Why did we encounter gusher in a stapes surgery case? Was it enlarged medial aperture of the cochlear aqueduct?

BACKGROUND AND PURPOSE: Preoperative prediction of cerebrospinal fluid (CSF) gusher is important for stapes surgery. According to the current opinion settled among otologists and radiologists, the issues of whether enlarged cochlear aqueduct might be a cause of CSF gusher in stapes surgery and which segment of the aqueduct should be taken into account to diagnose enlarged cochlear aqueduct in computerized tomography (CT) are controversial. The case we encountered led us to hypothesize that enlarged cochlear aqueduct might cause CSF gusher in stapes surgery and that shape and diameter of medial aperture of the cochlear aqueduct are important in this prediction. METHODS AND RESULTS: Enlarged medial aperture of the cochlear aqueduct with a shape differed from that of the other side was retrospectively diagnosed in thin-slice CT in a patient who had been undergone middle ear and stapes surgery for conductive hearing loss. This finding went unnoticed in preoperative CT. In the small fenestra stapedotomy operation, CSF gusher occurred through opening in the ill-defined, fixed and thickened stapes footplate. A piece of temporalis fascia and reshaped incus were appropriately placed which stopped the gusher. Re-evaluation of preoperatively taken CT showed that anterior-posterior and superior-inferior diameters of the medial aperture were 11.7 mm and 2.87 mm in CSF gusher side versus 2.95 mm and 1.88 mm on the other side, respectively. Its shape in gusher side differed from that of the other side. CONCLUSION: This report is the first to show video-documented CSF gusher in a patient with enlarged medial aperture of the cochlear aqueduct. It appears to be plausible to propose that these findings have to change the otologists' and radiologists' perspective to the cochlear aqueduct. It can be deduced that difference in shapes of the medial aperture in both sides might be an indicator of potential CSF gusher.

Anatomical Variations in Patients with Ménière Disease: A Tomography Study

Abstract Introduction The etiology of Ménière disease (MD), a difficult-to-treat condition with great morbidity, remains controversial in the literature. The possible clinical and diagnostic impact of anatomical variations of the temporal bone among patients with MD has been recently studied. Objective To identify anatomical variations of the temporal bone associated with the diagnosis of MD. Methods Thirty-seven patients were included, although each ear was considered separately (n = 74). A case group (nA = 33) was composed of the affected ears of patients with definiteMDand a control group (nB = 41) was used consisting of the ears of individuals who did not meet the criteria for MD and of the contralateral ears from patients with unilateral disease. Tomographic images from the individuals included in the study were submitted to a blinded and systematic evaluation regarding a broad variety of anatomical variations of the temporal bone. Obtained data were compared statistically between the groups and after stratifying the study sample. Significance level was set at 0.05. Results Among the affected ears, it was observed an increased number of tomographic scans in which the vestibular aqueduct could not be identified (p = 0.01, Fisher exact test). No statistically significant differences were observed when comparing the affected and contralateral ears frompatients with unilateral MD, between affected ears from patients with unilateral and bilateral disease or between contralateral ears of patients with unilateral affection and patients without the disease. Conclusion Some anatomical variations might be more frequent in the affected ears of patients with MD, such as the lower rates of individualization of the vestibular aqueduct.

The Human Cochlear Aqueduct and Accessory Canals: a Micro-CT Analysis Using a 3D Reconstruction Paradigm.

