Utility of Magnetic Resonance Imaging in Differentiating Cerebrospinal Fluid Leak from Middle Ear Effusion.

OBJECTIVE: To demonstrate the clinical utility, sensitivity, and specificity of standard magnetic resonance imaging (MRI) sequences in differentiating temporal bone cerebrospinal fluid leaks from all other middle ear effusions. STUDY DESIGN: Retrospective imaging review. SETTING: Academic medical center. SUBJECTS: Patients with cerebrospinal fluid leaks or other middle ear effusions who also underwent MRI. METHODS: Patients were assigned to cerebrospinal fluid leak and other effusion cohorts based on clinical course, findings at surgery/myringotomy, and beta-2 transferrin fluid analysis. Reviewers blinded to the clinical outcome examined T1-weighted, T2-weighted, diffusion-weighted, fluid-attenuated inversion recovery (FLAIR), and 3-dimensional (3D) acquired T2-weighted MRI sequences. For each sequence, fluid imaged in the temporal bone was graded as either similar or dissimilar in signal intensity to cerebrospinal fluid in the adjacent subarachnoid space. Signal similarity was interpreted as being diagnostic of a leak. Test characteristics in predicting the presence of a leak were calculated for each series. RESULTS: Eighty patients met criteria (41 leaks, 39 other effusions). The 3D T2 series was 76% sensitive and 100% specific in diagnosing a leak, and FLAIR was 44% sensitive and 100% specific. The T1-weighted (73% sensitive, 69% specific), T2-weighted (98% sensitive, 5.1% specific), and diffusion-weighted (63% sensitive, 66% specific) series were less useful. CONCLUSIONS: MRI, with attention to 3D T2 and FLAIR series, is a noninvasive and highly specific test for diagnosing cerebrospinal fluid leak in the setting of an indeterminate middle ear effusion.

Masticator Space Foreign Body in a Child Presenting With Otorrhea and Granulation Tissue of the External Auditory Canal.

OBJECTIVE: We report an unusual case of masticator space foreign body in a patient presenting with otorrhea and granulation tissue within the external auditory canal (EAC). METHODS: Case report. RESULTS: A 16-month-old male presented with fever, unilateral otorrhea, facial swelling, leukocytosis, and granulation tissue within the EAC that failed to respond to conventional medical treatment. Computed tomography scan showed EAC and middle ear opacification and soft tissue swelling involving the masticator space. Given concerns for malignancy, biopsies of tissue within the EAC and of a newly detected right buccal mass were performed, revealing granulation tissue. Concern persisted for neoplasm, however, and magnetic resonance imaging was obtained, showing a masticator space foreign body and possible osteomyelitis of the mandible and pterygoid plates. The patient underwent urgent operative removal of a 3 cm crayon fragment from the masticator space and debridement of granulation tissue arising from a small defect at the inferior medial cartilaginous EAC. He likely sustained foreign body injury several weeks earlier upon falling from standing height while biting a crayon. Postoperatively, he was observed in hospital on intravenous antibiotics and improved significantly. He has since fully recovered. CONCLUSION: Masticator space foreign bodies may present with erosion and granulation tissue of the EAC.