Apical petrositis.

We evaluated a 57-year-old woman who developed symptoms consistent with apical petrositis on the right. She had a history of chronic mastoiditis and otitis media. Computed tomography (CT) and magnetic resonance imaging (MRI) clearly demonstrated that she did indeed have apical petrositis (figure).

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The petrous apex of the temporal bone may be pneumatized (filled with mucosa-lined air cells) in 33% of normal individuals and is often asymmetric). (1) Air cells may be found extending from the mastoid, middle ear, and following tracts above and below the cochlea and into the petrous apex. (2) Because the petrous apex contains mucosa-lined air cells, a middle ear infection can lead to obstruction and inflammation of the apex cells. This in turn can lead to various clinical processes, such as the development of a mucocele, cholesterol granuloma, and apical petrositis; on the other hand, petrous apex effusion is sometimes an incidental finding of no clinical significance. (3)

Apical petrositis can be acute or chronic, and it can be the result of an infection of the middle ear to the pneumatized air cells of perilabyrinthine and apex of the temporal bone. (3) Apical petrositis is considered by some to be synonymous with Gradenigo's syndrome. (3) This syndrome occurs as a result of the spread of otitis media to the petrous apex, the trigeminal ganglion, and the VIth cranial nerve in the area of Dorello's canal, and it produces lateral rectus palsy. (4) Classic Gradenigo's syndrome is rarely seen; when the process is severe there may be involvement of other cranial nerves. (4,5)

It is a matter of debate as to whether apical petrositis always occurs in the pncumatized apex because petrositis has also been described in the nonpneumatized apex, probably secondary to a hematogenously spread infection. Petrous apex infection and osteomyelitis may also be a result of coalescent mastoiditis and purulent middle ear infection. (3)

References

(1.) Chole PA. Petrous apicitis: Surgical anatomy. Ann Otol Rhinol Laryngol 1985;94:251-7.

(2.) Curtin HD, Sorn PM. The petrous apex. Otolaryngol Clin North Am 1995;28:473-96.

(3.) Nemzek WR. Swartz JD. Temporal bone: Inflammatory disease. In: Som PM, Curtin HD, eds. Head and Neck Imaging 4th ed. St. Louis: Mosby, 2003:1173-1229.

(4.) Graamans K. Neurological disorders of the head and neck. In: Jones AS, Phillips DE, Hilgers FL, eds. Diseases of the Head and Neck, Nose and Throat. London: Arnold, 1988:616-27.

(5.) Chole RA, Donald PJ. Petrous apicitis. Clinical considerations. Ann Otol Rhinol Laryngol 1983;92:544-51.

From the Department of Radiology, Louisiana State University Health Sciences Center, New Orleans.