The pseudotumor cerebri.

Pseudotumor cerebri is the most appropriate term yet devised for classifying clinical patterns marked by papillary edema, uni- or bilateral, without major clinical signs and with normally sized cerebral ventricles, in which clinical or radiological investigations have ruled out the presence of a space occupying lesion of infective process. Because pseudotumor cerebri is a syndrome and its etiologies are many and varied, it is still difficult to make a diagnosis other than by exclusion. However, the knowledge that has accumulated as a result of epidemiological, clinical, neuroradiological, and experimental research enables us to say that the explanation of pseudotumor cerebri lies, on the one hand, in a sluggishness of the intracranial venous circulation with a consequent increase in cerebral blood volume and slowing of cerebrospinal fluid absorption and, on the other, in the onset of cerebral edema, either hypo-osmolar or vasogenic. The differing extent to which these three components participate in the clinical pattern depends on the etiology, but the resulting syndrome is always the same, though varying in clinical expression and pathogenesis.