Auditory function recovery following acoustic overstimulation.

OBJECTIVE: To examine electrophysiological data from auditory brainstem responses (ABRs) and distortion product otoacoustic emissions (DPOAEs) in chickens following acoustic overstimulation. MATERIAL AND METHODS: A total of 15 white 15-day-old Leghorn chickens were used. The animals were anesthetized with Equithensin, and placed with their heads in a special holder. Click stimuli were generated by a Nicolet CA1000 device and ABRs were recorded subcutaneously using three stainless-steel electrodes. An ILO 92/DP analyzer was used to determine DPOAEs. The noise was generated by a Promax GB 212 device. The acoustic exposure was provoked with a 2-kHz pure tone at 120 dB SPL for 24 h. ABRs and DPOAEs were determined before and immediately post-exposure and 5, 15, 21 and 30 days after the traumatic exposure. RESULTS: In our control DPgram response, the maximum amplitudes (dB SPL) occurred at 1, 1.5, 2, 3 and 4 kHz and the minimum amplitudes at 0.7, 5 and 6 kHz. Immediately following acoustic overstimulation an amplitude loss in all frequencies was detected (p < 0.001). Five days after noise exposure only the amplitude loss at 3 kHz remained. Three waves with positive and negative peaks appeared in our control ABR recordings. An important threshold shift was detected in the ABR response immediately after acoustic overstimulation. Its complete recovery occurred 15 days after the acoustic trauma. CONCLUSION: Recovery of the DPgram response was detected 5 days after acoustic overstimulation, whereas the normal ABR threshold appeared on the 15th day.

Distortion-product otoacoustic emissions study of the noise-induced toughening effect in rats.

OBJECTIVE: To compare the toughening effects in rats induced by pure tones and a broadband noise (BBN). MATERIAL AND METHODS: Sprague-Dawley female albino rats (n = 148; 8-10 weeks old) were used. Three experimental groups were established as follows. Toughening only: 38 rats, divided into 3 subgroups, were exposed to different conditioning sounds (2 and 4 kHz and a BBN of 0.25-6 kHz, respectively) at 75-85 dB sound pressure limit (SPL) for 8 h/day for 10 days. Acoustic trauma only: 54 rats, divided into 3 subgroups, were exposed to different conditioning sounds as above for 24 h at 100-110 dB SPL. Toughening plus acoustic trauma: 56 rats, divided into 3 subgroups, were exposed to different conditioning sounds as above, followed 8 h later by traumatic exposure to the conditioning sound at 110 dB SPL for 24 h. 2f1-f2 distortion-product (DP) otoacoustic emission measurements were obtained from the right ear of each animal pre-exposure, immediately post-exposure and after 8 h of the traumatic or conditioning exposure. RESULTS: In our control DPgram response, the maximum amplitude occurred at the highest frequencies (2, 3, 4, 5 and 6 kHz). No statistical differences between the control DPgram and the DP toughening (2 and 4 kHz and BBN)responses were found. Only 2 and 4 kHz frequencies induced a protective effect against traumatic sound exposures to the same frequencies, and this finding was statistically significant. CONCLUSION: The toughening phenomenon induced using 2 and 4 kHz pure tones and BBN in rats does not modify the DPgram response. Nevertheless, only 2 and 4 kHz frequencies induce a protective effect against traumatic sound exposures to the same frequencies.

[Comparative study of the use of manual and mechanical suturing in the closure of the mucosal defect in total laryngectomy]. / Estudio comparativo entre el empleo de la sutura manual y la sutura mecánica en el cierre del defecto mucoso en la laringectomía total.

With the present study we try to achieve an objective confirmation of the efficacy given by the mechanical suture in the closing of the pharyngeal defect following a total laryngectomy against the conventional manual suture with absorbable material. Therefore we have studied three random groups of patients: in the first one we include those who had a manual suture (n = 50), in the second one those who had performed a mechanical suture with closed technique (n = 38) and in the third one those who had a mechanical suture with an open technique (n = 12). We have checked that mechanical suture with a closed technique improves significantly the surgical length (212 minutes), the beginning of the oral feeding (10.73 days) and the time of in-hospital stay (13.5 days). Mechanical sutures with a closed technique also reduce the rate of complications such as fistulae (5.26%), infection (0%) and haemorrhage (0%).

