Effect of lidocaine on salicylate-induced tinnitus in guinea pigs: A focus on the auditory cortex.

This study aimed to investigate the effects of the intravenous administration of lidocaine in the auditory cortex after the systemic administration of salicylate. Healthy male albino Hartley guinea pigs were divided into two groups. The control group received only lidocaine, whereas the experimental group received lidocaine after checking for the effects of salicylate. Extracellular recordings of spikes in the primary auditory cortex and dorsocaudal areas in healthy albino Hartley guinea pigs were continuously documented (pre- and post-lidocaine, pre- and post-salicylate, and post-salicylate after adding lidocaine to post-salicylate). We recorded 160 single units in the primary auditory cortex from five guinea pigs and 155 single units in the dorsocaudal area from another five guinea pigs to confirm the effects of lidocaine on untreated animals. No significant change was detected in either the threshold or Q10dB value after lidocaine administration in the primary auditory cortex and dorsocaudal areas. Spontaneous firing activity significantly decreased after lidocaine administration in the primary auditory cortex and dorsocaudal areas. Next, we recorded 160 single units in the primary auditory cortex from five guinea pigs and 137 single units in the dorsocaudal area from another five guinea pigs to determine the effects of lidocaine on salicylate-treated animals. The threshold was significantly elevated after salicylate administration; however, no additional change was detected after adding lidocaine to the primary auditory cortex and dorsocaudal areas. Regarding the Q10dB value, lidocaine negated the significant changes induced by salicylate in the primary auditory cortex and dorsocaudal areas. Moreover, lidocaine negated the significant changes in spontaneous firing activities induced by salicylate in the primary auditory cortex and dorsocaudal areas. In conclusion, changes in the Q10dB value and spontaneous firing activities induced by salicylate administration are abolished by lidocaine administration, suggesting that these changes are related to the presence of tinnitus.

The effect of systemic administration of salicylate on the auditory cortex of guinea pigs.

OBJECTIVE: To investigate the effect of systemic administration of salicylate as a tinnitus inducing drug in the auditory cortex of guinea pigs. METHODS: Extracellular recording of spikes of the primary auditory cortex and dorsocaudal areas in healthy male albino Hartley guinea pigs was continuously performed (pre- and post-salicylate). RESULTS: We recorded 160 single units in the primary auditory cortex from five guinea pigs and 156 single units in the dorsocaudal area from another five guinea pigs. The threshold was significantly elevated after the administration of salicylate in both the primary auditory cortex and dorsocaudal areas. The Q10dB value was significantly increased in the primary auditory cortex, whereas it has significantly decreased in the dorsocaudal area. Spontaneous firing activity was significantly decreased in the primary auditory cortex, whereas it has significantly increased in the dorsocaudal area. CONCLUSION: Salicylate induces significant changes in single units of both stimulated and spontaneous activity in the auditory cortex of guinea pigs. The spontaneous activity changed differently depending on its cortical areas, which may be due to the neural elements that generate tinnitus.

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.

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.

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.

Neurotological findings in a patient with narrow internal auditory canal: a case report.

We report neurotological findings in a patient with unilateral narrow internal auditory canal, as confirmed by computed tomography. The patient presented no auditory brainstem response on the affected side. Vestibular tests including vestibular-evoked myogenic potentials (VEMP) and caloric test revealed normal function of both inferior and superior vestibular neural pathways.

A case of meningoencephalic herniation of the temporal bone.

A case of cerebrospinal fluid leakage from a meningoencephalic herniation of the temporal bone is presented. Computed tomography and magnetic resonance imaging were useful for a diagnosis of meningoencephalic herniation. After surgical treatment, no recurrence was observed during a 6-month follow-up period.

A rare case of olfactory neuroblastoma with intracranial extension.

Olfactory neuroblastoma (ONB) is a rare form of head and neck tumor, and further ONB presenting an intracranial extension is extremely rare. Therefore, at the present time there is no established therapeutic standard supported by oncological studies. Our report documents a patient who underwent a craniotomy in combination with transnasal approach for tumor excision, followed by postoperative irradiation. We conclude that the patient shows no evidence of recurrence during the 11-year follow-up involving sinus CT scans and endoscopic examinations.

Two cases of Aspergillus sinusitis with bone destruction.

We experienced the clinical courses of two cases of destructive Aspergillus in paranasal sinuses in which an Aspergillus fungus ball was formed, and which caused bony destruction are described. The case in which a nidus could not be completely surgically removed and with intervening diabetes had an unfavorable prognosis. It is recommend to perform an early expanded operation as well as to administer a sufficient amount of antifungal drugs for the treatment of destructive Aspergillus in paranasal sinuses.

A case report of difficult diagnosis in the patient with advanced laryngeal tuberculosis.

We report a patient with severe laryngeal tuberculosis (LTB) involving thyroid cartilage and combined with whole-bone metastasis. A 57-year-old male had presented only with hoarseness. Radiological findings were indicative of suspected metastasis from a malignant tumor. However, tuberculosis was considered by histopathological findings, and so sputum samples were tested for acid-fast bacilli and purified protein derivatives of tuberculin in order to detect the presence of LTB. A polymerase chain reaction confirmed the diagnosis. Anti-tuberculous medications were effective in resolving the hoarseness, and the removal of the mass in the right wing of thyroid cartilage was confirmed by computed tomography (CT).

Subcutaneous emphysema secondary to tonsillectomy: a case report.

We report a patient in whom subcutaneous emphysema developed shortly after a tonsillectomy. A 55-year-old female with a chronic tonsillitis underwent a tonsillectomy, and about 8 h after surgery complained of swelling to the left side of the face and neck. There was crepitus and local tenderness in the left side of the neck. A CT scan revealed subcutaneous emphysema. The mechanisms underlying emphysema after tonsillectomy are discussed.

Effects of nimodipine on salicylate ototoxicity.

The purpose of this study was to examine the effects of nimodipine on salicylate ototoxicity in guinea pigs. The compound action potential (CAP) was recorded at the round window, and the cochlear blood flow (CBF) was measured simultaneously from the lateral wall of the basal turn of the cochlea by laser Doppler flowmetry. After administration of salicylate (100 mg/kg), the CAP thresholds were significantly elevated, by 5 to 20 dB (p < .05), and the CBF was significantly decreased (p < .05). After administration of nimodipine (2 mg/kg), the CAP thresholds were unchanged, but the CBF had increased significantly (p < .05), while systemic blood pressure had decreased significantly (p < .05). Simultaneous administration of both salicylate (100 mg/kg) and nimodipine (2 mg/kg) resulted in significant elevation of the CAP thresholds (p < .05), while the CBF did not decrease. These results suggest that nimodipine prevents the decrease in CBF induced by salicylate, but that nimodipine does not prevent the deterioration in the CAP.

Quinine affects the response properties of compound action potentials elicited by periodic click trains.

The effects of systemically applied quinine on the compound action potential (CAP) were investigated in 5 guinea pigs. A dose of 200 mg/kg body weight of quinine hydrochloride was administered intramuscularly, and CAPs were recorded at the round window before and after administration. The CAP thresholds of the animals were elevated by 5 to 25 dB approximately 30 minutes after administration, and thresholds recovered in some animals during the experimental session. The CAP waveform elicited by the click train stimulus was abnormal after administration of quinine. The amplitude of the CAPs elicited by the second click was larger than that of those elicited by the first click. These changes may be induced by an abnormally broadened N1 response to the first click in the click train following quinine administration. In contrast, the CAP waveforms elicited by the second click and by the following clicks in the click train appeared normal.