The authors describe four cases of subependymoma studied with computed tomography (CT) and review 18 previously reported cases in an attempt to define the most characteristic CT presentation of this rare, benign tumor. Subependymoma usually appears as an isodense, or even hypodense, intraventricular tumor on plain CT scan and shows minimal or no enhancement in postcontrast studies. Differential diagnosis between subependymoma and the more malignant true ependymoma is difficult, particularly when the tumor occurs in the posterior fossa. Recognition of subependymoma should prompt the surgeon to attempt radical tumor removal because it can be achieved without sacrificing contiguous tissue and carries a good prognosis.

We present a series of 56 children who suffered severe head injuries, with a Glasgow Coma Score (GCS) of less than 8. The cases were classified according to the type of morphologic lesion on computed tomography (CT) scan. Intracranial pressure (ICP) was monitored in all children in this series. A protocol that included artificial ventilation and other measures of treatment for intracranial hypertension was applied. Results were analyzed according to age, type of lesion, and ICP. The usefulness of the ICP recording and of obtaining a correct classification of lesions using the CT scan is emphasized.

A group of 78 severe head injury patients showing computerized tomography (CT) findings of the so-called "diffuse axonal injury" is analyzed. These patients represent 20% of the authors' series of severe head injury. Twenty-three patients showed small intraparenchymal haemorrhages in the CT scan study, 15 intraventricular haemorrhage and 40 patients had both intraparenchymal and intraventricular haemorrhages. Signs of brainstem haemorrhagic contusion were seen in 29 (38%) patients. Generalized brain swelling superimposed on the above findings was present in 75% of the cases. Raised intracranial pressure, which was found in 50% of the patients, correlated with the presence of ventriculocisternal collapse in the CT scan and an unfavourable outcome. Only 4 patients in this series made a good recovery, 13 developed a moderate disability, 11 a severe disability, 12 became vegetative and 38 (49%) died. The prognosis with this post-traumatic lesion is the worst in the authors' severe head injury series after excluding cases with subdural haematoma.

Eighteen children with severe head injuries and diffuse brain swelling were studied. They were separated into two groups based on the computed tomography (CT) findings. Seven patients had small ventricles in the normal location and small or absent cisterns. Eleven had these signs plus small deep-seated intraparenchymal hemorrhagic foci and/or intraventricular hemorrhage. Patients in the first group were in relatively good neurological condition; their intracranial pressure was easily controlled and all had a favourable outcome. On contrast, children in the second group had a more severe clinical presentation, frequently had uncontrollable intracranial hypertension, and more than 50% died.

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