Cystic Vestibular Schwannoma

Vestibular schwannomas are the most common lesions of the cerebellopontine angle. Cystic vestibular schwannomas are less common and present with different clinical and imaging features. They tend to be larger and have a shorter clinical course prior to symptomatic presentation. Also, due to the possibility of rapid enlargement of the cystic elements, conservative management with follow-up is not recommended.

The rate of postoperative complications may also be different between cystic and solid vestibular schwannomas. The main postoperative complication is damage to the facial nerve near its entrance into the porus acusticus, especially when there are multiple cysts or when the cysts are on the anterior surface of the tumor.

On imaging, cystic vestibular schwannomas can have a single small cyst or multiple intramural cysts of variable size. The intramural cysts may have higher signal intensity than that of cerebrospinal fluid, but may also be isointense to cerebrospinal fluid on both T1- and T2-weighted images. Intramural cysts also demonstrate circumferential enhancement.

The images above reveal a predominantly cystic mass at the left cerebellopontine angle with extension into the porus acusticus (red arrow). There is thin circumferential enhancement with a thin septum with the cystic component. There is a solid component anteriorly that demonstrates homogeneous enhancement. The FLAIR image reveals mild edema within the adjacent cerebellum and middle cerebellar peduncle. No restricted diffusion was seen within the cystic component (not shown).

References

• Benech F, Perez R, Fontanella MM, Morra B, Albera R, Ducati A. Cystic versus solid vestibular schwannomas: a series of 80 grade III-IV patients. Neurosurg Rev. 2005 Jul;28(3):209-13.
• Tali ET, Yuh WT, Nguyen HD, Feng G, Koci TM, Jinkins JR, Robinson RA, Hasso AN. Cystic acoustic schwannomas: MR characteristics. AJNR Am J Neuroradiol. 1993 Sep-Oct;14(5):1241-7.