Infracochlear Approach Research Articles

Novel Multiportal Approach to the Internal Auditory Canal for Hearing-Preserving Surgery: Feasibility Assessment in Dissections

State-of-the-art, minimally invasive endoscopic transcanal surgery of the internal auditory canal (IAC) sacrifices the cochlea with complete hearing loss. With a combination of the transcanal infracochlear and transmastoid retrolabyrinthine approaches, we aim to preserve hearing and enable minimally invasive surgical treatment of vestibular schwannoma. In this study, we investigate the anatomical indications and the feasibility of both approaches in dissections, in human whole head specimens. We operated whole head anatomical specimens with a four-handed technique, using the retrolabyrinthine approach as the main surgical corridor and the infracochlear approach for endoscopic visualization. We tested 4 different powered surgical systems. We collected intraoperative data on the size of the access windows, the surgical freedom, and the exposed area of the IAC. Finally, we evaluated the outcome in postoperative computed tomography scans. Six out of 14 sides were anatomically suitable and qualified for the surgery based on preoperative computed tomography. In all attempted sides, the IAC could be reached and opened, leaving the ossicular chain and the labyrinth intact. 51%-75% of the length and 22%-40% of the circumference of the IAC could be exposed. All tested instruments were beneficial at different stages of the surgery. The four-handed technique enabled good maneuverability of the instruments. The combined multiportal approach to the IAC is feasible with a good surgical exposure and full anatomical preservation of hearing. State-of-the-art surgical instruments in specimens with suitable anatomy are sufficient to perform this approach.

Патология верхушки пирамиды височной кости

The review of papers, focused on studying various neoplasms, diagnosis, selection of surgical approach, complications, and recurrence rates of the petrous apex lesions, that have been published in 2008–2022, is provided. Effusion, mucocele, cholesterol granuloma, cholesteatoma are the most common benign lesions of the petrous apex. Such surgical approaches as translabyrinthine, transcochlear, endoscopic endonasal approach and the middle cranial fossa approach are most often used during treatment. The middle cranial fossa approach, infracochlear approach and endoscopic transnasal approach are recommended for patients with preserved hearing. In case of disseminated lesions, when the carotid artery and the jugular bulb should be additionally controlled, transcochlear and translabyrinthine surgical corridors could be used.

Hearing-Preserving Approaches to the Internal Auditory Canal: Feasibility Assessment from the Perspective of an Endoscope

Minimally invasive transcanal transpromontorial endoscopic approaches to the internal auditory canal sacrifice the cochlea. Two hearing-preserving approaches, the exclusively endoscopic transcanal infracochlear approach and the endoscope-assisted transmastoid retrolabyrinthine approach, have been controversially discussed in the literature. In this study, we examine the feasibility of these 2 approaches by means of three-dimensional surface models, a population-based analysis of the available surgical space, and dissections in human whole-head specimens. We reconstructed three-dimensional surface models based on clinical high-resolution computed tomography scans of 53 adult temporal bones. For both approaches, we measured the maximal extensions and the area of the surgical access windows located between landmarks on the surrounding anatomic structures. We then identified the limiting extensions and derived the cumulative distribution to describe the available surgical space. Dissections were performed to validate the corridors and landmark selection. The limiting extension for the infrachochlear approach is 7.0 ± 2.7 mm from the round window to the dome of the jugular bulb. The limiting extension for the retrolabyrinthine approach is 6.4 ± 1.5 mm from the dura of the posterior fossa to the facial nerve. The cumulative distribution shows that 80% of the cohort have access window extensions ≥3 mm for both approaches. This study shows that in a high percentage of the measured cohort, the access windows are sufficiently large for endoscopic approaches to the internal auditory canal. With appropriate instrumentation, these hearing-preserving minimally invasive approaches may evolve into alternatives to surgical treatment.

Infracochlear approach to the petrous apex: a report of two cases

Purpose: Presentation of the infracochlear approach to the petrous apex of the temporal bone, based on two clinical cases.
 Case report: Infracochlear approach to the petrous apex of the temporal bone was performed on two patients with cholesterol granuloma and plasmocytoma. The procedure was performed through the external auditory meatus, the tympanomeatal flap was raised, and the triangular/rectangular window bounded by the internal carotid artery, jugular vein, and round window of the cochlea was drilled out to the petrous apex.
 Conclusion: Infracochlear approach to petrous apex is a safe operating procedure that preserves the normal external auditory canal and middle ear conductive mechanism. It is the most direct and least invasive of all procedures to reach the petrous apex, and it is suitable for both drainage procedures and biopsy of lesions in the petrous apex of the temporal bone.

