A 48-year-old man with a history of cholesteatoma presented for hearing rehabilitation after a multi-year history of hearing loss. He had two prior resections of a left-sided cholesteatoma in 2008. He denied having otorrhea, aural fullness, facial nerve symptoms, or any other associated symptoms or modifying factors. His physical exam showed a normal external auditory canal on the right and copious debris in the ear canal on the left with a small canal wall down cavity. After ear cleaning, some impacted debris was found superiorly by the tympanic membrane. His audiogram also showed a severe mixed hearing loss on the left and normal hearing on the right (Fig. 1).
Diagnosis: Recurrent Cholesteatoma and Tegmen Defect
Conductive hearing loss years after a temporal bone surgery for chronic otitis media can occur due to various causes. The primary cause of chronic otitis media or cholesteatoma is Eustachian tube dysfunction, which unfortunately is not cured after surgery. Therefore, the patient may continue to develop retraction, middle ear inflammation, etc. Also, a previous prosthesis can get displaced or extrude through the tympanic membrane due to the forces created by the retracting tympanic membrane. Other causes include new bone formation, which occurs as a result of inflammation or surgical trauma and leads to conductive hearing loss, middle ear scarring, ossicular destruction from cholesteatoma or granulation, and dehiscence of the horizontal canal, facial nerve, or dura, which can be in contact with the ossicles.
In the case of this patient, we highly suspected that a recurrent cholesteatoma caused his hearing loss due to the impacted debris superiorly. Chronic ear disease is usually evaluated using high-resolution computed tomography (HRCT) imaging, which provides detailed information on the size and location of something. However, distinguishing between cholesteatomas, mucosal inflammation, canal debris, fluid, and granulation tissue caused by inflammation or other neoplasms is difficult. If suspicion is high for cholesteatoma, a combination of HRCT and diffusion-weighted magnetic resonance imaging (MRI) can reveal complementary information about the types of tissue in the image. On diffusion-weighted MRIs, a cholesteatoma can be differentiated from granulation tissue by its high signal intensity caused by a high keratin content. This patient's HRCT scan showed a potentially large area of cholesteatoma (Figs. 2, 3, 4, 5), but when an MRI was also obtained, the actual area of cholesteatoma was found to be much smaller (Fig. 6; left upper image).
Imaging should be obtained when there is suspicion for cholesteatoma or when surgical treatment is planned. Many patients go to a new medical practice without providing their medical records, including prior operative reports. When presented with a patient who reports a prior otologic surgery but doesn't provide any operative report, clinicians should consider the possibility of an occult cholesteatoma as a cause of the auditory symptoms, even if the patient has no history of cholesteatoma, since iatrogenic (caused by the surgery) cholesteatoma rarely occurs. Imaging may also be obtained after surgery to determine if any of the mass remains and if another procedure is necessary. T2-weighted images can show if the tissue has high water content, which would appear brighter than the brain (Fig. 6; upper right). Using axial (echoplanar) diffusion-weighted imaging (DWI), cholesteatomas as small as 5 mm can be detected. A nonechoplanar DWI sequence (or HASTE sequence) can differentiate cholesteatomas as small as 3 mm. In this patient, the DWI sequence showed that the soft tissue in the mastoid was most likely a cholesteatoma (Fig. 6). Using the localizer function on the imaging software, one can see the exact location of the finding on the HASTE sequence (upper left) on the other sequences. In this patient, the cholesteatoma was located more posteriorly and superiorly near the brain.
HRCT is useful in presurgical planning to evaluate for any bony erosions, such as in the bony tegmen that separates the brain from the ear. The tegmen is divided into the tegmen mastoideum (above the mastoid) and the tegmen tympani (above the middle ear). On HRCT, this patient was found to have a large tegmen mastoideum defect (Fig. 5). These defects can occur spontaneously or be caused iatrogenically via surgery. If a defect in the dura mater is also present, it can result in cerebrospinal fluid (CSF) leakage and even dehiscence of brain tissue through the tegmen tympani into the middle ear. This is an important consideration for any revision surgery since any trauma to the dura or bone can increase the risk of CSF leakage, otorrhea, and even meningitis or brain abscess.
If a cholesteatoma is seen on imaging, it is important to determine if it is residual or recurrent. A residual cholesteatoma develops when a portion of the cholesteatoma matrix, the live tissue around the cholesteatoma, is left behind after removal of a cholesteatoma. This residual tissue tends to grow into a pearl (ball) of cholesteatoma and gradually becomes larger. A recurrent cholesteatoma is when another retraction pocket develops and a new cholesteatoma forms. Ideally, surgery should help reduce the chance of both of these processes. A residual cholesteatoma is minimized by getting a good visualization during surgery and using endoscopes to look around bony ledges (Ear Nose Throat J. 2012 Dec;91:527-32.) Lasers can be used to destroy residual cholesteatoma (Otol Neurotol. 2015 Jan;36:61-4.). A recurrent cholesteatoma can be prevented by closing off spaces where the tympanic membrane can potentially retract into, such as the pars flaccida region. The closure is best performed using cartilage, which can be obtained from the concha or the tragus.
When reporting results of a cholesteatoma surgery, clinicians may use the term recidivism, which is a combination of residual and recurrent cholesteatomas. The patient was found to have a recurrent cholesteatoma that appeared to have started at the pars flaccida. It was also very small, as seen on the MRI. Had a residual cholesteatoma been present, we would have expected it to be much larger (over 1 cm) since it would have been growing for 12 years. Recurrent cholesteatomas in the middle ear commonly occur in the epitympanic recess and posterior mesotympanum, where the tympanic membrane can retract into. The patient elected to undergo revision surgery for his recurrent cholesteatoma and potential rehabilitation of hearing.
BONUS ONLINE VIDEOS: VISUAL DIAGNOSIS
Read this month's Clinical Consultation case, then watch the accompanying videos from Hamid R. Djalilian, MD, to review the patient's imaging for yourself.
- Video 1. Axial (horizontal) CT of the temporal bones showing abnormalities of the left temporal bone.
- Video 2. Coronal (parallel to face) CT showing the large tegmen defect.
- Video 3. Sagittal (parallel to ear) CT of the temporal bone showing the relationship between the facial nerve and the area in question.
- Video 4. Coronal (parallel to face) HASTE sequence showing the area of the cholesteatoma.
- Video 5. Axial (horizontal) T2 MRI showing the area of the abnormality on the T2 axial sequence.
- Video 6. Coronal (parallel to face) T2 MRI showing the area of abnormality on the T2 coronal sequence and the brain and mastoid relationship.
Watch the patient videos online at thehearingjournal.com.