Computed tomographic characteristics of chronic subdural hematomas

Although medical history and physical examination should lead to diagnosis of chronic subdural hematomas, 40% of these patients are likely to be misdiagnosed because many of these symptoms occur in other disease processes, such as transient ischemic attacks, stroke, dementia, and tumors. Computed tomography remains one of the most useful tools in the evaluation of these patients because of its rapidity, cost, availability, and pathologic sensitivity.     

Reversible dementia in patients with chronic subdural hematomas

OBJECT: Neuropsychiatric changes following surgery for chronic subdural hematomas (CSDHs) were analyzed in 26 patients (21 men and five women) by using the Mini-Mental State Examination (MMSE) and the Hasegawa Dementia Scale-Revised (HDS-R) to determine factors that potentially contribute to neuropsychiatric recovery. METHODS: Burr hole irrigation was performed in every patient to treat the CSDH. The patients' profiles, including age and sex, neuroimaging findings (such as hematoma volume and thickness, as well as midline shift), and preoperative and postoperative scores on the MMSE, HDS-R, and activities of daily living (ADL) scale were recorded. According to preoperative MMSE scores, eight patients (30.8%) were classified as mentally healthy and 18 (69.2%) as suffering from dementia before surgery. Nine of the 18 patients with dementia recovered to a normal psychological state following surgery. Surgery improved not only the patients' independence in ADL (p = 0.0026), but also their neuropsychiatric functions such as orientation and calculation, as estimated by scores on the MMSE (p = 0.0002) and the HDS-R (p = 0.0008). Factors affecting neuropsychiatric status on admission were midline shift (p = 0.0398) and ADL score (p = 0.0124); factors that could be used to predict neuropsychiatric recovery after surgery were patient age (p = 0.0027) and ADL score (p = 0.0193). The results of a logistic regression analysis demonstrated that significant predictors of neuropsychiatric recovery after surgery include the following: patient age (p = 0.0049, odds ratio [OR] = 0.842) and preoperative ADL (p = 0.0056, OR = 0.471), MMSE (p < 0.0001, OR = 1.895), and HDS-R (p = 0.0073, OR = 1.303) scores. Results of subgroup analyses demonstrated that patients younger than 74 years of age and those who had preoperative scores lower than 5 on the converted ADL scale, higher than 10 on the MMSE, or higher than 9 on the HDS-R on admission were found to have a significantly better recovery of neuropsychiatric functions after surgery. CONCLUSIONS: Dementia is reversible in many patients with CSDH, and surgery can improve not only independence in ADL, but also neuropsychiatric functions. Patients who are younger and/or those who have lower preoperative ADL scores and/or higher preoperative MMSE or HDS-R scores will achieve a good recovery with regard to neuropsychiatric functions after surgery. Estimations of neuropsychiatric function based on MMSE and HDS-R scores were found to be useful in predicting functional outcomes in patients with CSDH.     

Regional cerebral blood flow and metabolism in chronic subdural hematoma

There are two hypotheses on how chronic subdural hematoma causes hemiparesis and other focal neurologic symptoms without, in most cases, leaving permanent neurologic deficits. One hypothesis is that the reduced regional cerebral blood flow (rCBF) caused by either compression or distortion of the local or remote brain tissue is responsible for hemiparesis. The other hypothesis is that the reduction in rCBF alone is not sufficient to cause permanent hemiparesis.     

Comparison of cerebral blood flow in computed tomographic hypodense areas of the brain in head-injured patients

OBJECTIVE: Hypodense lesions identified on computed tomographic (CT) scans are often assumed to indicate ischemia. The purpose of this study was to investigate regional cerebral blood flow (rCBF) in hypodense areas of the brain after severe traumatic brain injury. METHODS: CBF was measured by stable xenon-enhanced CT scans. Hypodense areas were identified, and rCBF values as well as CT density were averaged for the region. RESULTS: Thirty (60%) of the 50 patients had a total of 45 hypodense regions, which were associated with either contusion (n = 30) or areas of infarction (n = 15). rCBF in the hypodense regions was variable, ranging from a low of 3.3 to a high of 72.5 ml/100 g/min. The cause of the lesion was the major factor associated with the level of rCBF. Although the average decrease in CT density was similar for the two types of lesions, the average rCBF was significantly lower and the difference in rCBF between the lesion and the contralateral side was greater when the hypodense lesion was associated with a contusion. A critical reduction in rCBF (<20 ml/100 g/min) was found in 19 (63%) of the hypodense regions associated with contusions but in only 4 (27%) of those from areas of infarction. CONCLUSION: Hypodensity on plain CT scans does not always indicate reduction in CBF. This association was found more commonly when the low-density area was associated with a contusion. In hypodense areas associated with infarction, rCBF was variable and not commonly in the ischemic range at the time the CBF measurement was obtained.     