Symptom: Serous Middle Ear Effusion and Hearing Loss

Symptom: Serous Middle Ear Effusion and Hearing Loss

Surgical anatomy of the transcanal infracochlear approach.

The objective of this study is to describe the detailed surgical anatomy of the infracochlear approach to prevent complications and to compare the postauricular transcanal microscopic and endoscopic approaches to reach the petrous apex. Cadaver heads were dissected using a binocular surgical microscope, endoscopes, and an electric drill. The dimensions of the access field that could be reached and manipulated with surgical instruments and straight drill via postauricular transcanal microscopic and endoscopic approaches were evaluated. Both postauricular microscopic and transcanal endoscopic approaches were considered to be inapplicable in cases with a tympanic cavity located jugular bulb closer than 3mm to the cochlea. This relationship was seen in 3 (9%) sides of the cadavers. In 4 specimens (12%), a cochlear aqueduct with an open lumen was detected. Both postauricular microscopic and transcanal endoscopic approaches reached a nearly identic dissection area. Detailed anatomy of the approach and measurements about the topography of the third portion of the facial nerve from the tympanic cavity were presented. Both traditional microscopic postauricular and endoscopic transcanal approaches provided comparable access areas to the inferior petrous apex with wide exposure, and radiologic measurements were compatible. A tympanic cavity located jugular bulb in close relation with cochlea was the only instance that restricted the applicability of this technique.

Exclusive endoscopic transcanal approach to lateral skull base lesions: Institutional experience of 3 cases

IntroductionMajority of petrous bone and lateral skull base pathologies are benign in nature. The complex anatomy usually warrants an extensive approach with associated morbidity. Case summaryTwo cases of petrous bone cholesteatoma (1 congenital cholesteatoma with facial palsy and 1 acquired cholesteatoma) and a case of glomus tympanicum were treated with exclusive endoscopic transcanal approach. The cases of petrous cholesteatoma were addressed with trans-promontorial and infra-cochlear approaches. The mean operative time was approximately 140 min. No CSF otorrhoea was noticed in the post-operative period. The average period of hospital stay was 3.7 days. ConclusionIn the subset of cases with limited benign disease an endoscopic trans-canal approach is a better alternative to an external approach. It decreases operative time, blood loss, chance of meningitis, morbidity and hospital stay. The lack of depth perception is a major hurdle which can be come over by experience in endoscopic middle ear surgery. This approach can create direct access to cochlea/petrous apex/internal auditory canal (IAC)/Supra-geniculate ganglion region.

Basis of endoscopic dissection of the ear with analysis of endoscopic anatomy. Part 2.

Nowadays, endoscopic transcanal otosurgery with confident steps is becoming a practice. Obviously, any new method of intervention needs to be repeatedly tested by the surgeon before it is used on the patient. This is why dissection work is so important and popular. Working on biomaterial sets itself several tasks: training manual skills of working with an endoscope and an instrument in the middle ear cavities, stage-by-stage training for performing specific interventions, detailed analysis and repetition of anatomy and topography of structures. This article presents a step-by-step dissection algorithm with an analysis of the anatomical landmarks of each area, such as the prototype. The proposed training protocol allows practicing such interventions as endaural atticotomy, types of ossiculoplasty, stapedoplasty, decompression of the facial nerve to the geniculate ganglion area, infracochlear and transpromontorial approaches to the internal auditory canal. Keywords: endoscopic otosurgery, transcanal otosurgery, chronic otitis media, otitis media, otitis media in children, otodissection, endoscopic otodissection.

