Inflammatory Pseudotumor of the Temporal Bone Leading to Atypical Superior Semicircular Canal Dehiscence Syndrome: A Novel Case Report

Abstract

Inflammatory pseudotumor of the temporal bone is a benign idiopathic inflammatory process that is rarely encountered in clinical practice. We describe a novel case of a patient who developed superior semicircular canal dehiscence syndrome in the setting of active inflammatory pseudotumor of the temporal bone. One female patient found to have inflammatory pseudotumor of the temporal bone. After treatment with mastoidectomy and steroids, she subsequently developed superior semicircular canal dehiscence syndrome. The patient initially underwent myringotomy and pressure equalization tube placement for a unilateral effusion. Imaging with computed tomography and magnetic resonance imaging revealed a lytic mastoid mass. A complete mastoidectomy was diagnostic for inflammatory pseudotumor and the patient was treated with adjuvant long-term corticosteroids. After this procedure, she was discovered to have new development of symptomatic superior semicircular canal dehiscence syndrome. She eventually underwent a trans-mastoid repair of her superior semicircular canal dehiscence. The patient's clinical course is described with emphasis on the development of superior semicircular canal dehiscence syndrome in the setting of active inflammatory pseudotumor of the temporal bone. The patient's radiographic and clinical history were found to be consistent with inflammatory pseudotumor of the temporal bone. She underwent a therapeutic mastoidectomy with long-term post-operative corticosteroids. During her post-operative course, she developed symptoms of vertigo, hearing loss, and autophony. She was subsequently diagnosed with superior semicircular canal dehiscence and treated with a trans-mastoid repair of the dehiscence. Her symptoms satisfactorily resolved after this surgery. Inflammatory pseudotumor of the temporal bone is a rare benign inflammatory process. We present what is to our knowledge the first description of superior semicircular canal dehiscence syndrome developing in the setting of inflammatory pseudotumor.