Facial Recess Research Articles

A technique for implantation of a 3-dimensional penetrating electrode array in the modiolar nerve of cats and humans.

We believe that direct intraneural stimulation of the modiolar nerve using an array of electrodes will have lower thresholds, offer greater frequency selectivity and more stimulation sites, and have a greater frequency representation than conventional cochlear implants. To describe a potential auditory prosthesis based on electrical stimulation of the modiolar cochlear nerve and to report the development of a surgical approach in human and animal models. Cadaveric human and animal studies conducted in temporal bones indicated that an array of penetrating microelectrodes could be implanted in the modiolar nerve. Cat studies using anesthesia were performed to develop the surgical procedure in an animal model. Nerve viability was assessed by measurement of electrically evoked auditory brainstem responses at different stages of the surgery. Two fresh cadaveric human temporal bones, 3 cat cadavers, 1 pig cadaver, and 6 anesthetized cats were used in the experiments. We were able to implant arrays containing 20 microelectrodes in the human modiolar nerve after exposure by a modified extended facial recess approach. In animals, the modiolar nerve was accessed by the transbulla and the middle fossa approach. The cat was chosen as the appropriate animal model, and the transbulla approach was selected. The round window was exposed by ventral access to the bulla and after cochleostomy; drilling the modiolar bone exposed the modiolar nerve. The mean +/- SD diameter of the exposed nerve in cats was 1.64 +/- 0.07 mm (n = 9), and the mean +/- SD exposed length was 2.50 +/- 0.11 mm (n = 9); this is adequate to accommodate 20 microelectrodes. The electrically evoked auditory brainstem responses indicated nerve survival during and after the surgery. The surgical technique allows implantation of up to 20 microelectrodes in the cat and human modiolar nerve. The nerve survives the surgical procedure. This work enables studies in the electrophysiological properties and consequences of long-term implantation.

Round window gentamicin absorption: an in vivo human model.

Using a novel human labyrinthine sampling model, in vivo gentamicin absorption through the round window can be measured. A prospective study. Gentamicin was delivered either transtympanically (preoperative) or through a facial recess approach (intraoperative). The lateral semicircular canal and vestibule were opened, and by means of a microsyringe, labyrinthine fluid was aspirated. A sample of serum was also drawn. In all patients cerebrospinal fluid was also drawn. The samples were analyzed using a standard chemistry analyzer. Intratympanic gentamicin diffused through the round window membrane and achieved concentrations in the labyrinthine fluid ranging from 0 to 16 mg/L. Intratympanic gentamicin was absorbed into the systemic circulation in 4 of 11 patients with serum levels ranging from 0.3 to 0.4 mg/L. No gentamicin was detected in the cerebrospinal fluid. Intratympanic gentamicin diffuses rapidly through the round window membrane and achieves significant levels in the inner ear. Thus, this new model can be used to assess round window permeability to clinically relevant medications such as steroids and ototopical antibiotics.

The role of computerized tomography in the preoperative assessment of chronic suppurative otitis media.

Twenty patients awaiting mastoid surgery for chronic suppurative otitis media underwent preoperative high resolution computerized tomography (CT) of the temporal bones. The CT scans were compared with the intraoperative findings. CT was helpful in determining the anatomy of the middle ear and mastoid, and accurately predicted the extent of the disease process in the sinus tympani and facial recess. However, it was unable to distinguish between cholesteatoma, mucosal disease and fluid, and it contributed little to the surgical management of the patients. This suggests that routine preoperative CT scanning of patients before uncomplicated virgin mastoid surgery is of questionable value.

Temporal bone histopathology related to cochlear implantation in congenital malformation of the bony cochlea.

