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Predicting Dural Tear in Compound Depressed Skull Fractures: A Prospective Multicenter Correlational Study
Original Article
Predicting Dural Tear in Compound Depressed Skull Fractures: A Prospective Multicenter Correlational Study Shemsedin Musefa Salia1, Hagos Biluts Mersha2, Abenezer Tirsit Aklilu2, Abat Sahlu Baleh2, Morten Lund-Johansen3
BACKGROUND: Compound depressed skull fracture (DSF) is a neurosurgical emergency. Preoperative knowledge of dural status is indispensable for treatment decision making. This study aimed to determine predictors of dural tear from clinical and imaging characteristics in patients with compound DSF.
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METHODS: This prospective, multicenter correlational study in neurosurgical hospitals in Addis Ababa, Ethiopia, included 128 patients operated on from January 1, 2016, to October 31, 2016. Clinical, imaging, and intraoperative findings were evaluated. Univariate and multivariate analyses were used to establish predictors of dural tear. A logistic regression model was developed to predict probability of dural tear. Model validation was done using the receiver operating characteristic curve.
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RESULTS: Dural tear was seen in 55.5% of 128 patients. Demographics, injury mechanism, clinical presentation, and site of DSF had no significant correlation with dural tear. In univariate and multivariate analyses, depth of fracture depression (odds ratio 1.3, P < 0.001), pneumocephalus (odds ratio 2.8, P [ 0.005), and brain contusions/ intracerebral hematoma (odds ratio 5.5, P < 0.001) were significantly correlated with dural tear. We developed a logistic regression model (diagnostic test) to calculate probability of dural tear. Using the receiver operating characteristic curve, we determined the cutoff value for a
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Key words Black Lion score - Brain contusion - Depressed skull fracture - Dural tear - Neurosurgery - Pneumocephalus - Skull fracture -
Abbreviations and Acronyms CI: Confidence interval CSF: Cerebrospinal fluid CT: Computed tomography DSF: Depressed skull fracture ICH: Intracerebral hematoma
positive test giving the highest accuracy to be 30% with a corresponding sensitivity of 93.0% and specificity of 43.9%. CONCLUSIONS: Dural tear in compound DSF can be predicted with 93.0% sensitivity using preoperative findings and may guide treatment decision making in resource-limited settings where risk of extensive cranial surgery outweighs the benefit.
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INTRODUCTION
I
njuries are substantial causes of morbidity and mortality affecting 973 million people worldwide and resulting in 4.8 million deaths in 2013. According to the World Health Organization, by 2020, head injury will surpass many diseases as a major cause of death and disability.1-4 Depressed skull fracture (DSF) is a serious injury that occurs in up to 6% of all head injuries and 11% of severe head injuries. Approximately 68%e86% of DSFs are compound fractures, and dural tear, which has a significant association with cranial infections, occurs in a great proportion of these (10%e52%).5-12 The incidence of infection in compound DSF can reach 10.6% and infection is associated with a significantly higher incidence of persistent neurologic deficit, late-onset epilepsy, and death. Operative management reduces the incidence of infection to 4.6%.11,13 Therefore, these fractures warrant immediate treatment, which may vary in complexity from simple skin débridement and wound closure to fracture
OR: Odds ratio ROC: Receiver operating characteristic From the 1Neurosurgery Unit, Department of Surgery, Hawassa University Comprehensive Specialized Hospital, Tabor Sub-city, Hawassa, Ethiopia; 2Neurosurgery Unit, Department of Surgery, Addis Ababa University Tikur Anbessa Specialized Hospital, Lideta Sub-city, Addis Ababa, Ethiopia; and 3Department of Neurosurgery, Haukeland University Hospital, Bergen, Norway To whom correspondence should be addressed: Shemsedin Musefa Salia, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2018) 114:e833-e839. https://doi.org/10.1016/j.wneu.2018.03.095 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2018 Elsevier Inc. All rights reserved.
