Macrocephaly in infancy: benign enlargement of the subarachnoid spaces and subdural collections

Abstract

<jats:sec> <jats:title>OBJECTIVE</jats:title> <jats:p>Benign enlargement of the subarachnoid spaces (BESS) is a common finding on imaging studies indicated by macrocephaly in infancy. This finding has been associated with the presence of subdural fluid collections that are sometimes construed as suggestive of abusive head injury. The prevalence of BESS among infants with macrocephaly and the prevalence of subdural collections among infants with BESS are both poorly defined. The goal of this study was to determine the relative frequencies of BESS, hydrocephalus, and subdural collections in a large consecutive series of imaging studies performed for macrocephaly and to determine the prevalence of subdural fluid collections among patients with BESS.</jats:p></jats:sec> <jats:sec> <jats:title>METHODS</jats:title> <jats:p>A text search of radiology requisitions identified studies performed for macrocephaly in patients ≤ 2 years of age. Studies of patients with hydrocephalus or acute trauma were excluded. Studies that demonstrated hydrocephalus or chronic subdural hematoma not previously recognized but responsible for macrocephaly were noted but not investigated further. The remaining studies were reviewed for the presence of incidental subdural collections and for measurement of the depth of the subarachnoid space. A 3-point scale was used to grade BESS: Grade 0, &lt; 5 mm; Grade 1, 5–9 mm; and Grade 2, ≥ 10 mm.</jats:p></jats:sec> <jats:sec> <jats:title>RESULTS</jats:title> <jats:p>After exclusions, there were 538 studies, including 7 cases of hydrocephalus (1.3%) and 1 large, bilateral chronic subdural hematoma (0.2%). There were incidental subdural collections in 21 cases (3.9%). Two hundred sixty-five studies (49.2%) exhibited Grade 1 BESS, and 46 studies (8.6%) exhibited Grade 2 BESS. The prevalence of incidental subdural collections among studies with BESS was 18 of 311 (5.8%). The presence of BESS was associated with a greater prevalence of subdural collections, and higher grades of BESS were associated with increasing prevalence of subdural collections. After controlling for imaging modality, the odds ratio of the association of BESS with subdural collections was 3.68 (95% CI 1.12–12.1, p = 0.0115). There was no association of race, sex, or insurance status with subdural collections. Patients with BESS had larger head circumference Z-scores, but there was no association of head circumference or age with subdural collections. Interrater reliability in the diagnosis and grading of BESS was only fair.</jats:p></jats:sec> <jats:sec> <jats:title>CONCLUSIONS</jats:title> <jats:p>The current study confirms the association of BESS with incidental subdural collections and suggests that greater depth of the subarachnoid space is associated with increased prevalence of such collections. These observations support the theory that infants with BESS have a predisposition to subdural collections on an anatomical basis. Incidental subdural collections in the setting of BESS are not necessarily indicative of abusive head injury.</jats:p></jats:sec>

D2-Hydroxyglutaric Aciduria Type II with Subdural Hemorrhage Identified in a 3-Month-Old Infant: A Case Report

“…The proposed mechanism for subdural bleeding with enlarged subarachnoid spaces is similar to the mechanism proposed for GA1and for D2-HGA Type II, whereby the bridging veins spanning this enlarged subarachnoid space are under increased tension and are, as a result, more susceptible to shear forces from minor trauma or in the absence of trauma by way of typical child handling. 5,7,10…”

Co-occurring Hydrocephalus and Polygenic Risk in Autism Spectrum Disorder: A Danish Population-based Cohort Study

“…(10) A relatively common presentation is the Benign Enlargement of the Subarachnoid Space (BESS) or benign external hydrocephalus, that is asymptomatic and usually resolves spontaneously before the child reaches the age of two years. (11,12) Most hydrocephalus patients though, present with symptoms, but not necessarily the well-known acute symptoms of increased intracranial pressure or an obviously increased head circumference. They may just as well be presenting with normal or only slightly increased head circumference, and variable degrees of psycho-motoric delay or failure to thrive during infancy.…”

Response to the Letter to Editor: “Do Inter-Country Differences in the Frequency of Abusive Head Trauma Reflect Different Proportions of Overdiagnosis of Abuse or True Differences in Abuse?”

“…7 Recent studies reported infrequent presence of SDH=SDC among children with BEH=BESS; that is, SDC was seen among 5.6% of 108 children with BESS 8 and 5.8% of 311 imaging studies of children with BESS. 9 As Ulf et al mentioned, we cannot deny the possibility of over-diagnosing possible AHT due to limitation of using available ICD-10 codes from DPC database. Considering the incidence rate of BEH=BESS, 4 there might be approximately 400 children with BEH=BESS born each year because the annual number of live births is about one million in Japan.…”