Computed-tomography of bilateral isodense chronic subdural hematomas

Summary While unilateral chronic isodense subdural hematomas as a result of indirect signs of a space-occupying lesion are easily recognizable on computed tomography (CT) and clearly diagnosed on the angiogram, bilateral chronic isodense subdural hematomas may cause considerable difficulty. In two cases with CT false negative findings we observed, retrospectively, significant small cellae mediae and also the main part of the anterior horns sharply pointed and approaching one another. Three further cases showed the same ventricular configuration, which we called hare's ears sign. This sign together with clinical data is always suspicious of chronic bilateral isodense subdural hematomas and carotid angiography is indicated. Other possible signs are: subtle midline shift if the size of the hematoma varies, changed formation of density of brain tissue, non-appearance of cerebral sulci especially in elderly patients, and eventually the visualization of a membrane after intrevenous injection of contrast material.     

Acute subdural hematomas: atypical CT findings

Seventy-one patients with acute subdural hematomas were examined by CT within 72 hr of a documented head injury. Lesions often did not have the classical appearance of a homogeneous, high-density extracerebral collection of blood in a crescentic configuration. Specifically, 28 patients (39%) had mixed-density subdural hematomas (MDSDH) with various degrees of low-density blood within the subdural space. In 10 of these 28 patients, the hematoma had a relatively localized mass effect with a convex inner margin, occasionally mimicking the appearance of an epidural hematoma. The MDSDH group differed from the typical homogeneous high-density subdural hematomas in that they were larger (average maximal thickness was 18.1 mm versus 8.0 mm), had more midline shift, and had a higher mortality rate (50% versus 26%). Four patients with MDSDH demonstrated an unusual pattern of ventricular compression with trapping of cerebrospinal fluid in the body of the ipsilateral ventricle and compression of the body of the contralateral ventricle. This pattern has to our knowledge not been previously described. Possible causes of the low-density regions within the hematomas include unclotted blood in an early stage of hematoma development, serum extruded during the early phase of clot retraction, or cerebrospinal fluid within the subdural space due to an arachnoid tear.     

Diffuse dural gadolinium MRI enhancement associated with bilateral chronic subdural hematomas

Chronic subdural hematomas (CSDHs) typically present with cognitive dysfunction and a history of trauma. Localized dural enhancement on postcontrast MRI scans associated with the surrounding membrane has been described in CSDH. We present an 83-year-old man with rapidly progressing cognitive dysfunction 4 weeks after head trauma related to a fall. MRI showed CSDHs, which in addition to localized dural gadolinium enhancement, showed a marked diffuse, symmetric, contiguous pachymeningeal enhancement of the supratentorial and infratentorial intracranial dural mater. Meningeal biopsy failed to disclose an infectious or neoplastic cause of the enhancement and instead showed fibrocollagenous change. We conclude that diffuse dural enhancement on MRI scans associated with CSDH cause does not necessarily indicate a superimposed process such as infection or malignancy. CSDH should be considered in the differential diagnosis of diffuse dural enhancement, especially when supported by appropriate clinical findings.     

新生儿蛛网膜下腔出血的CT评价

目的探讨新生儿蛛网膜下腔出血的CT影像特征及其临床意义。方法回顾分析79例临床证实、CT资料齐全的新生儿蛛网膜下腔出血患儿的CT特征,所有患儿均在初治疑诊后3～48h内经常规CT扫描。结果 CT扫描证实,79例中镰刀征15例（19.0%）,三角征28例（35.4%）,表现为侧裂池、前后纵裂池高密度影17例（21.5%）,小脑幕增宽19例（24.1%）。结论新生儿蛛网膜下腔出血CT表现具有特征性,有助于判定病情严重程度,预测患儿预后,以及指导临床治疗。     

Age determination of subdural hematomas with CT and MRI: A systematic review

Objectives

To systematically review the literature on dating subdural hematomas (SDHs) on CT and MRI scans.

Methods

We performed a systematic review in MEDLINE, EMBASE and Cochrane to search for articles that described the appearance of SDHs on CT or MRI in relation to time between trauma and scanning. Two researchers independently screened the articles, assessed methodological quality and performed data extraction. Medians with interquartile ranges were calculated. Differences were tested with a Mann–Whitney U or Kruskal–Wallis H test.

