Biomedical subjects

Yi-Ho Young

Publications and source records attributed to Yi-Ho Young.

50 records · Page 3Linked to original sources

PubMed2003

Effect of irradiation on vestibular evoked myogenic potentials in nasopharyngeal carcinoma survivors.

BACKGROUND: This study aims to investigate the effect of irradiation on vestibular evoked myogenic potentials (VEMPs) in nasopharyngeal carcinoma (NPC) survivors, because radiotherapy to NPC covers a column from the basal skull to the clavicle level. METHODS: Twenty-two irradiated NPC survivors and five fresh NPC patients were subjected to VEMP testing, which is evoked by short-tone burst (95 dBHL, 500 Hz) stimulation. Interactions among VEMPs and radiation effects, such as radiation dosage, postirradiation interval, radiation-induced otitis media, sensorineural hearing loss, or canal paresis, were then explored. RESULTS: The mean latencies of p13 and n23 in irradiated ears were significantly delayed compared with either pr-irradiated ears or normal control ears. Delayed VEMPs represented 50% in ears with a mean radiation dosage of 71 Gy, whereas it represented 100% in those with a mean radiation dosage of 123 Gy. Ears with radiation otitis media revealed higher occurrence (65%) of delayed VEMPs than those without radiation otitis media (29%, p <.05), possibly because of radiation sequela affecting the brainstem and neck. However, delayed VEMPs were unrelated to sensorineural hearing loss or canal paresis caused by irradiation. CONCLUSIONS: Delayed VEMPs in NPC survivors are possibly due to radiation-induced otitis media, a brainstem lesion, or neck fibrosis. Hence, VEMP testing may expand the test battery for clinicians to explore balance problems in NPC survivors after irradiation.

Adult↗

PubMed2003

Vestibular evoked myogenic potentials using simultaneous binaural acoustic stimulation.

The aim of this study is to investigate the feasibility of recording vestibular evoked myogenic potential (VEMP) using simultaneous binaural acoustic stimulation (B-VEMP), and compare it with that using monaural acoustic stimulation (M-VEMP). Seven healthy volunteers were evoked by initial B-VEMP test and subsequent M-VEMP test, whereas vice versa in another 7 volunteers. All 14 subjects demonstrated both B-VEMPs and M-VEMPs, without significant difference in the latencies of p13 and n23. When using interaural amplitude difference (IAD) ratio for interpreting amplitude, B-VEMPs did not differ significantly from that of M-VEMPs. Hence, B-VEMPs can produce information equivalent to M-VEMPs in terms of response rate, latencies, and IAD ratio in healthy subjects. Likewise, similar results were also shown in the patients with unilateral Meniere's disease. In conclusion, B-VEMPs provide neither different information nor less variability, as compared with M-VEMPs. In addition, B-VEMPs can offer information on unilateral inner ear (saccular) pathology similar to that by M-VEMPs. Furthermore, recording from binaural stimulation can be used as a possibly more convenient mode compared with two monaural recordings, especially when testing young or old or disabled patients, since a continuous muscular effort is required during recording.

Acoustic Stimulation↗

PubMed2003

Vertigo from herpes zoster oticus: superior or inferior vestibular nerve origin?

OBJECTIVE/HYPOTHESIS: This study aims to analyze which division of vestibular nerve in the internal auditory canal is responsible for inducing vertigo in patients with herpes zoster oticus (HZO). METHODS: Eight patients (three men and five women) suffered from auricular vesicles, otalgia, and facial palsy, and five of them also had vertigo. Each patient received a battery of tests, including neurological examination, blood examination, audiometry, caloric test, electronystagmography, and vestibular evoked myogenic potential (VEMP) test. RESULTS: All five HZO patients with vertigo had facial palsy on the lesioned side and spontaneous nystagmus beating toward the healthy side. Absent VEMPs were noted in five patients, absent caloric response was noted in four, and sensorineural HL was noted in three. Compared to another three HZO patients without vertigo, all revealed normal responses in both the caloric test and the VEMP test. On MRI scan, two out of four had abnormal gadolinium enhancement along the nerve segments within the internal auditory canal. Six months after treatment, a follow-up caloric test and VEMP test in these eight patients did not alter the results compared with before treatment. CONCLUSION: The nerve trunks within the internal auditory canal are widely affected in HZO patients with vertigo. Both superior division and inferior division of the vestibular nerve attribute to the vertiginous attack. Further, large numbers of HZO patients undergoing caloric testing and VEMP testing are required to support this tentative conclusion.