Estudio comparativo entre el empleo de la sutura manual y la sutura mecánica en el cierre del defecto mucoso en la laringectomía total / Comparative study between the use of manual versus mechanical sutures in the closing of the mucous defect following a total laryngectomy

Con el presente estudio se pretende realizar una confirmación objetiva de la eficacia de la sutura mecánica en el cierre del defecto faríngeo tras laringectomía total, frente a la sutura convencional manual con material reabsorbible. Para ello hemos estudiado tres grupos aleatorios de pacientes: en el primero incluimos aquellos a los que se realizó sutura manual del defecto postlaringectomía total (n=50), en el segundo aquellos en los que se practicó sutura mecánica con técnica cerrada (n=38), y en el tercero aquellos a los que se realizó sutura mecánica con técnica abierta (n=12). Hemos comprobado que el empleo de la sutura mecánica con técnica cerrada mejora significativamente los tiempos de intervención (212 minutos), inicio de la ingesta oral (10,73 días) y estancia hospitalaria (13,5 días) respecto a los otros tipos de sutura. Así mismo, este tipo de sutura mecánica disminuye la incidencia de complicaciones como faringostomas (5,26%), infección (0%) y hemorragia (0%) (AU)

With the present study we try to achieve an objective confirmation of the efficacy given by the mechanical suture in the closing of the pharyngeal defect following a total laryngectomy against the conventional manual suture with absorbable material. Therefore we have studied three random groups of patients: in the first one we include those who had a manual suture (n = 50), in the second one those who had performed a mechanical suture with closed technique (n = 38) and in the third one those who had a mechanical suture with an open technique (n = 12). We have checked that mechanical suture with a closed technique improves significantly the surgical length (212 minutes), the beginning of the oral feeding (10.73 days) and the time of in-hospital stay (13.5 days). Mechanical sutures with a closed technique also reduce the rate of complications such as fistulae (5.26%), infection (0%) and haemorrhage (0%) (AU)

Morphometric study of the paranasal sinuses in normal and pathological conditions.

Prospective and retrospective morphometric CT (axial and coronal) research was performed with 100 healthy persons and 163 patients (145 males, 118 females, mean age 50 years, range 1-88 years). The patients were classified into the following groups: chronic sinusitis (n = 85), polyposis (n = 25), mucoceles (n = 13), benign tumors (n = 20) and malignant tumors (n = 20). After initial calibration with the scale (in cm) displayed on the CT image, each paranasal sinus was outlined following its bone inner surface. The data were processed with a high-resolution analysis system, and volumes were calculated using an integration areas rule. The ethmoid, maxillary and sphenoid sinuses exhibited an increase in volume for a period of up to 15 years, afterwards maintaining similar values. The frontal sinus grows in a monomodal pattern (peak at 30 years). The volumetric results (mean and standard deviation) in the normal adult group were as follows: maxillary sinus 13.07 cm3 (6.8), ethmoid 5.5 cm3 (2.0), sphenoid 3.5 cm3 (2.6) and frontal 3.7 cm3 (3.6). Primary frontal and maxillary sinus hypoplasia appeared in 3.9% and 1.3% of cases, respectively. The anatomic variations were as follows: concha bullosa 8.3%, Haller cells 3.2% and Onodi cells 8.3%. The sinusitis values (adults) were greater than those in the normal group: 14.4 cm3 (7.3), 6.8 cm3 (2.9), 2.9 cm3 (1.9) and 4.2 cm3 (5.2), with the exception of the sphenoid, but the difference was not statistically significant. Finally, we propose a new classification for paranasal sinus tumors (benign and malignant), volumetric T (vT), taking into account the morphometric tumoral volume and the mean volumetric value of normal sinuses.

[Intramuscular epithelioid hemangioma of the parapharyngeal space]. / Hemangioma epitelioide intramuscular del espacio parafaríngeo.

A clinical case of epithelioid hemangioma of the scalene muscle that occupied the parapharyngeal space is reported. The patient was a 34 year old man with a 2-month history of sensation of pharyngeal foreign body and mild dysphagia. The exploration revealed a tumor of the posterior and lateral wall of the oropharynx that extended from the rhinopharynx to the hypopharynx. The diagnostic sequence included CT, MRI, Doppler echography, and arteriography, which identified a right post-styloid tumor located behind and medial to the jugular vein, internal carotid artery, and vagal nerve, but did not affect arterial blood flow. The patient underwent surgical treatment consisting of lateral cervicotomy, tumor excision, and histological study.

