Imaging of the Mastoid, Middle Ear, and Internal Auditory Canal After Surgery: What Every Radiologist Should Know

Imaging of the Postoperative Temporal Bone

Evaluation of the postoperative temporal bone can be difficult given the complex anatomy of this region and the myriad surgical approaches for management of a variety of conditions. This article provides an understanding of common postsurgical changes of the temporal bone and their typical imaging appearances. Ultimately, greater radiologist knowledge of postoperative temporal bone imaging findings will help to serve patients and referring clinicians with prompt diagnosis and recognition of expected postintervention changes compared with postoperative complications and/or disease recurrence.

Radiological evaluation of the postsurgical middle ear

OBJECTIVE

The radiological evaluation of the postsurgical middle ear is complex due to the intricate anatomy of this region and the wide variety of procedures and materials used iin middle ear surgery. Knowledge of these factors will enable normal postsurgical changes to be differentiated from complications. This article describes the most common surgical procedures in the middle ear, their indications, and the normal radiological appearance after these procedures. It reviews the most common causes of failure in stapes surgery, in surgery for chronic otitis media, and in surgery for cholesteatoma, suggesting the best imaging method to assess the middle ear in each case.

CONCLUSION

Computed tomography enables the evaluation of prostheses and the aeration of the cavities, whereas magnetic resonance imaging makes it possible to characterize the possible occupation of the cavities and is the technique of choice for the follow-up of closed mastoidectomy for cholesteatomas.

FDA MAUDE database analysis of titanium middle ear prosthesis

Purpose

Partial ossicular replacement (PORP) and total ossicular replacement prostheses (TORP) are used to restore ossicular chain function. Despite favorable auditory outcomes, these interventions have associated risks and complications. This study examines the FDA MAUDE database for ossicular chain prosthesis adverse events to highlight complications, interventions, and root cause analysis (RCA) findings.

Materials and methods

The MAUDE database was searched for Medical Device Reports (MDRs) relating to PORPs and TORPs from 2010 to 2020. MDR event descriptions were reviewed, and adverse events were identified as a device issue, patient issue, and/or packaging issue that occurred intraoperatively or postoperatively.

Results

Our search identified 70 MDRs which included 110 reported adverse events. Events consisted of 63 device issues, often due to device breaks and displacements, 39 patient issues, including common complaints of hearing loss and erosion, and 8 packaging issues. When comparing PORPs and TORPs, TORPs had more reported device issues whereas PORPs had more packaging issues. Intraoperative device issues were commonly resolved by completing the procedure with a backup device and most postoperative device issues required additional surgery. For devices returned to the manufacturer, RCA determined that most breaks were caused by modification and/or mishandling or that the product met specifications with an undetermined cause for the break.

Conclusion

Device issues were the most common adverse events and frequently required subsequent intervention. Displacement occurred more often with TORPs and was associated with changes in hearing or erosion. The findings of this study are purely descriptive and may not have direct clinical relevance.

Radiological evaluation of the postsurgical middle ear

OBJECTIVE

The radiological evaluation of the postsurgical middle ear is complex due to the intricate anatomy of this region and the wide variety of procedures and materials used iin middle ear surgery. Knowledge of these factors will enable normal postsurgical changes to be differentiated from complications. This article describes the most common surgical procedures in the middle ear, their indications, and the normal radiological appearance after these procedures. It reviews the most common causes of failure in stapes surgery, in surgery for chronic otitis media, and in surgery for cholesteatoma, suggesting the best imaging method to assess the middle ear in each case.

CONCLUSION

Computed tomography enables the evaluation of prostheses and the aeration of the cavities, whereas magnetic resonance imaging makes it possible to characterize the possible occupation of the cavities and is the technique of choice for the follow-up of closed mastoidectomy for cholesteatomas.