OBJECTIVE: We sought to study the anatomic variations of the cochlear aqueduct and its accessory canals in human temporal bones using micro-CT and a 3D reconstruction paradigm. More knowledge about the anatomic variations of these structures, particularly at the basal turn of the cochlea and round window niche, may be important to better preserve residual hearing as well as the neural supply during cochlear implant surgery. METHODS: An archival collection of 30 human temporal bones underwent micro-CT and 3D reconstruction. A surface enhancement paradigm was applied. The application displays reconstructed slices as a 3D object with realistic 3D visualization of scanned objects. Virtual sectioning or "cropping" of the petrous bone presented subsequent areas. Thereby, the bony canals could be followed from inside the basal turn of cochlea and middle ear to the jugular foramen. RESULTS: The cochlear aqueduct was always paralleled by an accessory canal containing the inferior cochlear vein. It ran from the basal turn of the cochlea and exited laterally in the jugular foramen. In 70% of the cases, a secondary accessory canal was observed and it derived mostly from a depression or infundibulum located in the floor of the round window niche. This canal also exited in the jugular foramen. The secondary accessory canal occasionally anastomosed with the primary accessory canal suggesting that it contains a vein that drains middle ear blood to the cranial sinus. CONCLUSION: Micro-CT with 3D surface reconstruction paradigm offers new possibilities to study the topographic anatomy of minor details in the human inner ear. The technique creates simulated transparent "castings" of the labyrinth with a coinciding surface view through enhancement of contrast between boundaries. Accessory canals that drain blood from the cochlea, spiral ganglion, and middle ear could be characterized three-dimensionally.

Comparison of Endolymphatic Duct Dimensions and Jugular Bulb Abnormalities Between Meniere Disease and a Normal Population.

BACKGROUND: The pathogenesis of Meniere disease (MD) has not been fully understood. According to the widely accepted theory, imbalances due to overproduction and/or impaired absorption of endolymph may cause endolymphatic hydrops, which is the hallmark pathological finding in MD. Some developmental temporal bone abnormalities may impair endolymph circulation and absorption, and these abnormalities could be a part of MD pathophysiology. However, structural features of the temporal bone cannot explain MD pathophysiology definitively. The authors aimed to determine the length and width of the endolymphatic duct (ED) along with jugular bulb (JB) abnormalities in MD patients and normal controls using high-resolution computed tomography, and to discuss the results supporting and opposing endolymphatic hydrops based on the data obtained. METHODS: Thirty-six ears of 18 patients with unilateral MD and 34 ears of 17 normal subjects were enrolled. Jugular bulb abnormalities and ED dimensions were evaluated in 3 groups: affected and unaffected ears of MD patients, and healthy controls. The ED dimensions and JB abnormalities were evaluated with high-resolution computed tomography. RESULTS: The ED was found to be significantly shorter and narrower in the affected ears of the MD patients than in the healthy control group. In addition, more JB abnormalities were detected in the affected ears of the MD patients than in the healthy control group. However, there was no difference between the affected and unaffected ears of the MD patients. CONCLUSION: Structural ED abnormalities and JB abnormalities may be predisposing factors for the development of Meniere disease, but cannot fully explain MD pathophysiology.

X-ray microtomography study of otic capsule deficiencies: three-dimensional modelling of the fissula ante fenestram.

BACKGROUND: The postulated sites of perilymph fistulae involve otic capsule deficiencies, in particular, at the fissula ante fenestram. Histological studies have revealed this to be a channel extending from the middle ear, and becoming continuous with the inner ear medial to the anterior limit of the oval window. The relationship between a patent fissula and symptoms of perilymph fistula is contentious. OBJECTIVE: The understanding of the anatomy of the fissula ante fenestram is incomplete. Histopathology is inherently destructive to the delicate ultrastructure of the middle and inner ear. Conversely, X-ray microtomography allows non-destructive examination of the otic capsule. In this study, we used X-ray microtomography to characterise the fissula ante fenestram. MATERIALS AND METHODS: We imaged cadaveric temporal bones with X-ray microtomography. We used the Avizo Fire (Visualization Science Group, Merignac Cedex, France) software to perform post-processing and image analysis. RESULTS: Three-dimensional modelling of the fissula ante fenestram allowed stratification into four forms: rudimentary pit; partial fissula; complete occluded fissula; and complete patent fissula. CONCLUSION: X-ray microtomography showed that the fissula ante fenestram is present in various forms from rudimentary pit to complete deficiency of the otic capsule. This understanding may have implications for otologic surgery and clinical diagnosis of perilymph fistula.

