The recovery from AP adaptation in sensorineural hearing loss.

CONCLUSIONS: An abnormally slower action potential (AP) recovery from adaptation (decreased recovery, dR) was characteristically detected in many ears with sensorineural hearing loss (SNHL) but not Meniere's disease and idiopathic sudden SNHL. We assumed that this abnormal AP recovery from adaptation was attributed to an imbalance in the distributions of auditory neurons with high and low spontaneous firing rates. The significant difference of initial hearing level between dR and normal AP recovery groups (nR) was assumed to partially result from AP recovery being determined by the inner hair cell synapse, and not from outer hair cells. OBJECTIVE: This study aimed to detect the AP recovery pattern in SNHL. METHODS: Electrocochleography (ECochG) was performed transtympanically in 30 patients with SNHL. AP recovery was measured by a paired click stimulation paradigm as a function of inter-click intervals from 5 to 100 ms. RESULTS: The high prevalence of dR (9 of 30 ears) appears to be a characteristic ECochG finding in SNHL. Initial hearing level differed significantly between dR and nR groups.

Electrocochleography in Meniere's disease: recovery from adaptation of the auditory action potential.

CONCLUSIONS: High prevalence rate of an enhanced summating potential (SP)/action potential (AP) ratio (≥0.35) is considered to result largely from the imbalances of Ca(2+) homeostasis in the endolymphatic space. An increase in Ca(2+) is thought to augment the SP. Furthermore, a greater inflow of Ca(2+) into inner hair cells is supposed to influence the disturbed release of neurotransmitter, which may induce pathological functioning of inner hair cell synapses. We speculate that such abnormal synaptic functioning is responsible for the development of abnormally increased AP recovery from adaptation (iR). OBJECTIVES: This study aimed to record the AP recovery from adaptation (AP recovery) and to investigate its clinical significance in association with other electrocochleography (ECochG) findings in Meniere's disease. METHODS: ECochG was performed transtympanically in 27 patients with Meniere's disease. AP recovery was measured by a paired-click stimulation paradigm as a function of interclick intervals from 5 to 100 ms. RESULTS: High prevalence of SP/AP ratio was observed in 27 patients. iR, suggesting abnormal functioning of inner hair cell synapse, was in many cases combined with an enhanced SP/AP ratio.

Electrocochleographic findings in recurrent idiopathic sudden sensorineural hearing loss.

CONCLUSION: The main differences in electrocochleography (ECochG) between recurrent and nonrecurrent idiopathic sudden sensorineural hearing loss (iSSNHL) were the high prevalence of an abnormally increased action potential (AP) recovery (iR) in nonrecurrent iSSNHL and the very low prevalence of iR in recurrent iSSNHL. An enhanced SP/AP ratio, low AP threshold, low initial hearing level, and up-sloping type of audiogram appear to be favorable prognostic factors in recurrent iSSNHL. OBJECTIVES: This study aimed to characterize differences in ECochG findings and other confounding prognostic factors between recurrent and nonrecurrent iSSNHL and to estimate how these findings are related to hearing outcome in recurrent iSSNHL. METHODS: ECochG was performed transtympanically in 23 and 42 ears with recurrent and nonrecurrent iSSNHL, respectively. AP recovery was measured using a paired-click stimulation paradigm. Differences in ECochG findings associated with confounding prognostic factors between recurrent and nonrecurrent iSSNHL, and between three outcome groups were assessed. RESULTS: iR was significantly more common in nonrecurrent iSSNHL (16 ears) than in recurrent iSSNHL (1 ear). In the outcome of recurrent iSSNHL, the prevalence rates of an enhanced summating potential (SP)/AP ratio, lower AP threshold, lower initial hearing level, and up-sloping type of audiogram were significantly higher in the cure group than in the improvement and no-recovery outcome groups.

Prognostic evaluation of electrocochleography in idiopathic sudden sensorineural hearing loss.

