Prognosis of arachnoid cyst is generally excellent and is usually associated with a benign disease course, despite being symptomatic in a few patients.

• Arachnoid cyst usually develops asymptomatically and remains asymptomatic in most patients through their lifetime;
• Most are found incidentally;
• In a few patients they may have: headaches, hydrocephalus, ataxia/gait imbalance, seizures, dizziness, visual changes, hearing loss, vertigo, nausea/vomiting, speech abnormalities, cervical myelopathy with syrinx;
• In a paper from 2013, 203 patients with arachnoid cysts were followed up, with only 5 patients presenting with enlargement of the cyst and only 2 developing symptoms that could be due to the arachnoid cyst. ^[1]

• Arachnoid cysts may, rarely, enlarge and complicate with the symptoms previously described such as hydrocephalus, seizures, hearing loss, visual changes and cervical myelopathy.

• In a very restricted selection of cases they may be surgically treatment, but surgery may occasionally result in complications including:
  • Subdural hygroma;
  • Subdural hematoma;
  • Pseudomeningomyelocele;
  • Subdural empyema;
  • Wound complications;
  • Meningitis;
  • Hydrocephalus;
  • Seizure;
  • Need for more surgical procedures after a failed initial surgical attempt.^[1]

• The prognosis of arachnoid cyst is often good, and in the majority of cases won’t demand treatment.
• Without treatment, in a few cases the symptoms may worsen over time.
• Surgical decompression of the arachnoid cyst yielded a reduction in 66% of the patients of less than 50% of the preoperative volume. 82% were asymptomatic after the procedure, while 12% reported no relief and 6% experienced worsening of the symptoms. ^[2]