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L’impianto uditivo del tronco cerebrale e una modalita di riabilitazione dell’udito le cui indicazioni sono rare. Si tratta delle situazioni dove l’impianto cocleare e impossibile o inefficace: presenza di tumori delle vie uditive, ossificazioni cocleari e malformazioni della coclea e del nervo uditivo. La principale e la neurofibromatosi di tipo 2. Le indicazioni sono poste dopo una valutazione pluridisciplinare e il posizionamento del portaelettrodi, la cui configurazione e adattata all’anatomia del tronco cerebrale, e eseguito durante un intervento da parte di un’equipe oto-neuro-chirurgica. I risultati ottenuti dal punto di vista funzionale sono variabili e possono raggiungere, nei casi migliori, quelli ottenuti con un impianto cocleare.

Cochlear implant in adults is a procedure, dedicated to rehabilitate severe to profound hearing loss. Because of technological progresses and their applications for signal strategies, new devices can improve hearing, even in noise conditions. Binaural stimulation, cochlear implant and hearing aid or bilateral cochlear implants are the best opportunities to access to better level of comprehension in all conditions and space localisation. By now minimally invasive surgery is possible to preserve residual hearing and use a double stimulation modality for the same ear: electrical for high frequencies and acoustic for low frequencies. In several conditions, cochlear implant is not possible due to cochlear nerve tumour or major malformations of the inner ear. In these cases, a brainstem implantation can be considered. Clinical data demonstrate that improvement in daily communication, for both cochlear and brainstem implants, is correlated with cerebral activation of auditory cortex.

La finalidad de este articulo consiste en describir los aspectos esenciales de las tecnicas quirurgicas referentes a las protesis auditivas implantables que estan disponibles en la actualidad. Cuando se ha considerado util recordar la anatomia quirurgica, se ha hecho hincapie en los puntos fundamentales. Se revisaran los implantes cocleares, los implantes auditivos del tronco del encefalo, las protesis auditivas osteointegradas y, por ultimo, los implantes de oido medio. Se detallaran las indicaciones, los principios de funcionamiento y los resultados. Se ha previsto un apartado especial para algunas indicaciones especiales que pueden requerirse una modificacion de la tecnica estandar. Asimismo, se describen las complicaciones, que, por desgracia, son una parte integrante de las tecnicas quirurgicas.

Questo articolo ha lo scopo di descrivere l’essenziale delle tecniche chirurgiche riguardo agli ausili uditivi impiantabili attualmente disponibili. Quando e stato giudicato utile richiamare l’anatomia chirurgica, l’accento e stato posto sui punti essenziali. Saranno passati in rassegna gli impianti cocleari, gli impianti uditivi del tronco cerebrale, gli ausili uditivi ad ancoraggio osseo e, infine, gli impianti dell’orecchio medio. Sono ricordati le indicazioni, i principi di funzionamento e i risultati. Sono affrontate le varianti chirurgiche. E stato previsto uno sviluppo per le indicazioni particolari quando puo derivarne una modificazione della tecnica standard. Analogamente sono trattate le complicanze, parte purtroppo integrale delle tecniche chirurgiche.

Resume Introduction La neurofibromatose de type 2 (NF2) est une maladie genetique, a transmission autosomique dominante caracterisee par la presence de schwannomes vestibulaires bilateraux. Etat des connaissances Les autres manifestations de la NF2 incluent des meningiomes, des schwannomes, des ependymomes, localises en intracrânien ou intrarachidien, ainsi que des lesions cutanees et ophtalmologiques. En l’absence de schwannome vestibulaire bilateral, un ensemble de criteres permet neanmoins de diagnostiquer la NF2. L’expression phenotypique de la maladie est variable. Les principaux facteurs de mauvais pronostique sont un âge precoce a l’apparition des premiers symptomes et un nombre eleve de tumeurs au diagnostic. Le produit du gene NF2 , Merlin/Schwannomin est aussi implique dans le developpement de la majorite des schwannomes et meningiomes sporadiques. Perspectives et conclusion La prise en charge des patients NF2 necessite une equipe oto-neurochirurgicale experimentee, dans le cadre de « cliniques NF2 ». Une surveillance clinique et paraclinique annuelle prolongee est souhaitable. Un protocole de depistage familial est propose. Classiquement, seules les tumeurs symptomatiques sont traitees. Certains proposent une attitude active precoce sur les schwannomes vestibulaires afin de preserver l’audition. Lorsqu’un traitement est indique, la chirurgie est le traitement de reference des tumeurs. L’implant auditif du tronc cerebral a une place de choix dans la rehabilitation de l’audition des patients NF2.