[study of acoustic trauma in hunters using otoacoustic emission recording]. / Estudio del trauma acústico en los cazadores mediante el registro de las otoemisiones acústicas.

Transitory otoacoustic emissions (TOAE) were analyzed in 48 ears of male hunters (age range: 30-45 years: mean age: 37 years) and in a population with normal hearing. All the ears had TOAE. The incidence of TOAE for the 1, 2, 3, 4, 5 and 6 KHz frequential bands was significantly lower in hunters than in the normal subjects (p < 0.001). The mean amplitude of TOAE was significantly lower in hunters (9.2 dB SPL) than in the control group (16 dB SPL; p < 0.001). The amplitude of the TOAE for the frequencies 1, 2, 3, 4, 5 and 6 KHz was significantly lower in hunters than in controls (p < 0.001).

[The study of ototoxicity in Gallus domesticus by recording distortion products]. / Estudio de la toxicidad auditiva en el Gallus domesticus mediante el registro de los productos de distorsión.

Distortion products (DP) were recorded and a morphological cochlear study was made of a sample of 60 ears from chickens (Gallus domesticus. Leghorn breed) and the ages of 15, 23, 29 and 60 days, after intoxication by intramuscular gentamicin injection (40 mg per kg weight and day for 8 days). Spontaneous or transitory otoacoustic emissions were not obtained in any case. DP recordings showed a 2F1-F2 response in every frequency band ranging from 0.7 to 6 KHz. The DP incidence shifted with the age of the chickens and differed significantly (p < 0.001) in the groups of 29 and 60 day-old chickens (m = 100%) and in the 29-day-old (m = 64%) and 60-day-old (m = 62%) intoxicated chickens. We found no significant differences in DP amplitude in subpopulations. In the intoxicated groups, the proximal segment of the ototic membrane disappeared in the macula lagenae and a loss of contact with the hair cells appeared. Degenerative vacuolar phenomena were observed in the support cells and cellular loss in the spiral ganglion.

[The influence of contralateral acoustic stimulation on distortion products]. / Influencia de la estimulación acústica contralateral en los productos de distorsión.

The suppressor effect of contralateral broad-band white noise stimulation at 60 dB SPL on distortion-product otoacoustic emissions (DPOAEs) from 40 human ears was examined. The sample was composed of 9 females and 11 males, age 21-28 years. All the ears had DPOAEs. The 2-6 kHz bands had an incidence of 100%, but 0.7 kHz was found in only 27%. Eighty-eight percent of the frequency points recorded had an amplitude of more than 3 dB SPL over background noise. Nevertheless, DPOAE amplitude decreased for frequencial bands 1 to 6 kHz when contralateral acoustic stimulation was employed. However, these differences were only statistically significant for 1.5, 2 and 3 kHz frequencies. No significant differences were found between the ears of a subject or between sexes.

A contribution to the structural pattern differences between the apical and basal spiral ganglions in mammals.

The purpose of this paper was to establish a mammalian comparative study between the neuronal spaces of the upper versus the basal cochlear turns. We studied with light microscopy i) Webster albino rat embryos at various gestational days (GD), and a postnatal (PN) series; ii) kittens 3 weeks old; iii) pigmented guinea pig embryos and also PN specimens; iv) diverse human fetuses. As from the 16th GD, the apical spiral ganglion primordium of the rat appears as a spherical cluster of cells immersed in the mesenchymal modular tissue whereas the basal spiral primordium displays a pyramidal shape with its apex towards the auditory receptor. Both ganglions keep this shape until the rat becomes adult. This structural pattern also appears in the cat, guinea pig and in human material. This morphological model enables a radial stratification of the peripheral and central auditory nerve projections. A thin uni- or bicellular connective layer covers the tympanic scala side of the apical spiral ganglion as from 8 hours after birth in the rat. No gap is detected in this layer which is: mesenchymal in the embryonic and fetal stages (rat, guinea pig, human), connective in PN rat and kitten, and osseous in PN guinea pig and in the human neonate.

[Parameters of normalcy in transient otoacoustic emissions]. / Parámetros de normalidad de las otoemisiones acústicas transitorias.

