Extra-axial fluid collections are described as fluid collection that are external to the brain parenchyma. These include epidural hematomas, subdural hematomas, and subarachnoid hemorrhages. Intra-axial fluid collections develop within the brain parenchyma. Extra-axial fluid collections in children are classified as symptomatic and asymptomatic. Symptomatic extra-axial fluid collections have been classified as effusions, hematomas, or hygromas. Their appearance on computed tomography (CT) scans and the treatment for each are identical (Figure 149-1).1 CT scan images of symptomatic extra-axial fluid collections usually demonstrate ventricular compression and flattening or obliteration of the cerebral sulci on CT scans (Figure 149-1). Asymptomatic or benign subdural fluid collections usually appear as a hypodensity over the frontal lobes with dilation of the cortical sulci, interhemispheric fissure, and Sylvian fissure. The ventricles are usually normal in size or slightly enlarged with no evidence of transependymal flow.
CT scan image of a subdural hemorrhage.
Common presenting symptoms of a symptomatic extra-axial fluid collection include a depressed level of consciousness, lethargy, irritability, a large head, seizures, or vomiting. The physical examination may reveal fever, a full fontanel, gaze paresis, hemiparesis, increased tone, lethargy, macrocephaly, and retinal hemorrhages. Markwalder has done an excellent review of the pathophysiology and experimental studies of chronic subdural hematomas.2
Most extra-axial fluid collections result from head trauma, whether due to accidental trauma or nonaccidental trauma (NAT) formerly known as abuse.3 Other causes include the placement of a ventriculoperitoneal shunt and postinfectious bacterial meningitis. The etiology of intracranial hemorrhage and extra-axial fluid collections is quite varied (Table 149-1). Acute and chronic subdural fluid collections are not rare problems during infancy. Males are affected more commonly than females.
TABLE 149-1The Etiologies for Intracranial and Extra-Axial Fluid Collections |Favorite Table|Download (.pdf) TABLE 149-1 The Etiologies for Intracranial and Extra-Axial Fluid Collections
External hydrocephalus in a child with ventriculomegaly and extracerebral fluid
Extracerebral space is enlarged and filled with CSF-like fluid from the head being too large for the enclosed brain
Ventriculoperitoneal shunt malfunction
Look for a clear history of injury or trauma in the presence of an acute or chronic subdural hematoma.3 Consider the possible etiology of NAT if a history of an injury is not forthcoming or if the history does not make sense. It is incumbent upon the medical team to rule out abuse. This may require a period of inpatient observation, social services consultation, forensics consultation, a radiographic skeletal survey, a bone scan, and possibly an ophthalmological consultation. The presence of retinal hemorrhages in association with a subdural fluid collection is highly suspicious for NAT.4 Admission to the ...