Epidemiology of Benign External Hydrocephalus in Norway – a population based study

Publication date: Available online 24 April 2017
Source:Pediatric Neurology
Author(s): Ulrikke Straume Wiig, Sverre Morten Zahl, Arild Egge, Eirik Helseth, Knut Wester
BackgroundBenign external hydrocephalus (BEH) is defined as a rapidly increasing head circumference (Occipitofrontal circumference - OFC) with characteristic radiological findings of increased subarachnoid cerebrospinal fluid (CSF) spaces on neuroimaging. To our knowledge, the incidence of BEH has not been previously reported, and there is no available information on the ratio of BEH in the population of hydrocephalic children.MethodsThis study is retrospective and population-based, geographically covering two health regions in the southern half of Norway with a total mean population of 3.34 million in the ten-year study period, constituting approximately 75 % of the Norwegian population. Children with a head circumference crossing two percentiles, or above the 97.5^th percentile, and with typical imaging findings of enlarged frontal subarachnoid spaces with or without enlarged ventricles were included. Children were excluded if they had a history of head trauma, intracranial haemorrhage, CNS infection, other known causes of hydrocephalus, or prematurity defined as birth prior to 37 weeks of gestation.ResultsA total of 176 children fitting the criteria were identified, giving an incidence of 0.4 per 1000 live births. 152 (86.4%) of the patients were male, and mean age at referral was 7.3 months. Increasing head circumference was the main reason for referral in 158 patients (89.8%) and the only finding in 60 patients (34.1%). 37 children (21%) had normal ventricles on imaging, the remainder had increased ventricular size. The incidence of paediatric hydrocephalus in Norway is reported to be 0.75 per 1000 live births, thus BEH accounts for approximately 50% of hydrocephalic conditions in this population.ConclusionsThe incidence of BEH was found to be 0.4 per 1000 live births in this population.



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