Complicaciones y causas de fallo en cirugía de implante coclear en pacientes del servicio de otorrinolaringología del Hospital Universitario Clínica San Rafael / Complications and causes of failure in cochlear implant surgery patients in the “Hospital Universitario Clínica San Rafael” service

Este estudio corresponde a un análisis descriptivo de los pacientes del Hospital Universitario Clínica San Rafael llevados a cirugía de implante coclear entre enero/2000 a diciembre/2010 y describe la ocurrencia de complicaciones menores y mayores en la cirugía de implante coclear con un mínimo de seguimiento de 12 meses. Las complicaciones de la cirugía de implante coclear se dividen en dos categorías; complicaciones menores y mayores. Las complicaciones menores son aquellas que pueden, o no, producir una disminución en el funcionamiento del implante, pero que se resuelven de manera espontánea o con tratamiento conservador, sin necesidad de realizar una nueva intervención quirúrgica, e incluyen: dolor local, tinnitus, vértigo, alteraciones del gusto, infección, fístula de líquido cefalorraquídeo y parálisis facial. Las complicaciones mayores son aquellas que requieren reintervención quirúrgica o explante. Se logró recopilar la información de 172 pacientes, 88 (51,16%) de sexo masculino y 84 (48,83%) de sexo femenino, con unas edades entre los 3 y los 71 años promedio de 22,1 años. El porcentaje global de complicaciones fue del 22,67% incluyendo las complicaciones menores y mayores, que corresponde a 39 implantes. El porcentaje de fallos es de 3,4%, que representa un total de 6 implantes. El porcentaje de reimplantes es de 5,2% del total, que corresponden a 09 implantes, siendo la causa más común falla técnica del dispositivo (06), seguido por falla por impacto (03). En cuanto a las complicaciones, se presentaron 12 complicaciones mayores que corresponden al 6,97%. El porcentaje de complicaciones menores en nuestro estudio fue de 15,6% (27)...

The following study corresponds to a descriptive analysis in patients from the Hospital Universitario Clínica San Rafael, which received cochlear implant surgery between january/2000 and december/2010. It describes the incidence of minor and major complications in the cochlear implant surgery, with a minimum follow up of 12 months. The complications of the cochlear implant surgery are divided in to two main categories: minor and major ones. The minor complications are those that can, or cannot, produce a decrease in the performance of the implant; but resolves spontaneously or with medical treatment, without making any surgery. Its clue symptoms involve: local pain, tinnitus, vertigo, taste alterations, infections, CSF fistula and facial paralysis. The major complications require a second surgery intervention or explants. The clinical histories of 172 patients were obtained, in which 88 (51,16%) were men and 84 (48,83%) were women, all with ages that comes from 3 to 71 years giving an average of 22.1 years old. The percentage of global complications was of 22,67% included the minor and major complications, that correspond to 39 implants. The fail percentage is of 3,4%, representing a total of 6 implants. The re-implants percentage corresponds to 5,2% from 9 implants that were in total, leading to the main cause of technical device fail (06), following by a fail for an impact cause (03). There were 12 major complications presented that correspond to 6.97%. The percentage of minor complications on the following study was of 15,6% (27)...

Impact of electrode insertion depth on intracochlear trauma.

OBJECTIVE: To assess the effect of cochlear implant (CI) insertion depth and surgical technique on intracochlear trauma. STUDY DESIGN AND SETTING: Twenty-one fresh human temporal bones were implanted with CI electrodes and underwent histologic processing and evaluation. Specimens were grouped into 3 categories: 1) soft implantation technique and standard electrode; 2) soft implantation technique and flexible prototype array; 3) forceful implantations and standard electrode. Based on the grading system (1 to 4), 2 numeric values were calculated indicating the overall severity of cochlear damage (trauma indices). RESULTS: Mean trauma index values were 13.8, 36.3, and 59.2 for group 1, 2, and 3, respectively. Differences in cochlear trauma (trauma index) were nonsignificant between specimens in groups 1 and 2 but were significant between groups 1 and 3. CONCLUSION: This study gives evidence that intracochlear trauma increases with deep insertions. Thus, in cases where cochlear integrity might be important, limited insertions should be achieved.

Rupture of Reissner's membrane during acute endolymphatic hydrops in the guinea pig: a model for Ménière's disease?

CONCLUSION: The changes in cochlear function during a destructive acute endolymphatic hydrops were relatively small. This might be consistent with the hypothesis that an endolymphatic hydrops is a marker of disordered inner ear homeostasis rather than the cause of the clinical symptoms of Ménière's disease. OBJECTIVE: Assessment of cochlear function during induction of a destructive acute endolymphatic hydrops. MATERIALS AND METHODS: During repetitive microinjections of 0.5 microl of artificial endolymph at a rate of 50 nl/s the 2f1-f2 and f2-f1 cochlear microphonics distortion products (CMDP) and 2f1-f2 distortion products otoacoustic emissions (DPOAE) were recorded in the guinea pig. RESULTS: A 'catastrophe' occurred in the inner ear when 2.5-3.5 microl of artificial endolymph was injected. A rupture of Reissner's membrane was then found, most often in the apical turn of the cochlea. This rupture had only minor effects on the endocochlear potential, whereas it caused a marked decrease in 2f1-f2 DPOAE amplitude. The 2f1-f2 and f2-f1 CMDP amplitude increased during each injection prior to the rupture. After the rupture the f2-f1 CMDP amplitude decreased during each injection, possibly due to a shift of the cochlear transducer operating point position.

Histopathology of cochlear implants in humans.

