In the pediatric population, complex regional pain syndrome (CRPS) is a challenging condition that leads to chronic psychosocial dysfunction. This case is of a 12-year-old male patient, 50 kg, who, after twisting his right ankle, started to present intense pain. Without adequate diagnosis and treatment, his family sought a pain specialist. During the evaluation, a change in sensitivity and temperature was observed, besides hyperalgesia, allodynia, redness, edema, and motor dysfunction, being diagnosed with CRPS. Ultrasound-guided sciatic blocks were performed on the affected limb, increasing the interval between crises, reducing pain intensity, and promoting a return to daily activities.