The incidence, amplitude and frequency spectrum of transitory otoacoustic emissions (TOAE) were analyzed in a sample of 232 normal hearing ears, after click stimulation to determine normal parameters. 116 subjects, 58 female ranging in age from 18 to 30 years, mean age 23.1 years, and 58 male were from 18 to 32 years, mean 23.7 years, were included in this study. TOAE were normal in all ears, 132 (57%) ears had TOAE at all frequencies between 0.5 and 5 kHz. The mean amplitude of TOAE was 16 dB SPL (SD 3.77) and the highest amplitude was elicited at 1-2 kHz frequency. The intensity of stimulation correlated directly with evoked response amplitude and the subject's age correlated inversely with the incidence and amplitude of TOAE.

[Standard parameters of distortion products]. / Parámetros de normalidad de los productos de distorsión.

In this study we have analyzed the incidence, range, frequency spectrum and threshold of distortion products in a sample of 232 normal hearing person. 116 younger adults, 58 female ranging in age from 18 to 30 years (mean age 23.1) and 58 males ranging in age from 18 to 32 (mean age 23.7) were included in the study. In all the ears studied, the presence of distortion products in a normal ear were found with regularity in the frequency region between 700 to 6,000 Hz. Higher incidence occurred in younger people and women but was not statistically notable. There is a direct correlation between distortion products amplitude and its primary intensity. Distortion products amplitude increases progressively from low (770 Hz) to high frequencies (6,000 Hz). The amplitude of distortion products and its mean value is higher in women, in all frequencies, except in the 700 to 1,000 Hz region. Input/output function had a mean of 50 dB SPL at 1 kHz, 43.8 at 2 kHz, 38.4 at 4 kHz and 33.5 at 6 kHz.

[Normalcy parameters of spontaneous otoacoustic emissions]. / Parámetros de normalidad de las otoemisiones acústicas espontáneas.

In the present study we analyze the spontaneous otacoustic emissions (SOAEs) in a sample of 232 hearing-preserved ears. The examination was performed in people of the same gender aged 18 to 32 years (mean age 23.35) and always in the ear of the same side. We have found that the incidence of the SOAEs was 42.6% of the ears and 53.5% of the individuals, being modified by sex, age and audiometric threshold. Incidence in females was 58.62% and in males 26.72%. Mean age of the group presenting SOAEs was 22.68 years, while in the group without SOAEs was 23.85% years. The audiometric threshold in patients with SOAEs was lower (7.27 dB HL) that in those ears without SOAEs (8.17 db HL). Other parameters studied were the number of peaks, the intensity and the frequency of spontaneous otacoustic emissions. The number of peaks of the SOAEs varied from 1 to 12 (mean 3.1). Women showed higher number of peaks than men did. The intensity was ranged between 3 and 51 db SPL (mean 20.1 db SPL). The frequency spectrum presented a range from 488 to 6,103 hertzs, with a higher incidence (48.5%) in the frequency bands of 1,000 and 2,000 Hz. All these data were statistically significant.

Morphologic and morphometric study of human spiral ganglion development.

A light microscopic study of the spiral ganglion was done in human embryos and fetuses measuring 45, 50, 60, 74, 90, 134, 270 mm crown-rump length (crl), and in a one-day-old neonate. Morphometric evaluations of i) cell and nuclear area, ii) nuclear area/cell area ratio, iii) ganglion area, iv) cell concentration/surface unit, and v) distance between the first neuron and the receptor were made, and the results statistically evaluated. In earlier stages of development, spiral ganglion primordia appeared as a cluster of neuroblasts and some schwannoblasts immersed in the mesenchymal tissue, close to the ductus cochlearis. A honeycomb pattern in the spiral ganglion neurons was observed in the basal turn of a 74 mm crl fetus. In later stages, the basal turn of a 90 mm crl fetus showed a spatial organization. Peripheral and central fibers of the acoustic nerve appeared stratified in early periods of development (45 mm crl embryo). From this stage on, both phenomena progress apicalwards until the neonatal period. A significant decrease in the nuclear area/cell area ratio was observed from the 134 mm crl fetus (17 weeks) to the neonatal stage in all turns. This led to a significant increase in cellular area from the 270 mm crl fetus (32 weeks) to the neonate, with no significant variation in nuclear area. The distance from the primordium of the organ of Corti to the spiral ganglion in the interval between 45 and 74 mm crl showed a significant increase in all turns.(ABSTRACT TRUNCATED AT 250 WORDS)