Adolescent↗

PubMed2003

Acute vertigo following cervical manipulation.

OBJECTIVE/HYPOTHESIS: Either licensed American chiropractors or traditional Chinese herbalists may produce vertiginous attack in a patient after cervical manipulation. The purpose of the study was to present our experience in treating these patients to determine the risk of this procedure. STUDY DESIGN: A retrospective study from May 1999 to April 2002. METHODS: Nine patients (one man and eight women) with acute vertigo after cervical manipulation were admitted and underwent a battery of audiometric and vestibular tests, accompanied by magnetic resonance imaging and magnetic resonance angiography examination. RESULTS: The mean interval for the onset of acute vertigo after cervical manipulation was within 1 day (17 h). Electronystagmography revealed multiple central signs. Magnetic resonance angiography scan also disclosed abnormality in the vertebral artery such as occlusion, stenosis, or slow blood flow in three patients. After treatment with dextran, relief of vertigo without neurological deficits was experienced in all nine patients. CONCLUSIONS: When there are multiple central signs in electronystagmography results or slow blood flow of the vertebral artery is displayed in neck on Doppler sonography or magnetic resonance angiography scan, the therapeutic benefits of cervical manipulation cannot be expected to outweigh its potential risk for the morbidity of cervical vessels.

Acute Disease↗

PubMed2003

Vestibular evoked myogenic potentials in brainstem stroke.

OBJECTIVES/HYPOTHESIS: Despite its widespread application in the posterior fossa tumor, the study of vestibular evoked myogenic potential (VEMP) in cases of posterior fossa stroke remains scarce. The purpose of the study was to establish the role of VEMP in patients with brainstem stroke. STUDY DESIGN: Retrospective study. METHODS: Patients with acute vertigo were admitted and underwent a battery of auditory vestibular tests including caloric and VEMP tests; then they were surveyed by magnetic resonance imaging scan. Seven patients (two men and five women) were demonstrated as having brainstem stroke, including infarction in five patients and hemorrhage in two. RESULTS: Clinical manifestations consisted of dizziness/vertigo in all patients, spontaneous nystagmus in five (71%), and ataxia in three. No patients had experienced conscious change or conventional neurological deficits (eg, long tract signs). Electronystagmography revealed abnormal findings on eye tracking test in 100% of patients, on optokinetic nystagmus test in 71% of the patients, and on caloric testing in 10 ears (71%), including absent ice-water caloric test response in 7 ears and canal paresis in 3 ears. Vestibular evoked myogenic potential testing displayed normal response in 3 ears and abnormal response in 11 ears (79%), including absent vestibular evoked myogenic potentials in 8 ears and delayed vestibular evoked myogenic potentials in 3 ears. When results of both caloric testing and VEMP test were combined, the abnormal rate increased to 93% (13 of 14 patients). CONCLUSIONS: Caloric testing assesses the vestibulo-ocular reflex, which passes upward through the upper brainstem, whereas VEMP testing evaluates the sacculocollic reflex, which travels downward through the lower brainstem. Hence, in evaluating the extension of brainstem stroke, both caloric and VEMP testing should be performed.

Adult↗

PubMed2003

Comparison of tone burst and tapping evocation of myogenic potentials in patients with chronic otitis media.

OBJECTIVE: Vestibular evoked myogenic potential (VEMP) has recently been broadly studied in cochleo-vestibular disorders to elucidate its mechanism. Because it is evoked by loud sound stimulation, impairment of the sound transmission through the middle ear may affect VEMP results. This study aims to compare the response rate of VEMPs using the tone burst method and the tapping method in patients with chronic otitis media (COM). DESIGN: Fourteen patients (22 ears) with conductive hearing loss due to COM were subjected to VEMP tests using both the tone burst method and the tapping method. Each ear was stimulated by a short-tone burst (95 dB nHL, 500 Hz), followed by tapping on the forehead with a tendon hammer, 200 times at a frequency of 5 Hz. RESULTS: Thirteen (59%) of the 22 ears showed positive VEMPs using the tone burst method, whereas 20 ears (91%) displayed positive VEMPs by the tapping method (p < 0.05). The latencies of wave p13 and n23, and the amplitude p13-n23 using the tone burst method were 13.4 +/- 4.1 msec, 20.5 +/- 4.6 msec, and 77.2 +/- 17.2 microV, respectively. These results do not significantly differ from those obtained using the tapping method. In ears with perforated eardrums (N = 11), five ears (45%) displayed positive VEMPs by the tone burst method; compared with nine ears (82%) with positive VEMPs using the tapping method, representing a nonsignificant difference. In ears with healed eardrums (N = 11), eight ears exhibited positive VEMPs by tone burst, with a mean air-bone gap of 25.6 +/- 15.2 dB at 500 Hz, in contrast to a gap of 30.0 +/- 22.9 dB in three ears without VEMPs, indicating no significant difference. CONCLUSIONS: When stimulating sound is attenuated by middle ear pathology, VEMPs are expected to be poorly elicited. Under such conditions, myogenic potentials may be evoked with the tapping method to elicit the absent VEMPs that result from middle ear or inner ear pathology.