Postoperative Imaging of the Temporal Bone

The anatomy of the temporal bone is complex, and postoperative imaging evaluation of this bone can be challenging. Surgical approaches to the temporal bone can be categorized didactically into tympanoplasty and ossicular reconstruction, mastoidectomy, and approaches to the cerebellopontine angle and internal auditory canal (IAC). In clinical practice, different approaches can be combined for greater surgical exposure. Postoperative imaging may be required for follow-up of neoplastic lesions and to evaluate unexpected outcomes or complications of surgery. CT is the preferred modality for assessing the continuity of the reconstructed conductive mechanism, from the tympanic membrane to the oval window, with use of grafts or prostheses. It is also used to evaluate aeration of the tympanic and mastoid surgical cavities, as well as the integrity of the labyrinth, ossicular chain, and tegmen. MRI is excellent for evaluation of soft tissue. Use of a contrast-enhanced fat-suppressed MRI sequence is optimal for follow-up after IAC procedures. Non-echo-planar diffusion-weighted imaging is optimal for detection of residual or recurrent cholesteatoma. The expected imaging findings and complications of the most commonly performed surgeries involving the temporal bone are summarized in this review. Online supplemental material is available for this article. ^©RSNA, 2021.

Beyond Tympanomastoidectomy: A Review of Less Common Postoperative Temporal Bone CT Findings

Postoperative temporal bone imaging after surgical procedures such as ossiculoplasty, tympanomastoidectomy, cochlear implantation, and vestibular schwannoma resection is often encountered in clinical neuroradiology practice. Less common otologic procedures can present diagnostic dilemmas, particularly if access to prior operative reports is not possible. Lack of familiarity with the less common surgical procedures and expected postoperative changes may render radiologic interpretation challenging. This review illustrates key imaging findings after surgery for Ménière disease, superior semicircular canal dehiscence, temporal encephalocele repairs, internal auditory canal decompression, active middle ear implants, jugular bulb and sigmoid sinus dehiscence repair, and petrous apicectomy.

CT Findings in the External Auditory Canal after Transcanal Surgery

BACKGROUND AND PURPOSE

Middle ear surgery is often performed through the external auditory canal, and the CT appearance of the external auditory canal after transcanal middle ear surgery can mimic erosive pathology such as carcinoma, external auditory canal cholesteatoma, or necrotizing external otitis. We reviewed the CT findings in a group of patients following transcanal surgery to highlight this potential pitfall in interpretation.

MATERIALS AND METHODS

Twenty-seven temporal bones in 25 patients with a history of a transcanal approach to the middle ear and available postoperative CT imaging were identified. Images were assessed for changes along or involving the walls of the external auditory canal, including widening, irregularity, bony defects, and soft tissue opacification.

RESULTS

Osseous changes along the floor of the external auditory canal were demonstrated in 25 of 27 (92.6%) temporal bone CT scans. Similar changes were present in the superior and anterior walls of the external auditory canal in 21 and 18 temporal bones, respectively. The anterior wall was the most common site for complete bony defects (10 of 27 temporal bones). The posterior wall was the least often involved, with osseous changes in 15 of 27 temporal bones and bony defects in 3 cases. Soft tissue thickening was seen most commonly along the floor. No patient was found to have a superimposed pathologic process of the external auditory canal.

CONCLUSIONS

CT findings in the external auditory canal after transcanal surgery include thinning, irregularity and/or flattening of the bone, soft tissue thickening, and bony wall defects. Although these changes may be subtle, they may mimic pathology and should be included in the differential diagnosis of osseous abnormality of the external auditory canal.

Postmastoidectomy effusion measurement using a delay-line ultrasound transducer: cadaver experiments

Mastoidectomy is a surgical procedure for removing mastoid air cells and has been used widely to establish drainage and cleaning infections from the mastoid bone. Computed tomography (CT) and magnetic resonance imaging (MRI) are the primary instruments used to clinically detect mastoid effusion following surgery. This study examines the feasibility of ultrasonography to detect postsurgical mastoid effusion. In vitro ultrasound measurements were conducted on 10 cadavers. For each sample, mastoidectomy was performed, and saline and whole blood samples were injected into the surgical mastoid cavity to simulate different effusion properties. A 2.25-MHz delay-line ultrasound transducer was used to obtain ultrasound backscattered data from the mastoid. The data were used to analyze echo intensity and the backscattered statistics by estimating the scaling and Nakagami parameters of the Nakagami distribution model. The results show that the scaling and Nakagami parameters can successfully detect mastoid effusion. Specifically, the Nakagami parameter is capable of characterizing the mastoid effusion properties. This indicates that ultrasound measurement based on a combination of delay-line transducer and Nakagami parameter estimation is a potential real-time diagnostic tool for evaluating mastoid effusion following mastoidectomy without radiation exposure.