Computed tomography of extracerebral hematoma.

The appearance on C.T. of 30 extracerebral hematomas is described. Acute subdural hematomas were seen as bandlike lesions with markedly increased, homogenous density. Epidural hematomas demonstrated a high density and a biconvex, lenticular shape. During the process of liquefaction the density decreases and three hematomas appeared as isodense lesions. The majority of chronic subdural hematomas presented a mildly to moderately decreased, nonhomogenous density, the clearly identifiable inner wall of the lesion being either convex or concave. Subdural hygromas showed a homogeneous, markedly decreased density. Almost all the hematomas caused compression of the homolateral lateral ventricle and displacement of midline structures, particularly of the septum pellucidum. In 60% of the hematomas a dilatation of the contralateral lateral ventricle, predominantly of the posterior part was seen. Acute hematomas presented oedema in varying degrees, in chronic hematomas oedema was usually absent. In the original interpretation extracerebral hematomas were recognized as a lesion on C.T. in 97% (1 false negative result), in 90%, the lesion was correctly diagnosed as an extracerebral hematoma (1 false negative and 2 incorrect). The series contained one false positive C.T. scan and 2 intracerebral hematomas were interpreted incorrectly as subdural hematomas. The review C.T. diagnosis proved to be correct in 100%. C.T. and angiography appeared to have about the same diagnostic accuracy. However, C.T. is a non invasive investigation and it provides valuable additional information with regard to all the intracranial contents. Therefore C.T. should be the method of first choice in the diagnosis of extracerebral hematomas.