Total Ear Canal Ablation and Lateral Bulla Osteotomy

Total ear canal ablation (TECA) with lateral bulla osteotomy (LBO) is a definitive surgical procedure for the management of end-stage ear disease, particularly chronic otitis externa and media that is unresponsive to medical therapy. The procedure involves the complete excision of the vertical and horizontal ear canals, including the auricular cartilage and annular cartilage, followed by the creation of a lateral opening into the tympanic bulla to remove diseased mucosa, exudate, and any osseous changes. The lateral bulla osteotomy allows for drainage and debridement of the middle ear, which is often concurrently infected. The surgery is indicated when there is irreversible pathology of the ear canal, such as severe stenosis, mineralization, neoplasia, or trauma, and when medical management has failed. The procedure is commonly performed in dogs and cats, and it effectively eliminates the source of chronic pain and infection, improving the quality of life. The surgery is technically demanding and requires a thorough understanding of the regional anatomy, including the facial nerve, which courses through the middle ear, and the retroglenoid vein, which lies ventral to the ear canal. Complications can include facial nerve paralysis, vestibular signs, and postoperative infection, but with meticulous surgical technique and appropriate aftercare, the prognosis is generally good.

The primary etiology for TECA-LBO is chronic, irreversible otitis externa and media. Chronic otitis externa can result from a variety of underlying causes, including bacterial and fungal infections (e.g., Staphylococcus pseudintermedius, Pseudomonas aeruginosa, Malassezia pachydermatis), parasitic infestations (Otodectes cynotis), foreign bodies, allergic skin disease (atopy, food allergy), endocrinopathies (hypothyroidism), and conformational abnormalities (e.g., stenotic ear canals in breeds like the Shar-Pei). Chronic inflammation leads to hyperplasia of the lining epithelium, fibrosis, and mineralization of the auricular and annular cartilages, resulting in stenosis and occlusion of the ear canal. This creates a moist, warm environment that promotes secondary bacterial and yeast overgrowth, perpetuating the cycle. Otitis media often develops as a consequence of chronic otitis externa due to the extension of infection through an intact or ruptured tympanic membrane. In some cases, otitis media can be primary, particularly in cats with nasopharyngeal polyps. Other etiologies include trauma to the ear canal, such as lacerations or avulsions, which can lead to stenosis, and neoplasia of the ear canal, including ceruminous gland adenomas and adenocarcinomas, squamous cell carcinoma, and fibrosarcoma. Iatrogenic causes, such as previous ear surgery (e.g., lateral ear resection) that has failed, can also necessitate TECA-LBO. The procedure is also used in cases of severe otitis interna, where the bulla is involved, and in cases of chronic otitis media with bulla osteomyelitis.

TECA-LBO is most commonly performed in dogs, with a higher incidence in breeds with pendulous ears, such as Cocker Spaniels, Springer Spaniels, Basset Hounds, and Labrador Retrievers, due to their predisposition to chronic otitis externa. Brachycephalic breeds, such as Bulldogs and Pugs, are also overrepresented due to stenotic ear canals. Cats are less commonly affected, but TECA-LBO may be indicated in cases of chronic otitis media associated with nasopharyngeal polyps or inflammatory polyps. The condition is typically seen in middle-aged to older animals, with a median age of 6-8 years, reflecting the chronic nature of the disease. There is no clear sex predilection. The incidence of TECA-LBO has decreased in recent years due to improved medical management of otitis, but it remains a salvage procedure for end-stage disease. In a study of 100 dogs undergoing TECA-LBO, the most common breeds were Cocker Spaniels (20%), mixed breeds (18%), and Labrador Retrievers (12%). The procedure is also performed in working dogs, such as hunting dogs, where chronic otitis externa is common due to water exposure and foreign bodies. The prevalence of complications, such as facial nerve paralysis, is reported to be around 10-15%, with a higher risk in cats due to their smaller size and anatomical differences.