Histopathologic findings in temporal bones with congenital malformations of the bony cochlea may provide insight into cochlear implantation planning, surgical approach, and complications. Patients with congenitally malformed cochleae account for an increasing percentage of candidates for cochlear implantation. Few studies on the relationship between histopathologic findings of temporal bones with malformation of the bony cochlea and cochlear implantation have been reported. We studied 21 temporal bones from 12 cases with congenital malformations of the bony cochlea. Ages ranged from stillborn to 50 years. Length of the cochleae and dimensions of facial recesses were measured with light microscopy. Other malformations associated with a shortened cochlea were determined, emphasizing how they affect cochlear implantation. The average length of the malformed cochlear duct was 22.84 +/- 0.69 mm. Average dimensions of facial recesses were not significantly different between malformed cochleae and the controls. Other malformations included enlarged cochlear aqueduct (43%), abnormal facial nerve course (57%), enlarged vestibular aqueduct (52%), aplasia of the middle ear (19%), malformed ossicles (67%), abnormal oval window (57%), and abnormal round window (29%). A shortened cochlear duct may cause an incomplete insertion of the implant electrode. Because dimensions of the facial recesses are similar to normal cases, a facial recess surgical approach is recommended. An enlarged cochlear aqueduct may cause perilymphatic oozing or gushing on fenestration of the cochlea. An anomalous course of the facial nerve is a common finding. Tympanic malformations such as round and oval window deformities and small middle ear cleft should be noted preoperatively to better guide surgery.

Cochlear implant electrode insertion: Jacobson’s nerve, a useful anatomical landmark

The classical technique in approaching the scala tympani through the round window niche by way of facial recess has not always been successful. There have been recent reports on false insertion of the electrode array into the hypotympanic cells tracts or infralabrynithine cells tracts. In these cases the round window niche are situated posterior, or obliterated due to bony growth, or sclerosed at the basal turn of the cochlea. Therefore, successful intubation of the scala tympani much depends upon the position of the round window niche and patency of the basal turn of the cochlea. The present study was conducted in an attempt to elucidate factors that determine the ease of insertion of an electrode array, and to by-pass the initial turn of the basal cochlea (hook area). The jacobson's nerve (JN) landmark was used to perform cochleostomy by drilling anteriorly or through the nerve. The inferior segment position of the basal turn of the cochlea studied in relation to the JN and successful intubation of the scala tympani was achieved. Also, critical anatomical measurements were made pertaining to this surgical technique.

Measurements of drill-induced temperature change in the facial nerve during mastoid surgery: a cadaveric model using diamond burs.

The purpose of this study was to investigate the changes in temperature in the facial nerve that occur during mastoid drilling by the facial recess approach and to confirm the beneficial effects of constant irrigation while drilling. Mastoid drilling was performed on human cadaveric temporal bones by means of 4-mm diamond burs with and without irrigation. There were 6 subjects in each group. Changes in facial nerve temperature were recorded on a continuous-output monitor. Significant changes were found in temperature for both the irrigation and non-irrigation groups (p < .0001). Constant irrigation minimized the rise in temperature. Facial recess drilling poses a potential threat to cranial nerve VII via thermal injury. The temperature elevation in the non-irrigation group was significantly greater than that in the irrigation group and was greater than the tolerable limits of peripheral nervous tissue. This finding supports the need for constant irrigation during the approach to the facial recess in mastoid surgery.

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

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. Prospective. 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. 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. 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.

Topographical relationships among the facial nerve, chorda tympani nerve and round window with special reference to the approach route for cochlear implant surgery.

The topographical relationships among the facial nerve (FN), chorda tympani nerve (CT), and round window (RW) in 22 temporal bone specimens were analyzed morphometrically in order to examine which route is widest through the facial recess between the FN and CT during cochlear implant surgery and in order to establish some criteria to assist in the evaluation of the best surgical approach. Two lines, i.e., the FN-RW line and CT-RW line, were speculated as limitations of a visual field for this surgery. According to the relative position of these structures, including the posterior wall of the external auditory canal (EAC) and an inserted pin-gage that indicates the hypothetical widest approach route, the relationships were classified into five types. Most frequently, the widest approach route through the facial recess did not point directly at the RW, but at the basal turn at the promontory. Moreover, this approach route crossed the FN-RW line in a posterior to anterior direction and the CT-RW line frequently crossed the posterior wall of the EAC. The latter seemed to provide a critical landmark for avoiding damage to the CT during cochlear implant surgery. Therefore, we recommend inserting the electrode into the basal turn.

