Abstract
PurposeTo evaluate the anatomical variations of dural venous sinuses in children with external hydrocephalus, proposing a radiological grading of progressive anatomic restriction to venous outflow based on brain phase-contrast magnetic resonance venography (PC-MRV); to evaluate the correlation between positional plagiocephaly and dural sinuses patency; and to compare these findings with a control group to ascertain the role of anatomical restriction to venous outflow in the pathophysiology of external hydrocephalus.MethodsBrain MRI and PC MRV were performed in 97 children (76 males, 21 females) diagnosed with external hydrocephalus at an average age of 8.22 months. Reduction of patency of the dural sinuses was graded as 1 (stenosis), 2 (complete stop) and 3 (complete agenesis) for each transverse/sigmoid sinus and sagittal sinus. Anatomical restriction was graded for each patient from 0 (symmetric anatomy of patent dural sinuses) through 6 (bilateral agenesis of both transverse sinuses). Ventricular and subarachnoid spaces were measured above the intercommissural plane using segmentation software. Positional plagiocephaly (PP) and/or asymmetric tentorial insertion (ATI) was correlated with the presence and grading of venous sinus obstruction. These results were compared with a retrospective control group of 75 patients (35 males, 40 females).ResultsBoth the rate (84.53% vs 25.33%) and the grading (mean 2.59 vs mean 0.45) of anomalies of dural sinuses were significantly higher in case group than in control group. In the case group, sinus anomalies were asymmetric in 59 cases (right-left ratio 1/1) and symmetric in 22. A significant association was detected between the grading of venous drainage alterations and diagnosis of disease and between the severity of vascular anomalies and the widening of subarachnoid space (SAS). Postural plagiocephaly (39.1% vs 21.3%) and asymmetric tentorial insertion (35.4% vs 17.3%) were significantly more frequent in the case group than in the control group. When sinus anomalies occurred in plagiocephalic children, the obstruction grading was significantly higher on the flattened side (p ≤ 0.001).ConclusionDecreased patency of the dural sinuses and consequent increased venous outflow resistance may play a role in the pathophysiology of external hydrocephalus in the first 3 years of life. In plagiocephalic children, calvarial flattening may impact on the homolateral dural sinus patency, with a possible effect on the anatomy of dural sinuses and venous drainage in the first months of life.
Highlights
External hydrocephalus, known as subarachnomegaly, benign pericerebral collections or benign enlargement of the subarachnoid spaces (BESS), is a childhood condition, characterized by macrocrania and widening of the subarachnoid spaces, especially in the frontal area, frequently associated with mild ventricular dilatation and with generally benign and selflimiting course [1,2,3,4,5,6,7,8,9,10,11,12]
We prefer the term “external hydrocephalus” because we do not like to use the term “benign” for a condition that has been frequently associated with some degree of early delayed development; can have, rarely, surgical implications; and it is not limited to subarachnoid or pericerebral spaces since significant ventriculomegaly is a constant part of the neuroradiological features
The aim of this study is to investigate the prevalence and possible role of the altered intracranial venous drainage in external hydrocephalus through a retrospective case–control study and a review of the literature
Summary
Known as subarachnomegaly, benign pericerebral collections or benign enlargement of the subarachnoid spaces (BESS), is a childhood condition, characterized by macrocrania and widening of the subarachnoid spaces, especially in the frontal area, frequently associated with mild ventricular dilatation and with generally benign and selflimiting course [1,2,3,4,5,6,7,8,9,10,11,12]. Child's Nervous System (2021) 37:3021–3032 primary hydrocephalus (0.75 per 1000 live births) in a pediatric setting in the same population [11]. In most cases, it is idiopathic; secondary forms may be related to prematurity, intraventricular hemorrhage, subdural hematoma, meningitis, or increased intracranial venous pressure [3, 4, 6, 11, 12]. Classic Barlow’s theory (immaturity of arachnoid granulations) is not applicable in all cases, in early infantile period [13]
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