[Dehiscence of the superior semicircular canal: approach and CT scan classifications]. / Déhiscence du canal semi-circulaire supérieur: approche et classification scanographiques.

UNLABELLED: The syndrome of dehiscence of the superior semicircular canal (DCSS) is primarily associated with vertigo and/or hearing loss. The dehiscence may be completely asymptomatic and represent an incidental finding on radiological investigation. OBJECTIVES: To demonstrate the advantages of a volume rendered CT study of the petrous temporal bone of patients with hearing loss, and to demonstrate the effectiveness of its systematic application in the protocols of examination. To propose a radiological classification of DCSS with a therapeutic application. MATERIAL AND METHOD: The examination technique which was performed in incremental mode (axial and frontal sections) and in "volume rendered" mode, on a high resolution apparatus is described. The authors studied 154 scans of the petrous temporal bone obtained by this technique. They correlated the cases of DCSS with the indications for the radiological examination. Each 3d CT scan was studied and the type of fistula described. The authors propose a classification of fistulae into three types, depending on 3d CT scan appearance. RESULTS: Out of 154 CT scans of the petrous temporal bone (77 patients), 13 cases of DCSS were discovered. DCSS was bilateral in 4 cases. The primary indication for investigation was the assessment of conductive or mixed hearing loss. The "volumetric" technique was compared with standard imaging techniques and/or reconstructed images in the superior canal plane. The correlation was perfect in all the cases. The description of the fistulae allowed a classification into 3 types: Type I (symmetrical fistula, 8 cases); Type II (asymmetrical fistula, 3 cases) corresponding to the canal dome; Type III (2 cases) involving the foot of the canal. CONCLUSION: The increased frequency of DCSS in this series (prevalence of 17% against 0.5% in post mortem studies) is probably explained by the selection bias of the patients and also by the systematic application of this novel radiological technique. We propose to include this protocol in all CT scans of the temporal bone, particularly when investigating symptoms consistent with a syndrome of Minor or the Tullio phenomenom. This system of classification makes it possible to describe the fistula and to specify its location. This should prove to be a valuable aid for pre-operative planning and intra-operative localisation of the fistula.

[Skull vibration induced nystagmus test]. / Le test vibratoire osseux vestibulaire.

OBJECTIVES: To establish during a consensus meeting the fundamental basis, the validity criteria, the main indications and results of the skull vibration induced nystagmus test (SVINT) which explores the vestibule high frequencies. MATERIAL AND METHODS: The SVINT is applied on the mastoid process (right and left sides) at 100 Hz during 10 seconds on a sitting upright subject. Total unilateral peripheral lesions (tUVL: operated vestibular shwannomas, vestibular neurectomies) and partial unilateral peripheral lesions (pUVL: preoperative neuromas, Meniere's disease, vestibular neuritis, chemical labyrinthectomies) were studied. Thirty-six patients had brainstem lesions and 173 normal subjects were used as controls. RESULTS: The SVINT is considered positive when the application of the vibrator produces a reproducible sustained nystagmus always beating in the same direction following several trials in various stimulation topographies (on the right and left mastoid). The skull vibratory nystagmus (SVN) begins and ends with the stimulation; the direction of the nystagmus has no secondary reversal. The slow phase velocity (SPV) is>2 degrees /second. In tUVL the SVINT always reveals a lesional nystagmus beating toward the safe side at all frequencies. The mean SVN SPV is 10.8 degrees /s+/-7.5 SD (N=45). The mastoid site was more efficient than the cervical or vertex sites. Mastoïd stimulation efficiency is not correlated with the side of stimulation. The SVN SPV is correlated with the total caloric efficiency on the healthy ear. In pUVL the SVINT is positive in 71 to 76% of cases; the mean SVN. SPV (6.7 degrees /s+/-4.7 SD)(N=30) is significantly lower than in tUVL (P=0.0004). SVINT is positive in 6 to 10% of the normal population, 31% of brain stem lesions and negative in total bilateral vestibular peripheral lesions. CONCLUSIONS: SVINT is an effective, rapid and non invasive test used to detect vestibular asymmetry between 20 to 150 Hz stimulation. This test used in important cohorts of patients during the ten last years has demonstrated no observable adverse effect. SVINT complements other tests which evaluate lower frequencies (caloric test: 0,003 Hz) and the medium frequencies (Head-Shaking-Test (HST): 2 Hz; the head impulse test (HIT): 6 Hz). SVINT is useful in the diagnosis of labyrinthine hydrops or detection of acoustic neuromas. It is useful when the caloric test can not be practised because of middle ear problems. SVINT has its limits: in pUVL, the nystagmus direction is not always specific of the pathologic side and can change with the stimulus frequency. This test does not precisely point out the level of the lesion on the vestibular pathway.