The insertion of an intrascalar electrode array during cochlear implantation causes immediate damage to the inner ear and may result in delayed onset of additional damage that may interfere with neuronal stimulation. To date, there have been reports on fewer than 50 temporal bone specimens from patients who had undergone implantation during life. The majority of these were single-channel implants, whereas the majority of implants inserted today are multichannel systems. This report presents the histopathologic findings in temporal bones from 8 individuals who in life had undergone multichannel cochlear implantation, with particular attention to the type and location of trauma and to long-term changes within the cochlea. The effect of these changes on spiral ganglion cell counts and the correlation between speech comprehension and spiral ganglion cell counts were calculated. In 4 of the 8 cases, the opposite, unimplanted ear was available for comparison. In 3 of the 4 cases, there was no significant difference between the spiral ganglion cell counts on the implanted and unimplanted sides. In addition, in this series of 8 cases, there was an apparent negative correlation between residual spiral ganglion cell count and hearing performance during life as measured by single-syllable word recognition. This finding suggests that abnormalities in the central auditory pathways are at least as important as spiral ganglion cell loss in limiting the performance of implant users.

Experimental studies of vibratory trauma of Corti's organ. I: Electrophysiological measurements.

In the present-day environment, vibration concomitant with noise is most frequently observed, but even though it is regarded as only a weak, additional traumatic factor affecting the organ of hearing. This opinion is contrary to a number of reports on the damage of the hearing organ caused by vibration in workers of various branches of industry. As experiments on humans are rather difficult, the harmful effect of vibration is usually examined on laboratory animals. In the majority of studies dealing with this problem the presence of noise (purposely or casually) was found in most cases. The aim of this study was to determine the effect of isolated long-term whole-body vibration and vertical sinusoidal shaking (10 Hz frequency, 5 mm amplitude, and 2 g acceleration) on Corti's organ. The study was carried out on young guinea pigs of both sexes. Eighty four animals (30 control and 54 experimental) with Preyer's reflex and without otoscopically detectable changes were used. A group of 18 animals was subjected to vibration in noiseless shaking apparatus for 30, 90 and 180 days. After a one-month rest, cochlear microphonics were performed under urethane anaesthesia. Our modification of the phase-sensitive detection method was used. Cochlear microphonics at frequencies of 260 Hz, 500 Hz, 1 kHz and 2 kHz was recorded from the apex of the cochlea and for 4 kHz and 8 kHz from the region of the round window. As the cochlear microphonics values showed significant individual differences, all experimental samples were examined by means of non-parametric tests. The outcome of the study demonstrated a gradual but considerable cochlear microphonics voltage decrease in the range to 2 kHz. This result pointed to the generation of vibration-induced damage in outer hair cells of the fourth and third turnings of the cochlea in the guinea pigs under study.

Changes in cochlear function after double-membrane rupture in the guinea pig.

We measured the transiently evoked otoacoustic emissions (TEOAEs), compound action potentials (CAPs) and cochlear microphonics (CMs) in guinea pigs after rupture of the round window membrane alone (n = 5) or of the round window membrane with localized cochlear damage (n = 10). The localized cochlear damage entailed rupture of Reissner's membrane with damage to the stria vascularis. We determined the time course of changes in the total echo power (TEP) in TEOAEs and the minimal detectable levels of CAPs and CMs. The endocochlear potential (EP) was measured in the cochlea with localized damage. There were no changes in TEOAEs, CAPs or CMs in the guinea pigs subjected to round window membrane rupture alone, but the minimal detectable levels of CAPs and CMs were increased in all the guinea pigs in which TEOAEs were absent after rupture of the round window membrane with localized cochlear damage. Our results suggest that double-membrane rupture (rupture of the round window membrane with localized cochlear damage) produces acute sensorineural hearing loss. The hearing loss appeared to be related to damage to the cochlea, which may be induced by influx of potassium-rich endolymph into the perilymph, and by morphological damage to the scala media.

Insertional trauma of multichannel cochlear implants.

Insertional trauma to the cochlea from three different multichannel cochlear implant electrodes was evaluated in a single-blind controlled study in fresh human temporal bones. Sixteen fresh human temporal bones were implanted with one of three types of multichannel electrodes (Symbion/InnerAid, Cochlear/Nucleus, or Storz/UCSF). Seven temporal bones were used as controls where a cochleostomy only was created. The temporal bones were evaluated histologically and cochlear histograms of the trauma were created. Although the three electrode designs caused damage which was unlikely to hinder implant performance, a distinct pattern of trauma was seen with each of the three electrode types. The least traumatic of the three electrode designs in this study was the Nucleus type. The degree of insertional trauma may be relevant to changing indications for insertion of cochlear implants as well as for patients with device failure who require reimplantation.

Role of perilymphatic fistula in sudden hearing loss: an animal model.

The electrophysiologic response of the guinea pig cochlea was monitored after sequential lesions to Reissner's membrane and the round window (RW). Action potential (AP) responses to click stimuli were recorded from the RW before and after discrete puncture-type lesions were created in the cochlear partition of the second turn. Observed decrements were typically minor, comparable to no greater than 10 dB attenuation of stimulus intensity. The RW membranes then were perforated to create perilymphatic fistulas. Further monitoring demonstrated a rapid (within 5 to 10 minutes), severe decrement in AP amplitude and latency, with complete loss of the AP within 1 hour. Control animals with RW perforations alone did not show these decrements. Correct placement of the second turn lesions was documented by histology. We conclude that discrete lesions in the cochlear duct are not reflected in the AP input-output functions unless there is a fluid leak from the RW, and thus present a possible model for idiopathic sudden hearing loss.