Results

We included 22 studies describing 973 SDHs on CT and 4 studies describing 83 SDHs on MRI. Data from 17 studies (413 SDHs) could be pooled. There were significant differences between time intervals for the different densities on CT (p < 0.001). Time interval differed significantly between children and adults for iso- and hypodensity (p = 0.000) and hyperdensity (p = 0.046). Time interval did not differ significantly between abused and non-abused children. On MRI, time intervals for different signal intensities on T1 and T2 did not differ significantly (p = 0.108 and p = 0.194, respectively).

Conclusions

Most time intervals of the different appearances of SDHs on CT and MRI are broad and overlapping. Therefore CT or MRI findings cannot be used to accurately date SDHs.     

蛛网膜下腔出血磁共振成像与CT的对照研究

目的：利用磁敏感加权成像（SWI）、液体衰减反转恢复（FLAIR）、CT诊断蛛网膜下腔出血（SAH）,进一步比较联合磁共振成像（MRI） SWI/FLAIR与CT比较评估MRI是否优于CT。方法25例经临床证实的蛛网膜下腔出血的患者纳入本研究,所有患者均在发病3 d内进行CT、MRI检查。观察CT及MRI图片,将蛛网膜下腔分为8个区进行分析。结果总共145个区域被诊断为SAH,CT诊断了105个区域（72．4％）, FLAIR诊断了125个区域（86．2％）,SWI诊断了137个区域（94.5％）,FLAIR联合SWI诊断了135个区域（93．1％）。结论 FLAIR、SWI对于SAH的显示优于CT,FLAIR对颞枕部病灶的显示具有优势,SWI对中央区域的SAH比较敏感,将FLAIR、SWI两者融合,可以互补,能更准确地诊断SHA。     

Spontaneous spinal subarachnoid hemorrhage associated with subdural hematoma at different spinal levels

We describe the clinical features and MR-imaging findings of spontaneous spinal subarachnoid hemorrhage located in the lumbar spine associated with subdural hematoma at a higher, thoracic level in a 66-year-old man without neurological deficit. The sequential MR-imaging changes of hemorrhage at various stages in its evolution are portrayed. The possible pathogenetic mechanism for these very unusual, combined hemorrhages in both spinal compartments is discussed.     

自发性肾破裂、硬膜下血肿并蛛网膜下腔出血1例

患者，男34岁．无诱固突发上腹及有腰部剧痛．在个体诊所以肾绞痛治疗3日无效而来我院，自述有高血压病史。     

Effect of methemoglobin formation on the MR appearance of subarachnoid hemorrhage

Subarachnoid hemorrhage has a much higher intensity in magnetic resonance (MR) images with the passage of time. Acute subarachnoid hemorrhage is difficult to see; within 1 week its appearance has become intensified on T1-weighted images. Different concentrations of blood and lysed red blood cells in cerebrospinal fluid (CSF) were examined spectroscopically but did not significantly alter T1 and T2 relaxation of CSF acutely. Ultraviolet visible spectroscopy of bloody CSF stored hypoxically for 3 days showed the presence of methemoglobin. The iron in methemoglobin is paramagnetic; in combination with water this facilitates T1 relaxation. It is concluded that methemoglobin formation with T1 shortening at least partially accounts for the increasing intensity of the MR appearance of subarachnoid hemorrhage over time in the central nervous system and may also explain the intense appearance of subacute hemorrhage in MR images elsewhere in the body.     

大脑镰、小脑幕硬膜下血肿的CT诊断价值

大脑镰、小脑幕硬膜下血肿较少见,常与蛛网膜下腔出血、脑膜钙化不易鉴别而漏诊或误诊。本文收集36例大脑镰、小脑幕硬膜下血肿的CT资料结合文献分析如下。1资料与方法36例大脑镰、小脑幕硬膜下血肿中,男25例,女9例,年龄27~67岁,平均48岁。车祸伤31例、建筑工地坠落伤3例、击打     

Falx and interhemispheric fissure on axial CT: II. Recognition and differentiation of interhemispheric subarachnoid and subdural hemorrhage

Interhemispheric hyperdensity or unenhanced computed tomography was originally considered a sign of subarachnoid hemorrhage, the "falx sign." It has since been identified as a normal feature and has also been seen with interhemispheric subdural hemorrhage. To determine the differential features of interhemispheric hemorrhage, 50 patients with subarachnoid hemorrhage and 32 patients with interhemispheric subdural hematomas were reviewed. Subarachnoid hemorrhage produced anterior interhemispheric hyperdensity only, with a zigzag contour and extension from the calvarium to the rostrum of the corpus callosum. Interhemispheric subdural hematomas produce unilateral crescentic hyperdensities that are largest in the posterior superior part of the fissure, behind and above the splenium of the corpus callosum. Interhemispheric hyperdensity in children is more complex. Because the anterior part of the fissure is narrow in younger patients, subarachnoid hemorrhage may go undetected. Likewise, interhemispheric subdural hematomas in children are smaller and more difficult to recognize. They produce asymmetric thickening of the falx shadow with extension over the tentorium. They are, however, of great significance since they are generally seen in abused patients and carry a poor prognosis.     