전산화단층촬영상 소아의 측두골 계측

Background and Objectives: Radiographic imaging of the temporal bone is invaluable to the otologic surgeon contemplating cochlear implantation. HRCT scanning technology has increased the ability to assess the structures within the petrous pyramid. This study was performd to obtain anatomical data of developing temporal bone for pediatric cochlear implantation and to determine the normal course of skull and temporal bone development for the proper time of age for implantation. Materials and Methods: High-resolution temporal bone computed tomographic (CT) images of 56 patients were measured and analysed. Patients are aged from 1 to 19 years old. Using parameters are dimension of temporal bone, predictor for cochlear implantation, major feature, and cochlear ossification. Results: The growth of the skull and the Temporal bone was rapid during the first 5 years of life followed by gradual but steady development until the age of 15. Each portion of the Temporal bone was different in developmental rate and thickness of soft tissue covering temporal bone was variable. Also thickness of parietal bone, pneumatization and the size of facial recess was measured variably. No inner ear malformation and cochlear ossification was noticed radiologically. Conclusion: The results of analysis of temporal bone development will be utilized as anatomical data base for pediatric cochlear implantation. (J Clinical Otolaryngol 1999;10:195–201)

Surgical Anatomy of the Facial Nerve in Chinese Mastoids

Since racial differences in mastoid morphology exist, there may be racial differences in the surgical anatomy of the facial nerve in the mastoid. Thirty Chinese adult temporal bones were dissected. The facial nerve in the mastoid coursed vertically (60.0%), anteriorly (33.3%) and posteriorly (6.7%) in the sagittal plane. In the coronal plane, it coursed vertically (46.7%) and laterally (53.3%). The chorda tympani was found to have extratemporal origin in 53.3% and for the rest, the distance of its origin from the stylomastoid foramen averaged 3.17 mm (range 0.5–6.0 mm). The mean dimension of the extended facial recess was 4.40 mm (range 3.0–6.0 mm). The facial nerve was at a mean of 3.15 mm (range 2.0–5.0 mm) posterior to the most posterior point of the tympanic annulus and partially crossed the tympanic annulus from medial to lateral at this point. In conclusion, the typical surgical anatomy of the mastoid facial nerve as described in the Western literature may not apply to the Chinese.

Surgical considerations regarding cochlear implantation in the congenitally malformed cochlea

A 4-year-old girl with congenital profound deafness underwent cochlear implant surgery. Preoperative CT and MRI revealed that her inner ears had common-cavity or aplasia-type malformation. The bilateral internal auditory meatus were markedly narrowed. Audiometric examination demonstrated that only slight residual hearing remained in the low-frequency range and that a hearing aid would be of no benefit. Cochlear implantation was performed in her left ear. Because of the abnormal position of the facial nerve, the routine facial recess approach could not be performed. A canal-wall-down mastoidectomy was performed, and multichannel cochlear implant electrodes were inserted by careful drilling of the bony wall of the semicircular canal area. All 22 electrodes were completely inserted into the cavity. The patient can perceive sounds and her hearing ability is progressively improving. (Otolaryngol Head Neck Surg 1999;121:495-8.)

Surgical techniques to facilitate endoscopic second-look mastoidectomy.

