Cerebellopontine angle arachnoid cyst diagnosis

MRI (magnetic resonance imaging) scan techniques have led to cerebellopontine angle arachnoid cysts being more frequently diagnosed and with a higher degree of certainty. The need for further understanding of their natural history as well as for the development of a management rationale has been highlighted with this increased rate of diagnosis.

In the series of Alaani et al., these lesions have a characteristic location in the posterior-inferior aspect of the CPA below the facial nerve and vestibulocochlear nerves. These cysts did not show a change in size on repeated MRI scans and the patient's symptoms did not progress over the period of follow up ¹⁾.

Both vestibulocochlear nerves (VIII) with normal and symmetrical caliber and morphology are identified, with no evidence of areas of focal thickening that suggest the existence of intra or extracanalicular vestibular schwannoma. The round image up to 21mm in the right cerebellopontine angle follows the fluid signal in all the sequences and displaces the origin of the the facial nerves (VII), and the vestibulocochlear nerves (VIII), anteriorly. Findings are suggestive of a right cerebellopontine angle arachnoid cyst.