CONCLUSION: Abnormal action potential (AP) recovery from adaptation was manifested as increased recovery (iR) or decreased recovery (dR) relative to the normal recovery range. dR was not analyzed statistically due to the very small number of cases. iR is considered an unfavorable prognostic indicator, whereas a normal AP recovery (nR), enhanced SP/AP ratio (≥0.35), and lower AP threshold are favorable prognostic indicators for idiopathic sudden sensorineural hearing loss (iSSNHL). OBJECTIVES: This study aimed to determine the prognostic efficacy of AP recovery examinations associated with other electrocochleography (ECochG) findings in iSSNHL. METHODS: ECochG was performed transtympanically in 58 iSSNHL ears. AP recovery was measured by a paired-click stimulation paradigm, and hearing outcome was classified into three groups. Additionally, the relationships of other confounding prognostic factors to hearing outcomes were assessed. RESULTS: iR was significantly more common in the no-recovery group, while nR and an enhanced SP/AP ratio were significantly more common in the cure and improvement groups. The AP threshold was significantly lower in the cure group than in the other two groups. The other confounding prognostic factors generally showed similar trends to those reported previously.

Recovery from adaptation of the action potential in idiopathic sudden sensorineural hearing loss investigated using a paired-click stimulation paradigm.

CONCLUSION: We studied the compound action potential (AP) recovery from adaptation (AP recovery) in idiopathic sensorineural hearing loss (iSSNHL). Abnormal AP recovery was demonstrated in 15 of 45 patients, consisting of increased recovery (iR) over the normal range in 11 ears and decreased recovery (dR) under the normal range in 4 ears. The mechanisms for occurrence and clinical significance of these phenomena are currently unknown. OBJECTIVES: The purpose of this study was to investigate the pathologic features of AP recovery in iSSNHL. METHODS: Forty-five subjects with iSSNHL were enrolled and 18 normal-hearing subjects participated to assess the normal range of AP recovery. Equilevel paired clicks with inter-click interval from 5 to 100 ms were applied as acoustic stimuli. RESULTS: Eleven ears with iR and four ears with dR were found. The audiogram patterns of 11 iR and 4 dR ears exhibited 10 flat types, 3 high frequency loss types, and 2 low frequency loss types. Only 2 of 11 subjects with iR ears and 0 of 4 with dR ears complained of vertigo. No significant difference was observed in the comparison between AP threshold and hearing level of iR with those of normal recovery (nR) within the normal range.

Clinical significance of the summating potential-action potential ratio and the action potential latency difference for condensation and rarefaction clicks in Meniere's disease.

OBJECTIVES: This study was aimed to elucidate the diagnostic significance of the summating potential (SP)-action potential (AP) ratio and the AP latency difference between condensation and rarefaction clicks (AP con-rar difference) in Meniere's disease. METHODS: The AP and SP were recorded transtympanically in 67 patients with definite Meniere's disease. The SP/AP ratio and the AP con-rar difference were assessed in terms of 1) their interrelationship, 2) their relationship to hearing level, and 3) the rate of occurrence of abnormal values according to the stages of Meniere's disease. RESULTS: No correlation was found between the SP/AP ratio and the AP con-rar difference. Neither the SP/AP ratio in general nor the AP con-rar difference was correlated with the hearing level. However, enhanced values of the SP/AP ratio (0.35 or higher) were moderately correlated with the hearing level (r = 0.51), and their occurrence rate was 55.2%. An increased AP con-rar difference (0.13 ms or longer) was not correlated with the hearing level, and its occurrence rate was 50.2%; it appeared most frequently at stage 3 (p <0.05). CONCLUSIONS: An enhanced SP/AP ratio might not always indicate the presence of endolymphatic hydrops associated with an increase in endolymphatic pressure. An increased AP con-rar difference might reflect the presence of a biased basilar membrane resulting from an increased endolymphatic pressure, and hence it is diagnostically essential to simultaneously evaluate the SP/AP ratio and the AP con-rar difference.

Recovery of human compound action potential using a paired-click stimulation paradigm.