Mastoidoscopy has shown to be a safe, effective alternative to traditional second-look mastoidectomy. This study was undertaken to review surgical modifications to facilitate successful mastoidoscopy. Retrospective database review of all surgical procedures performed by the senior author (T.J.H.) since January 1995. All surgeries were performed in a tertiary hospital setting. Fifteen second-look procedures were performed in this series. Five were performed endoscopically, 10 with traditional techniques. In the traditional surgeries five were prior to the use of endoscopy, five had contraindications to endoscopic mastoidectomy. There were six residual cholesteatomas in the series, one in the endoscopic cases (20%), and five in the traditional cases (50%). No cholesteatomas were identified with microscopic examination performed after endoscopy. There were no complications in the series. Mastoidoscopy gives limited access to the mesotympanum, eustachian tube and, in particular, the sinus tympani. The creation of a wide extended facial recess with removal of the buttress at the fossa incudis and removal of the incus and head of the maleus will facilitate inspection of the middle ear. Additional techniques are necessary to view the sinus tympani. The fallopian bridge technique, and the infratympanic extended facial recess technique may allow better visualization of the middle ear. Mastoidoscopy offers a safe alternative to traditional techniques for second-look surgery. The morbidity appears similar to traditional techniques.

Surgical technique for the CLARION cochlear implant.

This paper describes a technique for implantation of the CLARION Multi-Strategy Cochlear Implant based upon the authors' surgical experience with the device. Although much of the procedure is similar to many commonly performed otologic operations, including implantation of other cochlear prostheses, several device-specific modifications are highlighted. Those modifications include a substantial bony seat, facial recess, and cochleostomy, and the use of an electrode insertion tool.

Use of bone wax in the prevention of cerebrospinal fluid fistula in acoustic neuroma surgery.

Use of bone wax in the prevention of cerebrospinal fluid fistula in acoustic neuroma surgery.

Surgical anatomy of the facial nerve and chorda tympani with special reference to cochlear implantation

The surgical anatomy of the facial nerve (FN), chorda tympani nerve (CT) and round window (RW) in 26 Japanese temporal bone specimens was analyzed. The relationships were classified according to the relative position of these structures and the posterior wall of the external auditory canal (EAC). Most frequently, the widest approach route through the facial recess did not point directly at the RW, but rather at the basal turn. Moreover, the approach route crossed the FN-RW line in a posterior to anterior direction (76.9%) and the CT-RW line frequently crossed the posterior wall of the EAC (92.3%). The latter seemed to provide a critical landmark for avoiding damage to the CT during cochlear implant surgery. Therefore, we recommend inserting the electrode into the basal turn at the promontory. Several other anatomical indices were measured and we extracted the index which was related to the maximum approach amplitude and direction. Preoperative diagnosis may be possible using these indices.

内耳奇形の小児に対する人工内耳埋込術と術後成績

Cochlear implantation in children with cochlear malformation is on the rise. However, only one case has been reported in Japan. The objective of this paper is to report the authors' experiences with cochlear implants in children with cochlear malformations and, to investigate the morphological classification of cochlear malformation, surgical procedure, complications, and speech perceptions after implantation. Five children (6 ears, including 1 Usher's syndrome and 1 CHARGE association) with congenital inner ear malformations were implanted with multichannel cochlear implants (Nucleus Mini 22 device) between 1994 and 1998. Malformations included common cavity deformity 2, and incomplete partition 4. On the other hand, 4 cases with incomplete partition deformity underwent cochlear implantation by the transmastoid facial recess approach, 2 patients with common cavity deformity received implantation by the transmastoid labyrinthotomy approach. Complications such as facial twitching, cerebrospinal fluid (CSF) gusger, and flap-related problems were encountered. Facial twitching occurred in 1 of 2 patients with common cavity where the electrode array extended into the internal auditory canal. CSF gusher was encountered in 1 of 4 patients with incomplete partition, and revision surgery was performed one week later. One patient had delayed cochlear implant infection and a split pericranial flap was used to cover the defect in the skin flap. Within 6 months, however, the revised pedestal site broke down because of recurrent flap infection. Finally, the cochlear implant was explanted, and the patient underwent a new cochlear implantation in the contralateral ear. All the patients had satisfactory speech reception and word acquisition, but still poor phonetic expression.

A human temporal bone study of stapes footplate movement.

