Discussion
Computed tomographic (CT) scan of brain revealed bilateral frontotemporal
atrophy, bilateral enlarged sylvian fissures and few hypodensities in
the lentiform nuclei.
Biochemical investigations clinched the diagnosis of Glutaric aciduria
type 1 (GA-1).
GA - 1 is an autosomal recessive inborn error of lysine, hydroxylysine
and tryptophan metabolism that results from a deficiency of glutaryl-CoA
dehydrogenase. The diagnosis of GA-1 is made by the presence of increased
urinary glutaric acid and 3-hydroxyglutaric acid and is confirmed by a
deficiency or absence of glutaryl-CoA dehydrogenase in cultured fibroblasts.
Because the levels of urine glutaric acid and 3-hydroxyglutaric acid may
be normal or only slightly elevated especially when the patient is clinically
stable, glutaryl-CoA dehydrogenase should be measured whenever GA-1 is
strongly suspected from clinical and/or radiological findings.
Common features on neuroimaging include increased spaces anterior to the
frontotemporal lobes (vs. frontotemporal atrophy) wide sylvian fissures,
(giving a "bat-wing" formation) and prominent interhemispheric
fissures (1). There may be diffuse hypodensity of the basal ganglia. A
prominent clinical feature of infants and children with glutaric aciduria
type 1 is macrocephaly (3) .
The fact that the radiographic findings are present 3 months before the
onset of clinical symptoms indicates that the metabolic defect can affect
the brain before the onset of clinical symptoms.
Metabolic disorders are often considered as a differential diagnosis in
abusive head trauma. Glutaric aciduria type 1, in particular, is mentioned
because of the presence of subdural effusions on imaging in this disorder
(4).
References
1. Brismar J, Ozand
PT. CT and MR of the brain in glutaric acidemia type 1: a review of 59
published cases and a report of 5 new patients. AJNR 1995;16:675-683.
2. Hartley LM, Khwaja OS, Verity CM. Gluteric aciduria type 1 and nonaccidental
head injury. Pediatrics 2001;105 :174-176.
3. Drigo P, Piovan S, Battistella PA, et al. Macrocephaly, subarachnoid
fluid collection, and glutaric aciduria type 1. J Child Neurol 1996;11:414-417.
4. Morris AAM, Hoffmann GF, Naughten ER, et al. Gluteric aciduria and
suspected child abuse. Arch Dis Child. 1999;80:404-405.
Contribution :
Dr Santosh Rai, Consultant Radiologist, Manipal
Hospital, Mangalore
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