S2 Level Cyst: Evaluation and Management Considerations

An S2-level cyst (likely a Tarlov/perineural cyst or meningeal diverticulum at the S2 sacral foramen) is often an incidental finding. Management depends on symptoms and size.

Types of S2 Cysts

• Tarlov (perineural) cyst: CSF-filled dilation of nerve root sleeve; most common at S1–S3. Usually asymptomatic.
• Meningeal diverticulum: Similar; communicates with subarachnoid space.
• Dermoid/epidermoid cyst: Congenital inclusion; may expand.
• Sacral meningomyelocele: Neural tissue in cyst — higher risk.

Symptomatic Presentation

• Radicular pain (S2 distribution: posterior thigh, calf, heel, plantar foot).
• Saddle paresthesias, bowel/bladder dysfunction (neurogenic).
• Perineal pain, sexual dysfunction.
• Mass effect on sacral plexus/cauda equina.

Evaluation

• MRI (with and without contrast) — characterizes cyst, nerve root relationship, enhancement.
• CT myelography if MRI contraindicated.
• Urodynamics if bladder symptoms.
• EMG/NCS for radiculopathy confirmation.

Management

• Asymptomatic/small: Observation; serial MRI if enlarging.
• Symptomatic:
  • Conservative: NSAIDs, neuropathic agents (gabapentin), pelvic PT.
  • Image-guided aspiration ± fibrin glue (temporary relief).
  • Surgical: cyst fenestration/plication, microsurgical excision, shunting — for progressive neuro deficit or intractable pain.

Key Point

Most Tarlov cysts are incidental. Neurosurgical referral if symptomatic or enlarging. Do not operate on asymptomatic cysts.