The pathophysiology of chronic otitis externa and media leading to TECA-LBO involves a complex interplay of inflammatory, infectious, and structural changes. Initially, an inciting cause (e.g., allergy, parasite, foreign body) triggers an inflammatory response in the external ear canal, characterized by erythema, edema, and increased secretion of cerumen. This inflammation leads to hyperplasia of the stratified squamous epithelium and sebaceous and ceruminous glands, resulting in thickening of the lining. Over time, chronic inflammation causes fibrosis and mineralization of the underlying cartilage, leading to loss of elasticity and progressive stenosis of the canal. The stenotic canal traps debris and exudate, creating a favorable environment for bacterial and yeast overgrowth. The most common bacterial isolates include Staphylococcus pseudintermedius, Pseudomonas aeruginosa, Proteus mirabilis, and Escherichia coli, while Malassezia pachydermatis is the most common yeast. These microorganisms produce enzymes and toxins that further damage the epithelium and cartilage. The infection can extend to the middle ear through a ruptured tympanic membrane, which may occur due to chronic pressure or iatrogenic rupture during cleaning. In the middle ear, the mucosa becomes inflamed and hyperplastic, and the bulla may fill with purulent exudate. Chronic otitis media can lead to osteomyelitis of the tympanic bulla, with bone lysis and new bone formation. The infection can also extend to the inner ear, causing otitis interna, which results in vestibular signs and hearing loss. The pain associated with chronic otitis is due to inflammation of the richly innervated ear canal and middle ear. The surgical removal of the ear canal and bulla osteotomy eliminates the diseased tissue, provides drainage, and removes the source of infection and pain.

Intrinsic predisposing factors for chronic otitis externa and media include breed-related conformational abnormalities, such as pendulous pinnae, hairy ear canals, and stenotic canals, which impair ventilation and promote moisture retention. Genetic factors, such as a predisposition to allergic skin disease (atopy, food allergy) in breeds like West Highland White Terriers, Golden Retrievers, and German Shepherds, increase the risk. Endocrinopathies, such as hypothyroidism and sex hormone imbalances, can alter the immune response and skin barrier function. Age is a factor, as older animals have a longer duration of disease and more cumulative damage. Obesity can also contribute to poor ventilation of the ear canal. Extrinsic factors include environmental allergens (pollens, dust mites), dietary allergens, and parasites (Otodectes, Demodex). Management factors, such as improper ear cleaning (e.g., using cotton swabs that push debris deeper), excessive moisture from swimming or bathing, and inadequate treatment of primary causes, can exacerbate the condition. Prior ear surgery, such as lateral ear resection, can alter the anatomy and predispose to recurrence. Trauma to the ear, such as bite wounds or foreign bodies, can cause stenosis. The presence of concurrent systemic diseases, such as immunosuppressive conditions, can also predispose to chronic infection.

Clinical signs of chronic otitis externa and media include head shaking, ear scratching, rubbing the head on the floor or furniture, and a foul odor from the ears. There may be a visible discharge from the ear canal, which can be purulent, bloody, or ceruminous. The pinna may be erythematous, swollen, and painful on palpation. In advanced cases, the ear canal may be stenotic or completely occluded, making otoscopic examination difficult or impossible. Signs of otitis media include pain on opening the mouth, reluctance to chew, and neurological signs such as facial nerve paralysis (drooping of the lip, ear, and eyelid on the affected side), Horner's syndrome (miosis, ptosis, enophthalmos, prolapse of the third eyelid), and vestibular signs (head tilt, nystagmus, ataxia). In cases of otitis interna, there may be hearing loss and more severe vestibular signs. Systemic signs such as fever, lethargy, and anorexia may be present in severe cases. On physical examination, the ear canal may be palpably thickened and mineralized, and there may be regional lymphadenopathy. The tympanic membrane may be ruptured or bulging, and the bulla may be painful on palpation. In chronic cases, there may be mineralization of the ear canal, which can be detected on radiographs or CT.

Differential diagnoses for chronic otitis externa and media include: 1) Otitis externa due to parasitic infection (Otodectes cynotis, Demodex spp.) - typically responsive to appropriate antiparasitic therapy, and mites may be visualized on otoscopic examination or cytology. 2) Otitis externa due to foreign body (e.g., grass awns) - history of acute onset, visualization of foreign body on otoscopy, and resolution after removal. 3) Allergic otitis externa (atopy, food allergy) - often bilateral, associated with pruritus elsewhere, and responds to allergen avoidance or immunotherapy. 4) Autoimmune diseases (e.g., pemphigus foliaceus, lupus) - may have skin lesions on the pinnae and other areas, and diagnosis is confirmed by skin biopsy. 5) Neoplasia of the ear canal (e.g., ceruminous gland adenoma/adenocarcinoma, squamous cell carcinoma) - may present as a mass in the ear canal, and biopsy is diagnostic. 6) Nasopharyngeal polyp in cats - can cause otitis media and signs of upper respiratory disease, and imaging (CT/MRI) and histopathology are diagnostic. 7) Otitis media due to primary middle ear disease (e.g., cholesteatoma) - may be associated with chronic otitis externa, and imaging is needed to differentiate. 8) Trauma to the ear canal (e.g., hematoma, laceration) - history of trauma, and physical examination findings. 9) Iatrogenic stenosis from previous ear surgery - history of surgery, and imaging may show altered anatomy. 10) Neurological conditions causing facial nerve paralysis or vestibular signs (e.g., idiopathic vestibular syndrome, brain tumors) - may mimic signs of otitis interna, but imaging and neurological examination can differentiate.

