[Superior semicircular canal dehiscence mimicking otosclerosis: usefulness of imaging]. / Déhiscence du canal semi-circulaire antérieur mimant une otospongiose: intérêt de l'imagerie.

OBJECTIVES: To emphasize the role of computerized tomography (CT) in the etiologic work-up of stapes surgery failure. MATERIAL AND METHODS: Helical high resolution CT scan of the temporal bone with axial and coronal views and multiplanar reconstructions was performed in a patient who had undergone unsuccessful stapedectomy. RESULTS: CT scan demonstrated a well located prosthesis, the absence of the radiological hallmarks of otosclerosis, and revealed a superior semicircular canal dehiscence (SSCD). The diagnosis of SSCD was retrospectively considered accountable for the preoperative clinical and audiometric presentation that had mimicked otosclerosis. CONCLUSION: CT is the diagnostic test of choice in elucidating stapes surgery failure (with persistent or recurrent conductive hearing loss), whereas SSCD should be systematically considered among its causes.

Does adding intravenous fentanyl to caudal block in children enhance the efficacy of multimodal analgesia as reflected in the plasma level of catecholamines?

BACKGROUND AND OBJECTIVE: Several studies showed that single analgesic modality management can attenuate perioperative stress, but little is known about the effect of multimodal analgesia on catecholamine responses to surgical trauma in children. METHODS: Fifty children (American Society of Anesthesiologists Grade I or II) were randomly allocated to one of two groups: one received general anaesthesia and a caudal block (control group), and one group was given general anaesthesia, caudal block and intravenous (i.v.) fentanyl 2 microg kg(-1) (fentanyl group). Plasma epinephrine and norepinephrine concentrations were measured three times during the perioperative period: at induction time (T(0)), at the end of surgery (T(1)) and when the children were fully awake in the postanaesthesia care unit (T(2)). RESULTS: There was a significant reduction in the catecholamine levels in the two groups when (T(1)) and (T(2)) were compared with T(0). When plasma epinephrine levels (at T(0), T(1) and T(2)) between the two groups were compared, a statistically significant reduction at T(2) was obtained in the fentanyl group, when compared with the control group. However, plasma norepinephrine levels showed no statistically significant difference between the two groups (at T(0), T(1) and T(2)). CONCLUSION: These findings suggest that the multimodal analgesic approach of adding i.v. low-dose fentanyl to a caudal block may decrease the plasma epinephrine release in children undergoing inguinal herniotomy.

Width of the extended facial recess: a numerical study of ultrahigh-resolution computed tomography and its implications in minimally invasive otologic surgery.

BACKGROUND: Methods of minimally invasive computer-assisted otologic surgery lag behind other fields. The reason seems to be the extremely small dimensions of the corridors between important structures in the temporal bone and the fact that these structures are encased in bony frameworks, are obscured before drilling, and are not movable. The extended facial recess is a surgical pass to the tympanic cavity. It is bounded medially by the facial nerve and laterally by the tympanic annulus, and varies among individuals. For computer-assisted, minimally invasive temporal bone surgery, high-resolution definition is critically important. AIMS: To determine the width of the extended facial recess and evaluate the computerized findings as a pre- and intraoperative aid to otologic surgery planning. METHODS: Bilateral temporal bone high-resolution computed tomographic images of 100 male and 100 female patients were measured twice at five levels (caudal to cephalic), first using a window-independent algorithm (extended facial recess, full-width at half-maximum), implemented in a computed tomographic image-processing workstation, and then manually with calipers on the same axial computed tomographic images. RESULTS: As expected, the extended facial recess, full-width at half-maximum method yielded the widest values superiorly (4.15 +/- 0.41 mm in the female patients and 4.32 +/- 0.54 mm in the male patients). From this level down, the extended facial recess, full-width at half-maximum method yielded values that tapered gradually to 2.50 +/- 0.56 mm in the female patients and 2.42 +/- 0.46 mm in the male patients at the most interior level. The manual method (extended facial recess, computed tomographic images) yielded a significantly higher value than that obtained with the objective, window-independent method at all levels, and at some levels was higher by as much as one-third. At Level 2, which corresponded roughly to the round window, the extended facial recess was 4.00 +/- 0.65 in the female study group and 4.11 +/- 0.67 mm in the male study group. CONCLUSION: Image processing methods such as extended facial recess, full-width at half-maximum method might lead to fine tuning and thus improvement of computer-assisted otologic surgery. Before clinical application and complete dependence on these automated methods during otologic surgery, their reliability should be further validated.

