Excavating Meckel's cave: Cavum-trigeminale-cephaloceles (CTCs)

Background and purpose: Cavum-trigeminale-cephaloceles (CTCs) are rare lesions of Meckel's cave and the petrous apex. Despite distinctive imaging features, they are frequently mistaken for other petrous apex lesions. In contrast to many of these entities, CTCs do when asymptomatic not require any invasive work-up or even surgical excision. Since correct diagnosis has profound impact on clinical decision-making, we report on a series of CTCs with distinct imaging features and their important differential diagnoses. Material and methods: We report a retrospective series of 5 patients with CTCs and the associated imaging features including the absence of diffusion restriction and solid contrast enhancement as well as their size, anatomical location with regard to adjacent structures and the remodeling or erosion of surrounding bony structures. Results: Our series contains the largest CTC that has, to the best of our knowledge, been reported so far. It revealed a deep cervical extension and was initially mistaken for a branchial cleft cyst. Furthermore, we show that CTCs can erode or remodel important structures such as canal's nervi hypoglossi, canalis Vidiani, foramen rotundum, ovate, lacerum and spinosum without causing clinical symptoms. Conclusion: In contrast to previous reports in which asymptomatic CTC did not include critical structures such as the foramina rotundum, ovate, lacerum or spinosum or the hypoglossal or Vidian canal, we show that CTCs can be asymptomatic even when eroding or remodeling such clinically important structures. When extending below the skull base, CTCs are a rare differential diagnosis to cystic cervical lesions such as type II branchial cleft cysts. (C) 2015 Elsevier Masson SAS. All rights reserved.