Traditional techniques for structural facial rejuvenation of the lower and middle thirds of the face are based on manipulation of the loose, displaced tissue (surgical lifting) and on the replacement of tissue volume (eg, implants and fillers). On the middle third of the face, fat redistribution contributes to ptosis of the nasolabial fold.1-4 The most direct and simple treatment for correction of this condition involves fillers composed of various materials.4 The first and most commonly used material was bovine collagen, which attenuated facial defects; however, this approach had the drawback in that 75% of the correction had disappeared by month 6.5 Stabilized hyaluronic acid (HA) fillers were introduced in 1998, and have since proven very effective and more durable than previous methods. The first injectable nonanimal stabilized HA (NASHA) filler was approved by the US Food and Drug Administration (FDA) in 2003 in the form of a gel containing 100,000 particles/mL. Today, several products are marketed throughout the world. According to the American Society for Aesthetic Plastic Surgery, these fillers account for almost 80% of all fillers used. In the United States alone, they were used in 2 million infiltrations in 2006.6-19
One of the most common side effects of facial filling is pain; therefore, it is necessary to develop an effective analgesic that does not reduce the efficacy of treatment. Lidocaine is an amide-type local anesthetic that has fewer side effects than other members of its group.20 Its rapid onset, moderate duration, and local anesthetic activity make it the most versatile and widely used anesthetic. A new dermal filler combining lidocaine with HA in a single presentation has proven satisfactory in relieving pain.21
Our objectives were to study the pain relief achieved by incorporating 0.3% lidocaine in the preparation and to determine whether or not this combination affected efficacy, patient satisfaction, and durability of the correction. We used reflectance confocal microscopy (RCM) to analyze the histopathological changes in the superficial dermis and epidermis after infiltration using HA or HA combined with lidocaine.22-26
We performed a comparative, parallel-group, double-blind trial with the participation of an external observer. The study sample comprised 119 patients older than 18 years (116 women and 3 men; mean age, 46.6 years) (Table 1). The predominant classification on the Wrinkle Severity Rating Scale (WSRS)5 was grade 2 to 3.