Abstract
Sequential changes of clinical symptoms and computed tomography (CT) scans were investigated in 20 patients of chronic subdural hematoma treated by osmotherapy utilizing intravenous 20% mannitol 1, 000 ml daily for 2 weeks. Plain, contrast enhancement, and 4-hour-delayed contrast enhancement CT scans were taken once every week for 4 weeks from the start of the treatment and then once every month until hematoma disappeared. Though the clinical symptoms aggravated slightly in 4 cases during the first or second week, all the cases became asymptomatic at the end of the treatment and showed no recurrence thereafter. Sequential changes in CT scans are summarized as follows. 1) Plain CT scans showed that the hematoma started to reduce in size rapidly after termination of the treatment. Density of hematoma decreased sequentially, although it increased transiently in 9 cases. After treatment, the hematoma disappeared after 3 months in 18 cases, after 4 months in one case, and 5 months in one case. 2) In contrast enhancement CT, two types of contrast enhancement were observed: ribbon-like cortical enhancement and linear enhancement beneath the hematoma. These enhancement effects were seen in 80% of cases (cortical enhancement in 70%, linear enhancement in 10%) before the treatment. The cortical enhancement decreased through the treatment and disappeared in 2 months after the treatment. 3) The contrast enhancement effects within the hematoma cavity (evaluated as the relative increase of the CT numbers in the 4-hour-delayed contrast enhancement CT scans) were closely related to the hematoma reduction rate; the more marked and lasting the enhancement effects, the more delayed was the hematoma to be reduced by osmotherapy. These results may support the authors' previous view, based on an elect ronmicroscopic study, that the permeability in the sinusoidal channel layers of the outer membrane of the hematoma increases in the active and growing stage and gradually normalizes in the healing stage. The delayed contrast enhancement study is thought to be useful in evaluating the activity of chronic subdural hematoma.