Resume Objectifs Le but de cette etude est de presenter les principes de l'implant auditif du tronc cerebral (ITC) et d'evaluer le benefice apporte par cette technique innovante dans differentes indications. Materiel et methodes Les indications de l'ITC sont : la neurofibromatose de type 2 (NF2), les ossifications cochleaires totales bilaterales, les associations de schwannome vestibulaire a une surdite controlaterale et les malformations cochleaires majeures et aplasies du nerf auditif. Le bilan preoperatoire comporte une evaluation clinique, orthophonique, radiologique, et psychologique. La voie d'abord chirurgicale est retrosigmoide ou translabyrinthique. L'evaluation du benefice apporte en termes de perception auditive est realisee avec ou sans le support de la lecture labiale, pour des mots et phrases sans contexte. Resultats Les resultats montrent que, chez les patients NF2, le meilleur benefice fonctionnel auditif est obtenu dans les cas de schwannome vestibulaire de taille moyenne, avec une privation auditive du cote implantee breve ou nulle. Les facteurs de mauvais pronostic sont une privation auditive prolongee, un diametre cisternal superieur a 30 mm, une difficulte a la mise en place du porte-electrodes en peroperatoire et l'activation de moins de dix electrodes avec des sensations auditives. Dans les cas de surdite totale postmeningitique avec ossification cochleaire totale, le resultat obtenu est tout a fait comparable a celui des implants cochleaires dans cette indication (surdite postmeningitique sans ou avec ossification partielle). Il en est de meme pour les autres indications non tumorales (hors NF2). Conclusion Ces resultats demontrent que l'ITC apporte un benefice fonctionnel chez les patients NF2, ce d'autant que la privation auditive est breve et que le volume tumoral est limite. En cas d'ossification cochleaire postmeningitique, le resultat est comparable a celui d'un implant cochleaire, pour des cochlees non ou partiellement ossifiees.

I fluidi del labirinto, perilinfa ed endolinfa, hanno un doppio ruolo fisiologico: concorrono all’attivazione delle cellule ciliate cocleari e vestibolari attraverso la trasmissione del segnale meccanico e partecipano alla trasformazione del segnale in un messaggio nervoso attivando fenomeni molecolari tra i liquidi e le cellule ciliate. Grazie alle osservazioni, tanto istologiche quanto terapeutiche, che hanno suggerito l’esistenza di una relazione tra udito e omeostasi dei fluidi dell’orecchio interno, molti studi hanno permesso di precisare i caratteri fisicochimici dei fluidi del labirinto. Alla fine degli anni Cinquanta due scoperte hanno segnato una svolta decisiva nello studio di questi fluidi: la misura di un potenziale di riposo elevato e positivo nell’endolinfa cocleare (+80 mV rispetto al sangue o alla perilinfa) da parte di Von Bekesy e la dimostrazione di concentrazioni elevate di potassio e basse di sodio nell’endolinfa cocleare e vestibolare da parte di Smith et al. Questi risultati hanno guidato le ricerche, in particolare nella coclea, per i trenta anni successivi, ricerche sviluppate a partire da concetti e tecniche elaborati per la fisiologia cellulare e per la fisiologia dei trasporti transmembranari. Nei successivi venti anni sono state applicate le tecniche di biologia cellulare e molecolare allo studio dell’orecchio interno. La tappa seguente e stata superata con l’identificazione di numerose mutazioni coinvolte nella comparsa di sordita sindromiche o non sindromiche. Attualmente, la composizione dei fluidi del labirinto e ben stabilita, sono state precisate le origini rispettive di perilinfa ed endolinfa, sono stati chiariti i meccanismi cellulari implicati nella secrezione di ciascuno di questi liquidi e sono stati identificati alcuni dei sistemi regolatori di tali fluidi. I progressi realizzati nella comprensione dei meccanismi fisiopatologici implicati nel mantenimento dell’omeostasi dei fluidi dell’orecchio interno dovrebbero permettere, in un prossimo futuro, di aprire nuove strade per la terapia delle sordita e delle vertigini legate direttamente o indirettamente alle anomalie di tali fluidi.

