Editor,—It was with great interest that we read the recent annotation and commentary by Drs Wilkins and Sunderland.1 Recently, an unusual presentation of a neurometabolic disorder, glutaric aciduria type I (GAI), was recognised to mimic shaken baby syndrome. As this association has only been described in two case reports,2 3 we would like to take this opportunity to heighten the awareness of the paediatric community.

GAI is an autosomal recessive inborn error of metabolism, with initially normal development and only mild to moderate macrocephalus.2 4 Because the bridging veins are elongated and thus seem to be more vulnerable, minor head injuries can lead to subdural haematomas, sometimes repeatedly raising a suspicion for shaken baby syndrome.2 3 Due to subarachnoidal effusions minimal trauma can similarly cause retinal haemorrhage further supporting the suspicion of shaken baby syndrome.

The clinical hallmark of GAI is a sudden encephalopathy, mostly occurring between 7 and 18 months of age.3 4 Subdural haematomas, often of different stages, and lesions in the basal ganglia may be found on neuroimaging, again raising the suspicion of child abuse. If surgical shunting of subdural hygromas and haematomas is attempted without knowing the diagnosis of GAI, effusions may even increase and further clinical deterioration occur, probably triggered by the catabolic stress during the operation and postoperative period. The children are left with a distinctive severe dystonic disorder, which maybe jugded as the consequence of severe brain injury afflicted by non-accidental injury.

As subdural haematomas of different stages and lesions in the basal ganglia, occurring in an encephalopathic child without a convincing history of adequate trauma, are characteristic for both shaken baby syndrome and GAI, urinary organic acids and serum carnitine concentrations should be evaluated in the differential diagnosis. If diagnosed early, GAI is a treatable disease. In addition, there is the possibility of prenatal diagnosis and early treatment of affected siblings, and, most importantly, psychosocial consequences can be avoided for the parents suspected of child abuse.