Hi my husband 38 yrs old, has been suffering with headaches, blurred vision and imbalancing, he had a ct scan and mri which shows having a arachnoid cyst in the posterior fossa region with mass effect something serious?

See specialist soon: I am hesitant to answer here for your husband for privacy reasons. But I will provide general comments. 1. Above symptoms happen from the arahnoid cyst with dilation of ventricles (inner chambers inside brain). There may be other reasons as well. 2. I would go see a neurosurgeon or neurologist very soon. Or go to ER for getting admitted to the hospital, so these problems can be addressed sooner.