The Role of Obesity in Iatrogenic Encephaloceles of the Temporal Bone

Objective:Acquired encephaloceles of the temporal bone may be traumatic, spontaneous, or from chronic ear disease or previous surgery. Iatrogenic encephaloceles arise in the setting of previous mastoidectomy and traditionally involve both bony dehiscence and dural injury. We aim to classify and analyze the pathogenesis, clinical presentation, and treatment options for patients with iatrogenic tegmen defects and encephaloceles of the temporal bone.Study Design:Retrospective chart review.Setting:Single tertiary academic center.Patients:Subjects with iatrogenic tegmen defects and encephaloceles of the temporal bone were included.Intervention:Patient demographics, history, symptoms, radiographic data, intraoperative findings, management, follow-up, and outcomes were recorded.Outcome Measures:Primary outcome measures included patient characteristics, time from primary otologic surgery to surgical repair, location of the defect, and management strategy including surgical approach, methods, and follow-up.Results:Iatrogenic tegmen injuries or encephaloceles were identified in 18 patients and divided into intentional or unintentional. The latter group presented immediately, early, or late, as determined by intraoperative identification or from delayed symptoms. Eleven patients presented late with previously unrecognized encephaloceles. Compared with patients presenting with incidentally noted tegmen dehiscence during revision mastoidectomy, a significant proportion of patients with late encephaloceles had BMI ≥30kg/m² (p=0.03).Conclusion:The majority of iatrogenic encephaloceles are unintentional, unrecognized, and may present many years after primary surgery. Similar to spontaneous encephaloceles of the temporal bone, obesity is associated with iatrogenic encephaloceles, although the rate of progression and timing is unclear. We recommend primary repair of any unintentional tegmen defect encountered during mastoid surgery, especially in obese patients.