We report the MRI findings of six unusual lesions of the internal auditory canal: three haemangiomas, one lipoma, one metastasis and one traumatic neuroma. We compare the findings to those of 20 intracanalicular schwannomas. We noted the site and size of the tumour, its signal intensity, borders and the homogeneity of enhancement were studied on T1-weighted images before and after intravenous contrast medium and T2-weighted images. Most schwannomas were homogeneous lesions, isointense on T1- and T2-weighted images, and strongly enhancing. Spontaneous high signal on T1-weighted images, heterogeneous contrast enhancement and extranodular enhancement were helpful for recognising lesions other then schwannomas; site, size and signal on T2-weighted images were not. All the haemangiomas had a specific pattern of contrast enhancement, with an anterior core intensely enhancing portion and a posterior portion which enhanced moderately or not at all.

The cause of sudden sensorineural hearing loss (SHL) remains unknown, even though studies have evidenced two main hypotheses: a latent virus infection due to herpesvirus and a local decrease in cochlear blood flow caused by vasospasm and/or hyperviscosity. Clinical evaluation and diagnostic tests should always be performed, to rule out an acoustic neuroma, revealed in 5–26% of cases by a sudden deafness. The two main major prognostic factors are the severity of hearing loss and the time from onset to treatment, suggesting that two groups of patients are susceptible to benefit from therapy: patients with a hearing loss of less than 40 dB, managed within 2 months from the onset, and patients with a hearing loss of more than 40 dB, treated within 1 month after the onset of deafness. Steroids appear to be the only treatment available with a significant beneficial effect on SHL.

The efficacy and tolerability of ceftibuten 400 mg o.d. or 200 mg b.i.d. was compared with amoxicillin/clavulanate (AMX/CA, 500 mg/125 mg) t.i.d. in the treatment of acute sinusitis. This was a multicenter, open, randomized, parallel-group 8-day study. In total, 450 patients were evaluable for safety and 400 patients for efficacy. At day 10, clinical cure rates were 83% in the ceftibuten 400 mg o.d. group, 87% in the ceftibuten 200 mg b.i.d. group and 89% in the AMX/CA t.i.d. group; the clinical/radiological cure rates were 52, 44 and 56%, respectively. Clinical and clinical/radiological cure rates at day 40 for the ceftibuten 400 mg o.d. group, ceftibuten 200 mg b.i.d. group and the AMX/CA t.i.d. group were similar, with clinical cure rates of 81, 82 and 87%, and clinical/radiological cure rates of 62, 58 and 63%, respectively. Most adverse events were mild. Ceftibuten, 400 mg o.d. or 200 mg b.i.d., was equally effective and well tolerated as AMX/CA t.i.d. in the treatment of acute sinusitis.

