The Laryngoscope Lippincott Williams & Wilkins, Inc. © 2004 The American Laryngological, Rhinological and Otological Society, Inc. Relationship of Petrous Temporal Bone Pneumatization to the Eustachian Tube Lumen Albert Jen, MD; Pina C. Sanelli, MD; Vishal Banthia, MD; Jonathan D. Victor, MD; Samuel H. Selesnick, MD Objectives/Hypothesis: Objectives were to deter- mine the incidence of petrous apex pneumatization and to define the relationship between a pneumatized petrous temporal bone and the eustachian tube lu- men. Study Design: Retrospective study with institu- tional review board approval including only adult pa- tients. Methods: One hundred head computed tomography (ct) scans and 204 petrous temporal bone CT scans performed at a tertiary teaching hospital were reviewed. The two senior authors (S.H.S., P.C.S.) independently reviewed the petrous temporal bone CT scans for grade of pneumatization. Pneumatized CT scans were then reviewed for the presence of a direct communication with the eustachian tube lu- men. Significance was determined using the  2 test and Pearson correlation of ranks. Results: The inci- dence of peritubal cells opening into the eustachian tube anterior to the tympanic orifice was 92%. Con- clusion: The direct communication of peritubal cells with the bony eustachian tube may play a role in the development of persistent cerebrospinal fluid rhinor- rhea after cerebellopontine angle surgery. Key Words: Eustachian tube, pneumatization, petrous temporal bone, acoustic neuroma, peritubal. Laryngoscope, 114:656 – 660, 2004 INTRODUCTION Acoustic neuroma surgery has evolved significantly since the early 1970s. With the microsurgical techniques used today, surgical management of acoustic neuroma is considered a safe procedure with minimal morbidity. However, despite experience and technology, complica- tions still occur. One complication that has been difficult to manage is postoperative cerebrospinal fluid (CSF) rhi- norrhea. Many methods have been introduced to prevent CSF rhinorrhea during translabyrinthine, suboccipital, and middle cranial fossa surgery for acoustic neuromas, yet these methods are not universally effective. Ulti- mately, the eustachian tube (ET) is the final common pathway for postoperative CSF rhinorrhea. Although the most likely pathway into the ET is through the ET orifice in the middle ear, direct ET communication with petrous apex air cells may exist. Thus, the relationship of the ET lumen with a pneumatized petrous temporal bone may impact the incidence of postoperative CSF rhinorrhea. The purpose of the present study was to define the rela- tionship between a pneumatized petrous temporal bone and the ET lumen. PATIENTS AND METHODS The current retrospective study was performed at a tertiary teaching hospital. Institutional Review Board approval was ob- tained. Only adult patients were included in the study. The computed tomography (CT) examinations were performed on GE Hispeed or Lightspeed scanners (General Electric, Milwaukee, WI). In the first aspect of the study, 100 computed tomography (CT) scans of the head were reviewed to determine the presence of petrous apex pneumatization. The head CT scans were per- formed according to routine departmental protocol using 5.0-mm contiguous axial sections without the intravenous administration of contrast. Standard head CT scans were reviewed, as opposed to petrous temporal bone CT scans, because patients undergoing a temporal bone imaging study were being assessed for disease in the temporal bone, which may be associated with hypopneuma- tization. Because head CT scans were most often obtained to investigate potential intracranial and extracranial disease, this bias was eliminated. The second aspect of the study involved grading petrous apex pneumatization. Retrospective review of 204 petrous tem- poral bone CT scans was performed by the two senior authors (S.H.S., P.C.S.) independently. The CT scans were performed as dedicated petrous temporal bone CT using direct axial and coronal imaging with 1.0-mm collimation. All images acquired during the CT of the temporal bones were reviewed by both of the senior authors who read the scan. If different images had different degrees of pneumatization, the maximum degree of pneumatization was reported. The two senior authors indepen- dently graded the degree of petrous apex pneumatization based From the Departments of Otorhinolaryngology (A.J., V.B., S.H.S.), Ra- diology (P.C.S.), and Neurology (J.D.V.), Weill College of Medicine of Cornell University, New York, New York, U.S.A. Editor’s Note: This Manuscript was accepted for publication October 22, 2003. Send Correspondence to Samuel H. Selesnick, MD, Department of Otorhinolaryngology, Weill College of Medicine of Cornell University, Starr Building, Suite 541, 520 East 70th Street, New York, NY 10021, U.S.A. E-mail: shselen@mail.med.cornell.edu Laryngoscope 114: April 2004 Jen et al.: Petrous Apex Pneumatization 656