Hematoma Density and Glasgow Coma Scale Are Independent Predictors to
Outcomes in Unilateral Chronic Subdural Hematoma
Jinn-Rung Kuo 1, 4, 6 , Che-Chuan Wang 1 , Huan-Fang Lee 3,5 , Chung-Ching, Chio 1 ,
*Kao-Chang, Lin 2,6
1 Department of Neurosurgery, Chi-Mei Medical Center, Tainan, Taiwan
2 Department of Neurology, Chi-Mei Medical Center, Tainan, Taiwan
3 Department of Nursing, Chi-Mei Medical Center, Tainan, Taiwan
4
Institute of Clinical Medicine, School of Medicine, National Cheng-Kung University,
Tainan, Taiwan
5
Department of Nursing & Institute of Allied Health Sciences, College of Medicine,
National Cheng Kung University, Tainan, Taiwan
6
Institute of Biotechnology, Southern Taiwan University, Tainan, Taiwan
Corresponding author: * Kao-Chang Lin, MD, Department of Neurology, Chi-Mei
Medical Center, Tainan, Taiwan
901 Chung Hwa Road, Yung Kang City, Tainan, Taiwan 710
Tel: 886-6-2812811; Fax: 886-6-2828928
E-mail: gaujang@mail2000.com.tw
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Abstract
Introduction: The relationships between Glasgow Outcome Scale (GOS), Glasgow
Coma Scale (GCS) and brain computerized tomography (CT) with unilateral chronic subdural hematoma (CSDH) are not consistent in studies.
Methods: Between Oct 2005 to March 2009, 93 unilateral CSDH patients (mean age
71 ± 11 years) were enrolled for analysis. The associations between GOS at discharge and the following variables on admission including sex, age, GCS, time interval from injury to emergency room, hematoma site, hematoma thickness, hematoma density, midline shift, ventricular sizes (Evan’s index and maximum diameter of third ventricle-3Vmax. D), and cortical atrophy on brain CT were evaluated.
Results: By multiple logistic regression statistics, the adjusted odds ratio (OR) in predicting the poor outcome was significant with GCS <15 [OR= 11.2, CI= 1.3-96.9, p = 0.028] and mixed density hematoma on brain CT [OR= 7.4, CI= 1.8-31.7, p =
0.007]. Using Receiver-Operating Characteristic (ROC) curve, the sensitivity was
73% and the specificity was 85%.
Conclude: In our preliminary study that mixed hematoma density and lower GCS were associated with poor prognosis in unilateral CSDH with sensitive prediction.
Key words: unilateral chronic subdural hematoma, Glasgow Coma Scale, Glasgow
Outcome Scale, prognostic factors
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Introduction
Chronic subdural hematoma (CSDH) is commonly seen in daily practice no matter in traumatic or other causes. It occurs more frequently in the elderly with poor prognosis if treated inappropriately.
1 From clinical experiences, the progression of
CSDH in disturbing conscious patients reflected the space-occupying entity.
2 The computed tomography (CT) remained the fast and useful tool to evaluate the happenings in the brain.
3 Searching literatures, the prognosis of CSDH can be predicted by age, neurological assessment (Glasgow Coma Scale-GCS), and imaging study such as hematoma density, midline shift, brain atrophy and hydrocephalus.
4-10
However, the obtained results were not consistent due to the heterogeneity of patients involved, uni- or bilateral CSDHs, or mixed with intracranial hemorrhage. The purpose of our study is to evaluate the correlations between variables in purely unilateral CSDH that most commonly seen in traumatic patients.
Methodology
Patients in traumatic injury with unilateral CSDH were enrolled from October
2005 to March 2009, in a referral tertiary medical center in southern Taiwan. This study was approved by IRB at our hospital. A complete history taking and neurological assessments were performed for each patient, and received brain CT at emergency room. All patients received operation on the lesion side, via burr-hole evacuation with closed system drainage. During surgery, we irrigated the subdural space with warm normal saline until the returning fluid became clear. We withdrew the subdural drainage tube postoperatively when the volume was less than 10 ml/ per day.