Resume Cette etude multicentrique evalue la diffusion de la ciprofloxacine dans les structures tissulaires de l'oreille moyenne apres des administrations reiterees de 500 mg par voie orale toutes les 12 heures. Les prelevements ont ete effectues en phase per-operatoire chez des patients adultes devant subir une intervention motivee par une otite chronique. L'administration de ciprofloxacine a debute 9 jours avant l'intervention. Les prelevements ont ete realises a differents intervalles apres la derniere prise afin d'evaluer l'evolution des concentrations en fonction du temps. Les concentrations maximales moyennes observees et les delais d'apparition de celles-ci ont ete les suivants : muqueuse de l'oreille moyenne (n = 16) : 5,54 ± 3,46 μg/g (3–4 heures), os cortical mastoidien (n = 21) : 1,07 ± 1,29 μg/g (4 heures). Les mesures effectuees 12 heures apres la derniere prise montrent que les concentrations de la ciprofloxacine dans la muqueuse de l'oreille moyenne sont encore au moins egales aux CMI de cet antibiotique vis-a-vis de la plupart des germes responsables des surinfections d'otites chroniques. Ces resultats permettent de penser que la ciprofloxacine administree a la posologie de 500 mg PO toutes les 12 heures peut constituer un traitement efficace des otites chroniques suppuratives. Ils devront etre confirmes par des etudes cliniques.

Four cases of facial nerve neuroma were evaluated by computed tomographic (CT) scan and magnetic resonance imaging (MRI). The extension of the tumor in the petrous bone or the parotid gland was well defined by MRI in all cases. CT scan was useful to demonstrate bone erosions and the relation of the tumor to inner ear structures. In cases of progressive facial palsy, CT and MRI should be combined to detect a facial neuroma and to plan the surgical approach for tumor removal and nerve grafting.

Twenty-seven patients with chronic middle ear infection were prospectively studied with pre- and post-contrast magnetic resonance (MR) images to assess the role of MR imaging in the recognition of middle ear tissue abnormalities. The findings were correlated with computed tomographic (CT) scans and surgical and pathologic data. Granulation tissue constantly appeared enhanced on studies done with gadolinium diethylenetriaminepentaacetic acid (DTPA), unlike cholesteatoma, cholesterol granuloma, or brain herniation into the middle ear cavities. Evaluation of extension and thickness of the inflammatory tissue with MR imaging was in accordance with surgical findings. In six cases, isolated granulation tissue misdiagnosed as either a cholesteatoma or herniated brain on CT scans was accurately evaluated on postcontrast MR images. When granulation tissue was associated with other soft-tissue masses, Gd-DTPA-enhanced MR images allowed accurate definition of the site and the extension of each lesion. Furthermore, abnormal meningeal enhancement was precisely depicted by MR images in two cases.

To evaluate results of cochlear implantation in patients with far-advanced otosclerosis.Sixteen patients with far-advanced otosclerosis had undergone unilateral (n = 13) or bilateral (n = 3) cochlear implantation. Surgical difficulties, incidence of complications and postoperative benefit were analyzed.A full electrode insertion was achieved in all patients without surgical difficulties. All patients demonstrated excellent benefit of cochlear implantation. Binaural implantation still improves speech performances, compared to unilateral implantation. In case of residual cochlear function of one nonoperated side, a stapes surgery, performed during the same surgical time as cochlear implantation, can improve speech scores and restore bilateral hearing. Facial nerve stimulation occurred only in 1 patient.Cochlear implantation is the method of choice for rehabilitation of patients with otosclerosis, presenting profound or total hearing loss. Patients obtain excellent benefit with a low rate of complications.

* orthophonistes, centre referent implant cochleaire adulte d'Ile de France et surdite genetique de l'adulte du Pr O.Sterkers, groupe hospitalier Pitie-Salpetriere bâtiment Paul Castaigne 50-52 bd Vincent Auriol 75013 Paris ** orthophoniste, Dr en neurosciences, service ORL du Pr G. Lamas, groupe hospitalier PitieSalpetriere 50-52 bd Vincent Auriol 75013 Paris ***Docteur, Unite d’Otologie, Implants Auditifs et Chirurgie de la Base du Crâne, Hopital PitieSalpetriere, AP-HP, Paris. **** Professeur, Unite d’Otologie, Implants Auditifs et Chirurgie de la Base du Crâne, Hopital PitieSalpetriere, AP-HP, Paris.