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elevation, débridement of contused brain, and closure of a dural defect.14 The decision regarding the need for extensive surgery may be a difficult one. In particular, it may be difficult to predict whether or not the dura mater is torn. The presence of dural tear mandates immediate surgical repair to avoid bacterial meningitis, subdural empyema, and brain abscess.11 The absence of dural tear may mandate conservative treatment to avoid more extensive cranial surgery.11,15,16 Few studies have explored the clinical and computed tomography (CT) scan findings to predict dural tear in a patient with a compound DSF.10 In this prospective study, using a logistic regression model, we investigated whether preoperative findings might predict dural tear in patients who underwent surgery for compound DSF.
MATERIALS AND METHODS This prospective, multicenter, correlational study to determine the predictors of dural tear in patients with compound DSF was approved by the Research Ethics Committee of the Department of Surgery, Addis Ababa University, Ethiopia. Informed consent was obtained from all individual participants included in the study and/or their legal caregivers. The study was conducted from January 1, 2016, to October 31, 2016, in 4 hospitals in Addis Ababa, Ethiopia, that provide neurosurgical service—Addis Ababa University Tikur Anbessa Specialized Hospital, African Leprosy Research Training Hospital, Zewditu Memorial Hospital, and Myungsung Christian Medical Center, with surgical bed capacity of 300, 53, 45, and 40 beds. Eight consultant and 35 resident neurosurgeons work in these hospitals on a rotational basis. Patients were included in the study if they had consented to undergo surgery, had received a CT scan of the head, and had consented to be involved in this research. Patients who did not undergo surgery, patients with penetrating head injury, and patients with obvious dural tear (cerebrospinal fluid leakage or oozing brain tissue) on clinical examination were not included. Clinical findings on admission, cause and site of injury, and detailed CT findings were recorded. On review of admission CT scans, the maximum depth of fracture depression in millimeters was measured from the inner table of the normal calvaria to the inner table of the depressed fragment. For purposes of this study, any air inside the cranial cavity close to the DSF was defined as pneumocephalus. Hyperdense areas on posttrauma CT scan measuring >10 mm were arbitrarily defined as intracerebral hematoma (ICH), whereas smaller lesions were categorized as brain contusion. In all surgical procedures, the dura mater was carefully inspected, and the status of dural patency was noted. A structured questionnaire was used for data collection. A convenience sampling method was used. A sample size estimation method for the proportion of binary (dichotomous) outcome was used: pð1 pÞ (1) d2 where N is the size of sample, Z is the z score for the desired level of confidence, p is the estimate of expected proportion with the variable of interest in the population, and d is the half-width of the desired interval (precision). N ¼ Z2
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A prospective study on compound skull fractures conducted by Rolekar9 reported the proportion of dural tear in operated DSF cases to be 10%. Hence, taking 10% as the estimate of expected proportion, 1.96 as the value of Z for 95% confidence level (CI), and 0.05 as the value of d, the calculated sample size was 139. However, 128 patients who fulfilled the inclusion criteria were identified during the study period, which constituted 92.1% of the estimated sample size. Baseline demographic and clinical data were compared using statistical tests based on the characteristics of the variables. Mean age and mean depression levels were compared using t test. Univariate analysis and multivariate analysis were used to establish predictors of dural tear. Logistic regression analysis was employed to predict the probability of dural tear from the predictor variables. A regression model was developed to predict the natural log of the odds of having dural tear: Y lnðoddsÞ ¼ ln ¼ a þ bx þ . (2) 1Y odds ð1 þ oddsÞ
(3)
odds ¼ eaþbxþ.
