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.

Oval window perilymph fistula in child with recurrent meningitis and unilateral hearing loss.

A 2-year-old boy presented to Ears, Nose and Throat (ENT) surgeons with unilateral hearing loss. Following a prodrome of upper respiratory tract infection (URTI), he developed two episodes of pneumococcal meningitis in quick succession. This case demonstrates an unusual cause of perilymph fistula diagnosed on imaging and confirmed surgically. He had failed the Newborn Hearing Screening Programme and was therefore referred to audiology, who confirmed profound sensorineural hearing loss in the right ear. MRI showed incomplete partitioning (type 1) of the right cochlea, suggesting cerebrospinal fluid (CSF) leak from the region of the stapes. Exploratory tympanotomy confirmed this, and proceeded to CSF leak repair, obliteration of the Eustachian tube, subtotal petrosectomy, abdominal fat grafting and blind sac closure. Although middle ear effusions are common; particularly in children with recent URTI, the possibility of otogenic CSF leak needs to be considered, especially in cases of recurrent meningitis.

Congenital perilymph fistula causing recurrent meningitis: lessons learnt from a single-institution case series.

OBJECTIVE: To study the steps involved in definitive evaluation and successful management of patients with congenital perilymph fistula presenting with recurrent meningitis. STUDY DESIGN: Case series with chart review. SETTING: Tertiary care center. SUBJECTS AND METHODS: The case records of 11 patients (12 ears) treated for congenital perilymph fistula presenting with recurrent meningitis were reviewed to ascertain their clinical, radiological, and intraoperative features and outcome following surgery. RESULTS: Most patients presented after at least 3 episodes of meningitis (range, 2-10 episodes). Ipsilateral hearing loss was present in 9 of 12 ears, with normal hearing in 3 patients. High-resolution computed tomography and/or magnetic resonance imaging scanning of the temporal bone contributed to the diagnosis in 75% of cases but was normal in 3 cases (25%). Oval window and round window defects were the most common (66.7% and 63.6%, respectively). Four ears (33.3%) had more than 1 defect. The unusual presentations included 2 patients who presented in adulthood, a patient with a defect in the medial wall of the attic, and 3 patients with normal radiological findings. Follow-up ranged from 1 to 11 years (median, 2 years). There were 2 failures following simple fistula closure with cessation of symptoms after vestibular obliteration. No patient was readmitted with recurrent meningitis after definitive surgery. CONCLUSION: Up to 25% of patients with recurrent meningitis secondary to congenital perilymph fistula may have normal audiological and radiological assessment necessitating exploratory tympanotomy. Vestibular obliteration, rather than simple fistula closure, prevents recurrence.

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.

Follow-up of cochlear implant use in patients who developed bacterial meningitis following cochlear implantation.

OBJECTIVES/HYPOTHESIS: The present study is a long-term follow-up of speech perception outcomes and cochlear implant use in three cases of meningitis that occurred after cochlear implantation. STUDY DESIGN: Case series study. METHODS: Study was performed on three children implanted with different models of Clarion devices, two of them with positioner. Recognition and comprehension were assessed via the Italian adaptation of GASP (TAP) test, and phonetically balanced bi-syllabic words in open-set. High resolution computed tomography scan acquisition was performed to obtain axial coronal and oblique multiplanar reconstructions of the cochlea. RESULTS: Two patients were affected by enlarged cochlear acqueduct and Mondini malformation the first carrying positioner. One patient had a normal cochlea, and the positioner could have been the main cause of bacterial spread. As a consequence of meningitis the child with normal cochlea and the other with enlarged vestibular acqueduct developed cochlear ossification, increased M-level and worsening of hearing outcomes. The child with Mondini malformation developed facial nerve stimulation. Contralateral implantation was performed in the first two patients. CONCLUSION: Bacterial meningitis occurring after cochlear implantation may induce cochlear ossification, facial nerve stimulation, and permanent or temporary loss of implant use. Planned follow-up with high resolution computed tomography and evaluation of M-levels could be useful prognostic tools in the management of these patients.

Unilateral hearing loss following shunt placement for normal pressure hydrocephalus with a unilateral patent cochlear aqueduct.