Acoustic Stimulation↗

PubMed2003

The influence of clicks versus short tone bursts on the vestibular evoked myogenic potentials.

OBJECTIVE: Vestibular evoked myogenic potential (VEMP) has become a diagnostic tool to evaluate the integrity of sacculo-collic reflex. To obtain a more consistent VEMP response in normal-hearing subjects, we examine whether clicks or short tone bursts are more effective in eliciting VEMP responses. DESIGN: Prospective study. Twenty-nine normal-hearing volunteers (58 ears) were given VEMP tests. Clicks and short tone bursts were presented alternately to evoke VEMPs. The latencies of peak p13 and n23, peak-to-peak interval and amplitude (p13-n23) were measured and compared. RESULTS: Click stimulation of 57 ears (98%) produced VEMPs (C-VEMPs), whereas 51 (88%) revealed positive short tone burst-evoked VEMPs (STB-VEMPs), exhibiting a significant difference (p < 0.05). Furthermore, C-VEMPs displayed shorter latency, longer interval and larger amplitude than STB-VEMPs, with a significant difference (p < 0.05), respectively. CONCLUSIONS: C-VEMPs had a higher response rate, shorter latency, and larger amplitude than STB-VEMPs. These findings suggest that click is superior to short tone burst to trigger VEMPs. Because C-VEMPs have a shorter p13 latency than STB-VEMPs, the interpretation of prolonged latency differs in each stimulus condition.

Acoustic Stimulation↗

PubMed2002

Neurotoxic mechanism of cinnabar and mercuric sulfide on the vestibulo-ocular reflex system of guinea pigs.

Cinnabar, a naturally occurring mercuric sulfide (HgS), has been combined with Chinese herbal medicine as a sedative for more than 2000 years. To date, its neurotoxic effect on the vestibulo-ocular reflex (VOR) system has not been reported. By means of a caloric test coupled with electronystagmographic recordings, the effect of commercial HgS and cinnabar on the VOR system of guinea pigs was studied. HgS or cinnabar was administered orally (1.0 g/kg) to Hartley-strain guinea pigs once daily for 7 consecutive days. A battery of electrophysiological, biochemical, and histopathological examinations were performed. The results showed that HgS induced a 60% caloric response abnormality (40% caloric hyperfunction and 20% hypofunction), whereas the abnormal responses appeared to be more severe (six out of six) in the cinnabar group. The Hg contents of whole blood and cerebellum were increased and correlated to their neurotoxic effects on the VOR system, indicating that both insoluble HgS and cinnabar could be absorbed from the gastrointestinal tract and distributed to the cerebellum. Although the vestibular labyrinth revealed no remarkable change under light microscopy, loss of Purkinje cells in the cerebellum was detected, and the enzymatic Na(+)/K(+)-ATPase activity of cerebellum (a higher inhibitory center of the VOR system) was significantly inhibited by HgS and cinnabar. Moreover, cerebellar nitric oxide (NO) production was increased significantly. Hence, we tentatively conclude that the increased Hg contents in the cerebellum following oral administration of HgS and cinnabar were responsible, at least in part, for the detrimental neurotoxic effect on the VOR system. Potentially, decreasing Na(+)/K(+)-ATPase activity and increasing NO production within the cerebellar regulatory center are postulated to mediate this VOR dysfunction caused by the mercurial compounds and cinnabar.

Administration, Oral↗

PubMed2002

Vestibular evoked myogenic potentials are intact after sudden deafness.

