When lumbar or cisternal pneumoencephalography is carried out on children with nonprogressive brain lesions causing mental deficiency, cerebral palsy or epilepsy, air is seen in the subdural space in at least a third of cases. This proportion is much larger in children 2 years of age or under.
The roentgenographic appearances of subdural air are described and the importance of not attributing these appearances to cerebral atrophy or hypoplasia is emphasized.
In approximately one third of cases in which air enters the subdural space, that is, in from 10% to 15% of all cases, recovery from pneumoencephalography is delayed by the development of signs and symptoms suggesting a rise in intracranial pressure.
In such cases fluid can usually be found by needling the subdural space. Typically this fluid is characteristic of that found in subdural hematoma. There is no evidence that such a collection of fluid was present before pneumoencephalography.
It is therefore suggested that as air enters the subdural space and the brain falls away from the dura, vessels may be torn as they cross this space to reach the superior longitudinal sinus, with the formation of what may be termed subdural hematoma artefacta.
Although the incidence of this complication is moderately high, its effects are seldom serious, provided the situation is appreciated and suitable treatment given. The length of time the child spends in the hospital is, however, often greatly prolonged and occasionally operation proves necessary for removal of a subdural membrane.
Since the subdural hematoma is an artefact occurring in the course of treatment, its removal does not influence the ultimate prognosis.
INJURIES OF THE SUPERIOR LONGITUDINAL SINUS