Hearing loss in patients who have undergone shunt placement for a hydrocephalus is perhaps an underestimated complication rather than a rare event. There appears to be a correlation between the occurrence of hearing loss and patient characteristics consistent with excessive drainage of cerebrospinal fluid (CSF) and patent cochlear aqueduct (CA). We present the case of a 77-year-old man with unilateral dominant sensorineural hearing loss after a shunt placement for normal pressure hydrocephalus (NPH) combined with a patent cochlear aqueduct. Based on our experience and a review of the literature, we suggest an early restoration of the reduced CSF pressure using a programmable valve as a treatment strategy, which might prevent the persistent hearing loss.

Syndrome of recurrent meninigitis due to congenital perilymph fistula with two different clinical presentations.

Recurrent meningitis secondary to a congenital labyrinthine anomaly is a rare clinical entity, diagnosis of which is dependent upon certain clinical, radiological and intraoperative features. In the following report we describe two children with congenital labyrinthine fistula and recurrent meningitis whose clinical presentation, radiological features and intraoperative findings were dissimilar and thus, illustrative of two different ways of presentation of this rare disorder. While one had a classical Mondini defect and unilateral hearing loss, the other had normal audiometric and radiographic findings. The fistulae were successfully closed via a tympanotomy approach in both the patients.

New aspects in the histopathology of the cochlear aqueduct in children.

OBJECTIVE: To study the histoanatomy and pattern of growth of the cochlear aqueduct in children of different ages. BACKGROUND: Since Du Verney described the cochlear aqueduct in 1684, its form, pattern of growth, patency, and function have been controversial. As most of the previous studies of the aqueduct were performed on adults, none had looked at its pattern of growth from the neonate to 9 years of age. In addition, previous histologic studies had suggested an age-dependent patency, but recent investigations had not statistically correlated patency with age. METHOD: Histologic sections of 137 temporal bones from 79 infants and children were studied by light microscopy. From this group, we selected 32 temporal bones from 18 infants, newborn to 9 years (average age 9.1 months, median 0.5 months), in whom the entire length of the cochlear aqueduct was visible on one histologic section. We measured the width of the orifices at the scala tympani (external aperture) and the subarachnoid space (internal aperture) and the length of the aqueduct, and noted the contents of the lumen. RESULTS: The measurements of the cochlear aqueduct were: length 4.19 mm (range 1.7-10.7 mm), width of the external aperture 435 microm (range 225-869 microm), width of the internal aperture 1,323 microm (range 699-2344 microm), mean diameter of the narrowest part (isthmus) 138 microm (range 68-244 microm), intraluminal mononucleated cells 6%, and erythrocytes 15%. CONCLUSIONS: Our findings demonstrate that, in the newborn, the cochlear aqueduct is short and patent. After birth, the duct lengthens significantly primarily by growth of the medial periosteal portion. There was no statistically significant change in the diameter of the external and internal apertures and the isthmus with age. With one exception, the cochlear aqueduct was always present and patent.

Enlarged cochlear aqueduct.

Enlargement of the cochlear aqueduct is a controversial topic, with experienced investigators doubting its existence because of a lack of published cases. We describe the CT appearance of an enlarged cochlear aqueduct in a patient with advanced congenital inner ear anomalies and congenital hearing loss. The intent of this article is to present the CT appearance of a presumably enlarged cochlear aqueduct and to underscore the need to examine this structure in patients with congenital hearing loss.

Fine structure of extracellular matrix and basal laminae in two types of abnormal collagen production: L-proline analog-treated otocyst cultures and disproportionate micromelia (Dmm/Dmm) mutants.