The recovery process from adaptation of the compound action potential (CAP) was studied using an equilevel paired click stimulation paradigm in humans with normal hearing. The CAP amplitude to the second click of paired clicks was normalized to the amplitude to the first click. The second-click CAP amplitude recovered as a function of interclick interval (ICI) between the first and the second click of a pair. A regression line fitted to the recovered amplitude data demonstrated the logarithmic function of the ICI. Full recovery times changed from 118 to 278 ms with increasing click intensity. The regression lines for higher click intensities exhibited two different slopes in two ICI ranges: from 3 to 100 and 120 to 300 ms. We suppose that the CAP recovery for ICI <100 ms is attributable to both the relative refractoriness of auditory nerve and the short-term adaptation mechanisms, while, for ICI >100 ms chiefly to the short-term adaptation mechanisms. The recovery process of the second-click CAP slowed with increasing intensity, which is a similar result to that obtained in the animal experiments by Parham et al. The input-output (I-O) curve of the second-click CAP amplitudes exhibited a different slopes above and below 60 dB normal hearing level (nHL). We assume that the mechanisms underlying this characteristic curve pattern differ from those for the I-O curve of the CAP in response to single-click stimuli. We expect that investigating the CAP recovery in pathological ears will provide clinically useful information on cochlear synaptic function.

Neck metastasis of a myxoid liposarcoma of the lower extremity.

We report the clinical features of two cases presenting metastatic neck tumors (in the anterior neck and submandibular regions) secondary to myxoid liposarcoma of the lower extremity. Both cases underwent repeated resection of primary legions of the lower extremities because of recurrences. Such repeated surgical procedures are thought to be a risk factor for distant metastasis resulting from hematogeneous dissemination of tumor cells, although there is considerable debate about multicentricity versus metastasis in liposarcomas. Where possible, therapy for liposarcomas should initially comprise complete and wide resection of the lesions. Combined therapy consisting of surgery and postoperative radiation and chemotherapy should be investigated in the future.

Abnormalities of the electrogastrogram in globus pharyngeus.

There appear to be multiple indicators for the presence of globus pharyngeus. We have assumed that patients with abnormal gastric motility can be included among those suffering from globus pharyngeus. Gastric motility can be examined non-invasively using the electrogastrogram (EGG). In this study, 32 patients (22 females, 10 males; mean age 55+/-13 years) with symptoms of globus pharyngeus consented to EGG recording. The EGGs of asymptomatic healthy adults (6 females, 10 males; mean age 28+/-5 years) were obtained as controls. No significant statistical difference was found in any of the measurement parameters between the two groups. However, we found that 9.4% of patients with globus pharyngeus exhibited abnormal gastric myoelectrical activity as measured by the EGG. This suggests that a small proportion of patients who complain of globus pharyngeus have abnormal gastric motility.

Age-related changes in the vestibular-evoked myogenic potentials.

OBJECTIVE: We sought to investigate the effects of gender and age on the vestibular-evoked myogenic potential (VEMP). STUDY DESIGN AND SETTINGS: Sixty healthy adult volunteers (28 male and 32 female) were investigated in this study. The subject age was distributed between 20 and 77 years old. RESULTS: No gender-related differences were detected in the VEMP. There was a significant correlation between age and both the evoking threshold and the pInII amplitude of the VEMP, whereas no significant correlation was observed between age and left-right differences of the VEMP. CONCLUSIONS: The correlation between age and the parameters of the VEMP is presumably secondary to age-related functional changes in the sensory and neural elements of the VEMP. It is safe to evaluate the VEMP using the value of the non-affected side when assessing unilateral lesions. However, it may be necessary to take age into account in evaluating the VEMP when bilateral lesions are suspected.

Cortical potentials evoked by horizontal rotatory stimulation: the effects of angular acceleration.

OBJECTIVE: To examine the potentials evoked by rotatory stimulation, which we consider the optimal means of invoking angular acceleration and which may lead to clinical applications in patients with vertigo. MATERIAL AND METHODS: Horizontal rotatory stimulation using a trapezoidal waveform was performed with 3 different angular accelerations (20, 15 and 10 degrees/s2) used sequentially, with alternating clockwise and counterclockwise stimulation, to normal subjects and a patient with bilateral loss of vestibular function. RESULTS: It is likely that angular accelerations of < 20 degrees/s2 produce minor somatosensory effects. Clear potentials were evoked in 13/18 ears (72%) of the normal subjects with stimulation at an angular acceleration of 15 degrees/s2. No response was recorded in the patient with stimulation at 15 degrees/s2. CONCLUSION: We suggest that an angular acceleration of 15 degrees/s2 is optimal for clinical examinations.