This study was designed to determine whether stapes movement is pistonlike or complex. The literature provides conflicting information on whether stapes footplate motion is only pistonlike or has other types of movement, such as hingelike or rocking. Using 10 freshly harvested human cadaver temporal bones, 3 targets were placed on the stapes footplate through an extended facial recess approach. The targets were 0.5-mm pieces of reflective adhesive material positioned on the long axis of the footplate at the anterior crus, central footplate, and posterior crus. Displacement and phase of the three targets were measured from 0.2 to 10 kHz at a 90dB sound pressure level input at the tympanic membrane. The measuring system was a sophisticated laser Doppler vibrometer (LDV). A computer program (Tymptest) calculated footplate displacement and relative phase at the three sites and the ratio of anterior-posterior rocking movement of the footplate long axis to displacement at the center. Below 2.0 kHz, stapes vibration is predominately pistonlike. Above 2.0 kHz, anterior-posterior rocking motion increases logarithmically with frequency, and, near 4.0 kHz, rocking and pistonlike motion are approximately equal. Stapes footplate vibration is primarily pistonlike up to 2.0 kHz but becomes more complex at higher frequencies because of an increase in anterior-posterior rocking motion. Hingelike movements were not observed. This information may be helpful in the design of ossicular replacement prostheses that mimic or improve upon normal stapes vibration.

High-resolution computed tomographic study of the retrotympanum

The aim of this study was to define the imaging of the retrotympanum precisely by means of high-resolution CT. Based on 66 scans of petrous bones performed in 49 patients observed in an otologic department, several retrotympanic structures were studied: the pyramidal eminence, ponticulus, subiculum, chordal ridge, tympanic sinus of Proctor, sinus tympani and recess of the facial n. The variations in morphology and depth were noted as well as the relationship between the pyramid and the facial canal. In a second phase the same anatomic structures were studied in 24 temporal bones removed from embalmed cadavers and investigated with the same radiologic technique. Anatomic correlations were made for six temporal bones to confirm the general applicability of our radiologic hypotheses. In CT the pyramidal eminence was visualised in 100% of cases, the chordal ridge in 52%, the ponticulus in 63% and the subiculum in 57%. As regards the different recesses, the sinus tympani was visualised in 95% of cases, the posterior tympanic sinus of Proctor in 38%, the fossula of Grivot in 47% and the facial recess in 80%. The mean depth of the sinus tympani was 2.7 mm and that of the tympanic sinus of Proctor was 1.65 mm; the fossula of Grivot was assessed as 2.1 mm and the facial recess as 2.2 mm. A better knowledge of these sinuses and their variations will aid the surgeon, particularly in a posterior tympanotomy or a retro-facial approach.

Cochlear Implantation in Deaf Children

A cochlear implant (CI) is a hearing device introduced in the 1980s for profoundly deaf subjects who gained little or no benefit from powerful hearing aids. This device comprises an electrode array inserted in the cochlea, connected to an internal receiver, and an externally worn speech processor. The CI transforms acoustic signals into electrical currents which directly stimulate the auditory nerve. Since the early 1990s, cochlear implantation in children has been developing rapidly. Although it is still difficult to predict how a child will perform with a cochlear implant, the success of cochlear implantation can no longer be denied. In this paper, some recent papers and reports, and the results of the various Nijmegen cochlear implant studies, are reviewed. Issues about selection, examinations, surgery and the outcome are discussed. Overall, our results were comparable with those of other authors. It can be concluded that cochlear implantation is an effective treatment for postlingually deaf as well as prelingually (congenital or acquired) deaf children with profound bilateral sensorineural deafness.

The anterior tympanotomy.

The mesotympanum can be approached by the two well known approaches, i.e. (1) the (per meatal) tympanotomy, by lifting the posterior annulus tympanicus and (2) the posterior tymanotomy, via the facial recess. Based on surgical experience of 1113 cases, this paper describes in detail the advantages, uses, limitations, possible complications, etc., of an (as yet) anonymous approach to the middle ear i.e. approaching the middle ear by lifting the anterior annulus tympanicus. The paper recommends a possible new nomenclature so as to avoid confusion in our understanding of the terminology.