The infracochlear approach for diagnostic petrous apicotomy

Diagnostic and therapeutic approaches to the petrous apex involve sub-/transtemporal, retrosigmoidal, infratemporal and-lesser invasive-e.g. infracochlear, infralabyrinthine or under favourable anatomic conditions, transsphenoidal surgical pathways. For diagnostic purposes, minimally invasive approaches should be preferred due to their lesser morbidity. This article illustrates the infracochlear approach to the petrous apex in the case of adiagnostic indication in apatient with an incidental, asymptomatic tumorous lesion of the right petrous apex with bony erosion. After the bone of the floor of the ear canal and the hypotympanum was removed, the carotid artery and the jugular bulb were identified using adiamond burr. The route to the petrous apex is triangled by the cochlea superiorly, the jugular bulb posteriorly, and the carotid artery anteriorly. After opening the petrous apex lesion, biopsies were taken. The defect in the floor of the ear canal and the hypotympanum was reconstructed with cartilage and temporalis fascia. The patient recovered quickly from surgery without vertigo or hearing loss. Histological evaluation showed achondrosarcoma. The patient opted for primary radiation therapy (C12, 63 Gy). The infracochlear approach is minimally invasive and can offer access to the petrous apex with minimal morbidity. The pathway, however, is narrow and deep and bounded by the jugular bulb and the carotid artery. The available space can be estimated from preoperative CT scans and, if possible, with 3D reconstructions. Navigation can additionally enhance safety.

Transcanal endoscopic infracochlear vestibular neurectomy: A pilot cadaveric study

PurposeEffective operative approaches for the treatment of refractory vertigo in Meniere's disease are invasive. Vestibular neurectomy can preserve hearing and has been shown to be effective; however, current approaches require an extensive craniotomy. Transcanal endoscopic approaches to the internal auditory canal (IAC) with cochlear preservation have been recently described and may offer a minimally invasive approach to selectively sectioning the distal vestibular nerves while preserving residual hearing. Materials and methodsThree cadaveric human heads were imaged using high resolution computed tomography (CT). Anatomic analysis of preoperative CT scans showed adequate diameters (>3 mm) of the infracochlear surgical corridor for access to the IAC. A transcanal endoscopic approach was attempted to section the vestibular nerve. Post-operative CT scans were assessed to define the operative tract, determine cochlear preservation and assess cochlear and facial nerve preservation. ResultsTranscanal endoscopic approach was successfully performed (n = 3) using 3 mm-diameter, 14 cm-length 0°, 30°, and 45° endoscopes and microsurgical drills. In all cases the tympanomeatal flap and ossicular chain remained intact. Internal auditory canalotomy was performed using angled instruments and confirmed in real time via lateral skull base navigation. The vestibular nerves were readily identified and sectioned with preservation of the facial and cochlear nerves. Post-procedure CT showed no violation of the cochlea. ConclusionA transcanal, infracochlear approach to the IAC may permit a minimally invasive approach to distal vestibular neurectomy in cadavers with appropriate anatomy.

Quantitative Analysis of Surgical Freedom and Area of Exposure in Minimal-Invasive Transcanal Approaches to the Lateral Skull Base.

We aim to provide objective data regarding the area of exposure (AOE) and the surgical freedom (SF) offered by the transcanal approaches to the lateral skull base. Minimal-invasive transcanal lateral skull base procedures have been recently developed and their clinical feasibility demonstrated. The reduced access size requires careful analysis and selection of suitable cases, qualifying for a minimal-invasive approach. We performed the mentioned approaches in standardized dissection using human whole heads. Surgical freedom is defined as the degree of movement liberty of the surgical instrument at predefined landmarks. We assessed SF at anatomical landmarks throughout the lateral skull base. Moreover, we measured the AOE, defined as the surface on the lateral skull base reached by every approach. We performed a total of 48 dissections under stereotactic image guidance in a total of 12 sides. The mean SF was assessed for the inferior petrous apex 602 mm, for the geniculate ganglion 1,916 mm, and for the fundus of internal auditory canal 1,337 mm. The AOE was measured for the infracochlear approach 55 mm, suprageniculate approach 67 mm, transpromontorial approach 11 mm, and for the expanded transpromontorial approach 93 mm at the fundus and 108 mm at the porus of the internal auditory canal. This study provides a quantitative description of minimal-invasive transcanal approaches to the lateral skull base. The AOE offered by the expanded transcanal transpromontorial approach is inferior but comparable to the reported AOE of transmastoidal approaches. The reported objective measurements may provide important information for future preoperative planning and patient counseling.