OBJECTIVE: To evaluate vestibular evoked myogenic potentials (VEMPs) in cases of sudden deafness, and to confirm the noncochlear origin of the VEMPs. STUDY DESIGN: Prospective study. VEMPs, which were evoked by short tone burst (95 dB nHL) stimulation, were recorded in 20 patients with unilateral, idiopathic sudden deafness. The results of the deaf ears were compared with those of the contralateral healthy ears and the normal control ears. The relations between VEMPs and the hearing level or caloric response were then investigated. RESULTS: All 20 of the deaf ears displayed normal biphasic VEMPs. The mean latencies of p13 and n23, as well as mean amplitude p13-n23, were 15.1 +/- 2.8 msec, 20.7 +/- 3.3 msec and 25.2 +/- 12.6 microV, respectively, not significantly different to either the contralateral healthy ears (p > 0.05) or the normal control ears (p > 0.05). Five deaf ears displayed canal paresis or absent caloric response, whereas the remaining 15 ears revealed normal caloric response. CONCLUSION: All the lesioned ears of patients with idiopathic sudden deafness exhibit normal biphasic VEMPs. Neither the hearing level nor the caloric response correlated to the VEMPs.

Adolescent↗

PubMed2002

Preoperative versus postoperative role of vestibular-evoked myogenic potentials in cerebellopontine angle tumor.

OBJECTIVE/HYPOTHESIS: Vestibular-evoked myogenic potential (VEMP) examination was performed on patients with a cerebellopontine angle (CPA) tumor to evaluate its clinical role. METHODS: Patients with a CPA tumor were subjected to caloric test and VEMP examination. Follow-up study was performed 1 year after the surgery. RESULTS: Six (69%) of the 9 tumors did not exhibit either caloric response or VEMP on the lesioned side. Three patients received tumor excision and all tumors involved both the superior and inferior vestibular nerves. Two (22%) of the 9 tumors had normal caloric responses but no VEMP. One underwent surgical excision, and the tumor originated from the inferior vestibular nerve. In the follow-up study, only 1 patient with epidermoid cyst presented complete recovery of caloric response and VEMP, whereas in the other 3 patients with vestibular schwannoma, the responses were all absent persistently. CONCLUSION: Before surgery, VEMP test can be used to predict the nerve of origin and to formulate the best surgical approach. After surgery, VEMP test can be used to define the nature of the tumor (compressing or infiltrating the nerve) and disclose the residual function of the inferior vestibular nerve.

Adult↗

PubMed2002

Augmentation of vestibular evoked myogenic potentials: an indication for distended saccular hydrops.

OBJECTIVE/HYPOTHESIS: Vestibular evoked myogenic potential (VEMP) testing has become a well-established test to explore the sacculo-collic pathways in human. The aim of the present study is to establish a clinical indication for saccular hydrops by VEMP testing. STUDY DESIGN: Prospective study. METHODS: Ten patients (three men and seven women) with Meniere's disease and 10 patients (four men and six women) with sudden deafness were admitted and given pure-tone audiometry and VEMP testing daily. Interaural amplitude difference over the sum of amplitudes of both ears was measured, and when the ratio exceeded 0.36, the test result was coined "augmented VEMP." RESULTS: During admission, three hydropic ears presented with augmented VEMP test results, with increased interaural amplitude difference ratio (mean difference ratio, 0.40+/-0.03). Seven hydropic ears had steady VEMP test results, with a mean interaural amplitude difference ratio of 0.15+/-0.07. Compared with the normal control ears, all had steady VEMP test results, with a mean interaural amplitude difference ratio of 0.14+/-0.11, which is significantly different from the hydropic ears with augmented VEMP test results (P <.05). In another 10 patients with sudden deafness, all had positive steady VEMP test results, with their mean interaural amplitude difference ratio of 0.14+/-0.12, which is similar to that in the control ears. CONCLUSIONS: Augmented VEMP test results are an indication of distended saccular hydrops, whose distended wall is in contact with the footplate. VEMP testing may be beneficial in differentiating the initial stage of Meniere's disease and sudden deafness.

Adolescent↗

PubMed2002

Vestibular evoked myogenic potentials in delayed endolymphatic hydrops.