Hearing impairment and tinnitus pitch in patients with unilateral tinnitus: comparison of sudden hearing loss and chronic tinnitus.

OBJECTIVES: The objectives were to analyze the results of pitch-matching and loudness-balance testing in patients with unilateral tinnitus and to evaluate the relationship between audiological findings based on the tinnitus-affected and tinnitus-unaffected threshold differences and tinnitus pitch by using linear interpolation methods. In addition, the effects of the duration of the tinnitus on this relationship were investigated. Sudden sensorineural hearing loss with tinnitus was selected for the "acute tinnitus" group, and unilateral tinnitus with unknown disease and a duration of more than 3 months was selected for the "chronic tinnitus" group. STUDY DESIGN: Retrospective study of the clinical records of patients. METHODS: One hundred thirty-two patients with unilateral tinnitus (comprising 68 female [51.5%] and 64 male [48.5%] patients) were investigated as subjects. Their mean age was 50.4 years (SD = 15.8 y). All patients underwent otoneurological testing, including the pure-tone audiogram and pitch-matching and loudness-balance tests. RESULTS: The mean difference in the hearing threshold between the tinnitus-affected ear and the tinnitus-unaffected ear was largest near the tinnitus pitch in both the acute and the chronic tinnitus groups. However, the relationship between hearing impairments and tinnitus pitch was somewhat different in the two groups: It exhibited a single smooth peak in the acute tinnitus group but a bimodal peak in the chronic tinnitus group. CONCLUSION: The results suggest that tinnitus is related to hearing impairment in the same frequency region in patients with sudden sensorineural hearing loss with tinnitus or in patients with chronic tinnitus, whereas some instances of chronic tinnitus are caused by reorganization in cortical cells.

Vestibular-evoked myogenic potential in patients with unilateral vestibular neuritis: abnormal VEMP and its recovery.

The incidence of inferior vestibular nerve disorders in patients suffering from unilateral vestibular neuritis and the recovery of these disorders were evaluated by monitoring the vestibular-evoked myogenic potential (VEMP). Eight patients ranged from 21 to 73 years that suffered from unilateral vestibular neuritis underwent VEMP and caloric testing. Abnormal VEMP was observed in two of the eight patients with unilateral vestibular neuritis. Two patients were diagnosed as having an inferior vestibular nerve disorder. One of these patients showed recovery of the inferior vestibular nerve function as assessed by the VEMP. Disorders of the inferior vestibular nerve function and their recovery was confirmed by our current results. The time course of recoveries of the superior and inferior vestibular nerve systems were similar in the two patients.

Effects of nimodipine on quinine ototoxicity.

The compound action potential (CAP) in response to a click train stimulus was recorded at the round window of guinea pigs. Administration of quinine hydrochloride (200 mg/kg) significantly elevated the CAP thresholds by 5 to 25 dB (p < .05), and the CAP waveform elicited by the click train stimulus was abnormal. The amplitude of the CAP elicited by the second click was bigger than that elicited by the first click. These changes may be caused by an abnormally broadened N1 response to the first click in the click train. In contrast, CAP waveforms elicited by the second and subsequent clicks appeared normal. After administration of nimodipine (2 mg/kg), the CAP thresholds and waveforms elicited by the click train stimulus were unchanged. Simultaneous administration of both quinine (200 mg/kg) and nimodipine (2 mg/kg) resulted in the same electrophysiological changes as those induced by quinine alone. These results suggest that nimodipine prevents neither the deterioration in the CAP nor the abnormal properties in the response to a click train stimulus.

Changes in CAP adaptation in experimentally induced endolymphatic hydrops.

OBJECTIVE: To determine the effect of experimentally induced endolymphatic hydrops (ELHs) on compound action potential (CAP) adaptation. METHODS: The CAP was recorded 1 month after surgical treatment to produce ELH. The CAP threshold in response to click stimuli showed no significant differences between the hydropic and control groups. The CAP was elicited from the retroauricular-exposed round window using a silver ball electrode. Click trains consisting of 10 clicks with an interclick interval (Deltat) of either 4 or 8 ms were delivered through a loudspeaker placed in front of the animals' ears. The patterns of adaptation to these click trains were evaluated as functions of Deltat and intensity level. RESULTS: An abnormal pattern of CAP adaptation was observed in hydropic ears. CONCLUSIONS: These findings suggest that early ELH influences CAP adaptation.

