Clinical Scorecard: The 4 F Technique (Fat, Fascia, Fibrin, and Fat) for Reconstructing the Skull Base in Endoscopic Transorbital Surgery

At a Glance

Key Highlights

• The 4F technique involves intradural autologous fat placement, extradurally applied fascia lata, fibrin glue fixation, and extradurally positioned autologous fat to fill dead space.
• This method aims to restore barrier integrity between intra- and extradural compartments and eliminate dead space to reduce risks of CSF leak, meningitis, and pneumocephalus.
• Applied in a series of 16 patients with various skull base lesions, the technique demonstrated effective reconstruction with attention to functional and esthetic outcomes.

Guideline-Based Recommendations

Diagnosis

• Preoperative neurological and ophthalmological assessments to evaluate lesion impact.
• Contrast-enhanced MRI to determine lesion location and growth pattern.
• Identification of dural defects or CSF leaks intraoperatively.

Management

• Perform superior eyelid endoscopic transorbital approach (SETOA) with or without extended variations depending on lesion extent.
• Use the 4F reconstruction technique for osteodural defect repair: intradural fat graft, extradurally placed fascia lata, fibrin glue fixation, and extradurally placed fat graft.
• Leave 2–3 mm of intentional proptosis post-reconstruction to accommodate postoperative edema resolution.

Monitoring & Follow-up

• Postoperative assessment for CSF leak, enophthalmos, proptosis, diplopia, ocular paresis, and wound infection.
• Follow-up ranging from 14 to 38 months to evaluate functional and esthetic outcomes.

Risks

• Potential life-threatening complications include cerebrospinal fluid leakage, meningitis, and tension pneumocephalus if reconstruction is inadequate.
• Risk of postoperative ocular complications such as diplopia or ocular paresis.
• Possible wound infection related to surgical approach.

Patient & Prescribing Data

Adults undergoing SETOA for intracranial lesions with dural opening or CSF leak

The 4F technique provides a reliable, watertight reconstruction method using autologous tissues and fibrin glue, minimizing postoperative complications and supporting functional and esthetic recovery.

Clinical Best Practices

• Ensure meticulous placement of autologous fat graft intradurally to seal dural defects.
• Apply fascia lata extradurally to cover the osteodural defect securely.
• Use fibrin glue to fix graft materials and enhance sealing.
• Fill dead space extradurally with autologous fat to prevent postoperative complications.
• Leave slight proptosis to accommodate postoperative edema and achieve binocular symmetry.
• Perform careful suturing of periosteum, orbicularis oculi muscle, and eyelid skin to optimize healing.

References

• Moe et al. 2010 - Introduction of TONES concept
• Moe 2022 - Recommendations on proptosis after reconstruction