OBJECTIVE/HYPOTHESIS: Vestibular evoked myogenic potential (VEMP) has become an established test to explore the sacculo-collic reflex. The study aims to investigate the VEMPs in cases of delayed endolymphatic hydrops because greatly dilated saccule was observed in histopathological specimens of delayed endolymphatic hydrops. STUDY DESIGN: Prospective study. METHODS: Twenty patients with delayed endolymphatic hydrops were subjected to pure-tone audiometry, caloric testing, and VEMP test. Delayed VEMP was defined as the latency of peak I exceeding 22.6 milliseconds or of peak II exceeding 33.1 milliseconds. Interaural amplitude difference over the sum of amplitudes of both ears was measured, and when the ratio exceeded 0.36, it was identified as augmented VEMP or depressed VEMP depending on whether the amplitude of the lesioned side was greater or less than the opposite side. RESULTS: The VEMP test revealed that 9 patients (45%) were normal, 6 (30%) exhibited absent VEMPs, and 5 (25%) displayed abnormal VEMPs, including delayed VEMPs in 2, depressed VEMPs in 2, and augmented VEMPs in 1. The caloric test indicated that 9 (47%) of the 19 ears exhibited normal caloric response, whereas 10 ears displayed abnormal caloric responses including canal paresis in 8 and absent caloric response in 2. Six ears had preserved both the caloric response and the VEMPs, whereas no ear demonstrated both absent caloric response and absent VEMPs. CONCLUSIONS: The residual caloric as well as saccular functions after ear insult may determine whether delayed endolymphatic hydrops will occur. These findings suggest that patients with sudden deafness or juvenile unilateral total deafness should undergo caloric testing and VEMP test to predict the occurrence of delayed endolymphatic hydrops in the future.

Adult↗

PubMed2002

Dextran-induced pulmonary edema in patients with sudden deafness.

OBJECTIVE: Pulmonary complication in cases of sudden deafness after dextran treatment is rarely reported. This study discusses the management of two cases and reviews the current literature. PATIENTS: Two (1%) of 204 patients with sudden deafness patients had fever, cough, and dyspnea after intravenous dextran infusion. Pulmonary edema was diagnosed after chest radiographic examination. RESULTS: After interruption of dextran, subsequent supportive treatment relieved chest discomfort and fever without any sequelae. The results of chest radiograph and laboratory studies, including hemogram, renal function, and arterial blood oxygen saturation, were normal. CONCLUSIONS: Patients receiving dextran treatment should have their clinical symptoms, renal function, chest radiographs, hemogram, and coagulation profiles monitored. If fever, bleeding, cough, or dyspnea occurs during treatment, dextran must be immediately stopped. Subsequent treatment should focus on dextran clearance to prevent further cascade complications.

Aged↗

PubMed2002

Differentiation between cerebellopontine angle tumors in cancer patients.

OBJECTIVE: The possibility of metastasis to the cerebellopontine angle should be considered when a cancer patient has inner ear-related symptoms, although such metastasis is rare. Distinguishing between an independent tumor and a metastasis presents a challenge to the clinician once magnetic resonance imaging reveals a space-occupying lesion in the cerebellopontine angle. This study attempted to differentiate between primary benign and metastatic malignant cerebellopontine angle tumors in cancer patients. SETTING: University hospital. PATIENTS: A total of 174 cancer patients with inner ear-related symptoms such as vertigo, hearing loss, or tinnitus were seen at the university hospital from January 1994 to December 2000. All patients underwent a battery of audiologic and neurotologic tests. Magnetic resonance imaging was performed either when the clinical presentation suggested vertigo of central origin or when sensorineural hearing loss developed. RESULTS: Magnetic resonance imaging confirmed tumors of the cerebellopontine angle in 6 (3%) of the 174 patients, including 3 men and 3 women. Their ages ranged from 46 to 80 years (mean 62 years). The final diagnoses were breast cancer with cerebellopontine angle metastasis (1), breast cancer with cerebellopontine angle epidermoid cyst (1), colon cancer with cerebellopontine angle metastasis (1), colon cancer with acoustic neuroma (1), nasopharyngeal carcinoma with cerebellopontine angle metastasis (1), and nasopharyngeal carcinoma with cerebellopontine angle benign tumor (1). CONCLUSIONS: When a cerebellopontine angle tumor is discovered in a cancer patient, metastatic cancer should be suspected when the tumor presents with deficits of the VIIth and VIIIth cranial nerves of rapid progression or bilateral involvement, or extracranial systemic metastasis. Laboratory examinations such as cytologic study of the cerebrospinal fluid and serologic study can assist in the diagnosis.

Aged↗