[Histological study of operated cases of chronic subdural hematoma in adults: relationship between dura mater and outer membrane].

In 31 consecutive operated cases of chronic subdural hematoma (CSH) in adults, a histological study of the outer membrane and the dura mater was reported. Only 3 cases had vascular connections between the dura mater and the outer membrane. The vessels from (or to) the dura mater entered into the sinusoidal channel of the outer membrane. Dura mater always showed normal findings and was distinctly separated from the outer membrane, except for vascular connections. Because of this, they were regarded as different tissues. Hemorrhages in and out of the hematoma cavity of the outer membrane were seen in all 12 cases and seemed to be a reason for enlargement of CSH. There were 16 cases of eosinophilic infiltration in the outer membrane. No positive reaction was seen to estrogen receptor staining of either the dura mater or the outer membrane.