[Traumatic subarachnoid hemorrhage--clinical study of 16 cases].

Three hundred and eighty three cases with head injury were admitted to our hospital during period from March 1985 to October 1986. Among these cases, 16 (4.2%) had subarachnoid hemorrhage as revealed on computerized tomography (CT) scan; other CT findings included epidural hematoma, subdural hematoma and/or cerebral contusion. Traumatic subarachnoid hemorrhage was most frequently found in the ambient and/or sylvian fissure. This suggests that head blow tended to product shear strain at the brainstem and in the direction from temporal tip to frontal base. Furthermore tentorial edge and sphenoid ridge may have played an important role in producing subarachnoid hemorrhage. Of the 6 cases with the hemorrhage localized in the unilateral cisterns, 5 cases had the hemorrhage in the cisterns opposite to the blow site. This suggests that shear strain was produced more strongly at the opposite side to the blow site. The cases with subarachnoid hemorrhage in the prepontine and/or interpeduncular cistern had severe brainstem damage and their prognosis was very poor, while those with the hemorrhage localized in the ambient cistern, quadrigeminal cistern and/or sylvian fissure without other findings had good prognosis.