Two Types of Delayed Post-Traumatic Intracerebral Hematoma

Takashi TSUBOKAWA

Department of Neurological Surgery, Nihon University School of Medicine, Tokyo 173

Summary The findings of repeated CT scans, clinicalcourses and pathologicalstudies in 28 cases of delayed post-traumatic intracerebral hematoma were studied retrospectivelyto elucidate the mechanism of bleeding and to establish adequate treatment. Based on the results obtained, it became clear that there are two types of delayed hematoma. In 10 of the 28 cases, initial CT findings within 6 hours after revealed cerebral contusion or hemorrhagic contusion, and spots of high density scattered in the low density zone gradually became confluent to form an irregularly shaped hematoma according to follow-up CT findings. This was termed "hematoma within a contusional area." In 15 of the 28 cases, initial CT findings within 6 hours after head injury revealed no abnormal density within the and the hematoma appeared suddenly 3 6 days after the injury. In eight of the 15 cases, emergency surgery was performed for the removal of epidural or . This type of hematoma is termed "contusional hem atoma" and constitutes the second group. In three of the 28 cases, both types of hematoma were observed. Based on histological findings for the two types of delayed hematoma. The first group may be induced by an anoxic vasodilation mechanism (Evans et al.9)), while the second group may be derived from a different mechanism related to ishemic changes and the free radical reaction caused by the reflow phenomenon (Tsubokawa et al.14-16)1 It is important to establish correct diagnoses 1for delayed hematomas based on differences between follow-up findings of repeated CT and an initial CT performed within 6 hours after head injury since the operative indications and operative results for the two groups are different as indicated by our 28 cases. Key words: Head injury, repeated CT, contusion, delayed hematoma

