What is the management of Sunken Flap syndrome?

Management of Sunken Flap Syndrome

Early cranioplasty is the definitive treatment for Sunken Flap Syndrome and should be performed as soon as the patient is medically stable to reverse neurological deterioration and improve outcomes.

Definition and Pathophysiology

Sunken Flap Syndrome (SFS), also known as "Syndrome of the Trephined" or "Sinking Skin Flap Syndrome," is a rare but serious complication following decompressive craniectomy. It occurs when the skin flap over the craniectomy site becomes severely depressed due to atmospheric pressure exceeding intracranial pressure, leading to:

• Compression of underlying brain tissue
• Altered cerebrospinal fluid dynamics
• Impaired cerebral blood flow
• Compromised brain metabolism

Clinical Presentation

SFS typically presents with:

• Progressive neurological deterioration after initial recovery
• Motor deficits (especially contralateral to craniectomy site)
• Cognitive decline
• Headaches that worsen with upright positioning
• Dizziness
• Severely depressed skin flap on examination

Risk Factors

Several factors increase the risk of developing SFS:

• Very large craniectomy defects
• Medial craniectomy border less than 2 cm from midline 1
• Extensive brain damage
• CSF diversion procedures (e.g., VP shunt) 2
• Delayed cranioplasty
• Re-surgery for craniectomy widening 1

Diagnosis

Diagnosis is based on:

• Clinical deterioration in a patient with previous craniectomy
• Visible depression of the skin flap
• CT imaging showing:
  • Midline shift toward the craniectomy site
  • Compression of the underlying brain
  • Effacement of sulci and ventricles on the affected side

Management

Immediate Interventions (Bridge to Cranioplasty)

For patients with acute neurological deterioration:

1. Paradoxical positioning:

   • Place patient in reverse Trendelenburg position (head down) 3
   • Avoid head elevation which can worsen symptoms

2. Fluid management:

   • Consider intravenous fluid administration to increase intracranial pressure 3
   • Avoid diuretics which can worsen the condition

3. Ventilation management:

   • Avoid hyperventilation which decreases cerebral blood flow 3
   • Maintain normocapnia

Definitive Treatment

Cranioplasty is the definitive treatment and should be performed early:

• Traditional practice of waiting 1-2 years after craniectomy is not recommended for patients with SFS
• Early cranioplasty (within 3 months of craniectomy) has shown dramatic improvement in neurological function 2
• Cranioplasty serves as a therapeutic intervention rather than merely a cosmetic procedure 2

Surgical Considerations

• Timing: As soon as the patient is medically stable and brain swelling has resolved
• Materials: Autologous bone flap (if preserved) or synthetic materials
• Technique: Careful elevation of the depressed flap to avoid further brain injury
• Post-operative care: Close monitoring for improvement in neurological status

Expected Outcomes

Early cranioplasty typically results in:

• Immediate improvement in neurological status in most cases 1, 2
• Reversal of motor deficits
• Improved cognitive function
• Resolution of headaches and other symptoms

Complications and Pitfalls

Common Pitfalls in Management

1. Delayed diagnosis:

   • Symptoms may be attributed to expected post-craniectomy state
   • Failure to recognize the syndrome leads to delayed treatment

2. Inappropriate management:

   • Traditional measures for increased intracranial pressure (head elevation, diuresis) worsen SFS
   • Delayed cranioplasty can lead to permanent neurological deficits

3. CSF dynamics issues:

   • VP shunts can precipitate or worsen SFS 2
   • Management is more complex in patients with CSF circulation disturbances 1

Post-Cranioplasty Complications

• Infection
• Bone flap resorption
• Seizures
• Hematoma formation
• Hydrocephalus

Prevention

• Consider early cranioplasty for patients with large craniectomy defects
• Careful planning of craniectomy size and location
• Cautious approach to CSF diversion procedures in craniectomy patients
• Regular monitoring for early signs of flap depression

Conclusion

Sunken Flap Syndrome represents a paradoxical management challenge in post-craniectomy patients. Recognition of this syndrome and prompt intervention with early cranioplasty is crucial for reversing neurological deterioration and improving patient outcomes.