Skull Base, Petrous Apex, Infection Treatment & Management
- Author: Andrea H Yeung, MD; Chief Editor: Arlen D Meyers, MD, MBA more...
In the absence of a severe life-threatening complication or chronic ear disease, the first line of therapy includes intravenous antibiotics for the treatment of the underlying infection. Antibiotics should be directed at the offending organism, which is typically one of the pseudomonads. In rare cases, tuberculosis has been identified as the cause, usually in individuals younger than 20 years.
If the patient is medically unstable and unable to tolerate general anesthesia, high-dose IV antibiotics may be attempted to eradicate the infection in place of surgery. Underlying sepsis as a result of the infection may be life threatening, and the patient should be stabilized as quickly as possible for anticipated surgical drainage of the infection.
For patients whose symptoms do not respond to appropriate antibiotics (eg, continued fevers, otorrhea, headache) or who develop complications from the infection, including CN deficits, abscess formation, or venous sinus thrombosis, surgical intervention is warranted.
Because of the complicated anatomic relationships involved with the petrous apex, various surgical approaches to petrous apicitis have been developed. No single standard approach to the petrous apex exists, and any of these approaches may be required depending on the clinical presentation.
In most patients, the petrous apex can be drained via a transmastoid approach to the temporal bone. These approaches involve a complete mastoidectomy. In patients with infections within the posterior aspect of the petrous apex, identifying fistulous tracts along the sinodural angle, the subarcuate air cell tract, and air cells inferior to the posterior semicircular canal is often possible. Enlarging these structures provides adequate drainage of the petrous apex.
Infections in the anterior portion of the petrous apex may be open to a hypotympanic-subcochlear approach or via the air cell tract below the posterior semicircular canal and superior to the jugular bulb. Typically, the margins of the exposure include the cochlea superiorly, the carotid artery anteriorly, and the internal jugular vein and bulb posteriorly. These approaches may require removal of the posterior canal wall for adequate exposure. A high or anteriorly placed jugular bulb may render this approach unfeasible.
In either of these cases, some surgeons advocate placing a drain, such as silastic draped from the infected site into the mastoid or hypotympanum, to maintain the patency of the drainage pathway and prevent recurrence of the infection.
A complete petrous apicectomy is reserved for patients who require additional exposure to the anterior petrous apex not afforded by the above routes. This classic procedure was originally described by Ramadier and was popularized by Lempert. The exposure involves removal of the anterior canal wall and condyle of the mandible; exposure of the epitympanum; avulsion of the tensor tympani; opening of the tensor semicanal; and then dissection in the triangle between the carotid artery (posterior), the cochlea (superior), and the middle fossa dura (anterior). This approach can be modified by preserving the anterior canal wall and condyle.
As noted by Chole, dissection between the cochlea and carotid must be avoided when attempting to preserve hearing because of the limited distance between these 2 structures. Infections within the anterior-most portion of the petrous apex, such as an epidural abscess, are probably best drained via a middle fossa approach.
Ogahlai has recently described a circumferential petrosectomy, a technique that removes the maximum amount of infected temporal bone while preserving the integrity of the peripheral auditory pathway and facial nerve. The circumferential petrosectomy removes most of the temporal bone around the external, middle, and inner ear. A combined retrolabyrinthine-apical petrosectomy is performed in conjunction with the fallopian bridge technique using a transmastoid and middle cranial fossa approach. A split temporalis muscle flap is used to bring vascularized tissue to the mastoid, jugular foramen, and petrous apex.
Improved proficiency in sinus endoscopy has led to increased acceptance of a transsphenoidal approach for lesions in this location. The transsphenoid approach to the petrous apex, a surgical procedure described for the first time by Montgomery in 1977. However, the presence of venous sinuses between the petrous apex and sphenoid, such as the cavernous sinus, can make this approach challenging. It can be considered for lesions located in the medial section of the petrous apex abutting and/or prolapsing into the posterior wall of the sphenoid sinus.
Even with surgical drainage, prolonged postoperative antibiotics are usually recommended, typically for 2-3 weeks.
Patients with chronic petrous apicitis may have accompanying osteomyelitis; if so, 3-6 weeks of IV antibiotics may be required.
If a canal wall–down procedure was required for surgical drainage of the apicitis, long-term care of a mastoid bowl cavity is required.
Follow-up visits should include evaluation to ensure the infection is completely eradicated because recurrence may occur if the surgical drainage pathways to the petrous apex become reobstructed.
Obtain a follow-up CT scan or MRI to ensure that the petrous apex is adequately drained. If the patient is asymptomatic, adequate drainage should occur within several months of discharge from the hospital. If the patient is symptomatic, follow-up imaging should occur sooner.
Outcome and Prognosis
Although death was a common outcome of these infections in the preantibiotic era, the use of antibiotics and improved surgical techniques have dramatically improved survival rates in patients with petrous apicitis. Because of the small number of patients who present today, no large series have examined outcomes of patients with petrous apicitis. Furthermore, the widespread availability of antibiotics and improved surgical techniques in use today make comparisons with older series unhelpful.
In a series of 8 patients by Chole and Donald, 7 patients had resolution of their infection, while 1 died of infection. Of these patients, 1 required a reexploration for continued drainage and another had persistent deficits of CN IX-XI. The remainder experienced resolution of their otorrhea and CN deficits.
Another report of 2 patients with Gradenigo syndrome treated with antibiotics and mastoid drainage demonstrated complete recovery of CN VII with treatment in both patients.
Resolution of CN palsies typically occurs over 3-4 weeks when adequately treated. Surgery in combination with antibiotics typically results in a more rapid resolution of CN deficits than antibiotics alone.
Overall, hearing results in patients undergoing surgery for all petrous apex lesions are quite good. In a large series examining hearing results in surgery for primary petrous apex lesions, hearing was preserved in approximately one half of patients, improved in approximately one third, and worsened in 4% (1 patient of 25). Although this group presented with various lesions within the petrous apex, including cholesterol granulomas, cholesteatomas, mucoceles, and eosinophilic granulomas, it is reasonable to believe that hearing results would be comparable, if not better, in patients with apicitis.
Future and Controversies
Although surgery has historically been the mainstay of therapy, some authors are advocating IV antibiotics as a first-line therapy for petrous apicitis. These authors point out the successful treatment of certain brain abscesses with medical therapy alone, as well as some patients with petrositis whose condition resolved over a prolonged period with IV antibiotics alone. However, the authors agree that a poor clinical response to antibiotics is an indication for surgical drainage.
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