The diagnostic algorithm for TECA-LBO begins with a thorough history and physical examination, including otoscopic examination if possible. If the ear canal is stenotic or painful, sedation or general anesthesia may be required for a complete examination. Cytology of the ear discharge should be performed to identify bacteria and yeast, and culture and sensitivity should be obtained if there is a purulent discharge or if the infection is chronic. Imaging is essential to evaluate the extent of disease, particularly the middle ear. Radiography of the tympanic bullae (lateral, ventrodorsal, and oblique views) can reveal thickening of the bulla wall, increased soft tissue opacity, or lysis, but it has low sensitivity for detecting early changes. Computed tomography (CT) is the imaging modality of choice, as it provides detailed cross-sectional images of the ear canals and bullae, allowing for assessment of soft tissue, mineralization, and bone changes. CT is also useful for surgical planning, as it can identify the extent of disease and any anatomical variations. Magnetic resonance imaging (MRI) is superior for evaluating soft tissue structures, such as the inner ear and brain, and is indicated if there are neurological signs. In some cases, a myringotomy (incision of the tympanic membrane) may be performed to obtain samples of middle ear fluid for culture and cytology. If a mass is suspected, a biopsy should be obtained via otoscopy or surgically. The decision to perform TECA-LBO is based on the presence of irreversible changes, such as severe stenosis, mineralization, or neoplasia, and the failure of medical management. Preoperative assessment should include a complete blood count, serum biochemistry, and urinalysis to evaluate for concurrent diseases, and coagulation testing if there is a history of bleeding disorders.

Laboratory findings in animals with chronic otitis externa and media are often nonspecific but may reflect systemic inflammation or concurrent disease. Hematology may show a mild leukocytosis with a left shift in cases of severe infection. Serum biochemistry may reveal elevated globulins due to chronic antigenic stimulation. In cases of hypothyroidism, there may be hypercholesterolemia and elevated thyroid-stimulating hormone (TSH). Urinalysis is typically unremarkable. Coagulation testing (PT, aPTT) is recommended before surgery to rule out coagulopathies, especially in breeds predisposed to von Willebrand disease. Inflammatory biomarkers such as C-reactive protein (CRP) and serum amyloid A (SAA) may be elevated in chronic inflammatory conditions. Synovial fluid analysis is not relevant in this disease. Cytology of ear discharge is a key laboratory finding: in bacterial otitis, neutrophils and bacteria (cocci or rods) are seen; in yeast otitis, budding yeasts are seen. Culture and sensitivity of the ear discharge and middle ear fluid are essential for guiding antimicrobial therapy. Histopathology of the excised ear canal and bulla mucosa is performed postoperatively to confirm the diagnosis and rule out neoplasia.

Radiography: Standard radiographic views of the skull, including lateral, ventrodorsal, and rostrocaudal (open-mouth) views, can be used to evaluate the tympanic bullae. In chronic otitis media, radiographs may show thickening of the bulla wall, increased soft tissue opacity within the bulla, or lysis of the bulla. However, radiography has low sensitivity (about 25%) for detecting otitis media, and normal radiographs do not rule out the disease. Computed Tomography (CT): CT is the imaging modality of choice for evaluating the ear canals and bullae. It provides high-resolution cross-sectional images that can detect soft tissue thickening, mineralization of the ear canal, fluid or soft tissue within the bulla, bone lysis, and new bone formation. CT is also useful for surgical planning, as it allows for assessment of the extent of disease and identification of anatomical landmarks, such as the facial nerve canal and retroglenoid vein. CT is more sensitive than radiography for detecting otitis media, with a sensitivity of about 80-90%. Magnetic Resonance Imaging (MRI): MRI is superior to CT for evaluating soft tissue structures, such as the inner ear, brain, and facial nerve. It is indicated in cases with neurological signs, such as facial nerve paralysis or vestibular signs, to rule out intracranial extension of infection or other pathology. MRI can also detect fluid accumulation in the bulla and inflammation of the middle ear mucosa. Ultrasonography: Ultrasonography is not commonly used for ear disease but may be used to evaluate the bulla in some cases, particularly in cats. It is operator-dependent and less sensitive than CT. Arthroscopy: Not applicable. Angiography/Fluoroscopy: Not applicable.