Zinc deficiency and tinnitus.

OBJECTIVE: To determine if there is a correlation between serum zinc levels and audiometric performance in tinnitus patients. METHODS: Seventy-three patients participated in this study. Patient's age was restricted to 20-59 years. All patients were examined at the otolaryngology outpatient clinic of the St. Marianna University Toyoko Hospital. The control group consisted of 38 age- and sex-matched healthy volunteers. A blood sample was taken to measure serum zinc levels. Hypozincemia was set at a level of the mean minus one S.D. in the control group. An average hearing sensitivity was calculated as the mean value of hearing thresholds at five frequencies: 250, 500, 1000, 2000, and 4000 Hz. Normal hearing was indicated when the hearing threshold at each of these frequencies was within 20 dB of normal thresholds. RESULTS: There was no significant difference in serum zinc levels between patients with tinnitus and controls. However, patients with tinnitus who had normal hearing had significantly lower serum zinc levels compared to controls. In contrast, no significant difference in serum zinc levels was found between patients with tinnitus who had hearing loss, and controls. A significant correlation between average hearing sensitivity and serum zinc level was observed. CONCLUSIONS: These findings suggest that zinc is involved in the generation of tinnitus, especially in patients whose hearing is relatively normal.

Physical therapy for benign paroxysmal positional vertigo patients with movement disability.

OBJECTIVE: Particle repositioning manoeuvres are broadly recognized effective for benign paroxysmal positional vertigo (BPPV), however, we think that these therapies are not suitable for all BPPV patients. In this study we investigate whether these manoeuvres can be used for BPPV patients with the movement disability. In addition, we introduce our habituation training (HT) and report the results of treatment with it. METHODS: Nine BPPV patients with the movement disability due to orthopedic disease were examined. For each patient we determined their movement disabilities, and assessed the suitability of particle repositioning manoeuvres, Brandt-Daroff (B-D) manoeuvre and HT for them. RESULTS: All of these nine patients had neck or trunk movement disabilities due to orthopedic disease, and we judged that particle repositioning manoeuvres and B-D manoeuvre were impossible or too risky to be employed in them. Although HT was suitable for them and symptoms and signs of them improved within a short period of time. CONCLUSION: Particle repositioning manoeuvres were not suitable for BPPV patients with the movement disability because these manoeuvres required various movements. These patients were able to perform HT depending on their capabilities. We think that HT is caused by the fatigability of BPPV, and it accelerates the natural curing process.

Patency of inferior meatal antrostomy.

OBJECTIVE: To evaluate the patency and effectiveness of inferior meatal antrostomy for the treatment of maxillary lesions. METHODS: Patients suffering from moderate-to-severe chronic sinusitis who underwent inferior meatal antrostomies at St. Marianna University Toyoko Hospital and followed up for at least 1 year after surgery were selected. Thirty sides of 27 patients were analyzed. Postoperative mucociliary function was examined in seven sides of seven patients. RESULTS: No closure was observed in all 30 procedures. Out of 30 antra, 26 (86.7%) had normal antral mucosa. Recurrent mucosal lesions inside the maxillary sinus were successfully treated through the inferior meatal window. No cases showed circular flow on the india ink test. All sinuses exhibited a discharge from the middle meatal window and three out of seven sinuses exhibited a discharge from the inferior meatal window. CONCLUSIONS: Although long-term follow-up is required to determine the patency of inferior meatal antrostomy, initial results are encouraging. The inferior meatal window provides both intra- and postoperative benefits.

Vestibular-evoked myogenic potentials in two patients with Ramsay Hunt syndrome.

We report on the function of the inferior vestibular nerve, as monitored by the vestibular-evoked myogenic potentials (VEMP), in two patients suffering from Ramsay Hunt syndrome. Both the patients presented canal paresis (CP) and hearing loss, but in one patient normal VEMP was recorded while the other presented vagus nerve paralysis plus no VEMP response at the highest stimulus intensity used in our institute (i.e., 105 dB nHL).