Quantitative imaging analysis of transcanal endoscopic Infracochlear approach to the internal auditory canal

PurposeA transcanal endoscopic infracochlear surgical approach to the internal auditory canal (IAC) in a human temporal bone model has previously been described. However, the proportion of patients with favorable anatomy for this novel surgical technique remains unknown. Herein, we perform a quantitative analysis of the transcanal endoscopic infracochlear corridor to the IAC based on computed tomography. Materials and methodsHigh resolution computed tomography scans of adult temporal bones were measured to determine the accessibility of the IAC when using an endoscopic transcanal, cochlear-sparing surgical corridor. ResultsThis approach to the IAC was feasible in 92% (35 of 38) specimens based on a minimum distance of 3mm between the basilar turn of the cochlear and the great vessels (jugular bulb and carotid artery). ConclusionsInfracochlear access to the IAC is feasible in the majority of adult temporal bones and has implications for future hearing preservation drug delivery approaches to the IAC.

Endoscopic Transcanal Retrocochlear Approach to the Internal Auditory Canal with Cochlear Preservation: Pilot Cadaveric Study.

Contemporary operative approaches to the internal auditory canal (IAC) require the creation of large surgical portals for visualization with associated morbidity, including hearing loss, vestibular dysfunction, facial nerve injury, and skull base defects that increase the risk of cerebrospinal fluid leak. Transcanal approaches to the IAC have been possible only via a transcochlear technique. To preserve cochlear function, we describe a novel endoscopic transcanal infracochlear approach to the IAC in cadaveric temporal bones. Navigation fiducials were secured on fresh cadaveric heads, and real-time computed tomography imaging was used for surgical guidance. With a combination of curved instruments and rigid angled endoscopy, a transcanal hypotympanotomy and subcochlear tunnel were created with superior extension to access the IAC. Postprocedure imaging and temporal bone dissection confirmed access to the IAC without injury to the cochlea or neighboring neurovascular structures.

Combined Lateral Microscopic/Endoscopic Approaches to Petrous Apex Lesions

Surgical treatment of lesions involving the temporal bone, petrous apex, or internal auditory canal is usually performed using the classical microscopic approach that necessitates wide external incisions and soft tissue dissection. At present, the main application of endoscopic surgery is in the surgical treatment of middle ear cholesteatoma, but with the natural evolution of the technique, there will be an increasing number of applications in lateral skull base surgery. This study aimed to describe the pilot clinical experiences of our institution with combined microscopic/endoscopic-assisted approaches to the lateral skull base. A retrospective chart review was performed on patients undergoing an operation between July 2005 and September 2011 for lateral skull base pathology using the endoscope-assisted technique. Nine patients (7 female, 2 male; mean age = 57.4 years) were reviewed and included in the present study. In all cases, the petrous apex lesion of each patient was unilateral: 6 cases had cholesteatoma of the petrous bone; 2 cases had cholesterinic granuloma of the petrous apex; and 1 case had a low-grade chondrosarcoma of the petrous apex. Overall, after a mean follow-up of 30.7 months, no residual disease has been found in our series up to the present time in the cholesteatoma group. In the cholesterinic granuloma group, only a partial success was obtained in the patient who underwent the infracochlear approach, since the most medial part of the pathology was not accessed and still persisted at neuroradiologic examinations made postoperatively. In our case series, lateral combined microscopic/endoscopic procedures have proved to be effective in the treatment of petrous apex lesions, allowing less destructive approaches compared to exclusive microscopic procedures.

Usefulness of Image Guidance in the Surgical Treatment of Petrous Apex Cholesterol Granuloma

The petrous apex is a pyramid-shaped structure, located medial to the inner ear and the intrapetrous segment of the internal carotid artery. Lesions of the petrous apex can be surgically treated through different surgical routes. Because of the important neurovascular structures located inside the temporal bone, anatomical 3D knowledge is paramount. For this reason, image-guided surgery could represent a useful tool. We report the case of a young woman who came to our observation for a trigeminal neuralgia due to a petrous apex cholesterol granuloma. The lesion was treated through the placement of a drainage tube via an infracochlear approach, with the aid of neuronavigation and intraoperative MRI. Preoperative CT scan images and intraoperative MRI images were fused for surgical planning. The accuracy of the neuronavigation system has proved to be good, and the safety of the procedure was enhanced. Therefore, neuronavigation and intraoperative MRI, though not available in all neurootological centres, should be considered useful tools in these challenging procedures.

Petrous Apex Cholesterol Granulomas: Endonasal versus Infracochlear Approach

Objectives: This study aims to investigate and compare the surgical anatomy of two different routes to access and drain petrous apex (PA) cholesterol granulomas: the expanded endonasal approach (EEA) and the transcanal infracochlear approach (TICA).