Jugular bulb abnormalities in patients with Meniere's disease using high-resolution computed tomography.

Temporal bone abnormalities such as hypoplasia of the vestibular aqueduct or hypopneumatization of the mastoid have been described in Meniere's disease (MD). Jugular bulb abnormalities (JBA) are one of the most common temporal bone abnormalities. The aim of this study was to evaluate the frequency of JBA in MD. Radiological data obtained by temporal bone high-resolution computed tomography of 200 ears of 167 MD patients (MD group) and 218 ears of 109 patients with normal inner ear function (control group) were analyzed retrospectively. The frequencies of high jugular bulb (HJB), jugular bulb diverticulum (JBD), inner ear adjacent jugular bulb (IAJB) and jugular bulb related inner ear dehiscence (JBID) were evaluated and compared between MD group and control group. IAJB was differentiated into vestibular aqueduct adjacent jugular bulb (VAAJB), cochlear aqueduct adjacent jugular bulb and posterior semicircular canal adjacent jugular bulb. JBID was further analyzed by differentiating into jugular bulb related vestibular aqueduct dehiscence (JBVAD), jugular bulb related cochlear aqueduct dehiscence and jugular bulb related posterior semicircular canal dehiscence. The frequencies of HJB, JBD and IAJB were higher in MD group compared to control group (21, 13.3 %, p = 0.036; 8.5, 3.7 %, p = 0.037; 13.5, 4.6 %, p = 0.001). No differences between both groups were seen in JBID (4.0, 2.3 %, p = 0.315). Most IAJB and JBID were seen in VAAJB and JBVAD. There is a higher frequency of JBA in patients with MD than in patients without inner ear symptoms. Temporal bones of MD patients might be constituted anatomically different, carrying predisposing factors for the development of clinically apparent MD.

Radiological findings of the cochlear aqueduct in patients with Meniere's disease using high-resolution CT and high-resolution MRI.

The objective of the present study was to evaluate the cochlear aqueduct (CA) in Meniere's disease (MD) and to disclose radiological differences of CA between MD and non-MD patients by means of high-resolution computed tomography (HRCT) and high-resolution magnetic resonance imaging (HRMRI). Radiological data of 86 ears of MD patients which were separated into 52 ears of diseased side group (MD-D group) and 34 ears of contralateral non-affected side group of unilateral MD (MD-ND group), 27 ears of patients with sensorineural hearing loss (SNHL group) and 56 ears of patients with somatoform dizziness and normal hearing (control group) were analyzed retrospectively. The bony type of CA, the bony length of CA, and the bony width of CA medial orifice was measured in HRCT. The visibility of CA in HRMRI was scored. Fluid length in CA and fluid width in medial orifice were measured in HRMRI. Data were compared between MD-D, MD-ND, SNHL, and control group. There were no significant differences in the bony type of CA, bony length of CA, bony width of CA medial orifice, and fluid width of CA medial orifice between MD-D, MD-ND, SNHL and control group (p > 0.05). However, CA fluid length of MD-D (5.13 ± 1.88 mm) and of MD-ND group (5.44 ± 1.81 mm) was significantly shorter than fluid length of SNHL (6.90 ± 1.55 mm) (p < 0.001, p = 0.001) and of control group (7.43 ± 1.24 mm) (p < 0.001, p < 0.001). The ratio between CA fluid length and CA bony length was the smallest in MD-D group (0.403; p = 0.009). CA bony dimensions of affected ears of MD are normal, but CA fluid length is decreased.

Enlarged cochlear aqueducts: a potential route for CSF gushers in patients with enlarged vestibular aqueducts.

