The article “Refinements in Nasal Reconstruction: The Cross-Paramedian Forehead Flap” and the “discussion” both recently published in the Journal of Plastic and Reconstructive Surgery (see full references below) give a truly nice review of the procedure.
Nasal reconstruction is often challenging. The forehead flap is a workhorse flap in nasal reconstruction. It provides similar skin color, texture, structure, and reliability. A disadvantage of the forehead flap includes a difficult arc of rotation. This can displace the medial eyebrow hair. The vertical design can encroach on the scalp which can risk incorporating unwanted hair into the nasal reconstruction.
Historically, the median forehead flap was based on a wide pedicle whose base sit in the center of the forehead. Both supratrochlear vessels were included. This pedicle did not extend below the eyebrows. This wide pedicle had the potential to increase the torsion on vessels which could then lead to compromising the blood flow to the flap. (photo credit)
The paramedian flap design is centered directly over the supratrochlear artery (note: only one vessel, not both) above the medial side of the eyebrow. The proximal flap does not extend below the eyebrow, resulting in shorter flap length.
The midline forehead flap combines features of both the median and the paramedian forehead flaps. The skin paddle is centered in the midline based on a unilateral supratrochlear vessel. The pedicle can be dissected at its emergence from the superior medial orbit.
The article describes the authors' modification of the established oblique paramedian forehead flap.
The cross-paramedian forehead flap is based on the supratrochlear vessel contralateral to the nasal defect. The flap is designed to extend across the midline of the forehead to the contralateral side. The flap is an axial pedicle flap until it crosses the midline. The distal third of the flap crosses the midline to become a random flap.
The flap is elevated in the subgaleal plane from distal to proximal to the supraorbital region. The dissection plane becomes subperiosteal at the level of the upper eyebrow. Inferior dissection is carried into the orbit in the subperiosteal plane to facilitate a safe arc of rotation without tension.
The periosteum is incorporated at the most inferior extent of the pedicle and carefully freed toward the supratrochlear vessels to facilitate flap rotation. The pedicle is designed with a narrow skin bridge 8 mm in width with a sufficiently wide subcutaneous and galeal pedicle to safely include the supratrochlear vessels. The narrow skin pedicle is carried below the medial eyebrow toward the medial canthus.
The forehead flap is mobilized and rotated downward into the nasal defect. If the flap appears robust, the frontalis muscle can be thinned from the distal half. The flap is folded on itself distally to replace the nasal lining if necessary. This design provides a longer hairless flap, which is advantageous when reconstructing lining. The donor site is closed primarily. We prefer to base the pedicle on the contralateral side of the defect because it provides a smooth arc of rotation and a longer non-hair-bearing flap.
The flap is divided and inset at 2.5 to 3 weeks. The skin width is narrow proximally and is excised in or parallel to the glabellar frown line. This results in a linear scar in the glabella region.
Secondary refinements of the forehead flap may be necessary to defat the flap and refine the aesthetic contour.
Both article and discussion are worth your time to read and study.
Refinements in Nasal Reconstruction: The Cross-Paramedian Forehead Flap; Plastic and Reconstructive Surgery:Volume 123(1)January 2009, pp 87-93; Angobaldo, Jeff M.D.; Marks, Malcolm M.D.
Discussion of Refinements in Nasal Reconstruction: The Cross-Paramedian Forehead Flap; Plastic and Reconstructive Surgery; Plastic and Reconstructive Surgery:Volume 123(1)January 2009pp 94-97; Menick, Frederick J. M.D.