INTRODUCTION
Botulinum neurotoxin A (BoNT-A) injection is a well-established option for the treatment of several disorders,1-3 and one of the most frequently requested non-surgical cosmetic procedures.4 IncobotulinumtoxinA (INCO, Xeomin®/Bocouture®, Merz Pharmaceuticals GmbH) is the only BoNT-A formulation approved in commercial markets worldwide and for the treatment of the upper-face wrinkles in Europe intentionally designed to contain only the active therapeutic component (150 kDa BoNT-A), therefore being free from unnecessary clostridial proteins, reducing the risk of the development of neutralizing antibodies.5-9 In contrast, abobotulinumtoxinA and onabotulinumtoxinA (ONA) contain the 150 kDa BoNT-A complexed with the hemagglutinin and non-toxic non-hemagglutinin proteins.5,7-9
Botulinum toxin treats dynamic wrinkles caused by hyperactive muscles. There are two antagonistic groups of muscles in the upper face: the eyebrow depressors (procerus, corrugator supercilii, and orbicularis oculi) and the frontalis, the only eyebrow elevator.6 This is a large, vertically oriented forehead muscle, originating in the galea aponeurotica and inserting into the skin of the eyebrow and nose root, where it blends with the procerus and orbicularis. Frontalis contractions raise the eyebrows and form horizontal forehead lines.10,11 Abramo et al classified four distinct anatomical types of the frontalis muscle and related them to four clinical patterns of forehead wrinkles.10 Moqadam et al related the “full shape†pattern to straight parallel lines, and the “V-shaped†one to wavy horizontal forehead lines.11 Therefore, based on the appearance of the patient’s forehead lines it is possible to infer the shape and distribution of the frontalis muscle, reinforcing the need for an individualized approach.The action of hyperkinetic muscles associated with the reduction of skin elasticity, flattening of the forehead, atrophy of fat pads and eyelid dropping contribute to the appearance of horizontal forehead wrinkles and eyebrow ptosis.12-14
There has been a progressive change in conceptualizing the aging process and facial rejuvenation, from an essentially two- dimensional to a three-dimensional approach that encompasses fat-pad volume, bone structure, and collagen loss, allowing better selection of aesthetic tools and treatment approaches.15 Treatment of the forehead can be particularly challenging, as
Botulinum toxin treats dynamic wrinkles caused by hyperactive muscles. There are two antagonistic groups of muscles in the upper face: the eyebrow depressors (procerus, corrugator supercilii, and orbicularis oculi) and the frontalis, the only eyebrow elevator.6 This is a large, vertically oriented forehead muscle, originating in the galea aponeurotica and inserting into the skin of the eyebrow and nose root, where it blends with the procerus and orbicularis. Frontalis contractions raise the eyebrows and form horizontal forehead lines.10,11 Abramo et al classified four distinct anatomical types of the frontalis muscle and related them to four clinical patterns of forehead wrinkles.10 Moqadam et al related the “full shape†pattern to straight parallel lines, and the “V-shaped†one to wavy horizontal forehead lines.11 Therefore, based on the appearance of the patient’s forehead lines it is possible to infer the shape and distribution of the frontalis muscle, reinforcing the need for an individualized approach.The action of hyperkinetic muscles associated with the reduction of skin elasticity, flattening of the forehead, atrophy of fat pads and eyelid dropping contribute to the appearance of horizontal forehead wrinkles and eyebrow ptosis.12-14
There has been a progressive change in conceptualizing the aging process and facial rejuvenation, from an essentially two- dimensional to a three-dimensional approach that encompasses fat-pad volume, bone structure, and collagen loss, allowing better selection of aesthetic tools and treatment approaches.15 Treatment of the forehead can be particularly challenging, as