L-Azetidine-2-carboxylic acid (LACA), a naturally occurring vegetable imino acid, can be incorporated into mammalian proteins in place of proline, thereby eliciting an inhibitory effect on collagen secretion. Exposure of explants of the embryonic mouse inner ear to LACA reduces the number of collagen fibrils in the otic capsule, gives rise to a dose-dependent derangement of the basal lamina, and ultimately results in dysmorphogenesis and retarded differentiation of the inner ear. Disproportionate micromelia (Dmm) is an incomplete dominant form of dwarfism characterized by a reduced quantity of type II collagen in the cartilaginous extracellular matrix (ECM). Abnormal morphogenesis in homozygotic Dmm mice resembles the abnormal morphogenesis observed in LACA-exposed otic explants, resulting in malformed inner ears with a bulky cartilaginous capsule and a lack or reduction of defined perilymphatic spaces (Van De Water and Galinovic-Schwartz, 1987). In this study, we examined by ultrastructural analysis LACA-exposed otic explants and inner ears of Dmm/Dmm mouse embryos for abnormalities in the collagenous constituents of the basal laminae and capsular ECM. We demonstrate, in comparison to normal embryonic mouse inner ears, a reduction in collagen fibrils and irregular cytodifferentiation of chondrocytes in the ECM of LACA-exposed and Dmm/Dmm inner ears as well as in the basal laminae of LACA-exposed specimens. In addition, we provide evidence of dysmorphogenesis of the otic capsule and perilymphatic spaces in LACA-exposed explants. Moreover, while previous studies demonstrated the anomalous development of sensory structures in otocyst explants following LACA exposure, in this study we provide evidence of the normal morphogenesis of otic epithelial-derived sensory structures in homozygotic Dmm/Dmm mouse embryos.

The cochlear aqueduct in pediatric temporal bones.

The cochlear aqueduct is a bony channel which contains the fibrous periotic duct and connects the perilymphatic space of the basal turn of the cochlea with the subarachnoid space of the posterior cranial cavity. Previous histological studies suggested that patency depended on age, whereas a more recent study showed no statistical correlation between age and patency. To clarify patency in pediatric cochlear aqueducts, we selected 21 temporal bones from 12 infants and children, varying in age from birth to 9 years, in which the cochlear aqueduct was fully visible on one histological section. Photographs were taken for documentation and the length and width of the orifice of the external aperture of the aqueduct at the scala tympani were measured and followed to the internal aperture at the subarachnoid space. The lumen of the duct was examined for mononucleated cells, blood cells and fibrous tissue. Measurements revealed that the mean length of the cochlear aqueduct was 4.6 mm (range, 2.4-10.7 mm), mean width of the external aperture was 484 microm (range, 225-869 microm), and mean width of the internal aperture was 1293 microm (range, 699-2344 microm). The mean diameter of the narrowest part (isthmus) was 151 microm (range, 75-244 microm). In all temporal bones the cochlear aqueduct was patent, with one exception. This latter temporal bone was from a 2-month-old girl with multiple intralabyrinthine anomalies, with the missing cochlear aqueduct believed to be due to an aplasia. Our results support prior measurements of the cochlear aqueduct and demonstrate a short and patent cochlear aqueduct in newborns. With growth, a significant increasing length of the duct was found.

Enlargement of the cochlear aqueduct: fact or fiction?

Enlargement of the cochlear aqueduct (CA) is often mentioned in the otologic literature, usually in its purported association with sensory hearing loss, stapes gusher, and transotic cerebrospinal fluid leak. In CT scans of 100 ears, the diameter of the CA medial aperture was found to be highly variable, ranging from 0 to 11 mm, with a mean of 4.5 mm. In contrast, the otic capsule segment was very narrow in every case. It could be visualized in only 56% of cases, none of which exceeded 2 mm in diameter. Several published reports of supposed CA enlargement presented images of a dilated medial aperture that was well within the range of normal variability according to the present study. In a thorough review of the literature on radiology of the CA, we were unable to find a single published image that convincingly demonstrated enlargement of the otic capsule portion. As radiographic CA enlargement has not been convincingly reported to date, it appears to be an exceedingly rare or perhaps even nonexistent malformation. It is important to recognize than even a radiographically normal CA may be hyperpatent. It is theoretically possible for increased fluid flow to result from either deficiencies in intraluminal membrane baffles or subtle canal enlargement beneath the resolution limits of CT scanning. However, as fluid flow through a tube is regulated by its narrowest point, it is extremely improbable that stapes gusher, transotic CSF leak, and vigorous perilymphatic fistula are generated by the CA when CT scans show any portion of it to be very narrow. A substantial body of evidence points to a deficient partition between the internal auditory canal and inner ear as causative in such cases. We propose that the criteria for the diagnosis of CA enlargement on high-resolution CT scan be a diameter exceeding 2 mm throughout its course from the posterior fossa to the vestibule.

