Presentation
Left sided facial weakness, MRI done to look for brain stem and CP angle.
Patient Data
Cisternal and canalicular segments of left facial nerve are not visualized.
A thin linear structure is seen on FIESTA sequence, accompanying the right VIIIth nerve in the cisternal segment, thus, confirming its presence. In the canal, it is seen in the anterosuperior aspect.
Brain parenchyma including brainstem are unremarkable.
The left facial canal is not seen beyond the genu.
The right facial canal is well visualized along its entire length.
Case Discussion
Congenital facial nerve aplasia is a rare cause of facial nerve paralysis. High-resolution 3D balanced steady-state gradient-echo sequences like 3D FIESTA (GE) are the mainstays for visualization of the facial nerve.