What are the symptoms and treatment options for arachnoid (cerebrospinal fluid-filled) cysts?

Symptoms and Treatment of Arachnoid Cysts

Arachnoid cysts are typically asymptomatic but can cause seizures, headaches, dizziness, and neurological deficits when symptomatic, requiring surgical intervention such as endoscopic fenestration or cyst excision for definitive treatment.

Clinical Presentation

Arachnoid cysts are discrete pockets of cerebrospinal fluid (CSF) found adjacent to normal CSF spaces in the brain or spine. Most remain asymptomatic throughout life 1, but when symptoms develop, they often present suddenly and may include:

• Neurological symptoms:

  • Seizures (most common presentation for temporal cysts) 2, 3
  • Focal neurological deficits (e.g., hemiparesis) 4
  • Dizziness 2

• Pressure-related symptoms:

  • Headaches 3
  • Increased intracranial pressure signs
  • Visual disturbances

• In severe cases:

  • Loss of consciousness 4
  • Status epilepticus 2
  • Uncal herniation (in cases of large or "tension" cysts) 4

• Spinal arachnoid cysts typically present with:

  • Lower limb weakness
  • Pain
  • Sensory disturbances 5

Diagnostic Approach

Diagnosis requires neuroimaging:

• MRI is the preferred imaging modality for initial evaluation, especially with volumetric 3D sequences 6
• CT scan is useful as a complementary study to detect calcifications and evaluate bone structure 6
• CT myelography may be necessary for spinal arachnoid cysts 6

Treatment Options

Treatment depends on symptomatology and cyst location:

Asymptomatic Cysts

• Observation is appropriate for asymptomatic cysts, as natural history studies show only 2.3% of cysts increase in size over time 1

Symptomatic Cysts

1. Surgical options for intracranial cysts:

   • Endoscopic fenestration - minimally invasive approach recommended for accessible cysts 6
   • Craniotomy with cyst excision - for large symptomatic cysts causing significant mass effect 4
   • Cystoperitoneal shunting - alternative for complex cases 4

2. Surgical options for spinal arachnoid cysts:

   • Extradural cysts: Laminoplasty with cyst excision and closure of dural defect 5
   • Intradural cysts: Fenestration of the cyst, especially for those anterior to the cord 5
   • Extensive cysts: Marsupialization may be considered 5

Treatment Outcomes

• Headaches: Studies show 4 out of 6 surgically treated patients experienced complete resolution of headaches 3
• Seizures: 3 out of 4 patients with temporal arachnoid cysts and seizures improved after surgery 3
• Neurological deficits: Most patients show substantial improvement in symptoms following appropriate surgical intervention 5

Important Considerations

• Sudden deterioration can occur with previously asymptomatic cysts, requiring emergency intervention 4
• Patients may develop resistance to anti-epileptic medications when seizures are related to arachnoid cysts 2
• The median duration of symptoms before surgery in spinal arachnoid cysts is approximately 9 months 5
• Cysts in certain locations (sellar and suprasellar) are more likely to be symptomatic than others 1

Follow-up Recommendations

• Regular imaging follow-up is recommended for both surgically treated and conservatively managed cysts
• For surgically treated patients, follow-up imaging should be performed to confirm adequate decompression
• Patients with seizures may require long-term anti-epileptic medication management even after surgical intervention

Arachnoid cysts represent a challenging clinical entity that often requires a high index of suspicion for diagnosis, particularly when presenting with non-specific symptoms like headaches or seizures. When symptomatic, surgical intervention offers the best chance for symptom resolution.