occurring immediately after trauma but with Introduction no typical posttraumatic apoplexy-like symp toms (Bollinger4), and has accounted for Delayed intracerebral hematoma following more than 50 % of traumatic intracerebral head injury is characterized by the appearance hematomas since CT was introduced in this of focal neurological signs or depression of particular field of diagnostics, computerized the level of consciousness, developing days or tomographic scanning (CT) is now the key weeks after the trauma. Prompt diagnosis diagnostic tool for this condition. However, and a decision concerning indication for even with CT it is difficult to make a correct surgery are necessary to minimize the harmful diagnosisof a delayed post-traumatic intracere effects that the hematoma may exert on the bral hematoma, to determine its exact patho already traumatized brain. genetic mechanism and to decide on the Because delayed traumatic intracerebral hem indication for surgery unless CT studies are atoma occurs in cases of severe head injury begun early after head injury and repeated is associated with focal neurological signs and until a hematoma of demonstrable size is depression of the level of consciousness formed (Tsubokawa et al. 14-16)) We reported previously that intracerebral after injury and diagnosis of delayed traumatic hematomas which, although not demonstrable intracerebral hematoma was ultimately estab in initial CT performed within 6 hours after lished by operation or autopsy were selected head injury, appear in repeated CT on 1 to 5 for the study (Table 1). days later can be classified into two types. One type includes those hematomas formed Results within a contused area which show evidence of cerebral contusion or hemorrhagic contusion in initial CT and are formed by the gradual I. Development and course of the two types of confluence of small hemorrhagic areas. The hematoma other type consists of those contusional hema In 10 of these 28 cases there was initial CT tomas which are not demonstrable, with no evidence of cerebral contusion or hemorrhagic evidence of contusion (Lanksch et al.101), in contusion, and a typical finding of multiple initial CT but appear within a normal brain punctiform or patchy areas of minor bleeding area later between 8 hours and 6 days after appearing in low density areas within 6 hours injury. after injury. These CT findings correspond The purpose of the present study was to respectively to Type I and Type II cerebral explore the possibility that these two types contusions according to the classification of of intracerebral hematomas are dissimilar Lanksch et al. Four of the 10 cases had an with respect to the mechanism of bleeding extracerebral hematoma, i.e., two with subdural and hence should be treated in a different way, hemorrhage and the other two with small based on CT findings, clinical courses and epidural hematomas at the fracture line. operative results obtained in our own series In all cases of Type I cerebral contusion of 28 cases of delayed traumatic intracerebral showing low density only in initial CT, the hematoma, and thereby to assess the clinical lesion developed into a hemorrhagic contusion value of the above classification. (Lanksch Type II10)) within 24 hours. By the third day of injury, these spots of bleeding Subjects gradually became confluent to form an ir regularly shaped hematoma (diameter of high From among the head injury cases seen at our density area exceeding 3 cm) which occupied hospital after the introduction of CT, 28 cases part of the initial low density area (Fig. 1). in which initial CT was nerformed 6 hours These hematomas are termed hematomas Table 1 Twenty-eight cases of traumatic delayed intracerebral hematoma classified into 2 groups based on CT findings, clinical courses and pathological findings. was performed within 24 hours after injury and four of them underwent additional decom pressive craniectomy. Among seven cases not undergoing emer gency evacuation surgery (three with subdural hematoma and four without extracerebral hematoma), an intracerebral hematoma became demonstrable in repeated CT scans within 24 hours after injury in two cases, within 48 hours in another two cases, and 3 to 5 days after injury in the remaining three cases. Fig. 1 CT scans illustrating the time course of Among eight cases in which an intracerebral delayed posttraumatic intracerebral hematoma hematoma developed after surgical removal (hematoma within a contusional area). A : Initial CT 5 hours after head injury. r of an extracerebral hematoma, the intracerebral subdural hemorrhage and 1-temporal contusion hematoma was formed within 4 hours after (Lanksch Type II) are observed. the operation in one case, 1 to 2 days after the B: CT findings 3 days after head injury. An operation in six cases and on the 5th postopera irregularly shaped intracerebral hematoma is tive day in one case. Intracerebral hematomas present in the contusion observed by the initial occurring after surgery for subdural or epidural CT. hematomas were ipsilateral to the preceding extracerebral hematoma in six cases and con within a contusional area since they are formed tralateral in the other two cases. from bleeding spots within a contused brain There were also three cases in the present area as reflected in the findings of repeated series where both a contusional hematoma and CT scans (Tsubokawa et al.14-16)) a hematoma within a contusional area were At the time when the diameter of the hema formed. In these cases, however, there was no toma exceeded 3 cm, shifting of the median concurrent extracerebral hematoma formation. structure was noted in eight of the 10 cases. In these two types of delayed traumatic In the other two cases where a hematoma intracerebral hematoma, impairment of con appeared at the frontal tip bilaterally or in the , no shifting of the median structure was seen. Fifteen of the remaining cases of delayed traumatic intracerebral hematoma had no abnormalities or only showed evidence of subarachnoid or sub or in CT performed within 8 hours after injury. The appearance of an intracerebral hematoma was recognized in repeated CT performed between 8 hours and 6 days after injury. This type of hematoma differed from hematomas within the contused area in that it did not show any contusion or high density spots in Fig. 2 CT scans illustrating the time course of the brain in initial CT (Fig. 2). It was arbitrarily delayed posttraumatic intracerebral hematoma termed a contusional hematoma (Tsubokawa (contusional hematoma). et al.14-16)) A: Initial CT 8 hours after head injury. There Initial CT scan findings were negative in are no visible pathological findings apart from r-subdural hematoma. This hematoma was re cases of contusional hematoma within 8 hours moved by emergency surgery just after the CT. after injury except in nine cases with concurrent B : CT findings 4 days after emergency cra subdural hematoma and two cases with con niotomy. There is no remaining r-subdural comitant epidural hematoma. In eight out of hematoma, but intracerebral hematoma is 11 case of extracerebral hematoma, evacuation observed in the 1-front-temporal area. sciousness ranging from confusion to a , returned to their premorbid life. Of the two anisocoria or impaired light reaction was noted patients treated nonsurgically, one had a in about 20% of the cases and hemiplegia was disability necessitating assistance in daily life present in 30% of the cases. However, no and the other successfully returned to a normal gross alterations of neurological symptoms life (Table 2). were seen to occur coincidentally with the Of the 15 cases of contusional hematoma, development of delayed intracerebral hema two presented brain stem symptoms immedia toma, nor were these instances in which late tely after sustaining injury, while in another apoplectic symptoms according to Bollinger there was confusion at the time of hospitaliza manifested themselves at the time of hematoma tion and a hematoma later developed in the formation. When a worsening of the preexisting right frontal lobe in the absence of impairment disturbance of consciousness occurs or no of consciousness. In a fourth case, a hematoma symptomatic improvement is noted after sur was formed in the occipital lobe 2 days after gical removal of an extracerebral hematoma, the operation for an epidural hematoma in development of delayed intracerebral hema the occipital region, but there was later im toma can be suspected. provement of consciousness with no shifting As mentioned previously, a hematoma of the median structure. These four cases within a contused area and a contusional were treated nonoperatively, while the remain hematoma coexisted in three out of the total ing 11 cases underwent evacuation of the 28 cases. However, these cases did not present hematoma as soon as it was discovered. any specific symptoms. Of the four nonsurgically treated patients, the two with symptoms immediately II. Methods of treatment of the two types of after injury had a fatal outcome, while the hematoma and therapeutic results other two who showed improvement of im Among the 10 cases of hematoma within a paired consciousness with no shifting of the contused area, two received conservative treat median structure in CT in spite of the develop ment only, while the other eight cases under ment of an intracerebral hematoma, were went surgical removal of the hematoma as soon successfully rehabilitated. as the diagnosis was established. During the Among the 11 patients undergoing surgery, operation, the brain surface was found to be three died postoperatively, two others con damaged and markedly swollen. The hematoma tinued to have some degree of disability and was present either as a mass or protruding into the remaining six returend to their premorbid adjacent edematous or necrotized brain tissue. life (Table 2). Two patients died postoperatively, another During surgery no appreciable damage was two had sequelae necessitating assistance in noted on the brain surface. The hematoma their daily activities and the remaining four formed a mass and adjacent brain tissues were Table 2 Operative results for traumatic delayed intracerebral hematoma affected mainly by edematous changes with no evidence of contusion. Discussion