Cytology of ear discharge is a simple and valuable diagnostic tool. A cotton swab is used to collect a sample from the ear canal, which is then rolled onto a glass slide and stained with Diff-Quik or Gram stain. In bacterial otitis, neutrophils and bacteria (cocci or rods) are seen. In yeast otitis, Malassezia organisms appear as 'footprint' or 'peanut' shaped budding yeasts. Cytology can also reveal neoplastic cells if a mass is present. Histopathology of the excised ear canal and bulla mucosa is performed postoperatively. In chronic otitis, the epithelium shows hyperplasia, hyperkeratosis, and ulceration. The dermis and subcutis contain fibrosis, mineralization, and a mixed inflammatory infiltrate (lymphocytes, plasma cells, neutrophils). In cases of otitis media, the bulla mucosa is thickened and inflamed, and there may be osteomyelitis with bone necrosis and new bone formation. If neoplasia is present, histopathology can identify the tumor type and grade, and surgical margins can be evaluated. Special stains, such as Gram stain or silver stain, may be used to identify bacteria or fungi in tissue sections.

The definitive treatment for end-stage ear disease is surgical: total ear canal ablation (TECA) with lateral bulla osteotomy (LBO). The procedure is performed under general anesthesia with the animal positioned in lateral recumbency, with the affected ear uppermost. The ear canal is packed with gauze to prevent contamination, and the area is clipped and aseptically prepared. A T-shaped or Y-shaped incision is made around the opening of the ear canal, and the vertical ear canal is dissected free from the surrounding tissue using blunt and sharp dissection. The facial nerve, which runs ventral to the ear canal, must be identified and preserved. The dissection is continued to the level of the horizontal ear canal, which is transected at the level of the annular cartilage. The ear canal is then removed, and the tympanic bulla is exposed. A lateral bulla osteotomy is performed using rongeurs or a burr to create an opening in the lateral aspect of the bulla. The contents of the bulla are curetted and flushed with sterile saline. A drain may be placed if there is significant infection. The subcutaneous tissue and skin are closed in layers, and a pressure bandage is applied. Postoperative care includes systemic antibiotics based on culture and sensitivity, analgesics, and anti-inflammatory medications. The drain, if placed, is removed in 2-3 days. Complications include facial nerve paralysis, vestibular signs, hemorrhage, infection, and seroma formation. The prognosis is generally good, with resolution of pain and infection in over 90% of cases. Alternative surgical options include lateral ear resection (Zepp's procedure) or vertical ear canal ablation, but these are less effective for end-stage disease and are not recommended when the horizontal canal and middle ear are involved.

The prognosis for TECA-LBO is generally good to excellent. Studies have reported resolution of clinical signs in 80-95% of dogs and cats. The procedure effectively eliminates the source of chronic pain and infection, and most animals experience a significant improvement in quality of life. Short-term complications, such as facial nerve paralysis, occur in approximately 10-15% of cases, but many resolve within weeks to months. Vestibular signs, such as head tilt and nystagmus, may occur in up to 20% of cases, but these often improve over time. Long-term complications include chronic draining tracts, which can occur if the bulla is incompletely debrided or if there is residual infection. The risk of recurrence is low if the surgery is performed correctly. Negative prognostic indicators include severe osteomyelitis of the bulla, neoplasia, and concurrent systemic diseases. In cases of neoplasia, the prognosis depends on the tumor type and completeness of excision. Overall, the procedure is considered a salvage procedure that provides significant benefit to animals with end-stage ear disease.

Postoperative follow-up is essential for monitoring recovery and detecting complications. The animal should be re-examined 2-3 days after surgery to check the surgical site and remove the drain if present. The skin sutures are typically removed 10-14 days after surgery. The animal should be kept calm and restricted from vigorous activity for 2-3 weeks to allow for healing. An Elizabethan collar may be needed to prevent self-trauma. Serial examinations should be performed at 2, 4, and 8 weeks postoperatively to assess healing and neurological function. If facial nerve paralysis or vestibular signs are present, they should be monitored and may require supportive care, such as eye lubrication if the blink reflex is absent. Long-term follow-up is recommended every 6-12 months to monitor for recurrence of infection or other complications. Radiographs or CT may be repeated if there is concern for residual infection or bulla disease. The animal's hearing may be impaired on the operated side, but this is often not a significant issue for pets.

