Wk 8, Case 5 - Review

Patient History
Mass follow-up. Hypertension, diabetes.

Findings
There is a heterogeneous T2 hyperintense enhancing mass within the left hypoglossal canal with bulk of mass extending into the posterior fossa with mass effect on the left cerebellomedullary and cerebellopontine angle as well as the left brachium pontis. This mass also extends into the left jugular foramen with prominent narrowing of the distal left sigmoid sinus and proximal left internal jugular vein with preservation of flow void similar to prior exam (series 902, images 82-103). This mass measures up to 3.1 cm (transverse) by 2.5 cm (AP) by 3.5 cm (CC) which is similar in size compared to prior MRI upon remeasurement and accounting for technical differences. There is also mass effect on the left posterior lateral fourth ventricle. No obstructive hydrocephalus. Preserved left V4 segment of the vertebral artery. There is a small area of contrast enhancement in the fundus of the left internal auditory canal in the superior portion. It is unclear whether this arises from the facial nerve or the superior vestibular nerve.

No acute infarction on diffusion imaging. No abnormal enhancement of the brain. No acute intracranial hemorrhage or abnormal extra-axial collection. Moderate mucosal thickening within the visualized paranasal sinuses. Clear tympanomastoid air cells.Mild luminal irregularity of the supraclinoid ICA segments, left greater than right, which may be basis of atherosclerotic disease. Otherwise the petrocavernous and supraclinoid ICA segments are within normal limits. The visualized MCA and ACA branches are normal without evidence of stenosis or aneurysm. The ACOM is present. Bilateral posterior communicating arteries are patent. There is a dominant patent left vertebral artery with diminutive right vertebral artery. The visualized cerebellar arteries are patent. The basilar and bilateral posterior cerebral arteries are patent without evidence of stenoses or aneurysm.

Impressions
1. Stable heterogeneously enhancing mass (3.1 x 2.5 x 2.5 cm) within the left hypoglossal canal with extension into the left cerebellomedullary and cerebellopontine angle as well as the left jugular foramen overall similar compared to prior MRI. These findings may reflect a left hypoglossal nerve schwannoma.
2. Enhancement in the fundus of the left internal auditory canal possibly representing an additional small schwannoma measuring 3 mm. This was also evident on prior study from March 9, 2016.