[Deafness caused by malformation of the inner ear. Current contribution of x-ray computed tomography]. / Les surdités par malformation de l'oreille interne. Apport actuel de l'examen tomodensitométrique.

Hearing loss due to malformations of the auditory system may involve morphologic abnormalities of the external canal, the middle ear, or the inner ear. Various combined malformations are possible. Audiologic assessment and computed tomography make it possible to perform a precise diagnostic evaluation of inner ear malformations. In a series of 71 children with congenital sensorineural hearing loss, 31 had computed tomographic evidence of malformations. Since 19 children had bilateral lesions, a total of 50 ears were studied. The cochleovestibular abnormalities were typed and correlated to the severity and progression of hearing impairment. The 3 most frequently encountered malformations were: 1) isolated large cochlear aqueduct (n = 12), 2) large vestibular aqueduct (n = 8) and 3) the Mondini malformation (n = 7). The most severe hearing losses were associated with cochlear hypoplasia and incomplete cochlear segmentation. The severity of hearing impairment decreased with the following abnormalities in the order given: 1) large cochlear aqueduct, 2) Mondini malformation and 3) large vestibular aqueduct. Among the 15 patients with progressive hearing loss, 13 had large cochlear aqueducts either isolated or concomitant with other lesions. While certain evident abnormalities, such as cochlear aplasia or Mondini malformation, are relatively easy to diagnose, other more subtle morphologic changes, such as large cochlear aqueduct, still need to be better defined according to precise criteria for radiographic evaluation.

Cochlear implants for congenital deformities.

There have been few accounts of multi-channel cochlear implants in patients with congenital structural deformities of the inner ear which are associated with severe and sometimes progressive deafness. These malformations can now be recognized easily on 2 plane thin section high resolution CT studies which are mandatory for the pre-implantation assessment. However, no attempt seems to have been made to describe which of these malformations would be suitable for an implant or for which would this procedure be contra-indicated. True Mondini deformity of both the cochlea and dilated vestibular aqueduct type would appear suitable for a multi channel implant, but this type of implant should not be used for a primitive otocyst, severe labyrinthine dysplasia or the characteristic X-linked deformity.

[The cochlear aqueduct and congenital perilymphatic fistula. An initial report]. / Aqueduc cochléaire et fistules péri-lymphatiques congénitales. Rapport préliminaire.

The authors present 3 preliminary case reports of congenital perilymphatic fistula and describe their approach, which in the presence of clinical symptoms composed of progressive or fluctuating deafness, should suggest the diagnosis of congenital perilymphatic fistula leading to examination of the cochlear aqueduct by high resolution computed tomography. An anomaly detected on the CT scan, particularly on the intermediate and internal segments, is a decisive argument in the decision to operate on these congenital perilymphatic fistulae.

Otologic manifestations of the hydantoin syndrome.

The temporal bones of a newborn infant with hydantoin syndrome showed multiple middle ear and inner ear anomalies. There was a constellation of bony and membranous defects involving the oval and round windows, cochlear ducts, cochlear aqueducts, endolymphatic ducts and sacs, and vestibular labyrinths. To the authors' knowledge, supernumerary vestibular sensory epithelial structures and an inner ear epidermoid cyst have not been previously reported. Wide communications between the subarachnoid space and inner ear were of surgical relevance.

Spontaneous cerebrospinal fluid otorrhea in association with a congenital defect of the cochlear aqueduct and Mondini dysplasia.

Unrecognized spontaneous cerebrospinal fluid (CSF) otorrhea led to recurrent bacterial meningitis in three children. The underlying cause of the spontaneous CSF otorrhea was proved to be a congenital cystic dilatation of the cochlear aqueduct and Mondini dysplasia of the temporal bone. The CSF leak recurred in all patients after an initial surgical attempts to close the defects through a tympanotomy. A suboccipital approach was used successfully to obliterate the CSF fistulas in two children; a translabyrinthine approach was used in the other. A search of the literature revealed that Mondini dysplasia is a congenital anomaly that can commonly cause spontaneous CSF otorrhea in children. The authors discuss the management of this uncommon entity on the basis of a literature review and their own experience.