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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 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, and lethargy are common presenting symptoms of symptomatic extra-axial fluid collections. 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. 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 cases of acute or chronic subdural hematomas. If a history of injury is not forthcoming, every opportunity should be seized to investigate the child and the social setting to screen for child abuse. It is incumbent upon the medical team to rule out abuse. This may require a period of observation, social services consultation, a radiological 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.


Percutaneous removal of the subdural fluid is useful in diagnosing active infection and rapidly lowering intracranial pressure in patients who are symptomatic. Repeated removal of the fluid by percutaneous aspirations has been advocated by some Neurosurgeons for definitive treatment of chronic extra-axial fluid collections.3,4 Subdural fluid collections in infants have a tendency to increase in size, are often bilateral, can be difficult to diagnose, and are most often seen in children under the age of two years. The combination of CT and MRI imaging is usually diagnostic.


A subdural aspiration (or tap) is usually performed by puncturing the anterior fontanel. However, it can also be approached through the coronal suture as well as through the soft cranium. The diamond-shaped anterior fontanel is formed by the junction of the sagittal, coronal, and frontal sutures (Figure 101-1). It measures approximately 4 cm in the anteroposterior plane and 2.5 cm in the transverse plane. ...

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