Paramedian Forehead Flap for Repair of Refractory High-Flow Anterior Skull Base CSF Leak

Background: The paramedian forehead flap (PMFF) has been well described for nasal reconstruction. However, it has not been reported for repair of high flow anterior skull base cerebral spinal fluid leak (CSF) with long-term follow-up. We present an interesting case of pericranial flap failure and recurrent high flow CSF leak in a cocaine abuser who again started using cocaine 16 months after his initial surgery. The patient initially presented with a high flow anterior skull base CSF leak, pneumocephalus, intra-cerebral and intra-ventricular infection secondary to an oro-cerebral fistula via defect in the hard palate and anterior skull base. The patent initially underwent bi-frontal craniotomy, exenteration of frontal sinus, abdominal fat graft, resection of intra-cerebral abscess and repair of high flow anterior skull base CSF leak and pericranial flap (PF). The patient had osteonecrosis of his nasal cavity devoid of nasal mucosa and turbinates secondary to chronic cocaine abuse, therefore nasoseptal and turbinate flaps were not available.

Methods: In cases of recurrent or refractory anterior skull base high flow CSF leak, nasoseptal flap and/or free flaps are most commonly utilized. In this case, we performed a redo bi-frontal craniotomy and utilized a pedicled and de-epithelialized PMFF based off of bilateral supratrochlear arteries to repair the anterior skull base defect.

Result: The patient has had greater than 3-year follow-up without recurrent CSF leak and returned to work and independent function. Primary closure of the forehead was achieved with good cosmetic outcome. Free flap reconstruction was not required. Potential recipient and donor site complications of free flap were avoided.

Conclusion: This case highlights the distinctive and well-described vascular anatomy that serves the PMFF and the PF. The PF is supplied by the supra-orbital and supra-trochlear arteries, whereas the PMFF is supplied by the supra-trochlear arteries. In the vast majority of cases a free flap would have been the reconstruction technique utilized in a similar case. Our review of the literature supports this statement. Despite the well-described and understood vascular anatomy of the PMFF, it appears underutilized as a vascularized pedicled flap for CSF leak repair and the reconstruction of anterior skull base defects. This may be due to the assumption that a failed PF means the PMFF is likely to fail. The de-epithelialized PMFF obviated the need for free flap and the potential recipient and donor site complications that may occur. The vascular anatomy differences of the PF and PMFF allow for the PMFF to be a viable option despite the previous utilization of a PF as long as the supra-trochlear arteries are Doppler able and deemed to have good flow preoperatively. The de-epithelialized PMFF adds to the vascularized reconstructive techniques utilized to repair complex refractory cerebral spinal fluid leaks and anterior skull base defects.

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