To investigate the surgical techniques and speech performance of multichannel auditory brainstem implant (ABI) in patients with bilateral acoustic neuromas (neurofibromatosis type 2).The nucleus 21 channel auditory brainstem implant was implanted into the lateral recess of the fourth ventricle through the translabyrinthine approach in 7 patients after removal of the tumor. The accurate placement of electrode array was ensured by the electromyogram monitoring of the 7th and 9th nerves and the electrically evoked auditory brainstem responses (EABR). Initial switch-on occurred six weeks postoperatively. Speech evaluation was performed every 3 months for the first year and annually thereafter.During the surgery, the lateral recess could be found and the typical EABR could be recorded in 6 cases. They later reported a significant benefit from the device. Two of the cases have achieved functional open-set speech understanding. In contrast, one patient with no EABR because of difficulty of the anatomic location during the surgery had no sensations postoperatively.The multichannel ABI could effectively restore auditory sensations in patients deafened by bilateral acoustic neuromas. The accurate location of the cochlear nucleus complex during surgery was the key factor for the success of the operation.

Round window (r.w.) administration of drugs involves the delivery of medication directly into the inner ear via the r.w. membrane, avoiding a systemic effect of the therapy. Earlier experimental studies suggest that a number of antioxidants and scavengers hold promise for ameliorating the tissue damaging capacity of reactive oxygen species in some acquired cochlear disorders. D-Methionine and thiourea are two small sulfur-containing molecules with an antioxidative and scavenging effect. The passage through the r.w. of radioactive D-methionine and thiourea administered by 1 h infusion to the r.w. was studied in a rat model. Levels of the tracers were measured in scala tympani perilymph (PLT) 17-254 min after r.w. administration. Both tracers pass the r.w. membrane readily. Peak levels were found in the earliest taken samples after the administration. The radioactivity in PLT of the basal turn reached a peak to about 1.5-1.9% of the irrigating medium radioactivity. Following the r.w. administration, the concentration of radioactive D-methionine and thiourea declined with a terminal half-life of 0.57 and 0.77 h, respectively. The distribution of the tracers at the cellular level was analyzed by autoradiography. The most intense expression was found in the lateral wall of the cochlea. It can be postulated that local delivery to the cochlea of D-methionine and thiourea via the r.w. gives high local concentrations of the substances in PLT in the basal turn.

Hemangiomas are tumors. Hemangiomas near the geniculate ganglion or in the internal acoustic meatus are well known but rare. We present two cases of hemangiomas located at the porus acusticus, an even more rare site. MRI showed a millimeter-sized tumor, located in the porus acusticus, developing perpendicular to the axis of the acoustico-facial nerves, surrounding them. They were hyperintense on T1-weighted images, strongly hyperintense on T2-weighted images with a characteristic progressive and marked enhancement after injection of gadolinium DTPA. Similar signal abnormalities were present in the adjacent temporal bone, and CT scan demonstrated a honeycomb appearance with intratumoral bony spicules. These imaging criteria allows differentiation between hemangioma and neurinoma. We hypothesize that this location is related to the presence of a rich vascular plexus of the dura mater in this area.

The auditory brainstem implant (ABI) is designed to restore useful auditory sensations in patients with neurofibromatosis Type 2 (NF2). The implantation is usually performed at the time of tumor removal in patients who do not undergo radiation treatment. The authors evaluated the performance of ABIs in three patients with NF2 in whom vestibular schwannoma continued to grow after radiation treatment. These three patients with NF2 received a 21-channel ABI; a translabyrinthine approach was used for both the tumor removal and the ABI placement. The interval between radiosurgery and the tumor removal plus device implantation ranged from 2 to 11 years. In all cases, the tumor was growing and the patients presented with total deafness. The mean number of active electrodes in these three patients was equivalent to the average results reported in other patients who received ABIs. The patients in this study used the ABI regularly for everyday life and obtained useful levels of environmental sound recognition. It is concluded that hearing function can be rehabilitated using ABIs in patients with NF2, even if radiosurgery fails to control the tumor growth.

