Children with bilateral temporal arachnoid cysts may have glutaric aciduria type 1 (GAT1); Operation without knowing that may be harmful

Background. Bilateral, temporal arachnoid cysts are common in patients with Glutaric aciduria type 1 (GAT1). The present study investigates whether bi temporal cysts may occur unrelated to GAT1, and it reports our experience w ith 2 GAT1 patients. Methods. During the last 11 years, the regional neurosurgical department ha s seen a total of 147 patients with arachnoid cysts in a population of 890. 000. Eight of these patients had bitemporal arachnoid cysts, 4 boys, 3 adul t females, and 1 adult male. Urine from 7 of these patients was examined wi th gas chromatography-mass spectrometry. Findings. Large amounts of glutaric acid were discovered in the urine of on ly 2 of these patients, both young boys with severe neurological symptoms o f the disease. One of them died 2 years after the clinical start of the dis ease. The remaining 5 urinary specimens contained Low (normal) concentratio ns of glutaric acid. Interpretation. For neurosurgeons, it is important to recognise that childr en with bitemporal arachnoid cysts may have GAT1, and that even simple surg ical procedures may be extremely harmful for such patients. All paediatric patients with bitemporal arachnoid cysts should therefore be screened for G AT1 before any surgical procedure takes place, especially if there is also macrocephaly, an acute encephalitis-like illness, or a dystonic, cerebral p alsy-like condition. It is concluded that bitemporal arachnoid cysts are ex tremely rare, and that they may well occur unrelated to GAT1.