Tympanoplasty
Chronic suppurative otitis media (CSOM), which is defined as a series of acute otitis media episodes lasting more than 12 weeks, can disrupt the tympanic membrane (TM), leading to a non-healing perforation. CSOM is the most frequent infectious disease in children around the world. Upper respiratory tract infection, malnourishment, and poor hygiene are all risk factors. Otorrhea that flows into the external ear canal through the TM perforation is a sign of CSOM, as is hearing impairment. The hearing loss is usually a modest conductive loss; however, ossicular chain erosion can develop in some cases, resulting in a more significant audiologic change. Perforations in the tympanic membrane can occur in either the pars tensa or pars flaccida (though the former is more common); the perforation can also be classified as marginal or central, as well as wet or dry (persistent otorrhea or no active otorrhea respectively), based on its location relative to the annulus.
CSOM with cholesteatoma is a variant of CSOM. Cholesteatomas are a prevalent form of the acquired disease that affects the middle ear. They are made up of a sac of squamous epithelium that grows in the attic and can spread beyond the TM, eroding bone and destroying the ossicular chain. Cholesteatoma has comparable signs and symptoms as CSOM, such as foul-smelling otorrhea, hearing impairment, TM perforation, and attic retraction.
Tympanoplasty is a surgical treatment that involves repairing a perforated TM, either with or without ossiculoplasty, with the goal of preventing reinfection and restoring hearing function. The most prevalent indication is CSOM; big invasive cholesteatomas may necessitate mastoidectomy and TM reconstruction. The history of tympanoplasty dates back to the 1950s when Wullstein and Zollner pioneered the technique of reconstructing the perforated TM and restoring the middle ears' sound transmission mechanism with overlay grafts. Surgical techniques of tympanoplasty have evolved since then.
Related Anatomy and Physiology
The tympanic cavity, commonly known as the middle ear cleft, is located within the petrous temporal bone. The innermost layer of the TM, the Eustachian tube opening, and the ossicular chain (malleus, incus, stapes) are all anatomical features of the middle ear. The tympanic antrum and aditus link the middle ear cleft to the mastoid air cells posteriorly, whereas the Eustachian tube links the nasopharynx anteriorly, enabling the middle ear to balance the pressure with the surrounding environment.
The TM makes up the majority of the middle ear cleft's lateral wall. It is made up of three layers: a stratified squamous epithelial outer layer that runs parallel to the external ear canal, a fibrous stratum (lamina propria) middle layer that is the most dominant component and brings stability to the TM, and an inner layer that runs parallel to the middle ears' cuboidal mucosa. Solid collagen fibers run through the fibrous stratum, and their restricted capacity to stretch enables high compliance with minuscule acoustic pressure displacements but resistance to additional stretching at elevated pressures.
Anatomically, the TM is divided into the pars flaccida superior and the pars tensa inferior. The pars flaccida is located anterior and posterior to the malleolar ligaments and is thinner than the pars tensa because it lacks a core fibrous layer. The pars tensa, which covers the area below the malleus' neck, makes up the bulk of the TM. The TM is further divided into four quadrants by two imaginary lines, one running horizontally across the umbo and the other perpendicularly through the malleus handle. The complex spatial relationships between the components of the middle ear are vital for otologic surgeons, and surgery is frequently affected by both the functional and anatomical aspects of the middle ear.
The TM is the vibratory driver of the middle ear apparatus in terms of function. Sound energy, in the form of air pressure waves, is carried from the TM to the fluid inside the inner ear via the ossicular chain, resulting in a liquid wave. The TM and ossicular chains' function is to magnify sound energy and transfer it to the cochlea, which converts mechanical energy into electrical nerve signals.
Tympanoplasty Types
According to the Wullstein classification, there are five forms of tympanoplasty:
- Type I Tympanoplasty. In circumstances where the ossicular chain is normal, repair of a new tympanic membrane is required; the middle ear space is nearly restored to its original size and geometry.
- Type II Tympanoplasty. In circumstances when the malleus is partially eroded, repair of a new tympanic membrane is required; the new tympanic membrane is connected to the original incus with or without the malleus residue.
- Type III Tympanoplasty. In circumstances involving malleus and incus lesions, repair of a new tympanic membrane is required; the new tympanic membrane is attached to the capitulum of the stapes.
- Type IV Tympanoplasty. The procedure entails the creation of a new tympanic membrane and the establishment of an ossicular connection to a moveable stapes footplate with no crura; the new tympanic membrane is connected to the stapes footplate.
- Type V Tympanoplasty. In cases involving a fixed stapedial footplate, repair of a new tympanic membrane and formation of ossicular attachment to the scala vestibuli is required; a fenestra novovalis is also required; this is also known as malleovestibulopexy.
Tympanoplasty Indications
The purpose of tympanoplasty is to rebuild the TM, either with or without ossicular chain restoration, in order to prevent recurrent infections (otorrhea) and restore hearing. The most common indications are CSOM or CSOM with cholesteatoma. Iatrogenic perforation has also been noted in the literature as a reason for tympanoplasty in pediatric patients having ventilation tube insertion for otitis media with effusion. Traumatic TM perforations caused by mechanical stress that do not heal (acute perforations normally heal without therapy in roughly 82% of patients) may require repair.