In order to evaluate the decisional elements in the surgical strategy of deep-seated and/or extensive intratemporal lesions, a retrospective review of cases followed up between 1985 and 1996 in our department was undertaken. Eighty-one adult patients presenting temporal bone lesions located or extending beyond the middle ear limits excluding vestibular schwannomas and surgically treated were included. The population comprised 38 men and 43 women (mean age: 43 years, range: 17-81). Pre-, intra- and postoperative data were collected from medical files. The principal factors influencing the choice of the surgical approach were the location of the lesion and its presumed aggressiveness, the tumour involvement of the internal carotid artery and the labyrinth on preoperative imaging, and the preoperative hearing loss. A coherent algorithm based on these factors can be proposed for the surgical management of intratemporal lesions. High quality preoperative imaging is mandatory for the surgical planning.

Three patients with neurofibromatosis type 2 who had undergone previous cochlear nerve tumour removal were implanted with the Nucleus 21-channel auditory brainstem implant (ABI). The time intervals between tumour removal and implantation were 4, 5, and 7 years, respectively. Total bilateral deafness was confirmed before implantation. One patient was also blind after acute intracranial hypertension. The translabyrinthine approach was used in all cases. The choice of side for implantation depended on pre-operative magnetic resonance imaging study, the facial nerve function, the presence of recurrent and/or other lesions, and the patient's preference. Although the scarring of prior surgical procedure largely changed the anatomical structures in the cerebello-pontine angle, various landmarks could be found to locate the foramen of Luschka, where the ABI electrode was inserted into the lateral recess of the fourth ventricle. During surgery, the electrically evoked auditory brainstem responses were recorded to confirm that the ABI stimulation activated the auditory system; the electromyogram of the 7th and 9th nerves was helpful in finding the landmarks and minimising the triggering of the cranial nerves with ABI stimulation. The number of active electrodes was 21, 7, and 4 in the three patients. All obtained meaningful pitch scaling and useful auditory sensations. One patient, with 21 activated electrodes, has achieved functional open-set speech understanding. The second patient, with 7 activated electrodes, has benefited from environmental sound awareness and improved lipreading. The last, blind, patient, with 4 electrodes activated, achieved only perception of environmental sounds.

To evaluate the decisional elements in the surgical strategy for extensive intratemporal cholesteatomas.A retrospective review of cases followed up between 1985 and 1996.Tertiary referral center.Nineteen patients with temporal bone cholesteatoma extending beyond the middle ear limits and surgically treated were included. Preoperative imaging distinguished apical (8), infralabyrinthine (3), supralabyrinthine (3), retrolabyrinthine (1), and translabyrinthine (4) cholesteatomas.Apical and supralabyrinthine lesions were treated through a middle fossa approach. Infralabyrinthine and translabyrinthine locations were exposed through a subtotal petrosectomy or a transotic route, depending on the preoperative audiovestibular status and labyrinthine destruction on computed tomography. The retrolabyrinthine lesion was approached through a retrolabyrinthine route.Patients were assessed for postoperative audiologic and facial functions and for recurrence of tumor.The facial nerve was neither rerouted nor interrupted during surgery. Among the 12 patients with preoperative facial palsy (FP), 5 cases of improvement (42%), 6 cases of stable function (50%), and 1 case of mild deterioration (8%) were observed postoperatively. In patients without preoperative FP, facial function remained unchanged postoperatively. The labyrinth could be preserved in three patients (16%), with postoperative stable hearing function in two (11%), and a 40-dB mean auditory deterioration in one (5%). Complete macroscopic resection was obtained in all patients. Two cases (11%) of postoperative recurrence were observed.The surgical strategy, principally based on cholesteatoma location and preoperative auditory function, yielded a high rate of local disease control and facial function preservation.

