Cognitive outcome of patients with classic infantile Pompe disease receiving enzyme therapy

Objective: Classic infantile Pompe disease affects many tissues, including the brain. Untreated infants die within their first year. Although enzyme-replacement therapy (ERT) significantly increases survival, its potential limitation is that the drug cannot cross the blood-brain barrier. We therefore investigated long-term cognitive development in patients treated with ERT. Methods: We prospectively assessed cognitive functioning in 10 children with classic infantile Pompe disease who had been treated with ERT since 1999. Brain imaging was performed in 6 children. Results: During the first 4 years of life, developmental scores in 10 children ranged from aboveaverage development to severe developmental delay; they were influenced by the type of intelligence test used, severity of motor problems, speech/language difficulties, and age at start of therapy. Five of the children were also tested from 5 years onward. Among them were 2 tetraplegic children whose earlier scores had indicated severe developmental delay. These scores now ranged between normal and mild developmental delay and indicated that at young age poor motor functioning may interfere with proper assessment of cognition. We found delayed processing speed in 2 children. Brain imaging revealed periventricular white matter abnormalities in 4 children. Conclusions: Cognitive development at school age ranged between normal and mildly delayed in our long-term survivors with classic infantile Pompe disease treated with ERT. The oldest was 12 years. We found that cognition is easily underestimated in children younger than 5 years with poor motor functioning. Copyright

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