Symptoms

• Symptoms that may occur due to arachnoid cysts are seizures, paralysis, weakness, lack of muscle control, dementia, urinary incontinence, headache and developmental delays. In some cases, behavioral changes may occur.
  
  

Diagnosis

• Diagnosis of arachnoid cysts can be found on imagery from an MRI or CT scan. Additionally, a mini-mental state exam (MMSE) can help diagnose individuals with arachnoid cysts. An MMSE is a questionnaire-based test.
  
  

Treatment

• When symptoms become present, treatment intervention may become necessary. Treatment methods include needle aspiration (external drainage of the cysts) and cerebral shunt placement (internal drainage of the cysts.) In some cases, a craniotomy, surgical removal of the cysts, may be performed. In cases were seizures are present, medication to control the seizures may be prescribed.
  
  

Prognosis

• When treated, patients with arachnoid cysts usually make a full recovery. However, when left untreated, patients with arachnoid cysts may experience permanent neurological damage, according the the National Institute of Neurological Disorders.
  
  

Complications

• Complications can occur in some patients. Trauma to the head can cause the fluid from the cysts to spill into the subarachnoid space, the space between the arachnoid and matter surrounding the brain. Bleeding from vessels can occur and thus increase the size of the cysts. Additionally, if bleeding occurs from blood vessels on the outside of the cysts, a hematoma or hemorrhage can occur, resulting in excess pressure within the cranium.