Bilateral cochlear implantation in a patient with long-term deafness.

PURPOSE OF THE STUDY: 1) To report the case of a 70-year-old patient with a history of auditory deprivation for 80% of his life and who received bilateral cochlear implants and 2) to discuss different aspects of the case, including duration of auditory deprivation, the decision for bilateral implantation, age at implantation, and the use of this treatment modality for tinnitus. CASE REPORT: A two-stages bilateral cochlear implantation was performed in a 70-year-old patient with long-term deafness without operative or post-operative problems with excellent functional result. DISCUSSION: Various studies have reported that in patients with long-term auditory deprivation, the results of cochlear implants are delayed and sometimes unsatisfactory when compared to patients with more recent post-lingual deafness. However they did not contraindicate the surgery. The positive results with the first implant (both for the tinnitus and the hearing loss) motivated the patient and medical team to proceed to bilateral implantation. CONCLUSION: Patients with longstanding auditory deprivation can achieve good functional results even though at a slower rate. The use of bilateral cochlear implants accelerates and optimizes the final outcome.

[The neurotologic evaluation of vestibular schwannomas. Results of audiological and vestibular testing in 100 consecutive cases]. / L' evaluation neurotologique audio-vestibulaire des schwannomes vestibulaires. A propos de 100 cas.

OBJECTIVES: To determine the results and sensitivity of a comprehensive audiological and vestibular work-up in patients presenting with vestibular schwannoma (VS). MATERIAL AND METHODS: One hundred consecutive cases of VS diagnosed from January 2004 to May 2005 were prospectively studied. The tumour size was classified according to Koos classification and hearing was assessed according to the five-stage classification from the Tokyo consensus. A comprehensive work-up was conducted in all patients, including pure tone and speech audiometry, Brainstem Evoked Audiologic Potentials (BEAP) assessment, Vestibular Evoked Myogenic Potentials (VEMP) examination and bithermal caloric testing using videonystagmography, on both sides. BEAP responses were considered as normal or endocochlear when interwave intervals were normal, absent because of poor hearing or retrocochlear when wave 1 to 5 interval > 4.3 ms and/or when this interval was greater than > 0.25 ms between sides, or when no response was recorded when hearing was preserved. VEMP were considered as normal absent or diminished (amplitude < 50%, as compared with contralateral). Caloric responses were considered normal, reduced (reduced by > or = 30%) absent (reduced by > 80%). RESULTS: Fifty-six women and 44 men were examined (mean age 57.8 years). Left and right side were equally affected. Vertigo, tinnitus and hearing loss were the main presenting symptom in 21%, 32% and 68% of the cases, respectively. Eighty-two per cent were operated, 17% simply monitored and 1% irradiated. The tumours were Stage 1, 2, 3 and 4 in 14%, 28%, 21% and 37%, respectively. Hearing was class A in 9%, Class B in 34%, Class C in 14% and Class E-D in 43% of the cases. Globally, BEAP showed a retrocochlear pattern in 64% of the cases and no response in 30%. Abnormal responses of VEMP were observed in 94% of the cases. Caloric testing was abnormal in 61% and normal in 11%. Responses could not be analyzed in 28% of patients. Only one patient showed normal responses to the whole work-up (99% sensitivity). This patient had a small intrameatal tumour and actually complained of contralateral symptoms. CONCLUSION: The results suggest that a full audiovestibular assessment can help diagnose VS of all sizes. But false-negative results remain possible in small intrameatal tumours (1%). In addition it can give useful postoperative prognostic information.

[Vertigo and pathology of the cerebellospinal system]. / Vertige et pathologie du système nerveux central.