OBJECTIVE: We investigated whether the size of the cochlear aqueduct (CA) is increased in patients with enlarged vestibular aqueducts (EVAs) compared with individuals with normal inner ear anatomy. Furthermore, we assessed whether the size of the CA is related to the cerebrospinal fluid (CSF) gusher during cochlear implantation (CI) surgery. STUDY DESIGN: Retrospective study. SETTING: Tertiary referral center. PATIENTS: The medical records for 35 patients with a biallelic SLC26A4 mutation were reviewed. All of the patients were confirmed to have EVA by temporal bone computed tomography (TBCT) and biallelic SLC26A4 mutation by genetic analysis. Thirty-six age- and sex-matched patients without a mutation in the SLC26A4 gene were selected as comparison group. MAIN OUTCOME MEASURES: The diameters of the CA and vestibular aqueduct (VA) were measured, and the type of CA was evaluated using TBCT. RESULTS: The CA was larger in patients with EVA (2.39 ± 0.99 mm) as compared with controls (1.76 ± 0.87 mm; p < 0.001). The types that could be most easily visualized from the subarachnoid space to the cochlea were more common in patients with EVA. Furthermore, mean CA size was significantly larger in EVA patients with CSF gushers (3.65 ± 1.12 mm) as compared with those without CSF gushers (2.03 ± 0.66 mm; p < 0.001). CONCLUSION: The CA is a potential pathway for CSF gushers between the subarachnoid space and the inner ear. Therefore, we suggest that evaluation of the CA by TBCT may be helpful in predicting intraoperative CSF gushers in patients with EVA.

Enlargement of the cochlear aqueduct: does it exist?

Our intention was to evaluate whether enlargement of the cochlear aqueduct could play a role in dysfunctions of the inner ear. There is little literature dealing with the question of cochlear aqueduct (CA) enlargement and results of reported radiological examinations are contradictory. Therefore, we decided to analyse 400 high-resolution CT-scans of the temporal bone to examine the diameter of the CA. We used scan-data from a 64-line multislice spiral-CT-scanner stored in our PACS-System. CA-enlargement was defined as a diameter of more than 1 mm in the whole otic capsule portion. A classification with four types of CA's proposed by Migirov and Kronenberg in 2005 was applied. Statistical analysis of diameters, different CA-types and side asymmetry was performed. We did not find any CA exceeding 1 mm in diameter in the otic capsule portion, there is no evidence of CA-enlargement, not even in patients with inner ear malformation. A new aspect compared with published literature to date is that nearly in all cases CA was identified, but in different degrees. According to our findings, it seems to be very unlikely that CA-enlargement is a reason for pathologic inner ear condition as it is in case of large vestibular aqueduct.

Petromastoid canal and cochlear aqueduct in cochlear implant candidates.

OBJECTIVE: To present temporal bone fine channels in cochlear implantation candidates. METHODS: Review of the axial sections of 108 temporal bone CTs. In type I, the petromastoid canal (PMC) was invisible but appeared as channels in type II and type III, <0.5 and 0.5-1 mm wide, respectively, and in type IV was >1 mm wide. The cochlear aqueduct (CA) was visualized up to the vestibule in type 1, the medial two thirds in type 2, the external aperture and/or the medial third in type 3, and was undetectable in type 4. RESULTS: The PMC size and shape differed significantly between the young (aged <5 years) and older (aged 5-16 years) children and between the young children and adults. A wide PMC (>2 mm) was found in only children younger than 2 years. Children up to 2 years of age and those aged 2 to 5 years demonstrated similar findings. The CA types differed among the pediatric and adult CI candidates, with the main difference appearing after the age of 16 years. There was no correlation between CA and PMC types. CONCLUSIONS: It is likely that the age-related changes in CA and PMC are attributable to the developmental or age-related changes in skull base growth.

[Inner ear and subarachnoid spaces: relations and diseases]. / Oreille interne et espaces sous-arachnoïdiens.