Osteoid osteoma is a benign bone tumour which rarely occurs in the skull. A case of such a tumour in the posterior ethmoid region bulging into the anterior cranial fossa is reported in a 42-year-old woman who presented with intense frontal headaches. Excision of the tumour was performed through a subfrontal approach.

This study aimed to assess the results of hearing restoration with a cochlear or a brainstem implant in posterior fossa tumors.Six patients were selected. Two patients with an acoustic neuroma in the only-hearing ear (cases 1 and 2), one patient with a posterior fossa meningioma (case 3), one patient with bilateral facial neuroma (case 4), and two patients with bilateral acoustic neuroma (cases 5 and 6) participated.In cases 1 and 2, the patients had a cochlear implant inserted on the only-hearing ear opposite the acoustic neuroma. In case 3, the patient presented with total deafness on the left side and a 10-mm meningioma on the right side. A cochlear implantation was performed after removal of the meningioma on the right side. In case 4, the patient was operated on on both sides with bilateral postoperative deafness. A cochlear implantation was performed on the better hearing ear. In cases 5 and 6, patients underwent an auditory brainstem implantation after the exeresis of the second tumor.Promontory test results were positive for patients 1, 2, 3, and 4. After implantation, patients 1, 2, 3, and 4 scored 98%, 13%, 70%, and 30%, respectively, in open-set sentence recognition tests, whereas patients 5 and 6 scored 0% and 20%, respectively.In case of nonfunctional cochlear nerve, in acoustic neuroma, either bilateral and in the only-hearing ear, promontory test should be performed. If positive results, a cochlear implantation should be performed, because successful results could be expected. Overall results of cochlear implantation on speech discrimination are better than those obtained with a brainstem implant.

In the inner ear, the membranous labyrinth, a tight heterogeneous sensory epithelium, separates two compartments that are filled with fluids of completely different composition. The lumen of the membranous labyrinth is filled with endolymph, a K-rich, positively polarized fluid, whereas the surrounding spaces are filled with perilymph, with a composition similar to an usual extracellular fluid. The inner ear fluids play a major role in the cochlear and vestibular physiology by the transmission of the mechanical stimulus to the hair cells, on the one hand, and by the transduction of this signal to a nerve potential, on the other hand. Numerous studies have been performed in order to know the chemical and physical characteristics of the inner ear fluids. A high, positive transepithelial potential has been evidenced in the cochlea together with a high K concentration and a low Na concentration. During the last years, the composition of the inner ear fluids, the origins of endolymph and perilymph, and the cellular mechanisms involved in the secretion of these fluids have been a great part elucidated. The present paper is a review of the contribution of the lab to the understanding of the physiology of the inner ear.

This multicentre study evaluates the distribution of ciprofloxacin into the tissue structures of the middle ear following multiple dosing of one 500 mg tablet every 12 h. The samples were taken perioperatively from adult patients due to undergo surgery for chronic otitis. Administration of ciprofloxacin was instigated 9 days prior to the operation. The samples were taken at different intervals after the last dose in order to evaluate variations in concentration with time. The average peak concentrations recorded and the time taken to reach these concentrations were as follows: middle ear mucosa (n = 16): 5.54 +/- 3.46 micrograms/g (3-4 h): cortical bone of the mastoid process (n = 21): 1.07 +/- 1.29 micrograms/g (4 h). The measurements carried out 12 h after the last dose show that concentrations of ciprofloxacin in the middle ear mucosa were still at least as high as the minimum inhibitory concentration for this antibiotic for most of the pathogens implicated in acute exacerbations of chronic otitis. These results suggest that, administered as an oral dose of 500 mg every 12 h, ciprofloxacin may be an effective agent for the treatment of chronic suppurative otitis. These results now need to be backed up by clinical trials.

