What is the treatment approach for a patient diagnosed with an Arachnoidocele?

Treatment Approach for Arachnoidocele

The optimal treatment approach for arachnoidocele is surgical intervention for symptomatic patients, with specific surgical techniques determined by location, with fenestration being preferred over shunt placement as the initial treatment method. 1

Diagnostic Evaluation

Before determining treatment, proper diagnosis is essential:

• MRI with dedicated protocol is the gold standard for evaluation, including:

  • T1-weighted sequences before and after gadolinium
  • T2-weighted sequences
  • Diffusion-weighted imaging (DWI)
  • Axial submillimetric heavily T2-weighted sequences
  • Fluid-attenuated inversion recovery sequences 2

• CT myelography may be useful in specific cases where MRI shows findings suspicious for arachnoid cyst/arachnoid web or ventral cord herniation 3

Treatment Algorithm Based on Location

1. Intracranial Arachnoidocele

For Symptomatic Patients:

• First-line treatment: Surgical fenestration (marsupialization) - success rate of 64% 4
  • Endoscopic fenestration is preferred for supratentorial cysts (73% of cases) 1
  • Open surgical resection for complex or inaccessible cysts

For Asymptomatic Patients:

• Conservative management with regular imaging follow-up 1

2. Spinal Arachnoidocele

• Surgical approach: Laminectomy with fenestration 1
• For recurrence: Consider cystosubarachnoid (CS) or cystoperitoneal (CP) shunt placement 1
• Important surgical principles:
  • Decompression of the spinal cord
  • Breakdown of arachnoid adhesions
  • Establishment of CSF flow
  • Consider expansile duroplasty 5

Follow-up Protocol

• First MRI at 6-12 months post-surgery
• Subsequent scans at regular intervals:
  • Every 1-2 years for 5 years, then every 2-3 years if stable, or
  • Annually for 5 years, then every 1-2 years 2

Outcomes and Complications

• Expected outcomes:

  • 60% of patients show stable cysts with improved symptoms
  • 13% achieve complete symptom resolution
  • 13% have stable symptoms 1

• Potential complications:

  • Spasticity
  • Hemiparesis
  • CSF leak
  • Hydrocephalus
  • Subdural hygroma 1
  • Shunt malfunction (45% of procedures involving shunts) 4

Special Considerations

• Middle cranial fossa cysts: May cause progressive symptoms due to secondary bleeding, brain shift, or increased CSF pressure. Removal of cyst membranes with opening to basal cisterns is recommended 6

• Intraorbital extension: Rare cases of arachnoid cysts extending into the orbit through bony defects may present with proptosis and require specialized surgical planning 7

• Recurrence management: Cyst reaccumulation occurs in approximately 15% of cases and may require shunt placement as a second-line procedure 1, 4

The evidence strongly supports surgical intervention for symptomatic arachnoidoceles, with recent advances in neurosurgical techniques and neuroendoscopy favoring fenestration over shunt insertion as the initial treatment method to reduce the high rate of shunt-related complications 1, 4.