Digital Image Speckle Correlation to Optimize Botulinum Toxin Type A Injection: A Prospective, Randomized, Crossover Trial.

BACKGROUND: Historically, physicians have relied on their subjective measures when determining the site and dosages for botulinum toxin type A injections. Digital image speckle correlation is a technology that tracks pore movement from rest to maximal exertion, allowing for the determination of the optimal sites of injection. In this prospective, randomized, crossover trial, the efficacy of using digital image speckle correlation was compared to physician assessment in choosing botulinum toxin type A injection sites. METHODS: Ten female patients were analyzed in this blinded crossover study. Subjects were randomized to either injections based on digital image speckle correlation analysis or injections based on the 2004 facial aesthetics consensus recommendations. All patients received 20 U of botulinum toxin type A in the glabellar region and were crossed over and reinjected after 6 months. Follow-up was completed with the Facial Line Outcomes 11-item survey and repeated imaging with digital image speckle correlation, to measure patient satisfaction and degree of paralysis, respectively. Statistical comparison was completed by means of matched sample t test. RESULTS: On average, the digital image speckle correlation analysis provided 4.8 injection sites, whereas the practitioner chose five injections sites. Patients receiving digital image-directed injections had higher rates of satisfaction on the Facial Line Outcomes instrument (p = 0.0003) and a larger degree of paralysis (p = 0.003). Furthermore, muscle function returned to normal later in patients injected with digital image speckle correlation (17.9 weeks versus 20 weeks; p = 0.03). CONCLUSIONS: This study demonstrates the benefits of using digital image speckle correlation in determining optimal botulinum toxin type A injection location. Digital analysis allows practitioners to better treat facial rhytides by eliminating subjective decisions regarding dose and site of injection. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.