Cerebellopontine angle arachnoid cysts in adult patients: what is the appropriate management?

Arachnoid cysts can occur at different intracranial sites, including the cerebellopontine angle (CPA). The incidence of arachnoid cysts is 1 per cent of all intracranial lesions. Recent advances in MRI (magnetic resonance imaging) scan techniques have led to CPA 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. We present a series of five adult patients with different clinical presentations attributed to CPA arachnoid cysts. These lesions have a characteristic location in the posterior-inferior aspect of the CPA below the facial and vestibulocochlear nerves. These cysts did not show change in size on repeated MRI scan and the patients' symptoms did not progress over the period of follow up. Our findings would support a conservative management approach to the majority of these cysts.