cerebral was seen entering into the capsule, and this vein was considered to be not the bleeding source, but the result surrounded by the hematoma. 7) In the authors' experience, acute subdural bleeding never become en- capsulated after 10 or 15 days duration. 8) By some not too big blow, intradural bleeding is quite apparent. 9) Therefore, intradural bleeding may more easily develop by even slightest blow, when has hemorrhagic tendency. Pachymenigitis is of important as the disposition. 10) In the of chronic caused by pachymening- itis, abnormal fibrous proliferation is seen in the subendothelial part, where vessels are abundant. 11) The dura in some cases of chronic alcoholism showed quite the same to the severe pachymeningitis. 12) The dura of chronic subdural hematoma caused by relatively severe head trauma showed some difference ; irregular appearance of bleeding and organisation.

S-F-3. Bleeding Source of Chronic Subdural Hematoma

Jun-ichi KAWAFUCHI NeurosurgicalDepartment, Gunma UniversitySchool of Medicine

Bleeding source of the chronic subdural hematoma has been recognized by many previous studies. We attempted to elucidate the source of bleeding by the macroscopical and microscopical findings of the hematoma membranes. We have experienced for these ten years sixty cases of the chronic subdural hematoma. All hematomas were totally removed by the author except 3 cases, which were evacuated because the patients admitted in comatose state. The age and sexual incidence were as follows : under 10 years 2 ; 10 to 19 years 4 ; 20 to 29 years 8 ; 30 to 39 years 10; 40 to 49 years 18 ; 50 to 59 years 13 ; 60 to 69 years 4 and over 70 years 1 : male 60; female 0. Bilateral hematomas were proved in 3 cases. In the majority of cases (91.7x/) there was a definite history of injury to the head . In five cases the incidence of of head trauma could not be ascertened.

Results In 32 cases of the hematoma the origin of bleeding could be found during the removal of the hematomas; 21 from bridging vein, 11 from cortical vessels. In the cortical vessel group , torn vessels were arterial in three and venous in eight. In this group , transient initial loss of consciousness were found in 9 cases (82%), and its duration was ranged from 1 or 2

-112- minutes to 12 hours (average 3 hrs.). Neurological findings, such as hemi- paresis, aphasia, diplopia and etc., were proved in 9 cases (820%). Average duration of the free interval were 3 months. In the bridging vein group, transient initial loss of consciousness were observed in 4 cases, and its duration ranged from 1 minute to 30 minutes. Neurological changes were existed in 12 cases (56%). Average duration of lucid interval was 1.9 months. In remained 28 cases we could not find any source of bleeding. In this group, transient initial loss of consciousness was found in 11 cases (3900), and neurological findings were in 17 cases (60%). Average duration of lucid interval was 2.3 months. From the above-mentioned findings it was ascertained that there was some characteristic difference of symptoms between the cortical vessel group and other two groups of the chronic subdural hematomas. In cortical group, not only the loss of consciousness were longer than other groups, but also the lucid interval were also longer than others. These facts means in the cortical vessel group the cerebral damage seemed to be severe but the speed of accumulation of blood in the subdural space be slower than in other groups.

S-F-4. The Relationship between Head Injuries and Chronic Subdural Hematoma

Norio NAKAMURA Departmentof Neurosurgery,University of Tokyo

During the last 15 years, 135 cases of chronic subdural hematoma in adults,over 15 years of age, were admitted to the neurosurgicaldepartment of the University of Tokyo Hospital (Fig. 1). Over 91%/ of the total had sufferedfrom head injuries in the year prior to the admission(Fig. 2). Therefore, to find the relationshipbetween head injuries and chronic subdural hematoma,clinical investigationwas conducted on the histologicalaspects of subdural hematoma in general. In the case of severehead injuries followedby acute subdural hematoma, somefibroblasts were found to have infiltrated the clots located adjacent to the inner side of the dura mater, sometimeswithin 9 hours of the injury. On the 11th post-traumatic day, a thin granulation layer, composedof looseconnective tissue rich in vessels with thin walls, had already been producedjust beneath the dura, which is called the sinusoidal channel

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