Tympanoplasty Contraindications
Tympanoplasty contraindications can be classified as relative or absolute. Patient age (extremes of age), a non-functioning Eustachian tube, a dead ear, or consideration of tympanoplasty in the patient's better hearing ear are all relative contraindications. Uncontrolled cholesteatoma, otitis media consequences or complications such as brain abscess, meningitis, or lateral sinus thrombosis, cancer, or patient-specific anesthesia contraindications are all absolute contraindications.
Patient Preparation
A full investigation of middle ear function is carried out prior to operation, and the results can affect both the tympanoplasty technique utilized and the postoperative outcomes.
Any patient with otorrhea and hearing loss should have a thorough history and examination, which should include a focused head and neck assessment as well as an otoscope/microscope evaluation of the ear. This will reveal significant information about the size of the TM hole, its location (as previously noted, it is classified into quadrants), the type of otorrhea ('wet' or 'dry'), and whether active inflammation is present. For a comparative examination of the difference between air and bone conduction thresholds, tuning fork evaluation (Rinne and Weber's), pure tone audiometry (PTA) with speech discrimination, and tympanography should be conducted before and after surgery.
Simple tympanic membrane perforations seldom require imaging, but if they do, computed tomography (CT) is the ideal imaging technique. Computed tomography of the temporal bone is routinely used to plan surgical cholesteatoma management.
Patients undergoing tympanoplasty are increasingly using questionnaires to measure health-related quality of life outcomes in addition to clinical assessments of the middle ear. Physiological symptoms, psychological functioning, functional disability, and influence on day-to-day living and interpersonal interactions are the four dimensions most validated surveys measure. They are not now required as part of the preoperative workup for tympanoplasty, but as psychometric measurement techniques advance, they will likely produce scientifically effective and reliable results in the future.
Patients will give their consent to tympanoplasty prior to surgery. Pain, hemorrhage, infection, graft failure, recurrence, subsequent surgery, progressive hearing loss or deafness, disorientation, and facial nerve damage leading to facial palsy or chorda tympani nerve injury leading to taste abnormalities are all possible side effects. The operation is usually done under general anesthesia, and patients will have the chance to speak with an anesthesiologist before the procedure.
Tympanoplasty Surgery
A postauricular technique is used for the majority of middle ear surgery involving the TM; endaural (via the ear canal) and trans-canal procedures are also used. Each procedure has advantages and disadvantages, and the size of the TM hole, the size of the ear canal, and the doctor's choice are all elements to consider when determining which strategy to use. Trans-canal or endoscopic ear surgery has become more widespread, as in other subspecialties, due to a tendency toward less invasive procedures.
Regardless of the tympanoplasty procedure employed, the same theatrical preparations are performed. Antibiotics are frequently used as a preventative measure (although less so during endoscopic surgery). A head ring is used to keep the patient stable while he or she is lying supine on the operating table. The patient's hair will be removed in the postauricular area if necessary. Local infiltration (lidocaine with adrenaline) is required, as well as local hemostasis. Before beginning the operation, the ear canal is inspected and cleaned as needed, and the TM perforation and ossicles are evaluated under microscopic or endoscopic vision.
Grafts Types
Because autologous grafting material is readily available, biocompatible, and affordable, there is little justification to use synthetic substitutes. Autologous grafts are most typically created from temporal fascia or tragal perichondrium, however, fascia lata, canal skin, and periosteum have also been used in experiments. The decreased morbidity related to harvesting autologous grafts, namely less discomfort and enhanced cosmetic outcomes with no further scarring, is one of the main benefits of employing alloplastic grafts such as acellular dermal material and gelatin sponge. However, the cost of employing these grafts, as well as the threat of infectious disease transmission, usually outweigh the benefits. The majority of otologists choose to use autologous transplants in practice.
Temporalis fascia is more frequently used in practice than cartilage, with success rates of 94 percent to 98 percent in tympanoplasty; however, cartilage and perichondrium can be collected for greater stability by making an incision through the medial aspect of the tragal skin, perichondrium, and cartilage. While cartilage has been noticed to be more productive than temporal fascia in terms of sound conduction due to its tensile strength and resistance to shrinking. Because of the possibility to be mistakenly identified as cholesteatoma postoperatively and its rigid consistency, concerns have been raised about its sound conduction properties.
Microscopic Approach
When tympanoplasty is performed under a microscope, the postauricular and trans-canal approaches are commonly used. In current tympanoplasty, the Lempert endaural method is significantly less common. The surgeon makes a semicircular cut approximately 1 cm dorsal to the auricle skin fold, and the ear is folded anteriorly. This cut is carried down through the Musculo-periosteum, forming a Musculo-periosteal flap that is lifted towards the membranous ear canal, allowing access to the bony ear canal. Till the doctor reaches the tympanomeatal flap incisions, the skin along the posterior portion of the bone canal is raised. The tympanomeatal flap can then be lifted, allowing access to the middle ear. If necessary, an ossiculoplasty can be performed at this time to restore the ossicular chain. With scissors or cup forceps, the TM perforation edge is rejuvenated. To repair the TM, an underlay technique is employed, in which the limbus is undercut, the TM is elevated, and the perforation is filled with a graft medially. The autologous graft should fill both the TM hole and be attached to the ear canal for stability for the best results. When lifting the limbus from its bony sulcus, take care not to damage the chorda tympani in the posterior part.
