Sir, Alvarez and colleagues1 report a clinically useful metanalysis on the diagnostic value of subependymal pseudocysts and choroid plexus cysts seen on neonatal cerebral ultrasound. It appears that complex subependymal cysts at the caudothalamic groove may be more important clinically than simple cysts here or in the choroid plexus. Their analysis did not expose two other important conditions causing multiple and/or bilateral subependymal pseudocysts in the neonate. Firstly glutaric aciduria type 1(GA1) 2,3, although rare, is important, as it is a potentially treatable autosomal recessive disorder and signs such as macrocephaly may not be present in the neonatal period. In GA1 the subependymal cysts tend to be complex. Screening for this disorder is easy by urine organic analysis, blood spot glutarylcarnitine and plasma total and free carnitine estimations; if abnormal confirmation is by fibroblast glutaryl CoA dehydrogenase activity3 and mutation analysis. The second disorder to consider is in utero exposure to cocaine. While there is debate in the literature, many studies have shown an association with subpendymal cysts4, and subepedymal hemorrhage5. The effect on the foetus may be dose dependent 5 and is likely vascular in basis. In these cases a detailed antenatal history may identify the diagnosis.

1. Fernandez Alvarez JR, Amess PN, Gandhi RS, Rabe H. Diagnostic value of subependymal pseudocysts and choroid plexus cysts on neonatal cerebral ultrasound: a meta-analysis. Arch Dis Child Fetal Neonatal Ed. 2009 ;94(6):F443-F446. 2. Twomey EL,Naughten ER, Donoghue VB ,Ryan S. Neuroimaging findings in glutaric aciduria type 1 .Pediatr Radiol 2003 ;33: 823–830. 3. Hartley L.M, Khwaja O. S, Verity C.M, Glutaric Aciduria Type 1 and Nonaccidental Head Injury. Pediatrics 2001;107(1):174-175 . 4. Smith LM, Qureshi N, Renslo R, Sinow RM. Prenatal cocaine exposure and cranial sonographic findings in preterm infants. J Clin Ultrasound. 2001;29(2):72-77. 5. Frank D.A, McCarten K.M, , Robson C.D, Mirochnick M, Cabral H, Park H, Zuckerman B. Level of In Utero Cocaine Exposure and Neonatal Ultrasound Findings. Pediatrics. 1999;104(5 Pt 1):1101–1105.