3

The correlations between GCS, abnormal brain CT, and GOS at discharge were evaluated. For the convenience of data analysis, GCS group was divided into two categories of clear (GCS=15) and impaired conscious level (GCS <15). The CSDH on brain CT were classified as low-density (similar to cerebro-spinal fluid), isodensity
(similar to gray matter) and mixed-density hematoma.
3 The midline-shift on CT was defined as the absolute distance (mm) that the septum pellucidum of the brain was displaced away from the midline, which was determined as an average by calculating the distance between both inner tables inside the skull.
11 The ventricular size is evaluated by Evan’s index defined with maximum width of the anterior horns of the lateral ventricles / maximum inner skull diameter, and maximum diameter of third ventricle (3Vmax.D).
12 The cortical atrophy is defined as the sum of the width of the four widest sulci at the two highest scanning levels / maximum inner skull diameter.
13
The outcomes at discharge were categorized based on the GOS as (1) death; (2) persistent vegetative state; (3) severe disability (conscious but disabled); (4) moderate disability (disabled but independent) and (5) good recovery.
14
A score of 4 to 5 was defined as favorable outcome (moderate disability or less), and score of 1 to 3 was in poor results (severe disability or death).
Data were expressed as mean ± standard deviation. The Student’s t-test, Chisquare test and Fisher's exact test were used to assess statistical significance among all groups. Multiple logistic regression models were used for correlation between two continuous or categorical variables and defined as the independent risk factors for poor outcomes. Finally, logistic regression and the Receiver-Operating Characteristic
(ROC) 15 curve were used for statistics based on prognostic scoring models. All data were analyzed using qualified statistical software (SPSS for Windows, Version 16,
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SPSS Inc., Chicago, Illinois, USA). A p -value of less than 0.05 was considered significant.
RESULTS
During past 3.5 years, totally 123 CSDH patients were enrolled. By excluding 30 patients with bilateral CSDH (confirmed by two radiologists), there were 93 patients with 72 males (77.4%) and 21 (22.6%) females were analyzed. The age (mean ± SD) was 71 ± 11 years (range 51-91 years). The average GCS on admission were 13 ± 2.
Fifty-three percent of patients were clear conscious level (GCS=15), while 36.3% had
GCS 13 to 14, and 11.2 % had GCS 8-12. The overall GOS on discharge was 4.3
± 1.6.
Seventy-eight subjects (83.9 %) had a favorable outcome. Four patients died (4.3%) with primary or secondary causes. The trauma-related CSDH was 60.2% (56/93), with time-interval from injury to admission was 50.6 ± 30.7 days. The major presenting symptoms and signs in sequences were focal neurological deficits (61.3%), mental change (23.6%), and headache (15.1%) (Table1).
Using Chi-square and Fisher's exact statistics for categorical variables, the GCS
( p< 0.001) and hematoma densities (p < 0.001) were significantly associated with poor outcomes (Table 2). Table 3 disclosed ventricular Evan’s index (p= 0.002 ) and maximum diameter of third ventricle (p= 0.039 ) were also significantly relevant to the prognosis.
The multivariate logistic regression was performed on significant variables extracted from previous steps to determine the independent predictors to GOS. It was found the GCS level <15 [OR= 12.46, CI= 1.38-112.14, p = 0.024] and mixed hematoma density [OR= 7.58, CI= 1.63-35.12, p = 0.010] were statistically significant
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with GOS (Table 4). The Evan’s index and maximum diameter of third ventricle were not relevant. With simple linear logistic regression for the predictors, it still showed that GCS ( p = 0.028) and mixed hematoma density ( p = 0.007) were significant.
A prognostic scoring model by mathematical transform with Logit ( p ) = -4.425 +
2.419 x (GCS) + 2.007 x (hematoma density) was constructed within these significant variables. The score ≧ 1 was estimated as a poor outcome while score < 1 as a favorable one. Using Receiver-Operating Characteristic (ROC) analysis, the sensitivity was 73% and specificity was 85%. (Fig)
Discussion
The mixed hematoma density is generally considered as a hemorrhage contained much fresh blood either from un-resolution blood or re-bleeding.