Endoscopic Approach
Traditional postauricular and endaural techniques for TM perforation repair are more invasive than endoscopic treatment. It can provide doctors a better view of the middle ear structure without having to make any external incisions, which cuts down on operative and recuperation time. When compared to microscopic tympanoplasty, studies have shown equal perforation healing rates and audiologic recovery. Surgical manipulations including one hand are a disadvantage of endoscopic middle ear operation, as is the possibility for heat generation from the endoscopes' light source to injure adjacent structures.
A transcanal technique is used for endoscopic tympanoplasty. As before, the perforation's edges are de-epithelized as needed. The tympanomeatal flap and annulus are lifted, giving access to the middle ear through a cut in the ear canal (endaural, lateral circumferential, or swing door). The malleus is peeled away from the TM, and the ossicular chain is reconstructed if necessary (ossiculoplasty). The graft is inserted lateral to the malleus and medially to the TM remnant. In the middle and outer ear canal, gel foam sponges are introduced. A butterfly cartilage tympanoplasty procedure has lately been published in the literature, which does not involve the raising of a tympanomeatal flap. A graft is put transcranally, medial to the TM, and gel foam sponges are placed around the graft's border once it has reached an appropriate position.
Postoperative Monitoring
Adults and most children can get tympanoplasty as an outpatient operation. A tuning fork should be used to check postoperative hearing in the recovery area. Depending on the surgeon's decision, a pressure dressing should be withdrawn on the first or second postoperative day.
Patients will be able to wash their hair while maintaining a cotton ball with Vaseline in the canal for dry ear precautions, even though the ear must be maintained generally dry. Acetaminophen and/or ibuprofen are commonly used to treat pain. When a post-auricular method is utilized, narcotics like hydrocodone are commonly administered. Oral antibiotics can be administered for 6-7 days, depending on the surgeon's opinion. For hemorrhage or drainage, a cotton ball is changed in the external auditory meatus as appropriate. Postoperatively, ototopical drops are usually given for 9-21 days following surgery and then repeated until the first postoperative appointment. Some providers may delay the initiation of drops by a few days or weeks.
The ear is inspected under a microscope at the first postoperative visit. The remaining antibiotic ointment and lateral canal packing are withdrawn. All packing can be removed about 4 weeks following surgery, and a good assessment of the grafts' healing and neovascularization can be performed. The tympanomeatal flaps' granulation tissue is managed. As the graft heals, the ototopical drops are continued. Postoperative audiometric testing is postponed until the patient has fully recovered (usually 7-12 weeks). Follow-up appointments are planned to confirm complete healing and hearing recovery.
Tympanoplasty Complications
Tympanoplasty has been demonstrated to be successful in approximately 95 percent of patients in studies (in patients undergoing primary tympanoplasty using temporalis fascia graft). However, problems can arise with any procedure. Recurrence (including graft failure), conductive hearing impairment, TM perforation, and intraoperative or postoperative ventilation tube placement are the most common tympanoplasty problems.
Recurrence of TM perforation in 3.8 percent to 4.5 percent of patients (patients with cholesteatoma and high-risk perforations, respectively) and conductive hearing problems mandating revision in 2 percent (high-risk perforations with/without cholesteatoma) to 12 percent of patients were noted in a large case series analyzing over 1000 patients who had cartilage tympanoplasty (patients undergoing TM reconstruction to improve hearing). Aside from the method and graft type, patient comorbidities like diabetes, tobacco, and immunosuppression are important contributing factors that can affect postoperative outcomes.
The facial nerve and chorda tympani are two significant neural structures that traverse the middle ear. The facial nerve originates in the temporal bone and continues superior to the oval window along the posterior side of the tympanic cavity. Due to the considerable training of otologic surgeons doing tympanoplasty, the risk of iatrogenic trauma to the facial nerve is relatively low. During middle ear surgery, the chorda tympani will always be present, and in CSOM with cholesteatoma, it may have to be destroyed in order to achieve complete disease clearance.
Conclusion
A tympanoplasty is a surgical treatment that heals chronic perforations in the tympanic membrane. The remaining tympanic membrane is lifted through a surgical incision behind the ear or through the EAC skin. A graft is then put lateral to the head of the malleus and either medial or lateral to the natural tympanic membrane, most typically postauricular fascia. The EAC is packed with little gelatin sponges to keep the graft in place. If the tympanic membrane hole is caused by infectious causes, tympanoplasty is frequently combined with a mastoidectomy, which eliminates infected tissue from the mastoid air cells and improves aeration of the middle ear space. Approximately 90-97 percent of patients who have a tympanoplasty will have the perforation completely closed with a reduction in the air-bone gap. If the first operation fails to completely cure the perforation, you can try again with the same approach.