What is the treatment or monitoring for a slight interval enlargement of an infratentorial subdural hygroma?

Management of Infratentorial Subdural Hygroma

For a slight interval enlargement of an infratentorial subdural hygroma along the left cerebellar hemisphere, close clinical monitoring with serial imaging is recommended rather than immediate surgical intervention, unless neurological symptoms develop.

Evaluation and Monitoring Approach

Initial Assessment

• Evaluate for clinical symptoms that may indicate mass effect:
  • Headache, especially new or worsening
  • Nausea or vomiting
  • Balance difficulties or ataxia
  • Visual disturbances
  • Altered level of consciousness
  • Signs of brainstem compression

Imaging Recommendations

• Follow-up MRI of the head and orbits is the preferred imaging modality for monitoring 1

  • Superior to CT for evaluating posterior fossa structures
  • Better visualization of potential mass effect on brainstem and fourth ventricle
  • Higher resolution of intracranial and intraorbital structures
  • Recommended timing: 4-8 weeks after initial detection of enlargement

• CT scan without contrast can be used if MRI is contraindicated 2

  • More readily available and faster to obtain
  • Excellent for detecting acute changes in size or density

Monitoring Schedule

• Asymptomatic patients:

  • Clinical follow-up every 2-4 weeks
  • Repeat imaging in 4-8 weeks to assess stability
  • Continue monitoring until hygroma stabilizes or resolves

• Symptomatic patients:

  • More frequent clinical follow-up (weekly)
  • Earlier repeat imaging (2-4 weeks)
  • Consider neurosurgical consultation

Indications for Intervention

Most infratentorial subdural hygromas do not require surgical intervention 3, 4. However, intervention should be considered if:

1. Signs of brainstem compression develop
2. Obliteration of the fourth ventricle occurs regardless of clinical symptoms 1
3. Development of hydrocephalus due to CSF pathway obstruction 5
4. Progressive enlargement on serial imaging with associated symptoms

Surgical Management Options

If intervention becomes necessary, options include:

1. External ventricular drain (EVD) placement

   • Particularly useful if hydrocephalus develops 1, 5
   • Provides temporary relief while allowing for potential spontaneous resolution

2. Burr hole drainage

   • Simple and less invasive option for reducing mass effect 6
   • May be sufficient for symptomatic relief

3. Surgical evacuation

   • Reserved for cases with significant mass effect or neurological deterioration
   • Paramedian suboccipital mini-craniectomy approach preferred over large craniectomy (fewer complications) 1

Important Considerations and Pitfalls

• Differential diagnosis: Important to distinguish from chronic subdural hematoma, which may require different management 3, 6

• Natural history: Subdural hygromas may:

  • Resolve spontaneously over time
  • Remain stable without causing symptoms
  • Transform into chronic subdural hematomas
  • Rarely cause progressive mass effect requiring intervention 3, 7

• Anticoagulation management: If patient is on anticoagulation:

  • Consider temporary discontinuation if hygroma is enlarging
  • Wait at least 3-4 weeks after stabilization before restarting 2
  • Follow-up imaging should confirm stability before resuming anticoagulation

• Pitfall to avoid: Unnecessary surgical intervention for asymptomatic hygromas that may resolve spontaneously 6

Conclusion

The management of infratentorial subdural hygroma primarily involves vigilant clinical and radiological monitoring. Most cases will not require surgical intervention unless there is evidence of significant mass effect, fourth ventricle obliteration, or development of hydrocephalus. Serial imaging is essential to track the evolution of the hygroma and guide management decisions.