[Acute subdural hygroma in the posterior fossa (author's transl)]

Four cases of acute or subacute subdural hygromas in the posterior fossa were reported. All showed suboccipital skull fractures radiologically. Two cases of acute subdural hygromas were encounteded during the fiscal year from 1972 to 1973 at Toritsu Toshima Hospital. In the same period 254 patients with head injuries were admitted here and 106 demonstrated skull fractures. Among these 24 exhibited fractures in the suboccipital region. Among these 24 cases 8 showed signs and symptoms of space-occupying lesions in the posterior fossa and were confirmed later surgically (7 cases) or by autopsy (1 case), namely; three extradural hematomas, two acute subdural hygromas as mentioned above, three subdural hematomas with cerebellar contusions. Preoperative courses in these three acute subdural hygomas as well as three subdural hematomas were summarized as follows:lucid interval was followed by severe nuchal pain and rapid downhill course and finally by coma and panea. Retrograde brachial angiographies were performed in cases. The findings were not contributary to locate mass lesions, in three cases, partly because of delayed or faint filling of vessels caused by compression with hematoma or acute subdural hygroma. In short, differential diagnosis between subdural hematoma and subdural hygroma was difficult preoperating. Postoperatively, courses of subdural hematomas were poor or even fatal. On the contrary, patients of acute subdural hygromas showed rapid clinical improvement after evacuation of xanthochromic fluid. The authors stressed that suboccipital craniectomy should be performed as soon as possible to the patients with sugoccipital fractures when vital signs became progressively worse even if little findings were obtained by carotid angiographies. Subdural hygromas in the posterior fossa may have been present in those fatal cases where autopsy finds neither contusion nor hemorrhage but only brain edema or swelling.