(4)
Y ¼
eaþbxþ. (5) 1 þ eaþbxþ. where Y is the predicted probability of torn dura, 1 Y is the predicted probability of intact dura, x is the predictor variable, and e is the base of the natural logarithm (e ¼ 2.718 .). The Hosmer-Lemeshow goodness-of-fit test was used to check that the predictions made by the model fit perfectly with the observed data.17 Model validation was done using the receiver operating characteristic (ROC) curve.18,19 Statistical significance was set at P < 0.05. Data were analyzed using IBM SPSS Version 20 (IBM Corp., Armonk, New York, USA). Y ¼
RESULTS There were 128 patients (114 men; 89.1%) who fulfilled the inclusion criteria and were included. Fourteen patients were excluded because they presented with oozing brain tissue, cerebrospinal fluid leakage, or penetrating injury. Most patients (116; 90.7%) were <45 years old (mean age, 26.0 years; range, 3e65 years). Physical assault was the mechanism of injury in 77 (60.2%) cases. Of the assault cases, a stone was used in 44 (47.3%) cases, a stick was used in 33 (35.5%) cases, and other objects were used in 16 (17.2%) cases. Headache occurred in 108 (84.4%) patients, and loss of consciousness occurred in 98 (76.6%) of patients. Based on Glasgow Coma Scale score, 99 (77.3%) patients had mild head injury (Table 1). Frontal or parietal fractures accounted for 81 (63.3%) cases. Pneumocephalus was present in 74 (57.8%) cases, brain contusion/ICH was present in 79 (61.7%) cases, acute epidural hematoma was present in 34 (26.6%) cases, acute subdural hematoma was present in 5 (3.9%) cases, and intraventricular hemorrhage was present in 2 (1.6%) cases. The mean depth of fracture depression as measured from the inner table of the normal calvaria was 12.7 0.4 mm (range,
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ORIGINAL ARTICLE SHEMSEDIN MUSEFA SALIA ET AL.
PREDICTING DURAL TEAR IN COMPOUND DEPRESSED SKULL FRACTURE
Table 1. Demographic and Clinical Characteristics and Intraoperative Dural Status of Patients with Compound Depressed Skull Fracture (N ¼ 128) Dural Status
Characteristics
Intact Torn (% within Group) (% within Group)
Total (%)
24.1 1.7
27.5 1.7
26.0 1.2
13.1
14.0
13.7
49 (43.0)
65 (57.0)
114 (89.1)
8 (57.1)
6 (42.9)
14 (10.9)
Assault
34 (44.2)
43 (55.8)
77 (60.2)
Road traffic accident
10 (50)
10 (50)
20 (15.6)
Mean age, years SD Sex Male Female Mechanism of injury
Fall
4 (44.4)
5 (55.6)
9 (7.0)
Other mechanism
9 (40.9)
13 (59.1)
22 (17.2)
Headache
46 (42.6)
62 (57.4)
108 (84.4)
Vomiting
22 (36.7)
38 (63.3)
60 (46.9)
Seizure
4 (30.8)
9 (69.2)
13 (10.2)
Loss of consciousness
42 (42.9)
56 (57.1)
98 (76.6)
ENT bleed
12 (38.7)
19 (61.3)
31 (24.2)
7 (33.3)
14 (66.7)
21 (16.4)
10 (52.6)
9 (47.4)
19 (14.8)
Mild
45 (45.5)
54 (54.5)
99 (77.3)
Moderate
11 (44.0)
14 (56.0)
25 (19.5)
1 (25.0)
3 (75.0)
4 (3.1)
Clinical presentation
Motor deficit Language deficit
Univariate analysis was performed for each of the variables to determine their predictive statistical significance, odds ratio (OR), and 95% CI (Table 3). The P value for significance of correlation was set at P ¼ 0.05. Brain contusion/ICH (OR 5.519; 95% CI, 2.536e12.011; P < 0.001), pneumocephalus (OR 2.851; 95% CI, 1.380e5.891; P ¼ 0.005), and depth of fracture depression (OR 1.318; 95% CI, 1.179e1.475; P < 0.001) had statistical significance in predicting dural tear. These variables were included in the multivariate analysis (Table 4). In the multivariate analysis, the criterion for statistical significance was set at P ¼ 0.05. Depth of depression, pneumocephalus, and brain contusions/ICH were significant predictors of dural tear by ORs ranging from 1.3 to 5.5 (Table 3). Table 4 shows the logistic regression coefficients, Wald test, OR, and 95% confidence level for each of the predictors of torn dura. Using this output and entering it into the regression equation (Equation 2) generates the model for predicting torn dura as follows: lnðoddsÞ ¼ 4:207 þ 0:256 D þ 0:897 P þ 1:313 CH (6) where D is depth of fracture depression (in millimeters), P is pneumocephalus (1 ¼ present, 0 ¼ absent), and CH is brain contusion/ hematoma (1 ¼ present, 0 ¼ absent).