The purpose of this article is to describe, with 5 clinical cases, the physiological communications between the inner ear and the subarachnoid spaces (SAS) and present the imaging features with regard to. Therefore we briefly illustrate abnormal communications between SAS and perilymphatic fluids in certain cochlear and internal acoustic meatus (IAM) malformations and their consequences. Imaging features may depict diffusion pathway of bacterial meningitis to membranous labyrinth via the cochlear aqueduct or via the IAM. Rarely, in some patients referred for cochleovestibular symptoms, imaging features may display skull base tumors involving the area of cochlear or vestibular aqueduct aperture. Therefore, in patients referred for cochleovestibular symptoms, MR and CT study should carefully scrutinise not only the IAM but also the aperture of the cochlear and the vestibular aqueducts and the cerebellopontine meninges.

Repair of a cerebrospinal fluid perilymph fistula primarily through the middle ear and secondarily by occluding the cochlear aqueduct.

A 35-year-old man had a 5-year history of fluctuating hearing loss in his only hearing ear. History and diagnostic tests indicated a perilymph fistula, a diagnosis subsequently confirmed by exploration. Primary and secondary repairs temporarily ameliorated symptoms. A spinal fluid to middle ear fluid pathway was identified by radioactive tracer. A patent cochlear aqueduct indicated on computed tomography scan was found and repaired through a posterior cranial fossa approach. Hearing was preserved, remaining relatively stable during the 2-year follow-up period.

[Perilymphatic fistula]. / Fistule périlymphatique.

Perilymphatic fistulae are the first cause of perceptive deafness that may be amenable to surgical treatment. After a complete study of the literature, we have made a retrospective analysis of 48 ear explorations in 37 children. These children presented with a variable degree of progressive or fluctuating perceptive deafness without any obvious etiology. Computed tomography, especially aimed at detecting an abnormality in the patency of the aqueduct of the cochlea, seems to be the most efficient criterion of selection to establish an indication for surgical exploration. The extent of the perilymphatic fistulae and their location, mainly at the level of the fissura ante fenestram, call to our mind the possibility of an arrest in the differentiation of the otic capsule, with a persistent anomalous patency of the aqueduct of the cochlea. The results of this study mainly demonstrate stabilizations of hearing, while spectacular improvements still are anecdotal. On the other hand, morbidity is very low and mainly results from insufficient surgery to fill in the fistula. Further studies are needed, especially to better understand the pathophysiology of the perilymphatic fistulae, and their results must certainly be appreciated in the longer term.

Radiographic classification of the vestibular and cochlear aqueducts: the paired correlation between normal and abnormal vestibular aqueduct and cochlear aqueduct anatomy.

Multidirectional tomography (MDT) can be useful in determining the caliber, shape, and course of the vestibular aqueduct (VA) and cochlear aqueduct (CA). Clinical decisions have been based on the findings from MDT. Unfortunately, the clinical utility of these observations has been confusing and controversial because similar MDT techniques were not used. This study will address some of the difficult questions and clinical controversies derived from MDT observations. This new perspective has evolved with the use of high resolution computed tomography (HRCT). An analysis of 750 petrous bones for the occurrence of the various types of VAs and CAs using Gado's classification, further vestibular aqueduct and a variation of Gado's classification for the cochlear classification is reported. The distribution of the possible paired types of VA and CA are evaluated. MDT results indicate that the paired analysis in patients with inner ear dysfunction is not useful, cost effective, diagnostic, or of prognostic value. MDT can provide clinically valid observations of periaqueductal and perilabyrinthine pneumatization which is helpful in anticipating the size and position of the endolymphatic sac at the time of surgery for those few patients who may benefit from endolymphatic system surgery. However, when a comparison is made between MDT and CT of 60 ears in those same patients, the clinical limitations of MDT for inner ear diagnosis and prognosis became apparent. The future for HRCT scanning with reformatting holds potential for clinically meaningful visualization of inner and middle ear structures previously expected from MDT imaging.