Infracochlear Approach Research Articles

Computer-Assisted Morphometric Study of Human Temporal Bones for the Infracochlear Approach

Purpose: The infracochlear approach is one of the useful methods for access to the petrous apex. This approach is limited by the basal turn of the cochlea superiorly and the carotid artery anteriorly. To know the location of the cochlea and the carotid artery, human temporal bones were analyzed spatially by computer graphics.

Management of cholesterol granulomas of the petrous apex based on clinical and radiologic evaluation.

The purpose of this study was to analyze the imaging characteristics of 12 cholesterol granulomas as a function of their clinical symptoms. The results of the different surgical approaches and the management of these lesions are discussed. Retrospective case review. Five tertiary referral centers. Twelve patients managed for a cholesterol granuloma of the petrous apex. All patients were evaluated via computed tomography and magnetic resonance imaging. Eight patients required surgical drainage: through a conservative approach in seven patients (infralabyrinthine, n = 5; infracochlear, n = 2) and a transotic approach in one patient. Clinical and radiologic follow-up without surgery was the mode of treatment for four patients. The mean follow-up period was 18 months for patients who underwent operations and ranged from 6 months to 10 years for patients without operations. Four patterns of clinical symptoms were noted: retrocochlear signs by an involvement of the internal auditory meatus (n = 8), headaches by a traction of the dura (n = 4), serous otitis media by a compression of the eustachian tube (n = 2), and asymptomatic lesions with no involvement of the adjacent structures (n = 2). Hearing and facial functions were preserved in all the cases treated by a noninvasive procedure. No recurrence or complication was reported in the patients who underwent operations. None of the noninvasively treated patients with cholesterol granulomas showed significant enlargement on follow-up imaging. Clinical manifestations of cholesterol granulomas depend on their anatomic location and the involvement of the adjacent structures. Aggressive lesions in patients with residual hearing can be drained via an infralabyrinthine or an infracochlear approach with minimal morbidity. Follow-up must be preferred for patients with nonaggressive lesions. Although magnetic resonance imaging provides a specific diagnosis tool for cholesterol granulomas, computed tomography is essential for an accurate evaluation of the location of the cyst and choice of the surgical procedure.

Surgical management of petrous apex cholesterol granulomas.

To review surgical approaches for drainage of petrous apex cholesterol granulomas, define the criteria for the selection of each approach, and identify factors affecting surgical outcome. Retrospective chart review and follow-up survey questionnaire. Tertiary neurotologic referral center. Thirty-four patients who underwent surgical treatment for symptomatic cholesterol granulomas of the petrous apex, who had a minimum of 3 months of clinical follow-up care and, in some cases, postoperative radiologic follow-up studies. Drainage with or without removal of the cyst lining was achieved through the transcanal infracochlear, transmastoid infralabyrinthine, middle fossa, translabyrinthine, and transotic approaches. Silastic catheters were used to stent drainage sites in some cases. Relief of symptoms, postoperative cranial nerve function, clinical and radiologic recurrence, and need for further surgical intervention were evaluated. Imaging studies were reviewed to determine how anatomic information influenced surgical decisions and outcome. Clinical improvement of symptoms was observed in 28 patients (82%), and recovery of cranial nerve function was observed in 8 of 9 affected individuals. Serviceable hearing was preserved in all but 1 patient. Five patients required revision surgery for recurrent symptoms and lesions. All 5 patients had undergone drainage procedures without the use of stents. The size of the lesion did not influence the surgical outcome. Determination of the appropriate surgical approach to the petrous apex is based on hearing status in the affected ear and on the anatomic relationships between the lesion and the surrounding neurovascular structures. The translabyrinthine approach is useful in nonhearing ears. In hearing individuals, anatomy permitting, the transcanal infracochlear approach with stenting is the preferred approach for drainage of petrous apex cholesterol granulomas.

Periaqueductal Approach to Cholesterol Granulomas of the Petrous Apex

The periaqueductal approach for the drainage of cholesterol granulomas of the petrons apex is described. As with previously reported approaches, the periaqueductal approach takes advantage of the high pneumatization of the temporal bone in this disease. It requires dissection of the supralabyrinthine air cell tract as well as air cells medial to the posterior semicircular canal. This requires a circumferential bony dissection, skeletonization, and preservation of the vestibular aqueduct and the identification of the internal auditory canal. This periaqueductal approach preserves hearing and provides an alternative to the infralabyrinthine and infracochlear approaches when their use is precluded by variations in the temporal bone.

Transcanal infracochlear approach to the petrous apex

Computerized tomography and magnetic resonance imaging have now made it possible to reliably differentiate cholesteatoma from cholesterol granuloma of the petrous apex. The treatment for cholesteatoma is complete surgical excision when possible, whereas cholesterol granuloma needs only adequate drainage for control. A new transcanal infracochlear approach for drainage of cholesterol granuloma involving the anterior petrous apex is described. Absolute measurements from 10 cadaveric temporal bones were obtained to determine the distances between the cochlea, jugular bulb, carotid artery, and facial nerve. In all specimens the petrous apex was entered without invading the cochlea, carotid, or jugular bulb. Advantages of this technique include a more direct route to the petrous apex, dependent drainage, and preservation of the normal hearing mechanism, including the tympanic membrane. Clinical indications for this technique include failure of other treatment approaches and a high jugular bulb obstructing an infralabyrinthine approach. Experience to date shows that patients experience little difficulty from the procedure.