Table 2. Fracture Characteristics and Intracranial Findings and Intraoperative Dural Status of Patients with Compound Depressed Skull Fracture (N ¼ 128) Dural Status
Severity of head injury
Severe
None of the variables distributed showed significant difference between groups. ENT, Ear, nose, throat.
3e24 mm; SD 4.4). Mechanisms of injury and clinical characteristics of the study population are summarized in Table 1, and imaging characteristics are summarized in Table 2. At surgery, a dural tear was found in 71 (55.5%) patients, and intact dura was confirmed in 57 (44.5%) patients. The mean depths of fracture depression in the groups with torn dura and intact dura were 14.55 0.5 mm (SD 4.26) and 10.36 0.4 mm (SD 3.35), respectively (Table 2). The independent sample t test showed a statistically significant difference (t126 ¼ 6.079, N ¼ 128, P < 0.001) in the mean depths of fracture depression in the 2 groups. The observed distribution of dural status with respect to the independent variables is summarized in Tables 1 and 2. Demographics, injury mechanism, clinical presentation, and site of DSF were not significantly different between the 2 groups. Figures 1 and 2 show CT images of 2 patients with intraoperative findings of dural status.
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Characteristics
Intact Torn (% within Group) (% within Group)
Total (%)
Location Frontal
18 (38.3)
29 (61.7)
47 (36.7)
Parietal
19 (55.9)
15 (44.1)
34 (26.6)
Temporal
3 (33.3)
6 (66.7)
9 (7.0)
Occipital
4 (80.0)
1 (20.0)
5 (3.9)
13 (39.4)
20 (60.6)
33 (25.8)
10.36 0.4
14.55 0.5
12.7 0.4
3.35
4.26
4.4
Pneumocephalus
25 (33.8)
49 (66.2)
74 (57.8)
Contusions/ICH
23 (29.1)
56 (70.9)
79 (61.7)
AEDH
17 (50.0)
17 (50.0)
34 (26.6)
ASDH
2 (40.0)
3 (60.0)
5 (3.9)
IVH
0 (0.0)
2 (100)
2 (1.6)
2 bones involved Mean depth of depression, mm SD
Intracranial findings are based on head computed tomography scan. ICH, intracerebral hematoma; AEDH, acute epidural hematoma; ASDH, acute subdural hematoma; IVH, intraventricular hemorrhage.
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PREDICTING DURAL TEAR IN COMPOUND DEPRESSED SKULL FRACTURE
Figure 1. Axial computed tomography scan of the head of a 29-year-old man revealed fracture depression depth of 17 mm and pneumocephalus.
Intracerebral bleeding or contusions were not seen. The probability of dural tear according to the formula was 75.4%. A torn dura was found during surgery.
From Equation 6, a formula to calculate the probability of dural tear (Y) in patients with compound DSF can be derived. We decided to name this formula Salia’s formula (Equations 7 and 8) and its output the Black Lion score. Y ¼
eð4:207þ0:256Dþ0:897Pþ1:313CHÞ 1 þ eð4:207þ0:256Dþ0:897Pþ1:313CHÞ
(7)
After rounding, simplification, and inserting the value of e (¼ 2.72) into Equation 7, the formula becomes: D 2:72ð4þ4þPþCHÞ Y ¼ D 1 þ 2:72ð4þ4þPþCHÞ
(8)
A test of the full model versus a model with intercept only was statistically significant (c23 ¼ 47.469, N ¼ 128, P < 0.001). The Hosmer-Lemeshow goodness-of-fit test showed insignificant c2 test (c28 ¼ 6.737, P ¼ 0.565), indicating that predictions made by the model fit perfectly with the observed data. The ROC curve was used to evaluate the goodness of fit of the logistic regression model based on the simultaneous measurement of sensitivity and specificity for all possible cutoff points. The ROC curve for the present model (Figure 3) was located closer to the left upper corner (area under the curve ¼ 0.835; 95% CI, 0.766e0.904; P < 0.001), indicating that the model classifies the group with dural tear significantly better than by chance. The optimal cutoff point for positivity was determined by maximizing the sum of sensitivity and specificity (1.369) and using the maximum Youden index (0.369) across various cutoff points. The cutoff value for positivity giving the highest accuracy was 30% with a corresponding sensitivity of 93.0% and specificity of 43.9%. Based on this cutoff value, the minimum depth of fracture depression to predict dural tear was 13.2 mm if both of the other predictors were absent, 10.0 mm if only
