Facial nerve and chorda tympani schwannomas: Case series, and advantages of using non-rigid registration of post-enhanced 3D-T1 Turbo Field Echo and CT images (TURFECT) in their diagnosis and surgical treatment.

OBJECTIVE

Facial nerve schwannomas (FNSs) and chorda tympani schwannomas are very rare. Diagnosis of these tumors is sometimes difficult, and treatment consensus has not yet been reached. We report here a series of cases of FNS and chorda tympani schwannoma and highlight the usefulness of our newly developed technique of non-rigid registration of post-enhanced 3D-T1 Turbo Field Echo and CT images (TURFECT) in their diagnosis and treatment.

METHODS

MRI images were adjusted with the corresponding CT images in terms of angle and position in order to index the anatomical structures. The well-enhanced T1-Gd+ lesions of tumors having good blood flow show up as bright red after color mapping.

RESULTS

Between 2014 and 2018, five patients were diagnosed with schwannomas in the temporal bone: three with FNS and two with chorda tympani schwannoma. Gd-enhanced MRI showed only a high-intensity mass, and we could not detect the relationship between tumor-like mass and bone (including the ossicles) by MRI only. In contrast, TURFECT was very useful for diagnosing the precise location, allowing us to decide on an endoscopic surgical plan in some of our cases. An endoscope enabled visualization of the medial wall of the tympanic cavity and the status of the tumors, thus we could successfully perform transcanal endoscopic biopsy and resections.

CONCLUSION

TURFECT can be very useful for diagnosis of FNSs and chorda tympani schwannomas and for deciding surgical treatments such as a transcanal endoscopic approach.