Korean Journal of Cerebrovascular Surgery 2011;13(2):80-83.
Published online June 1, 2011.
The Fluid-Blood Level in a Spontaneous Intracerebral Hematoma.
Jung, Young Jin , Kim, Min Soo , Chang, Chul Hoon , Choi, Byung Yon
Department of Neurosurgery, Yeungnam University Medical Center and Medical School, 5 Daemyeung-dong, Nam-gu 317-1, Daegu, South Korea. cch0102@ynu.ac.kr
Abstract
A fluid-blood level is rarely seen on computed tomography (CT) studies of intracerebral hematomas (ICHs). The CT appearance of a fluid-blood level in an ICH has been associated with intratumoral bleeding, subdural hematomas, anti-coagulation and ruptured arteriovenous malformations. When fluid-blood levels are located around a hematoma with significant peri-hematoma edema, the fluid-blood level may merely indicate bleeding of recent origin. A fluid-blood could also represent a coagulopathy when the fluid-blood level is located in the center of a hematoma with less peri-hematoma edema. We report four cases of acute intracerebral hematomas in which fluid levels were noted on CT scans with a review of previous reports.
Key Words: Fluid-blood level, Intracerebral hematoma

Introduction

An intracerebral hematoma (ICH) is a major cause of death in patients. In patients with normal hemostasis who develop an ICH, computed tomography (CT) shows a homogeneous, hyperdense lesion in the acute stage.4)6)7)9) A fluid-blood level is rarely seen on CT studies of ICHs and in fact, a fluid-blood level is an unusual pattern for an ICH. Fluid-blood levels may be associated with diverse pathogeneses;1)4)6)9)10) however, little is known about the underlying mechanism by which fluid-blood levels form and the significance of fluid-blood levels within the cerebral parenchyma. The pathogenesis or etiology of the phenomenon is often overlooked by the physician. We present four cases of ICHs in which fluid-blood levels were noted on CT with a review of the previous reports.

Case Report

Case 1

A 62-year-old male was brought to the emergency room for evaluation of a severe headache. The admission physical examination revealed asynergia and a blood pressure of 110/70 mmHg, without evidence of significant trauma. The hematocrit (Hct) was 37.6%, the prothrombin time (PT) was 76.9 seconds (control, 12 seconds) and the partial thromboplastin time (PTT) was 86.9 seconds (control, 40 seconds). Two years prior to admission the patient had developed a right middle cerebral artery infarction, for which he was anti-coagulated (warfarin, 3 mg/day). On admission, the CT scan performed 17 hours after the onset of symptoms revealed an ICH with a fluid-blood level located within the center of the hematoma and peri-hematoma edema involving the cerebellum (Fig. 1A, B)

Case 2

An 80-year-old normotensive male was admitted to the hospital with motor weakness on the right side. He showed no evidence of external trauma. Ten years previously he have received a pacemaker for atrial fibrillation, followed by oral warfarin (2 mg/day). The Hct was 50.5%, the PT was 63.2 seconds (control, 12 seconds) and the PTT was 68.5 seconds (control, 40 seconds). He consumed an excessive amount of alcohol (2~3 bottles of Soju daily). A CT scan performed 8 hours after ictus revealed an ICH with a fluid-blood level and mild peri-hematoma edema in the left temporal area. The fluid-blood level was located within the center of the hematoma (Fig. 1C). The patient’s medical status rapidly worsened and he expired soon after admission.

Case 3

A 63-year-old female was admitted in a stuporous state. The physical examination revealed left hemiparesis and a blood pressure of 130/90 mmHg. The Hct was 41.2%, the PT was 10.9 seconds (control, 12 seconds) and the PTT was 30.9 seconds (control, 40 seconds). The white blood cell count, hemoglobin level and platelet count were 8,960/µL, 13.3 gm/dL and 313,000/µL, respectively. The patient had been taking anti-hypertensive medication with aspirin for 1 year. A CT performed 1 hour after ictus revealed a typically-located hypertensive hemorrhage with a fluid-blood level. The fluid-blood level was located adjacent to the hematoma (Fig. 2A). She underwent emergency surgery, but no cavity or cystic lesion was found. She had no evidence of a bleeding diathesis or abnormal clotting factors.

