PMC5309254_01
Lesion (white solid arrows) of the right petrous apex as viewed on different axial MRI sequences. (A) T2-weighted imaging shows a slightly heterogeneous lesion with parts isointense to white or gray matter. The dotted arrow shows the internal carotid artery. (B) The lesion is slightly hypointense to brain on T1 VIBE image and demonstrates slight peripheral enhancement following injection of gadolinium contrast. (C) The lesion is hypointense on diffusion trace image.
fneur-08-00048-g001.jpg
PMC5309254_01_fneur-08-00048-g001.jpg
F1
T2-weighted images (Figure 1). There was slight peripheral enhancement. The lesion appeared to abut the internal carotid artery and compress the right sixth nerve at Dorello's canal (Figure 2).
Close-up view (A) sagittal and (B) axial of the region of Dorello's canal. The lesion is seen to enter Dorello's canal (white arrows) and compress the right sixth nerve.
fneur-08-00048-g002.jpg
PMC5309254_01_fneur-08-00048-g002.jpg
F2
T2-weighted images (Figure 1). There was slight peripheral enhancement. The lesion appeared to abut the internal carotid artery and compress the right sixth nerve at Dorello's canal (Figure 2). What might be the reasons for such a remitting and relapsing course of a sixth nerve palsy associated with CG? In our patient, the granuloma was in contact with the internal carotid artery at the skull base (Figure 2).
Axial view of head CTs taken in (A) 2011, (B) 2015, and (C) 2016. A small lesion (arrow) causing mild bony abnormality of right petrous apex is visible on 2011. Both petrous apices are highly pneumatized. The lesion progressively erodes the right petrous apex over 5 years.
fneur-08-00048-g003.jpg
PMC5309254_01_fneur-08-00048-g003.jpg
F3
A careful retrospective review of sequential CT scans from 2011 to 2016 showed a petrous apex lesion in 2011, which increased in size and progressively eroded the right petrous bone over the next 5 years (Figure 3). This conjecture is supported by a visible increase in the size of the patient's CG compared to a scan 6 months previously (Figure 3).
Postoperative MRI images. (A) T2-weighted axial and (B) T1-weighted axial images after injection of gadolinium (B) show a notable regression of the right petrous apex lesion (white arrows). The content of the lesion is still heterogeneous. There is slight peripheral enhancement.
fneur-08-00048-g004.jpg
PMC5309254_01_fneur-08-00048-g004.jpg
F4
The postoperative MRI confirmed the reduction in the size of the cystic formation at the petrous apex (Figure 4).