Surgical Pathology of Subdural Hematoma

In 1934 one of us1reviewed a series of sixty-two cases of subdural hematoma and advanced the theory that the so-called chronic hematoma is only a late stage of an unrecognized earlier acute form. It was furthermore pointed out that so far as those data went there was evidence to show that every subdural hematoma starts as a mixture of blood and cerebrospinal fluid imprisoned in a space from which diffusion cannot readily take place. This mixture develops into a completely solid clot, at the one extreme, or a collection of fluid with a high protein content, at the other. The intermediate clots which possess any significant degree of fluidity were held to be expanding lesions. This was believed to be due to the osmotic effect of two fundamental factors: the dissolution of the blood and the diffusion of fluid across the piaarachnoid, which acts as a dialyzing membrane.