[Achalasia: UpToDate].

Achalasia is a primary esophageal motility disorder characterized by the absence of peristalsis and failure of relaxation of the lower esophageal sphincter (LES). Its etiology remains uncertain, with proposed mechanisms including autoimmune, infectious, and genetic factors. To review recent advances in the diagnosis and management of achalasia, with emphasis on functional classification, the role of emerging technologies, and the most effective therapeutic strategies. A narrative review of the literature in English and Spanish was conducted, including scientific articles, clinical practice guidelines, and recent international consensus statements (AGA 2024, ESGE 2025). The Chicago Classification v4.0 has improved the diagnostic accuracy of esophageal motility disorders through high-resolution esophageal manometry (HRM), facilitating more precise therapeutic decision-making. The peroral endoscopic myotomy (POEM) has demonstrated high clinical efficacy, particularly in type III achalasia. The laparoscopic Heller myotomy remains a valid option, especially when combined with fundoplication, while pneumatic dilation should be reserved for selected cases. Emerging technologies such as the EndoFLIP (Endoluminal Functional Lumen Imaging Probe) allow for dynamic assessment of the LES during diagnostic and therapeutic procedures, optimizing surgical planning and treatment individualization, while reducing complications and improving clinical outcomes. The modern management of achalasia requires an individualized approach. Treatment selection should consider the functional subtype, institutional expertise, and patient preferences.