Individual prefabricated titanium implants and titanium mesh in skull base reconstructive surgery. A report of cases.

Titanium implants can be shaped by traditional hand forming, press shaping, modular construction by welding, construction on full-size models shaped from CT coordinates and, most recently, by computer-assisted design and computer-assisted manufacturing (CAD/CAM) that consist in the direct prefabrication of individual implants by milling them out of a solid block of titanium. The aim of our study was to present a set of preliminary cases of an ongoing program of reconstructive procedures of the skull base using titanium implants. The subjects underwent ablative procedures of the skull base with reconstruction either by titanium mesh or individual prefabricated CAD/CAM implants. Six patients have been operated on successfully since 2000: two received prefabricated CAD/CAM titanium plates and four others underwent reconstruction with titanium mesh. The stability of CAD/CAM plates is superior to that of mesh, thus it is more useful in reconstructing large lesions of the frontal skull base and the temporal and occipital bones. Titanium mesh was successfully used for defects smaller than 100 cm(2) or where selected viscerocranial defects are complicated in design and less reproducible by CAD/CAM. The intraoperative design, shaping and adjustment characteristic of titanium mesh can be dispensed with when CAD/CAM implants are used. The 3-D data set used in the CAD/CAM process also operates in the navigated simulation and planning of the ablation contours, the latter being of great assistance in establishing the optimal future defect. As a disadvantage, CAD/CAM technology is more expensive than titanium mesh, and the process is time-consuming as it is carried out in advance of surgery.

Cochlear implantation in healthy and otitis-prone children: a prospective study.

OBJECTIVE: To evaluate and compare the timing of surgery, intraoperative findings, and otitis media-related outcome of cochlear implantation in children who are otitis-prone with their counterparts who are not otitis-prone. STUDY DESIGN: Prospective. METHODS: Children referred for cochlear implantation were assigned to a non-otitis-prone group (group A: normal otoscopy on their first visit after referral) or an otitis-prone group (group B: current or a recent history of otitis media at referral). Group B patients were managed using a structured protocol aimed at preimplantation otitis media control. The study reviewed pre-, intra-, and postoperative data. RESULTS: Of the 18 children studied, 8 were assigned to group A (mean age at referral, 40.6 mo) and 10 to group B (mean age at referral, 31.6 mo). For otitis media control, all otitis-prone children underwent ventilating tube insertion (various numbers of procedures before implantation). Only one otitis-prone child required cortical mastoidectomy also. Time from referral to implantation was similar in the two groups (mean, 6.6 mo). High-resolution computed tomography data showed mastoid pneumatization to be significantly smaller in the otitis-prone group, but the facial recess was not smaller in this group. During implantation, 10 children had inflamed middle ear mucosa. Seven of these belonged to group B. All of these seven children had a round window niche obliterated by the inflamed mucosa, which had to be removed for round window membrane identification. After implantation, only one child had drainage through the ventilating tube for more than 1 week. Two children in group B developed otitis media (1 year postimplantation) that was overcome within 1 week. There were no otitis media-related complications. CONCLUSIONS: If a structured protocol is used for the control of otitis media before cochlear implantation, otitis media should not require a delay in implantation. In otitis media-prone children, the round window niche is often obscured by inflamed mucosa. Its removal is mandatory for identification of the round window membrane. After cochlear implantation, otitis media is not a frequent occurrence.

Results of otovestibular tests in mild head injuries.

The neurotological workup of patients with minor head trauma was carried out prospectively. The preliminary results of the ongoing study were derived from 38 subjects (12 female, 26 male) at an average age of 33.5 years. All had been hospitalized after having suffered minimum head trauma followed by a temporary loss of consciousness, by amnesia, or by vomitting. The 38 subjects underwent the examination within 72 hours of the event and were summoned for a follow-up visit 3 months later. The anamnestic data show that the most frequent complaint was dizziness (81%). Tinnitus was noted in fewer than one-half of the patients, with a variety of descriptions. Twenty-six percent complained of hearing loss. The correlation between reported hearing loss and the finding on subsequent behavioral audiometry (within 72 hours after the event) was studied. The sensitivity of hearing loss (as complaint) was found to be only 40%, but its specificity was much higher at 83%. The overall equilibrium reflected in the composite score of the sensory testing in computed dynamic posturography actually worsened between tests. A good correlation was found between posturography results and symptomatology. We concluded that, after minor head trauma, most patients suffer from dizziness, and more than one-half complain of tinnitus or hearing loss. The unsteadiness does not subside within 3 months after concussion. A more protracted follow-up is required to summarize the outcome of head injury from a neurootological point of view. A clear correlation is found between complaints and posturography results. After minor head trauma, pure vestibular injuries are much less frequent than are central lesions. Motor dysfunction is less frequent than are the sensory abnormalities.