III. Histological findings for both types of A study of repeated CT, operative and his hematoma tological findings in 28 cases of delayed intra Four cases of contusional hematoma and two cerebral hematoma (in which the initial CT cases of hematoma within a contusional area was performed within 6 hours after injury) were examined for histological features of the showed that these hematomas could be rea hematoma per se and its surrounding brain sonably divided into two distinct types. One tissues. The hematomas within a contusional was the hitherto hypothesized delayed type of area contained coagulated blood only with no intracerebral hematoma, i.e., hematoma within cerebral vessels and nervous tissue. The sur a contusion which is formed by the confluence rounding brain tissues were edematous and of small bleeding spots occurring in the contused necrotic, the blood vessels were dilated and at area. The other was contusional hematoma times obstructed, hemorrhagic spots were seen which develops from a hemorrhage in an area in the perivascular areas and petechiae were appearing as normal density in CT as reported often noted even in fairly distant areas (Fig. 3). previously by Tsubokawa et al.14 -16) and In the contusional hematomas the reactions of Diazet et al.8). Those intracerebral hematomas the surrounding brain tissues were essentially which, as claimed by Evans & Scheinker,9) the same as in the former type apart from the develop from hemorrhages caused by anoxia fact that the necrotic areas in the adjacent and vasoparalysis occurring in a contused area tissues were thin and dilatation of small vessels of the brain correspond to hematomas within was seen within a limited zone (Fig. 4). Within a contusional area. This has been considered the hematomas, however, blood vessels, which to represent the main mechanism of formation were thrombosed and infiltrated by lymphoid of delayed intracerebral hematomas (Evans cells, developed (Fig. 4). et al.,9) Lanksch et al.,") Weigel et al., 17) Ariga et al.') and Tsubokawa et al.14-16)) If

Fig. 3 Histological findings for hematoma within a contusional area. The sur rounding brain tissue is edematous and necrotic, while blood vessels are dilated with small perivascular bleeding. Fig. 4 Histological findings for contusional hematoma. The findings in the brain tissue surrounding the hematoma are essentially the same as for a hematoma within a contusional area, except that the border line of the contusional hema toma is clearer than that in the other type of hematoma. One specific finding, however, is the presence of thrombosed blood vessels with lymphoid cell infiltra tion in the hematoma. the CT findings of contusion obtained by result of injury and the resultant alterations Lanksch are true, this would mean that no in give rise to an abrupt contusion has occurred at the time of injury increase in blood flow in the ischemic brain in cases of contusional hematoma. However, area before low density becomes demonstrable histological findings indicate that there is by CT, thus causing hemorrhages in areas obstruction of small vessels with a distinct surrounding the ischemic lesion. It is postulated, tendency for hemorrhages to occur in areas therefore, that at least two different mecha peripheral to the contused area, suggesting nisms exist for the development of delayed that the hematoma is apparently unrelated to intracerebral hematomas. the lesion of the contusion both spatially and Both types of intracerebral hematoma are temporally. Moreover, contusional hematomas associated with slight disturbances of con tend to occur following surgery for epidural or sciousness and tend to show gradual improve subdural hematomas. These facts strongly ment. In cases without shifting of the median suggest that local traumatic ischemia with structure, conservative treatment proved to be subsequent displacement of brain tissue and effective, while those with a deteriorated level changes in intracranial pressure as well as an of consciousness and shifting of the median increase in cerebral blood flow following structure required surgical treatment. In this surgical removal of coexisting extracerebral respect, no substantial differences were observed hematomas, are involved in the pathogenetic between the two types of hematoma. The mechanism of contusional hematomas. success rate for rehabilitation following opera It seems justified therefore to conclude that tive treatment was higher in contusional small cerebral vessels become thrombosed as a hematomas than in hematomas within a con tusional area. It thus became clear that there are two types of delayed intracerebral hematomas which are similar concerning indication for surgery but differ in the treatment measures required for necrosis or of the surround ing brain tissue as well as in the results and outcome of operative treatment. The present study stresses the importance of a 1-week repeated CT follow-up subsequent to initial CT performed within 6 hours after injury for the discovery of delayed intracerebral hema tomas, and also the necessity of differentiating between contusional hematomas and hema tomas within a contusional area by repeated CT and thereby formulating an appropriate therapeutic plan.

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