Case 4

A 61-year-old female was admitted with a drowsy level of consciousness and right hemiparesis. The physical examination revealed a blood pressure of 90/60 mmHg. The Hct was 29.3%, the PT was 12.2 seconds (control, 12 seconds) and the PTT was 28.5 seconds (control, 40 seconds). The white blood cell count, hemoglobin level and platelet count were 12,050/µL, 9.83 g/dL and 220,000/µL, respectively. Three years previously she had undergone a total gastrectomy due to tubular adenocarcinoma without metastasis. CT and magnetic resonance imaging (MRI) performed 4 hours after ictus revealed a large hemorrhage with a fluid-blood level located around the hematoma and peri-hematoma edema (Fig. 2B, C). Conventional angiography was performed, but we could not find any pathognomonic findings. She also underwent emergency surgery and no pathognomonic lesion was found. Pathologic study of the specimens revealed a normal blood clot without metastasis or amyloid angiopathy.

Discussion

ICH is devastating disorder that has a poor prognosis and high mortality rate. ICHs may have various causes and usually presents on CT scans as areas of high density relative to the adjacent brain.4)6)7)9) A fluid-blood level, a familiar finding in subdural and intraventricular hemorrhages, implies the presence of a pre-existing fluid- filled space in which red blood cell settling can occur. In intraparenchymal hemorrhage, because of the absence of a potential space, clot formation takes place without sedimentation,6) thus the association of a fluid-blood level is uncommon in ICHs.1)6)9)10) A fluid-blood level is defined as a region within the ICH that has the following features: 1) upper compartment hypodense to the brain; 2) lower compartment hyperdense to the brain and 3) a sharply defined horizontal interface between the upper and lower compartments.5)

The finding of an intracerebral fluid-blood interface has been reported in patients with metastatic melanoma and ruptured arteriovenous malformations and in cases of recent ICH.1)6)9)10) Anti-coagulation may also cause multiple intracerebral fluid-blood levels.4)

The mechanisms that may explain the formation of fluid-blood levels are not known, although a few hypotheses have been suggested. One possibility is that cerebrospinal fluid (CSF) might have dissected into the space created by the parenchymal hemorrhage, resulting in a CSF-blood level.9) In patients with AVMs, the origin of the fluid-blood level is believed to cause extravasation of blood into pre-existing cystic cavities.6) In neoplastic conditions in which a fluid-blood interface exists, there is frequently enhancement at the periphery of the lesion. These findings probably reflect the presence of local agents that lyse the blood clot. These factors have been found within intracranial tumors.5)

A possibility is that intracerebral hematomas with a fluid-blood interface secondary to a coagulation defect, prevent clot formation or lyse the coagulum once it is formed.5) Consumption of all clotting factors results in two components, creating a fluid-level.3)4) In vitro studies also support the hypothesis that an intracerebral hemorrhage fluid-blood level reflects the inability to either form or maintain a clot matrix.5) In cases 1 and 2, the fluid-blood interface could be explained by this hypothesis. Gebel et al.2) reported that hemorrhages caused by coagulopathy are large and have mild peri-hematom edema. This would be consistent with the finding that the activity of clotting factors may be related to formation of early peri-hematoma edema. In comparison to spontaneous ICHs, thrombolysis-related ICHs have visible peri-hematoma edema in < 50% of the cases with spontaneous ICHs and also had lower amounts of absolute and relative volumes of edema.2) In case 1, the initial CT scan showed a fluid-blood level with mild peri-hematoma edema (Fig. 1 A, B). In case 2, this revealed typical coagulopathy-related hemorrhage with a fluid-blood level and minimal visible peri-hematoma edema (Fig. 1 C). Cases 1 and 2 showed that coagulopathy-related ICH could present with atypical CT findings. Fluid-blood levels located in the center of the hematoma and mild peri-hematoma edema were seen. In this situation, therapies directed at reducing peri-hematoma edema may help to prevent the associated mass effect and potential herniation after ICH.8)