Sonovestibular symptoms evaluated by computed dynamic posturography.

The investigation of stability under bilateral acoustic stimulation was undertaken in an attempt to mimic the real-life conditions of noisy environment (e.g., industry, aviation). The Tullio phenomenon evaluated by computed dynamic posturography (CDP) under acoustic stimulation is reflected in postural unsteadiness, rather than in the classic nystagmus. With such a method, the dangerous effects of noise-induced instability can be assessed and prevented. Three groups of subjects were submitted. The first (group A) included 20 patients who complained of sonovestibular symptoms (i.e., Tullio phenomenon) on the background of an inner-ear disease. The second group (B) included 20 neurootological patients without a history of Tullio phenomenon. Group C consisted of 20 patients with normal hearing, as controls. A pure-tone stimulus of 1,000 Hz at 110 dB was delivered binaurally for 20 seconds during condition 5 and condition 6 of the CDP sensory organization test. The sequence of six sensory organization conditions was performed three times with two intermissions of 15-20 minutes between the trials. The first was performed in the regular mode (quiet stance). This was followed 20 minutes by a trial carried out in quiet stance in sensory organizations tests (SOTs) 1 through 4, and with acoustic stimulation in SOT 5 and SOT 6. The last test was performed in quiet stance throughout (identical to the first trial). A significant drop in the composite equilibrium score was witnessed in group A patients upon acoustic stimulation (p < .0001). This imbalance did not disappear completely until 20 minutes later when the third sensory organization trial was performed. In fact, the composite score obtained on the last SOT was still significantly worse than the baseline. Group B and the normal subjects (group C) showed no significant change in composite score. As regards the vestibular ratio score, again, group A marked a drop on stimulation with sound (p < .004). This decrease contrasted once more with the other two groups. The leading sensory organization pattern was vestibular dysfunction (i.e., 40%, 10%, and 0% before acoustic stimulation in groups A, B, and C, respectively). The initial proportion of vestibular dysfunction increased on acoustic stimulation to 55% in group A, but this subsequently decreased in the third trial. The percentages of vestibular dysfunction remained constant during repeated trials in the other two groups. The positive medical history of sonovestibular symptoms was confirmed objectively by CDP with sound stimulation with a high statistical significance. This establishes the described method as a sensitive testing technique for validating the existence of the Tullio phenomenon in patients with a variety of disorders of the inner ear, especially chronic noise-induced hearing loss and acute acoustic trauma. All patients who suffered phonic trauma, chronic exposure to noise (e.g., aviation employees, industry and army personnel), or other neurootological disorders and who complain of sonovestibular symptoms should be tested for the presence of the Tullio phenomenon. This should be carried out preferably by means of CDP with acoustic stimulation for an objective corroboration of their complaint before continuing activity in a noisy environment, thus preventing dangerous loss of balance when exposed to noise.

Correlations between audiogram and objective hearing tests in sensorineural hearing loss.

Owing to its subjective nature, behavioral pure-tone audiometry often is an unreliable testing method in uncooperative subjects, and assessing the true hearing threshold becomes difficult. In such cases, objective tests are used for hearing-threshold determination (i.e., auditory brainstem evoked potentials [ABEP] and frequency-specific auditory evoked potentials: slow negative response at 10 msec [SN-10]). The purpose of this study was to evaluate the correlation between pure-tone audiogram shape and the predictive accuracy of SN-10 and ABEP in normal controls and in patients suffering from sensorineural hearing loss (SNHL). One-hundred-and-fifty subjects aged 15 to 70, some with normal hearing and the remainder with SNHL, were tested prospectively in a double-blind design. The battery of tests included pure-tone audiometry (air and bone conduction), speech reception threshold, ABEP, and SN-10. Patients with SNHL were divided into four categories according to audiogram shape (i.e., flat, ascending, descending, and all other shapes). The results showed that ABEP predicts behavioral thresholds at 3 kHz and 4 kHz in cases of high-frequency hearing loss. Also demonstrated was that ABEP threshold estimation at 3 kHz was not affected significantly by audiogram contour. A good correlation was observed between SN-10 and psychoacoustic thresholds at 1 kHz, the only exception being the group of subjects with ascending audiogram, in which SN-10 overestimated the hearing threshold.