Anterior cranial base reconstruction with a reverse temporalis muscle flap and calvarial bone graft

Abstract

Background: Cranial base defects are challenging to reconstruct without serious complications. Although free tissue transfer has been used widely and efficiently, it still has the limitation of requiring a long operation time along with the burden of microanastomosis and donor site morbidity. We propose using a reverse temporalis muscle flap and calvarial bone graft as an alternative option to a free flap for anterior cranial base reconstruction.

Methods: Between April 2009 and February 2012, cranial base reconstructions using an autologous calvarial split bone graft combined with a reverse temporalis muscle flap were performed in five patients. Medical records were retrospectively analyzed and postoperative computed tomography scans, magnetic resonance imaging, and angiography findings were examined to evaluate graft survival and flap viability.

Results: The mean follow-up period was 11.8 months and the mean operation time for reconstruction was 8.4±3.36 hours. The defects involved the anterior cranial base, including the orbital roof and the frontal and ethmoidal sinus. All reconstructions were successful. Viable flap vascularity and bone survival were observed. There were no serious complications except for acceptable donor site depressions, which were easily corrected with minor procedures.

Conclusions: The reverse temporalis muscle flap could provide sufficient bulkiness to fill dead space and sufficient vascularity to endure infection. The calvarial bone graft provides a rigid framework, which is critical for maintaining the cranial base structure. Combined anterior cranial base reconstruction with a reverse temporalis muscle flap and calvarial bone graft could be a viable alternative to free tissue transfer.

Keywords: Bone transplantation; Skull base; Surgical flaps.

Fig. 1

Intraoperative photos of case 2 (A) About 2 cm above the superior temporal line, the pericranium was incised and the temporal muscle was elevated gently to the zygomatic arch. The path of the superficial temporal artery (white line) was confirmed. (B) Resection of the fibrous dysplasia resulted in an anterior to inner cranial base defect, including the right orbital roof. (C) The temporalis muscle was split from the superficial temporal fascia and a continuous running suture (white arrows) was loosely applied to prevent accidental separation between the temporalis muscle and the superficial temporal fascia in the capillary network area. (D) The reverse temporalis muscle flap was inserted into the defect site overlying the calvarial bone graft.

Fig. 2

Pre- and postoperative radiologic studies of case 1 (A) The mucocele (dotted line) extended to the frontal bone, frontal sinus, ethmoidal sinus, and orbital roof. (B) After resection of the mucocele, the supraorbital rim (arrow) was reconstructed with a calvarial bone graft. (C) Immediate postoperative CT showed the contour of the reverse temporalis muscle flap (dotted line). (D) One year after surgery, CT angiography showed viable flap vascularity (white arrow) and delineation (dotted line).

Fig. 3

Pre- and postoperative radiologic studies of case 2 (A) Extended fibrous dysplasia (dotted line) was invading the optic canal and ethmoidal sinus. (B) The orbital roof was reconstructed with a calvarial bone graft (white arrow). (C) Immediate postoperative CT showed the contour of the reverse temporalis muscle flap (dotted line). (D) On postoperative angiography, retrograde blood flow was confirmed from the superficial temporal artery to the deep temporal artery (white arrow). (E) Eleven months after the operation, CT showed a well-maintained calvarial bone graft with bone induction around the graft (white arrow). This patient underwent augmentation rhinoplasty six months postoperatively.

Fig. 4

Postoperative MRI of case 4 Nine months after surgery, the contour and the delineation of the bilateral reverse temporalis muscle flap were identified (dotted line).