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Image Source: Ear
What is a cholesteatoma?
A cholesteatoma is a lesion of the ear, formed by a mass of stratified keratinizing squamous epithelium. Cholesteatoma probably arises from the lateral epithelium of the tympanic membrane, and then grows as a self-perpetuating mass into the middle ear. This may activate local osteoclasts, possibly as a result of infection of the dead epithelium at the center of the lesion, with potentially serious consequences from local tissue destruction.
Cholesteatoma is a non-neoplastic, keratinizing lesion, characterized by the proliferation of epithelium with aberrant micro-architecture into the middle ear and mastoid cavity. The exact pathogenic molecular mechanisms behind the formation and propagation of cholesteatoma remain unclear.
Petrous Bone Cholesteatoma(PBC).
Congenital cholesteatoma and deep ingrowth of an acquired epitympanic cholesteatoma can result in supra-labyrinthine cholesteatoma, i.e. petrous bone cholesteatoma(PBC).
Primary acquired cholesteatoma may develop as an extension to form supra-labyrinthine or infra-labyrinthine cholesteatoma(PBC). A massive labyrinthine cholesteatoma is a diffuse type and involves the entire posterior and anterior labyrinth. It is usually asymptomatic, but slight unsteadiness, facial palsy, and partial or total sensorineural hearing loss may occur.
What are the symptoms?
Patients present with symptoms of recurring and foul-smelling ear discharge; Hearing loss can be progressive conductive or sensorineural. Conductive hearing loss is due to the impaired movement of ossicles, and further damage to the cochlea can cause irreparable sensorineural hearing loss, occasionally complicated by tinnitus.
Destruction of the bone which overlies the semi-circular canals (particularly the horizontal canal) can trigger vertigo or balance dysfunction.
How is it diagnosed?
Early detection makes it possible to implement surgical measures that are less invasive than conventional treatments and can help guard against hearing loss. Otoscopy, including pneumatic otoscopy, can be used to inspect the eardrum.
Otoscopic findings:
Primary acquired:
central perforation with cholesteatoma debris or retraction pocket
with squamous epithelium and debris.
Congenital and secondary acquired:
white or pearly mass behind the intact tympanic membrane
Imaging:
HRCT(High Resolution Computed tomography)is the primary imaging modality employed in this area to determine the extent of the disease and assist in the planning of a surgical approach.
Magnetic Resonance Imaging (MRI) is an alternative tool to detect cholesteatoma. DW-MRI(Diffusion weighted imaging-MRI) is applied in the assessment of postoperative cholesteatomas for identifying recurrent or residual cholesteatoma. MRI is more helpful to distinguish Petrous Bone Cholesteatoma(PBC) from other soft tissue lesions and the sequence of DWI-MRI is the best method to detect residual and recurrence of PBC.
Audiometry:
To assess the degree of hearing loss and to plan for hearing rehabilitation post-surgery.
Medical Management:
The application of antibiotic-steroid drops is required for patients with signs of acute infection (e.g., otorrhea) to reduce the occurrence of inflammation and granulation tissue. If patients are suffering from an advanced infection, oral or systemic antibiotics may be necessary.
However, the medical treatment regimens are unable to provide a complete cure for acquired cholesteatoma; rather, these therapies are used to control preoperative infection or inflammation and to reduce the risk of postoperative complications.
Surgical management:
In children with acquired cholesteatoma deserve special attention, given the more complex features associated with the pediatric form of the disease. For example, the underlying temporal bone of children is characterized by well-pneumatized air cells.
Extensive mastoid pneumatization provides adequate space, which allows the disease to spread, exacerbating the aggressive behavior of pediatric cholesteatoma. Also, the Eustachian tube is not fully
developed in children. Specifically, it is shorter than that of adults; as its opening to the nasopharynx is narrower, and it is positioned more horizontally. Finally, any delay in the diagnosis and/or treatment of cholesteatoma can have profound effects on language development, learning performance, and academic comprehension as a direct result of hearing loss.
Surgical Approaches:
Image Source: Cholesteatoma
Canal Wall Up (CWU) and Canal Wall Down (CWD) Mastoidectomies.
Numerous researchers have investigated different approaches to treat cholesteatoma; However, the primary treatment mode remains surgery.
The main goal of surgery is to control disease, that is, to create a dry, trouble-free, and recurrence-free ear.
Two types of surgical techniques are commonly applied: CWU and CWD mastoidectomies. CWU mastoidectomy necessitates the removal of all mastoid air cells while maintaining the integrity of contours in the ear canal.
CWD mastoidectomy involves removing the bony posterior canal wall to create a common cavity that combines the ear canal and mastoid.
In the CWU procedure, the maintenance of original normal contours, such as those of the external auditory canal can help alleviate the disadvantages of creating a cavity in the CWD procedure, which include a lifelong aural toilet, water exposure limits, caloric stimulation vertigo when cold air or water enters the cavity, prolonged recovery, a cosmetically unpleasing appearance, and difficulties in filling hearing aids.
Surgery remains the cornerstone for the treatment of PBC. Various surgical approaches include translabyrinthine - transcochlear approach, trans-otic approach, infralabyrinthine approach, and infracochlear approach.
Translabyrinthine- transcochlear approaches are aggressive approaches that require the sacrifice of any residual hearing with or without transposition of the facial nerve. The infra-labyrinthine approach and infracochlear approach are hearing preservation surgeries and post-surgery the cavity is closed permanently.
The middle cranial fossa approach, which may allow for hearing preservation, may be performed in patients with good hearing and normal facial nerve function, but requires a craniotomy, affords poor access, and may involve traction on important neurologic structures with potential for injury.
Hearing Interventions:
The secondary role of cholesteatoma surgery is to either improve hearing or restore serviceable hearing whenever possible.
The management of hearing impairment depends on the type of hearing loss and the degree to which hearing can be restored.
For instance, patients with minimal to no hearing loss may not require further hearing interventions. Moreover, hearing aids may be a useful solution for patients with sensorineural hearing loss, and reconstruction of the sound transformation mechanism (i.e., ossicular chain) may be beneficial for patients with conductive hearing loss caused by the destruction of ossicles.
Ossiculoplasty can be achieved through the placement of autologous grafts (e.g., bone or cartilage) or a prosthetic device (e.g., partial or total ossicular replacement prosthesis).
In the infra-labyrinthine approach and infra-cochlear approach, hearing rehabilitation can be done using various implants such as bone anchoring hearing implants and cochlear implantation.