were repaired with BOMF showed better results as well as the economic merits. In the BOMF cases, the average duration of silastic sheet stenting was 12.5 days and it could reduce the follow up period. CONCLUSION: BOMF demonstrated better results in the respects of duration of silastic sheet stenting, postope-rative crust formation, granulation and economic cost.