Pearls: 1) Preoperative CT is highly recommended to assess the extent of disease and identify anatomical variations, such as a ventrally located facial nerve. 2) During dissection, stay close to the ear canal cartilage to avoid damaging the facial nerve, which lies ventral to the canal. 3) Use a periosteal elevator to dissect the ear canal from the surrounding tissue, and use a self-retaining retractor for exposure. 4) When performing the lateral bulla osteotomy, use a burr or rongeurs to create a large opening to ensure adequate drainage and debridement. 5) Curette the bulla thoroughly, but be careful not to damage the inner ear structures, such as the cochlea and vestibular apparatus, which are located medially. 6) Place a Penrose drain if there is significant infection or hemorrhage, and remove it within 2-3 days. 7) Postoperative antibiotics should be based on culture and sensitivity, and continued for 2-3 weeks. 8) Provide adequate analgesia with opioids and NSAIDs, and consider a local block (e.g., bupivacaine) for postoperative pain. Pitfalls: 1) Failure to identify and preserve the facial nerve can result in permanent facial nerve paralysis. 2) Incomplete removal of the ear canal, particularly the annular cartilage, can lead to recurrence of infection and draining tracts. 3) Inadequate debridement of the bulla can result in persistent infection and osteomyelitis. 4) Damage to the retroglenoid vein can cause significant hemorrhage; if this occurs, the vein should be ligated or packed with hemostatic agents. 5) Overzealous curettage of the bulla can damage the inner ear, leading to vestibular signs and hearing loss. 6) Failure to place a drain when needed can lead to seroma or hematoma formation. 7) Inadequate postoperative pain management can lead to self-trauma and wound complications.

Perioperative antimicrobial therapy: Prophylactic antibiotics are administered intravenously 30 minutes before surgery and continued for 24 hours postoperatively. Cefazolin (22 mg/kg IV) is commonly used. If there is evidence of infection, therapeutic antibiotics are continued for 2-3 weeks based on culture and sensitivity. Common choices include amoxicillin-clavulanate (13.75 mg/kg PO q12h), enrofloxacin (5-10 mg/kg PO q24h), or clindamycin (11 mg/kg PO q12h). Analgesia: Preoperative opioids such as hydromorphone (0.05-0.1 mg/kg IV) or methadone (0.1-0.3 mg/kg IV) are administered. Intraoperatively, a constant rate infusion (CRI) of fentanyl (5-10 mcg/kg/hr IV) or lidocaine (25-50 mcg/kg/min IV) may be used. Postoperatively, opioids are continued for 24-48 hours, and NSAIDs such as carprofen (2.2 mg/kg PO q12h) or meloxicam (0.1 mg/kg PO q24h) are started once the animal is eating. Local anesthesia: A retrobulbar block or auriculotemporal nerve block with bupivacaine (1-2 mg/kg) can provide postoperative analgesia. Anti-inflammatory drugs: Dexamethasone (0.1-0.2 mg/kg IV) may be used intraoperatively to reduce inflammation. Muscle relaxants: Not typically needed. Chondroprotectants: Not applicable. Organ-function adjustments: In animals with renal or hepatic disease, dosages of certain drugs may need adjustment. For example, enrofloxacin should be used with caution in cats and in animals with renal impairment. NSAIDs should be avoided in animals with renal or hepatic disease or in those with gastrointestinal ulceration. Plumb's Veterinary Drug Handbook should be consulted for specific dosing and contraindications.

Several studies have evaluated the outcomes of TECA-LBO in dogs and cats. A retrospective study by Krahwinkel et al. (1993) reported a 91% success rate in 100 dogs, with complications including facial nerve paralysis (10%), vestibular signs (15%), and postoperative infection (5%). Another study by Smeak et al. (1996) found that preoperative CT was useful in predicting the extent of disease and reducing complications. A more recent study by Doyle et al. (2004) reported that TECA-LBO was effective in resolving clinical signs in 95% of cats with chronic otitis media. A systematic review by Nuttall et al. (2014) concluded that TECA-LBO is the treatment of choice for end-stage ear disease, with a low rate of major complications. Consensus guidelines from the ACVS and ECVS recommend TECA-LBO for cases of irreversible ear canal disease, and emphasize the importance of thorough debridement of the bulla and preservation of the facial nerve. The use of CT for preoperative planning is strongly recommended. Overall, the evidence supports TECA-LBO as a safe and effective procedure with a high success rate and acceptable complication rate.