Like cases 3 and 4, fluid-blood levels were noted in patients with spontaneous ICHs without any identified etiology or abnormal hemostasis.9) In these cases, several potential mechanisms were postulated, as follows: 1) the hematoma was acute and clotting of extravasated blood was not complete when the CT was performed; 2) following a sudden burst of blood within the brain parenchyma, there was an initial sudden demand, followed by rapid exhaustion of the blood clotting factors, resulting in settling of the heavier clotted blood posteriorly and layering of unclotted blood anteriorly and 3) following intraparenchymal bleeding, a normal clotting process followed and resulted in settling of clotted blood posteriorly and layering of serum anteriorly.9) In case 3, the operative findings revealed posteriorly-located clotted blood with a fluid collection which was suspicious for serum. In cases 3 and 4, the fluid-blood level was located around the hematoma with significant peri-hematoma edema, which differed from that of coagulopathy patients.

Although the number of cases is small and further studies are needed to support our hypothesis, we could hypothesize the following: 1) ICH with coagulation defects could demonstrate fluid-blood levels located within the center of the hematoma with lesser peri-hematoma edema on CT; 2) recent bleeding with normal hemostasis could present the fluid-blood level around the hematoma with peri-hematoma edema.

Conclusion

ICHs associated with fluid-blood levels are uncommon, and may be associated with diverse pathogeneses. When the fluid-blood level is located around a hematoma with significant peri-hematoma edema, the fluid-blood level could merely indicate bleeding of recent origin. The fluid-blood level could also be due to coagulopathy when it is located in the center of a hematoma with less peri- hematoma edema. Patients with occult pathology have a poor prognosis and require special treatment. Thus, an ICH with a fluid-blood level should prompt a thorough search for occult pathology.

REFERENCES

1)Dublin AB, Norman D. Fluid-fluid level in cystic cerebral metastatic melanoma. J Comput Assist Tomogr 3:650-2, 1979

2)Gebel JM, Brott TG, Sila CA, Tomsick TA, Jauch E, Salisbury S et al. Decreased perihematomal edema in thrombolysis-related intracerebral hemorrhage compared with spontaneous intracerebral hemorrhage. Stroke 31:596-600, 2000

3)Iplikçioğlu AC, Bayar MA, Kökes F, Yildiz B, Gökçek C, Buharali Z. A fluid level in an acute extradural haematoma. Neuroradiology 36:31-2, 1994

4)Livoni JP, McGahan JP. Intracranial fluid-blood levels in the anticoagulated patient. Neuroradiology 25:335-7, 1983

5)Pfleger MJ, Hardee EP, Contant CFJ, Hayman LA. Sensitivity and specificity of fluid-blood levels for coagulopathy in acute intracerebral hematomas. AJNR Am J Neuroradiol 15:217-23, 1994

6)Richmond T, Virapongse C, Sarwar M. Intraparenchymal blood- fluid levels: new CT sign of arteriovenous malformation rupture. AJNR Am J Neuroradiol 2:577-9, 1981

7)Weisberg LA. The fluid-blood level in intracranial haematoma due to anticoagulant medication. J Neurol Neurosurg Psychiatry 50:1076, 1987

8)Woo D, Broderick JP. Spontaneous intracerebral hemorrhage: epidemiology and clinical presentation. Neurosurg Clin N Am 13:265-79, 2002

9)Zilkha A. Intraparenchymal fluid-blood level : a CT sign of recent intracerebral hemorrhage. J Comput Assist Tomogr 7:301-5, 1983

10)Zimmerman RA, Bilaniuk LT. Computed tomography of acute intratumoral hemorrhage. Radiology 135:355-9, 1980



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