Clinical Experience with Mechanically Coupled Anastomoses in Skull Base Reconstruction

Background: The reconstruction of major skull base, scalp and calvarial defects with microvascular free flaps has revolutionized the predictable and safe conduct of multidisciplinary oncologic surgery of this region. While extended resections can be more confidently completed, this has not necessarily been accompanied by increased local control or cure. This is due to limitations of radiation tolerance of surrounding tissues, necessary acceptance of involved microscopically close or involved margins, tolerable morbidity, and the lack of specific medical oncologic agents for benign and malignant CNS tumors. Use of coupler devices in routine head and neck defects evolved into use in skull base, calvarial, and intracranial settings where flap loss can be catastrophic.

Methods: Mechanical microvascular anastomosis became increasingly widely used in head and neck reconstruction in the late 1980s and 1990s as a method to speed the process, and perhaps patency over hand-sewn anastomoses. These have been incorporated primarily in venous interposition graft and end-to-end, and end-to side venous configurations facilitated by vessel pliability and the ability to evert vessel walls over coupler pins. The coupler itself is constructed of 2 polyethylene rings and staggered ferromagnetic pins which match holes on the opposing ring through a friction fit, thus joining the vessels. Because of its construction, and the increased use and preference of MRI for perioperative evaluation early concern for heating and/or rotation, torquing or disruption of new anastomoses, it was studied in a relevant model and found in clinical experience, to be irrelevant.[1]

Conclusion: The use of the superficial temporal vessels for recipients is often preferred to save pedicle length, minimize the need for interposition vein grafts (doubling the number of anastomoses and thrombotic opportunity/risk), and often influenced by prior treatment (bicoronal flaps) in which ligation and scar may limit suitability. Additionally, the vein is often thin-walled and technically unusable. The incision for access to these vessels is usually placed immediately in the junctional creases of the ear and cheek, and thus several millimeters removed from the actual course of the vessels. In a broad and significant experience spanning 25 years including 40 skull base microvascular reconstructions, 15 of which used temporal recipient vessels, there have been 2 cases (one calvarial, one intracranial) where the coupler rings have eroded through the temporal skin, and self-ejected, without flap loss, and implying the acquisition of adequate venous supply to support flap survival. Given this observation, unique to this region, hand-sewn anastomoses are specifically recommended when using these vessels so as to minimize potentially catastrophic flap loss. Our experience in microvascular skull base reconstruction in this context is reviewed in support of this recommendation.

No conflict of interest has been declared by the author(s).

• Reference

• 1 DeLacure MD, Wang HZ. Magnetic resonance imaging assessment of a microvascular anastomotic device for ferromagnetism. J Reconstr Microsurg 1997; 13 (08) 571-574