Extra-axial fluid collections in children are classified as symptomatic and asymptomatic. Symptomatic, chronic extra-axial fluid collections have been variously classified as hematomas, effusions, or hygromas with differing definitions associated with each. It has been proposed that they all be classified together as extra-axial fluid collections because their appearance on CT scan and the treatment is identical.1 Symptomatic, chronic extra-axial fluid collections usually show ventricular compression and flattening or obliteration of the cerebral sulci on CT scans. Benign subdural fluid collections usually appear as a hypodensity over the frontal lobes with dilatation of the interhemispheric fissure, cortical sulci, and Sylvian fissure. The ventricles are usually normal or slightly enlarged with no evidence of transependymal flow.
Seizures, a large head, vomiting, irritability, depressed level of consciousness, and lethargy are common presenting symptoms of a symptomatic extra-axial fluid collection. The physical examination reveals a full fontanel, macrocephaly, fever, lethargy, hemiparesis, retinal hemorrhages, generalized increased tone, or gaze paresis. Markwalder has done an excellent review of the pathophysiology and experimental studies of chronic subdural hematomas.2
The majority of extra-axial fluid collections result from head trauma. Other causes include bacterial meningitis (postinfectious) and the placement of a ventriculoperitoneal shunt. The etiology of intracranial hemorrhage and extra-axial fluid collections are quite varied (Table 120-1). Acute and chronic subdural fluid collections are common problems during infancy. Males are affected more commonly than females. A clear history of injury or trauma should be sought in the presence of an acute or chronic subdural hematoma. Consider the possible etiology of child abuse if a history of 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, a radiographic skeletal survey, a bone scan, and possibly an ophthalmological assessment. The presence of retinal hemorrhages in association with a subdural fluid collection is highly suspicious for child abuse. Admission to the hospital for further observation is warranted if child abuse cannot be ruled out. The presence of congenital anomalies may predispose the child to subdural hematoma formation.
Table 120-1 The Etiologies for Intracranial and Extra-Axial Fluid Collections ||Download (.pdf)
Table 120-1 The Etiologies for Intracranial and Extra-Axial Fluid Collections
Extracerebral space is enlarged and filled with CSF-like fluid as a result of the head being too large for the enclosed brain
External hydrocephalus in a child with ventriculomegaly and extracerebral fluid
Ventriculoperitoneal shunt malfunction
Percutaneous removal of the subdural fluid is useful in diagnosing an active infection and rapidly lowering the intracranial pressure in the symptomatic patient. Repeated removal of the fluid by percutaneous aspirations has been advocated by some Neurosurgeons for definitive treatment of chronic extra-axial fluid collections.3...