Central vertigo is most often expressed by a feeling of dizziness, non or badly systematized, but it can also appear, more seldom, like an isolated acute vertigo or associated to other neurological signs. A precise clinical exam can lead to evidence essential clinical informations (significant ataxia, neurological signs, gaze nystagmus, pursuit anomaly,...). Almost all acute lesions of central vestibular pathways, as for the peripheral ones, lead to a harmonious vestibular syndrome. The vascular lesion of the vertebro-basilar territory and multiple sclerosis are two main causes to it. The pseudo-labyrinthine forms are essentially described in occlusion infarcts of the AICA and PICA, but a hematoma can lead to the same picture; the diagnostic of multi- or monosymptomatic forms with a peripheral lesion is often very difficult, the classical classification of the central and peripheral vestibular syndromes has become obsolete and should be abandoned.

[Vertigo and pathology of the cerebello-pontine angle]. / Vertiges et pathologie de l'angle ponto-cérébelleux.

Many pathologies of the cerebello-pontine angle can induce vertigo or dizziness. Usually they are due to benign or malignant tumors. Pathophysiology of this vertigo involve lesion of the labyrinth with erosion, of the endolymphatic sac by invasion or compression, or directly by lesion of the vestibular nerve like in vestibular schwannomas. The vestibular nerve can also be injured by extrinsic compression like in meningiomas. Finally very big tumors can be compressive on the cerebellum or on the brainstem inducing also dizziness. Vertigo is often an important symptom of cerebello-pontine angle tumors. In association with others it will guide the diagnosis. Nevertheless, auditory evoked potentials, video-nystagmography, and otolithic evoked potentials are very important to determine exactly if the vestibular nerve is injured and if there are signs of central compression before surgery.

[Reinforcing tympanoplasty with cartilage mosaic (differences from the palisade technique)]. / Tympanoplastie de renforcement en mosaïque de cartilage (différences avec la technique en palissade).

OBJECTIVES: To demonstrate the interest of cartilage mosaic tympanoplasty in the reconstruction of the tympanic membrane. MATERIALS AND METHODS: Retrospective series of 103 patients; the authors analyzed their results after cartilage mosaic tympanoplasty, with a mean follow up of 3.5 years (3 to 7 years). They explain the surgical technique in detail. The average gain was calculated on the difference of the pre-and post-operative thresholds in air conduction on the four frequencies 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz. RESULTS: The authors detail and analyze their anatomical and audiologic results. The total rate of closing of the tympanic membrane is 93.2%, accounting for 96 perforations closed among 103. A tympanic retraction sitting apart from the reinforced zone was noted in 0.97%, representative only one case of 103. Then the total rate of success is 92.23%, representing 8 failures of 103. The average pre- and post-operative air bone gap were 26.5 dB and 14.6 dB. The average gain was 12.5 dB (extremes of 0 dB to 40 dB). CONCLUSION: The authors show the great reliability of cartilage mosaic tympanoplasty to reconstruct the tympanic membrane. They widen the indications with all types of tympanoplasties. Especially with the recurrent perforations, and the perforations evolving in an inflammatory context and/or dysfunction of the Eustation tube. Their results show a major interest to use this technique in the anterior and inferior perforations, and whatever the ossicular chain status.

Electrical stimulation of the ear: clinical applications.

Electrical stimulation of the ear in humans was performed with an extracochlear electrode on the round window. With positive currents, suppression of tinnitus could be induced. With negative currents, auditory sensations were evoked. Since electrical stimulation with DC currents may be hazardous in the long term, it cannot yet be proposed for the suppression of tinnitus. However, electrically evoked hearing sensations with AC currents seem to be of definite interest for some totally deaf patients.

Extracochlear implants.

A unichannel extracochlear implant designed and made in our laboratory was tried on several patients. Results to date are very similar in all cases. Very rudimentary auditory information is provided, which can help totally deaf patients.

Transtympanic and surface recordings in the diagnosis of retrocochlear disorders.

A series of patients presenting with subsequently surgically confirmed central tumour involving the auditory pathways were investigated using both transtympanic electrocochleography (TT ECochG) and surface recordings of brainstem evoked responses (BER). While ECochG allows a detailed study of peripheral function, BER allow the investigation of neural conduction up to the level of the inferior colliculus. Valuable information can be obtained from: (1) comparison of the amplitudes of the sensory and neural components of the ECochG; (2) comparison of ECochG, BER and auditory thresholds; (3) time interval measurements between the auditory nerve response (N1 on the ECochG) and the inferior colliculus (wave P4-5 on BER); (4) contralateral comparisons. Similar measurements performed in pure cochlear pathologies, mainly in Meniere's disease, yielded very significant differences.