16, 17
Most clinicians thought it as a bad prognosis in bilateral traumatic CSDH. Oishi et al indicated that hematoma density is a risk factor for poor outcome in CSDH. 17 They speculated that patients with symptoms deterioration were due to repeated cycles of micro-bleed and fibrolysis in accumulated blood area. Kwon et al, 18 reported that mixed density of hematoma had the lowest post-operative drainage volume (mean 151 ± 86 ml) compared to low density (mean 413 ± 269 ml) and iso-dense of CSDH (mean 348 ±
257 ml). However, the poor prognosis was due to the greater viscosity of subdural blood difficulty to drain out, the air accumulation, or re-bleeding of micro-vessels that disturbing the integrity of brain function were speculated. Mori et al had different explanations in that traumatic patients with CSDH had blood in subdural space and would facilitate the formation of a medial membrane, especially in the elderly. This medial membrane formed internal capillaries or blood vessels that allowed plasma
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fluid leakage into and resultant enlargement of the subdural space. Re-bleeding and hyperfibrinolysis repeatedly occurred which caused the growth of CSDH.
19 In our study of unilateral CSDH, it revealed similar finding that mixed hematoma density was an independent predictor to poor outcome, which was consistent with bilateral
CSDH in previous publication.
Increasing ventricular size might happen from the effects of brain atrophy, aging process, or disturbance of the passage of cerebral spinal fluid due to internal obstruction or external mass compression.
5, 20 About 27 to 50% of post-traumatic patients could have hydrocephalus or ventricle enlargement depending on the severity of injury. A significant relationship between post-traumatic ventriculomegaly, defined as Evan’s index, with bad outcome was reported if the index ≧ 0.3. 9.20
However,
Abouzari et al
21
pointed out that hydrocephalus was not a sensitive predictor in
CSDH. This discrepancy might be due to the difference in definition and etiology of hydrocephalus. Brain atrophy is one of a risk factor for CSDH because it provided a potential space for hematoma expansion associated with risks of unfavorable outcome after CSDH. 5 In our group of unilateral CSDH, by univariate analysis, increase ventricular size was a risk factor ( p = 0.002) to GOS, while brain cortical atrophy was not. By using multiple logistic regressions in predicting the outcomes, the Evan’s index and ventriculomegaly (3Vmax.D) were not associated with GOS differed from that of bilateral CSDH. The sample size or selected cases might be a crucial role.
From our data, we contemplated that the causal relations between dynamic ventricular size and GOS was complicated and could be aggravated by systemic or dehydrated conditions. These observations deserve further evaluation in the future.
The GCS assessing the conscious level is one of the most important factors to
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predict outcome after head injury. 4 In our results, the impacts were ascertained in unilateral CSDH. It is frequently demonstrated as the first and major predictors, as in
Amirjamshidi and Ramachandran et al’s reports. 5, 6
Regarding to the statistics of linear and multivariate prognostic analysis, we used
ROC curve to estimate the predictive accuracy of GCS and hematoma density to GOS.
Our results disclosed that GCS and mixed hematoma density had valid accuracy in predicting the outcomes with sensitivity 0.73 and specificity 0.85. It emphasized that these two variables had sensitive values in predicting GOS in unilateral CSDH. This study had some limitations including small sample sizes, no complete post-operative
CT imaging for comparisons, clustering of mild severity of unilateral CSDH, and no adjusted confounders of systemic illness.
Conclusions
Based on our unique, and preliminary study of unilateral CSDH, we highlighted that a low GCS and mixed density hematoma on CT imaging were significantly associated with poor outcomes in patients with unilateral CSDH, and with a sensitive value in prediction. It can be as reference for community or regional hospitals to predict possible outcomes before transferring patients to medical center.
Acknowledgements
The authors thank all the participants from neurology, nursing department, and neurosurgery. We also thank Ms. Chin-Li, Li and Wen-Chun, Lin on the statistical analysis.
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