Petrous apex cholesterol granulomas: Endonasal versus infracochlear approach

The aim of this study was to investigate and compare the surgical anatomy of two different routes to access and drain petrous apex (PA) cholesterol granulomas: the expanded endonasal approach (EEA) and the transcanal infracochlear approach (TICA). Anatomic and radiologic study. The EEA and TICA to the PA were performed in 11 anatomic specimens with the assistance of imaging guidance. The PA was categorized into three zones: superior PA, anterior-inferior PA, and posterior-inferior PA. The maximum drainage window achieved by each approach was calculated using the imaging studies of each anatomic specimen. The EEA was able to reach superior PA and anterior-inferior PA in all specimens and posterior-inferior PA in 90%. The TICA did not provide access to superior PA in any case. The TICA was suitable to reach anterior-inferior PA in 80% of specimens and posterior-inferior PA in 60%. Based on the radiologic study, the EEA provided a drainage window three times larger than the TICA. The transnasal approach provides reliable access to the PA when combined with internal carotid artery exposure and allows for large drainage window. The transcanal approach is less versatile and more limited than the transnasal approach but provides access to the most posterior and inferior portion of the PA without Eustachian tube transection. Here we propose a new surgical classification that may help to decide the most suitable approach to the PA according to the location and extension of the lesion.

Petrous Apex Cholesterol Granulomas: Endonasal vs. Infracochlear Approach

Objectives: This study aims to investigate and compare the surgical anatomy of two different routes to access and drain petrous apex (PA) cholesterol granulomas: the expanded endonasal approach (EEA) and the transcanal infracochlear approach (TICA).

Double‐barrel stenting in infracochlear approach for drainage of petroux apex cholesterol granulomas

Double‐barrel stenting in infracochlear approach for drainage of petroux apex cholesterol granulomas

Radiographic Anatomy of the Infracochlear Approach to the Petrous Apex for Computer-Assisted Surgery

1) To define the surgical anatomy and dimensions of the infracochlear approach to the petrous apex through the use of high-resolution computed tomography and 2) use of digitized images of cadaveric temporal bones for computer simulation of infracochlear access using the Ohio Supercomputer Center/Ohio State University temporal bone simulator. The petrous apex is a surgically challenging area to access. Many routes have been described and used successfully in clinical practice. However, these routes have not been defined with the aim of application in computer-assisted surgery. The infracochlear approach, due to its access via a transcanal route, affords the opportunity for its potential application in minimally invasive computer-assisted surgery. High-resolution computed tomographic scans were performed on 102 cadaveric skulls (204 temporal bones). Standard measurements were taken using an open-source picture archiving and communication system software of the maximum height, width, and depth of the infracochlear approach. In addition, the maximum diameter of a circular fenestration that could be created in the infracochlear space without breaching the basal turn of the cochlea, internal carotid artery, or the jugular bulb was used to simulate a drill path. In addition, 5 temporal bone specimens (3 left, 2 right) underwent high-resolution computed tomography, with the digitized images being used to create simulated temporal bones for infracochlear surgical access; the transcanal infracochlear approach was then performed by the same surgeon on the cadaveric bone. The mean height, width, and depth of the infracochlear space in temporal bones with nonpneumatized petrous apices were 7.2 +/- 0.4, 9.4 +/- 0.8, and 17.5 +/- 1.0 mm, respectively. Corresponding dimensions in pneumatized petrous apices were 7.6 +/- 0.4, 10.1 +/- 1.1, and 18.6 +/- 0.8 mm, respectively. The mean diameter of the circular fenestra in the nonpneumatized petrous apices was 5.1 +/- 0.4 compared with 5.7 +/- 0.6 mm in pneumatized petrous pieces. This was statistically significant (unpaired t test; p value = 0.04). The time to perform a simulated infracochlear approach to the petrous apex ranged from 3.1 to 12.6 minutes (mean, 6.1 minutes). The time to perform the same approach on the cadaveric bone ranged from 4.32 to 14.1 minutes (mean, 9.3 minutes). Temporal bones with pneumatized petrous apices have an overall larger infracochlear space. The mean diameter of a circular infracochlear path that would avoid damage to vital structures was sufficiently large in both pneumatized and nonpneumatized petrous apices to have a potential application as a safe approach in computer-assisted surgery. Such an application is feasible with mating of a robotic system with computed tomographic- or magnetic resonance imaging-guided imagery, which is the next phase of this study.