Temporary tinnitus suppression in man through electrical stimulation of the cochlea.

While investigating the possibilities of electrically induced hearing in cases of profound deafness, we observed that very often an appropriate stimulation of the cochlea could result in tinnitus cancellation. We present here a progress report on that phenomenon, including 15 subjects. Such a cancellation was restricted to tinnitus subjectively localized in the ear under test, we observed no effect on noises localized in the other ear, or centrally. This suppression occurred so long as the cochlea was stimulated and stopped when the stimulation ceased. This phenomenon was very reproducible and did not seem to affect simultaneous normal acoustic hearing. It is hypothesized that this phenomenon acts through an inhibition of abnormal activity of sensorineural elements of the electrically stimulated cochlea.

Electrocochleographic measures of cochlear frequency selectivity in hearing loss of cochlear origin.

One of the basic functions of the cochlea is to separate out the frequency components which are present in complex sounds. This frequency selectivity can be measured objectively in the clinic from the compound action potential (AP) during transtympanic electrocochleography, using a two-tone masking paradigm. An AP is evoked by a test tone near to threshold, and a measure is made of the frequency bandwidth over which this AP can be suppressed by a continuous pure tone masker. In normal-hearing subjects, this frequency range is 0.17-0.39 octaves (test tone pip at 4 or 8 kHz). In patients with cochlear deafness, this bandwidth is greatly enlarged, ranging from 0.42-2.2 octaves. Some observations suggest that a deterioration in frequency selectivity can occur before any important threshold elevation. The early detection of this could be a warning sign of potential cochlear susceptibility. In the clinic the measure is already of use: a deterioration is a positive indication of cochlear involvement in a hearing loss.

The prognostic value of the stapedius reflex in peripheral facial palsy.

Stapedius reflex can provide useful prognostic information in FPs when the middle ear is normal. Its preservation may have a favorable significance in partial FP and Bell's palsy. Its loss, even though less reliable, can also have some value as an indicator for a poor prognosis in patients with total and herpes zoster FPs. Most importantly, our findings have shown that the SR alone is not sufficient to be of prognostic value, but is useful if combined with other clinical parameters and electrical responses.

[Rotatory impulse test does not replace caloric tests]. / L'épreuve rotatoire impulsionnelle ne remplace pas les tests caloriques.

We sought to determine whether the rotatory impulsional test was capable of exploring the canalar function with sufficient precision to replace the caloric test, as it has been recently affirmed. We first compared the observed preponderance from this test with that measured during a sinusoidal (20 and 4 s) test. We observed that, in the case of a significant preponderance for a given test, there was complete redondance with the preponderance observed with any other test. The rotatory impulsional test does not present any specific advantage compared to other kinetic test as far as the observation of the preponderance phenomenon. We then compared the preponderance with the results of the caloric tests and came to the following conclusions i) the absence of preponderance does not allow us to predict the absence of vestibular deficit, due to the fact that 37% of the deficits were compensated for including acoustic neuroma; ii) the presence of a preponderance does not allow a priori to say whether it is of vestibular, cervical, or central origin and systematic caloric tests shows that almost one fourth of preponderance observed is not associated with unilateral weakness iii) supposing that a clinical argument allow us to conclude as to the probable vestibular origin of a vestibular preponderance, the direction of this preponderance does not allow us to determine which side is involved. In fact, if the undercompensated deficits are 3 times more frequent than overcompensated deficits, the proportion of preponderance not linked to a significant deficit indicates that the probability of encountering a preponderance related to a specific undercompensated deficit is approximately 50%. We thus did not find in the rotatory impulsional test any specific advantage allowing us to predict the laterality of a vestibular lesion.

[Cochlear implants, which one to choose?]. / Implants cochléaires, que choisir?

The choice of a cochlear implant is a difficult one. A given type of implant does not yet correspond to a given type of patient. Our indications have to be refined by acquired experience and through the improvement of tests prior to implanting. The implants available present different features, but they all improve the communication of the profoundly deaf to different degrees, by attenuating their tinnitus.

[Peroperative catheterization of the Eustachian tube]. / Cathétérisme peropératoire de la trompe d'Eustache.

Peroperative catheterization of the Eustachian tube is an exploratory and management technique enabling a better understanding of the pathological phenomena, resulting in a more effective therapeutic orientation for short term lesions (infection). In the long term, tubal rehabilitation becomes a logical complement.