Determination of irreversible ischemia by xenon-enhanced computed tomographic monitoring of cerebral blood flow in patients with symptomatic vasospasm

In patients with subarachnoid hemorrhage, delayed neurological deficits, often followed by infarction, are believed to result from ischemia caused by vasospasm. Cerebral blood flow (CBF) data have been useful in predicting the risk of vasospasm in these patients and in distinguishing those deficits caused by vasospasm. Although CBF thresholds for infarction have been established in animals, few clinical studies have correlated CBF values with neurological symptoms and infarction. To assess the sensitivity to ischemia provided by xenon-enhanced computed tomography (Xe/CT) of CBF and to define the clinical significance of specific values that it measures, we compared the clinical, CT, and Xe/CT findings on CBF in 51 patients with subarachnoid hemorrhage caused by ruptured aneurysms. Each patient had 1 to 6 Xe/CT studies. Fourteen patients had symptomatic vasospasm. In all 14, the first post deficit Xe/CT study found abruptly reduced CBF, either regionally or globally. In 9 of these 14 patients, flow values fell below 15 ml/100 g/min in 2 or more adjacent 2-cm cortical regions of interest, and in all 9, concurrent follow-up CT scans showed infarction in these regions. Eight of the 9 had paralysis and a severe sensory deficit. No patient whose CBF remained above 18 ml/100 g/min developed infarction. The blood flow studies caused neither significant complications nor neurological deterioration. The Xe/CT CBF method appears very sensitive to the early detection of symptomatic vasospasm. In most patients with subarachnoid hemorrhage, this noninvasive technique can replace angiography to delineate the location and severity of vasospasm, and may be useful in predicting the development of infarction.     

Peritoneal drainage of chronic subdural hematomas in older patients

Most patients with chronic subdural hematoma are successfully treated with trephination and external drainage. However, hematomas with thick membranes may persist or recur, needing reoperation or major surgery such as craniotomy with membranectomy. In 14 patients aged over 60 years, internal peritoneal drainage of the hematoma by a low-pressure shunt system proved to be a reliable method of treatment with the following advantages: rapid neurological improvement; immediate mobilization; little stress for the patient; no recurrence; disappearance of the membranes; and slow and well-tolerated cerebral reexpansion without hypotension. Successful use of this method has been reported previously in children, but not in adults.     

Ruptured middle cerebral artery aneurysm and bilateral chronic subdural hematomas

BACKGROUND: While rupture of a cerebral aneurysm into the subdural space is rare, aneurysmal subarachnoid hemorrhage in the presence of subdural hematoma(s) is much more uncommon. Such a patient requires changes in routine perioperative management.CASE DESCRIPTION: A patient with a ruptured middle cerebral artery bifurcation aneurysm and bilateral subdural hematomas is presented. He underwent successful aneurysm clipping and subdural hematoma evacuations. At the time of surgery, measures commonly used to obtain brain relaxation were avoided. The patient was kept normovolemic, normocarbic, and normotensive. He recovered completely and resumed his prior occupation.CONCLUSIONS: Changes in standard techniques for a patient undergoing a pterional craniotomy for a ruptured cerebral aneurysm are required when bilateral extra-axial mass lesions are present.     

Prognosis of chronic subdural hematomas

This article considers factors that may be of prognostic value in evaluating the chronic subdural hematoma (CSH) patient. It also examines conditions that predispose the development of a CSH. Variables such as admission neurologic status and presenting symptomatology are reviewed. Radiologic parameters (i.e., CSH density and midline shift) and intraoperative findings (i.e., pressure and pulse) are discussed.     