Annales Francaises d'Oto-Rhino-Laryngologie et de pathologie cervico-faciale - Vol. 127 - N° 3 - p. 109

Gd-DTPA-enhanced MRI provided accurate demonstration of the site and extension of a haemangioma of the petrous bone. Enhanced-MRI could allow early detection and differentiation from the other more common tumours of the geniculate ganglion area, thereby permitting the surgeon to remove the tumour, while preserving the facial nerve. CT is, however, required to display the characteristic ossification in these tumours.

Objectifs Montrer l’interet de la sequence FLAIR (fluid-attenuated inversion recovery) dans le diagnostic positif des labyrinthites aigues. Materiels et methodes Etude retrospective. Relecture consensuelle par deux radiologues seniors. Trente patients ont beneficie d’une IRM pour un syndrome audio vestibulaire aigu. Le diagnostic de labyrin-thite aigue a ete pose chez 10 patients en IRM sur les sequences T2 volumiques et Tl injecte. La sequence FLAIR pratiquee en coupes epaisses a ete relue independamment des autres sequences et les resultats des differentes sequences ont ete compares entre eux. Resultats La sensibilite de la sequence FLAIR pour le diagnostic positif de labyrinthite aigue etait de 90%, sa specificite de 100%, sa valeur predictive positive de 100% et sa valeur predictive negative de 95%. Son interpretation etait plus consensuelle que les autres sequences (100% de resultats concordant, 90% pour le Tl et 80% pour le T2). Conclusion La sequence FLAIR est utile au diagnostic positif des labyrinthites aigues, son interpretation est plus aisee que celle des autres sequences. Interet actuel des sequences FLAIR volumiques avec coupes fines passant par le labyrinthe et possibilites de reconstructions.

Objectifs pedagogiques Savoir poser les indications d’une imagerie post-operatoire d’une chirurgie de l’angle ponto-cerebelleux et du meat acoustique interne. Savoir quel examen d’imagerie demander dans le cadre de ces indications. Connaitre les differents types de complications retrouvees precocement et tardivement dans le suivi post-operatoire de cette chirurgie, lors de l’exploration par scanner ou IRM. Messages a retenir Precocement les complications sont dominees par les complications neurologiques vasculaires : infarctus, hematome, thrombophlebite de la fosse posterieure. Plus rarement sont decrites des fuites de LCS, des embolies pulmonaires communes a toutes les chirurgies. De tres rares cas d’embolie pulmonaire graisseuse par migration de materiel de comblement ont ete decrites. Les fuites de LCS representent les principales complications a distance de la chirurgie de l’APC. De rares abces de la graisse de comblement ont ete observes.

Objectifs Evoquer en imagerie le diagnostic de lesion maligne du rocher. Materiels et methodes De 1998 a 2005, 24 lesions malignes du rocher ont ete examinees au scanner et en IRM injectee avant que les patients ne soient biopsies ou operes. Resultats APC et MAI : 6 (2 metastases, 3 medulloblasomes, 1 astrocytome pylocytique), apex petreux : 4 (1 carcinome adenoide kystique, 2 chondroblastomes, 1 chondrome), caisse du tympan : 2 (1 carcinome epidermoide, 1 adenocarcinome), mastoide : 3 (2 hystiocytoses X, un myelome), face posterieure et superieure du rocher : 4 (2 tumeurs du sac endolymphatique, 1 hystiocytose X, 1 plasmocytome), oreille externe : 1 carcinome epidermoide, foramen jugulaire : 2 plasmocytomes, diffus : 2 carcinomes epidermoides. L’ensemble des lesions presentait des aspects differents au scanner et a l’IRM mais toutes prenaient le Gadolinium. Conclusion Une lesion du rocher prenant le gadolinium et ne presentant pas les caracteristiques TDM et IRM des neurinomes, des hemangiomes ou des chemodectomes doit faire evoquer le diagnostic de lesion maligne dont l’etiologie pourra etre orientee parfois en fonction de la localisation. Une biopsie s’impose dans ces cas.