Benign enlargement of the subarachnoid space in infancy
Bulging anterior fontanelle.
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Dilated subarachnoid spaces in the frontal and temporal lobes with well demonstrated bridging cortical veins within the space. The ventricular size and the cortical sulci are normal.
A small subdural fluid collection is demonstrated on the left side with well demarcated vertical limit between both subarachnoid and subdural spaces, also the well noted cortical veins on the right side adjacent to the inner table of the skull; whereas in the left side the veins are displaced away from the inner table, as the subarachnoid space is displaced by the fluid within the subdural space.
The following is important in the diagnosis of benign enlargement of the subarachnoid space (BESS) in infancy:
- It may be complicated by subdural hemorrhage that is explained by the stretching of the stretching of the bridging subdural veins due to enlargement of the cerebrospinal fluid (CSF) spaces.
- The presence of subdural hemorrhage in children <2 years of age raises two distinct possibilities - non-accidental injury (NAI) and BESS. For medico-legal reasons, the distinction between both of them is important. The absence of other features of, such as bone fractures and cerebral injuries, favors the diagnosis of BESS rather than NAI.
- There is a normal development, although delayed milestones may be encountered.
- Usually resolves spontaneously by 2 years of age.
- The cause makes the subarachnoid spaces enlarged in these children is the delayed maturation of the arachnoid villi.
- BESS may present with macrocephaly.