Hematoma Density and Glasgow Coma Scale Are Independent Predictors to
Outcomes in Unilateral Chronic Subdural Hematoma
Jinn-Rung Kuo1, 2, 5, Che-Chuan Wang2, Huan-Fang Lee3,4, Chung-Ching, Chio2, KaoChang, Lin 5,6
1
Institute of Clinical Medicine, School of Medicine, National Cheng-Kung University,
Tainan, Taiwan
2
Department of Neurosurgery, Chi-Mei Medical Center, Tainan, Taiwan
3
Department of Nursing, Chi-Mei Medical Center, Tainan, Taiwan
4
Department of Nursing & Institute of Allied Health Sciences, College of Medicine,
National Cheng Kung University, Tainan, Taiwan
5
Institute of Biotechnology, Southern Taiwan University, Tainan, Taiwan
6
Department of Neurology, Chi-Mei Medical Center, Tainan, Taiwan
Corresponding author: Kao-Chang Lin, MD, Department of Neurology, Chi-Mei
Medical Center
901 Chung Hwa Road, Yung Kang City, Tainan, Taiwan 710
Tel: 886-6-2812811; Fax: 886-6-2828928
E-mail:gaujang@mail2000.com.tw
1
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
2
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,
4
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
5
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, 17Most 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
6
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.
Abouzari et al
21
9.20
However,
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
7
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.
8
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treatment and outcome in 1000 case. Clin Neurol and Neurosurg 2005; 107:223229.
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hematomas by computerized tomography. J Neurosurg 1977; 47:311-315.
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11
從腦出血密度及昏迷指數，作為單側慢性硬腦膜下出血的預後指標及敏感度評
估
郭進榮 1,4,6，王哲川 1，李歡芳 3,5，邱仲慶 1，*林高章 2,6 (通訊作者)
奇美醫學中心 神經外科 1，神經內科 2，護理部 3。
成功大學 臨床醫學研究所 4、臨床護理研究所 5，南台大學生物科技系 6。
摘要
前 言 : 使 用昏 迷 指數 (Glasgow Coma Scale), 預 後 指數 (Glasgow Outcome
Scale),及電腦斷層(CT)的變項，來評估慢性硬腦膜下出血(CSDH)預後，文獻上
並
無
一
致
性
結
論
。
方法: 從 94 年 10 月至 98 年 3 月，共收集了 93 例單一側 CSDH 的病人(年齡 71±
11 歲)。每位病患皆於急診接受電腦斷層檢查並手術。排除了雙側硬腦膜下出血
(由兩位放射專家確任)，我們使用多個變項，如年齡、性別、昏迷指數、到院
時間、出血位置、大小、厚度、密度(density)、腦移位情形、腦室大小(Evan’s
index)、第 3 腦室最大寬度(3Vmax. D)、皮質委縮等，來評估上述何者為最佳之
預
測
因
子
。
結果: 使用單變項及多變項分析，昏迷指數<15 預測不良預後為一般的 11
倍之多(OR= 11.2, CI= 1.3-96.9, p= 0.028)，出血密度高達 7 倍(OR= 7.4, CI= 1.831.7, p= 0.007)，兩者皆呈統計性意義。利用 Receiver-Operating Characteristic 來
測 量 兩 者 的 顯 著 情 形 ， 敏 感 度 高 達 73% ， 專 一 度 為 85% 。
12
結論: 在本前驅性觀察研究發現，單一側硬腦膜下出血對於預後不良的最佳
預測因子，為出血密度及昏迷指數，預測敏感度高於 7 成。不同於以往文獻多
為合併單、雙側病兆、或顱內出血討論，本文病患雖然不多，但仍具參考價值
及意義。對於區域或社區型醫院之轉診，提供病患較準確評估及說明。
關鍵字: 單側硬腦膜下出血，昏迷指數，預後指數，預測因子
台 南 縣 (710) 永 康 市 中 華 路 901 號 - 奇 美 醫 學 中 心 , 神 經 內 科
林高章醫師
901 Chung Hwa Road, Yung Kang City, Tainan, Taiwan 710
Tel: 886-6-2812811; Fax: 886-6-2828928
E-mail:gaujang@mail2000.com.tw
13