Bilateral Gasser's ganglion sarcoidosis: diagnosis, treatment and unsolved questions.

Magnetic resonance imaging is currently the best means for confirming clinical suspicion of neurosarcoidosis as well as being useful in the follow-up of corticosteroid-treated patients. We report the case of a 34 year old male presenting suspected Heerfordt's syndrome with concentric facial hypesthesia. Mediastinal and parotid sarcoidosis was diagnosed and magnetic resonance imaging showed bilateral sarcoid involvement of Gasser's ganglion cisternae (such involvement was not revealed by computed tomography). The patient received corticosteroid therapy, with a clinical and radiological improvement. Magnetic resonance imaging showed disappearance of Gasser's ganglion lesions despite the persistence of mild facial hypesthesia. This case is noteworthy for its extremely rare lesion site. Post-treatment discrepancy between the clinical picture and imaging results is probably due to low MRI resolution threshold. 18-FDG positron emission tomography imaging might perhaps overcome the limits of magnetic resonance imaging.