[Tympanoplasty in clinical practice: use and results]. / Tympanoplast en clinique: utilisation et résultats.

The halt in the use of allografts has resulted in the use in clinical practice in humans of a product that has been known for at least thirty years: collagen. Interesting experimental animal studies have been performed with the type I and type III collagen currently used: the Tympanoplast. This collagen, already used in numerous medical fields (digestive, renal and neuro-surgery) is of bovine origin. It is purified, and comes in the form of a reticulated plate. It is known for its qualities of reepithelialisation. We have been using it for more than a year for the reconstruction of the tympanic membrane. We use Tympanoplast 100 microns thick. All the cases of myringoplasties have been performed on dry ears, and essentially on partial perforations in reinforcement surgery. The results are most encouraging and depend on the surgical technique employed. On the other hand, the grafts performed on total perforations failed to produce the expected results. The paper presents work of the School, with the anatomical results and comments on the precautions to be taken when using Tympanoplast.

[Deafness after meningitis and cochlear implant in children]. / Surdité de l'enfant après méningite et implant cochléaire.

The authors have studied 70 postmeningitic hearing losses in children. The deafness was acquired before the age of 2 year-old in 71% of the cases. Profound losses were observed in 50% considering the 1000 Hz at +100 dB, on the best ear as a selection criterion, 31 cases/70 (= 44%) could benefit from a cochlear implant. Among these 31 cases, 71% (= 22 cases) are prelingually deafness, that is which have occurred before the age of 2 years old. In 2 profound deafness cases, a late improvement of initial threshold, brings to consider with caution the 6 to 12 months time limit which is recommended by the different teams. In 3 other cases of moderate or severe losses, an improvement of the thresholds has been also observed. Because of psychological disturbances or other after-effects, a very regular medical following of these children is needed.

[Multifrequency impedance audiometry and study of occupational deafness: "Teflag", a new test]. / Impédancemétrie multifréquentielle et exploration des surdités professionnelles, un nouveau test "le Teflag".

The mechanical acoustic theory compares the annular ligament of the stapes to an elastic plot; plot # 2. The coupled stapedial muscle and annular ligament partly ensure the dampening of acoustic impulses (low frequencies in particular) and helped by the stapes footplate, their transmission, by hydraulic pressure to the liquids of the cochlea. This muscle ligament couple represents the true impedance adaptor for the middle ear region. So as to study plot # 2 we have set up a test, called Teflag, using the otoadmittancemetre produced by Grason Stadler. This apparatus enables us to measure the functional state of the ligament (by the study of susceptance, representing the inverse of the reactive forces linked to the inertial mass of the system and to its compliance; in fact that of the ligament. We can also measure the level of the resistive intra-cochlear forces and those of the annular ligament (the study of conductance). Our study compares 25 normal hearing patients and 64 ears with professional deafness. The Teflag gives us an evaluation of the functional state of the annular ligament, from morphological abnormalities of susceptance. Age induced hearing loss differs from professional deafness. A classification into 5 stages has been established following evaluation of functional annular ligament pathology. There is no hearing without oscillation (of a molecular order) of this ligament, which clearly seems to be the key point of the receptor organ, and ensures the detection of sound.

[Auditory electrophysiology and retrolabyrinthine non-tumorous diseases]]. / L'électrophysiologie dans les atteintes rétrocochléaires sans tumeur.

The authors present 55 cases of non-tumoral retrocochlear impairment, studied over the period between 1984 and 1988 in the ENT University Clinic of Bordeaux. Deafness was the most frequent symptom leading patients to come for consultation (89%). The stapedial reflex was pathological in 70% of the cases. No conclusion could be drawn from electro-occulography. Only the early auditory evoked responses made it possible to reach the diagnosis of retrocochlear impairment in 35% of the cases. Electrocochleography was required in 65% of the cases to establish the topographic diagnosis. The neuro-radiological examination proved to be negative in 48 cases, and positive in 7 cases (6 atrophic symptoms, 1 left vertebral dolichoartery). Among the other etiologies, we noted 14 cases of auditory trauma, 12 vascular pathologies, 9 neurological pathologies, 7 cases of Ménière's disease, and 7 sudden onsets of deafness. The incidence of vasculo-nervous conflict reported by other authors appears very low in this series (with only 1 case).