CT诊断特殊征象的蛛网膜下腔出血

目的:探讨蛛网膜下腔出血的特殊CT征象,提高对此病变的诊断率。方法:回顾性分析17例经证实的具有特殊CT表现的蛛网膜下腔出血病例,分析其形成机理,CT表现特征及与硬膜下血肿的鉴别要点。结果:所有病例均含有颅骨内板下新月形高密度影这种酷似硬膜下血肿的CT表现,但具有内缘不锐利,密度较低且不均匀的特征。结论:CT可以诊断具此特殊表现的蛛网膜下腔出血并与硬膜下血肿鉴别。     

Increased density of tentorium and falx: a false positive CT sign of subarachnoid hemorrhage

Noncontrast computed tomographic (CT) findings in 10 patients with profound brain swelling or a mass effect revealed a high density of the falx and tentorium and thus suggested subarachnoid hemorrhage. Postmortem examinations performed shortly after the CT scans demonstrated no subarachnoid blood. A review of 100 CT scans drawn at random was carried out to assess the frequency of a hyperdense, noncalcified falx in the same population and failed to demonstrate this finding. Therefore, in the presence of profound brain swelling or a mass effect, factors other than subarachnoid hemorrhage may be responsible for increased density of the falx and tentorium on cranial CT head scans.     

Spontaneous subarachnoid hemorrhage with negative angiography: CT findings.

Computed tomography of 31 patients with spontaneous subarachnoid hemorrhage (SAH) but negative angiography was evaluated to find out whether the pattern of SAH as seen in CT offers indications for a possible reexamination with angiography. Based on the distribution and the amount of SAH, classification into three groups was possible: (a) 18 cases, normal CT (but blood in the CSF, gained by lumbar puncture) or SAH in the basal cisterns only; repeat angiography was negative in all these cases; (b) nine cases, SAH in the basal cisterns as well as in one or both Sylvian fissures; in addition, small amounts of blood in the interhemispheric fissure and/or in the sulci; repeat angiography revealed an aneurysm in one of these cases; (c) four cases, large quantities of blood in all subarachnoid spaces; in all but one of these cases a vascular lesion was visualized with repeat angiography or verified at autopsy. In conclusion, repeat angiography is mandatory in cases with SAH patterns that can be classified into group b or c, whereas it can be omitted in patients with small amounts of blood confined to the basal cisterns.     

CT of subarachnoid hemorrhage due to ruptured aneurysm

Computed tomographic scans in 81 consecutive patients wih subarachnoid hemorrhage due to ruptured aneurysm were analyzed for patterns of hemorrhage and lucency and correlated with the development of spasm and hydrocephalus. The circulation time was measured angiographically in representative cases of spasm. Hemorrhage corresponded in a general way to the fossa of aneurysm origin and, when there was parenchymal or ventricular hemorrhage, in more specific ways to anterior communicating, middle cerebral, and posterior inferior cerebellar artery aneurysms. Basal ganglionic hemorrhages due to aneurysm ruptures occurred in two cases and could not be distinguished by appearance from hypertensive hemorrhage. Regions of low attenuation (lucencies) were often persistent and had lateralizing value; they showed a high correlation with arterial spasm. Conversely, spasm, particularly of a distal type, showed a significant correlation with increased circulation time and the occurrence of brain lucency. In cases of multiple aneurysms arising from different vessels in which there was hemorrhage or lucency, CT scans correctly predicted the site of aneurysm in 77% of cases. Periventricular lucency was a weak predictor of progressive hydrocephalus, while an intraventricular hemorrhage was a strong predictor of moderate to severe hydrocephalus.     

The changing angiographic appearance of an arteriovenous malformation after subarachnoid hemorrhage

Summary The changing angiographic appearance of a cerebral arteriovenous malformation (AVM) illustrated hemodynamic changes that can occur following subarachnoid hemorrhage and antifibrinolytic therapy. Decreased size of this lesion suggested thrombosis of the AVM. This appearance actually represented a transient, vasospastic phenomenon which reversed with time. Although the AVM underwent significant changes acutely, little changed in the long term.