Aromatic L-amino acid decarboxylase deficiency (AADC-M) is a rare, autosomal recessive neurometabolic disorder caused by pathogenic variants in the DDC gene, leading to a severe impairment of dopamine and serotonin synthesis. The severe form of the disease is characterized by pronounced extrapyramidal movement disorders, oculogyric crises, autonomic dysregulation, and global developmental delay. Eladocagen exuparvovec is an adeno-associated virus type 2-based intraputaminal gene replacement therapy. This study describes the perioperative management, structured follow-up, and neurological outcome of five children with severe AADC deficiency who were treated at Heidelberg University Hospital. Over time, clinically relevant improvements in motor and nonmotor symptoms were observed, including bradykinesia, oculogyric crises, sleep disturbances, and irritability. An early start to therapy
and the concentration of homovanillic acid in the cerebrospinal fluid correlate with better motor function. The results support the effectiveness and standardized feasibility of intraputaminal gene therapy for severe AADC deficiency.