Relation of regional cerebral blood flow to hemiparesis in chronic subdural hematoma

To investigate the causative mechanism of hemiparesis in chronic subdural hematoma, 38 patients with unilateral chronic subdural hematoma were studied on the relationship between their clinical manifestations and regional cerebral blood flow measured with 133xenon inhalation (16 detectors on each side of the head, Initial Slope Index). Twenty-five patients with hemiparesis (hemiparesis group) and 13 patients with headaches only and without any neurological deficits (headache group) were examined before surgery for chronic subdural hematoma. Among the hemiparesis patients, 15 were examined after surgery. Preoperative regional cerebral blood flow values in the headache group were normal in all regions bilaterally and showed no significant regional difference in one hemisphere or interhemispheric difference between the corresponding regions in both hemispheres, whereas preoperative regional cerebral blood flow values in the hemiparesis group were generally around the lower limit of the age-matched normal value and were subnormal in some areas, and the regional cerebral blood flow values were significantly lower on the hematoma side than on the intact side in most regions. The rolandic region especially showed the lowest regional cerebral blood flow value of 32.3 in the Initial Slope Index on average and the most significant interhemispheric differences of regional cerebral blood flow. Such a preoperative reduction of regional cerebral blood flow in the hemiparesis group normalized along with clinical improvement after evacuation of the hematoma. It was suggested that localized cerebral blood flow reduction at the rolandic cortical region under the hematoma might be one of the causative factors of hemiparesis in chronic subdural hematoma.     

Spontaneous resolution of chronic subdural hematomas

Four patients with chronic subdural hematomas, all of which resolved spontaneously, were followed from the time of injury to resolution of the chronic subdural hematoma. Periodic computed tomographic (CT) scans showed spontaneous resolution 78, 174, 231, and 326 days after the development of the chronic subdural hematoma, respectively. Features of the CT scans and a possible mechanism of spontaneous resolution are discussed.     

Increases in cardiac output can reverse flow deficits from vasospasm independent of blood pressure: a study using xenon computed tomographic measurement of cerebral blood flow

INTRODUCTION: Vasospasm after subarachnoid hemorrhage remains a management challenge. The accepted treatment involves hypertensive, hypervolemic, hemodilution therapy. However, there is variation in the application of this treatment. Most authors increase mean arterial pressure (MAP), which can be associated with significant morbidity. Others increase cardiac output (CO). In this study, we examined the relationship between volume status, CO, and MAP and cerebral blood flow (CBF) in the setting of vasospasm. METHODS: A xenon blood flow tomography-based system was used to quantitate CBF. Sixteen patients with vasospasm after subarachnoid hemorrhage were treated with hypervolemia, phenylephrine to increase MAP, or dobutamine to increase CO. Direct CBF measurements were obtained before and after treatment. A strength of this study is that only one variable (central venous pressure, MAP, or CO) was manipulated in each patient, and the effect of this change was measured immediately. RESULTS: With phenylephrine, mean MAP increased from 102.4 to 132.1 mm Hg. In regions of diminished CBF due to vasospasm, mean CBF increased from 19.2 to 33.7 ml/100 g/min. Similarly, dobutamine increased the cardiac index from a mean of 4.1 to 6.0 L/min/m(2) and slightly decreased MAP. CBF increased from a mean of 24.8 to 35.4 ml/100 g/min. Both were statistically significant changes. With hypervolemia, the average central venous pressure increased from a mean of 5.4 to 7.3 cm H(2)O; no changes in mean CBF were noted. CONCLUSION: This article reports the first human study that shows with direct measurements the independent influence of CO in the setting of vasospasm. Increases in CO without changes in MAP can elevate CBF. This finding has immediate clinical application because CO manipulation is much safer than increasing MAP. Because both interventions were equally efficacious, our protocol has been changed to augment CO as a first measure. Induced hypertension is reserved for patients in whom this initial treatment fails.     

A brief history of chronic subdural hematomas

Examination of human remains tells us that subdural hematomas have been with mankind for thousands of years. Their recognition as distinct clinical entities is considerably more recent, and it has only been in the last century that the cause of chronic subdural hematomas has been adequately elucidated. The history of this discovery process is interesting and sheds light on the nature of scientific progress in general.     

Magnetic resonance images of chronic subdural hematomas

Magnetic resonance imaging (MRI) and computerized tomography (CT) scans of 18 patients with 20 chronic subdural hematomas were compared. In many ways, MRI was superior to CT for demonstrating the hematomas. In general, chronic subdural hematomas were hyperintense on both T1- and T2-weighted MRI. The T1 values of chronic subdural hematomas were significantly shorter than gray matter values and significantly longer than white matter values. The T2 values were significantly longer than both gray matter and white matter values. These findings were consistent with previous reports. However, six hematomas (30%) were iso- or hypointense on T1-weighted images. Possible mechanisms responsible for the difference in intensity of chronic subdural hematoma on MRI are discussed, and the important role of methemoglobin formation is emphasized.