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pneumocephalus was present, 8.0 mm if only brain contusion/ ICH was present, and 5.0 mm if both of the other predictors were present. An Excel sheet calculator was developed based on the formula for ease of practical application (see Supplement 1). DISCUSSION In the present study, 90.7% of patients were <45 years old, which is a higher percentage than reported by other studies (75%).7,9,11 This study also showed a male predominance of 89.1%, which agrees with other studies in the literature.7,10,11 Some studies reported physical assault to be the most common cause of DSF (30%e75%), as was the case in the present study (60%), whereas other studies reported road traffic accident as the most common cause of DSF.7,9-12 Headache (84.4%) and loss of consciousness (76.6%) were the most common presenting symptoms in this study, which is similar to other studies.9,10 Most studies reported the frontal or parietal bones to be the most common sites of DSF, which is in agreement with the present study.7-9 Although there are a few studies that report the incidence of brain contusions/ ICH, we found no literature depicting the incidence of pneumocephalus in this study population.8 DSF is a serious type of head trauma, with 68%e86% of cases being compound fractures.5-12 These fractures warrant immediate treatment, which may vary in complexity from simple skin débridement and wound closure to fracture elevation, débridement of contused brain, and closure of a dural defect.14 The decision regarding the need for extensive surgery may be a difficult one. In particular, it may be difficult to predict whether or not the dura mater is torn. The present study showed intraoperative findings of dural tear in 55.5% of cases with compound DSF; this percentage is similar to reports by Al-Haddad and Kirollos11 and Braakman,7 but it is higher than reported by Husien et al.12 and Rolekar.9 Pneumocephalus and
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PREDICTING DURAL TEAR IN COMPOUND DEPRESSED SKULL FRACTURE
Figure 2. Axial computed tomography scan of the head of a 55-year-old man revealed fracture depression depth of 5 mm, pneumocephalus, and
brain contusions/ICH were shown in the present study to have significant correlation with intraoperative finding of dural tear. To the best of our knowledge, there is no literature evaluating these imaging findings and dural status in such a study population. The present study also revealed the mean depths of fracture depression in the groups with torn dura and intact dura to be 14.55 4.26 mm and 10.36 3.35 mm, respectively. According to Shokouhi et al.,10 there is a significant correlation between depth of fracture depression and dural tear with the cutoff value for predicting dural tear being 14 mm with 77% sensitivity.
brain contusion. The probability of dural tear according to the formula was 32%. A torn dura was found during surgery.
The present study confirmed the significant correlation between depth of fracture depression and dural tear but with different cutoff values for predicting dural tear based on the presence or absence of other predictor variables. Although the study by Shokouhi et al.10 indicated the depth of fracture depression to be a predictor of dural tear, it displayed an average depth of fracture depression of 23.5 8.9 mm and 14.7 4.6 mm for the group with torn dura and for the group with intact dura, respectively. These findings are quite different compared with the findings of our study. Additionally, that study had a sample size about one third of ours (n ¼ 40), and other factors potentially important in
Table 3. Univariate Analysis for Predictors of Dural Tear in Patients with Compound Depressed Skull Fracture (N ¼ 128) Variable
OR (95% CI)
P
Sex
0.565 (0.184e1.736)
0.319
Dysphasia
Age
0.981 (0.956e1.008)
0.165
GCS
Mechanism
Variable
OR (95% CI) 0.682 (0.257e1.813)
P 0.443 0.735
0.829
DSF location
Headache
1.078 (0.274e4.239)
0.914
Depth of depression
1.318 (1.179e1.475)
0.458 0.000
Vomiting
1.832 (0.902e3.720)
0.094
Pneumocephalus
2.851 (1.380e5.891)
0.005
Seizure
1.923 (0.560e6.604)
0.299
Contusions/ICH
5.519 (2.536e12.011)
0.000
LOC
1.333 (0.587e3.027)
0.492
AEDH
0.741 (0.337e1.627)
0.455
ENT bleed
1.370 (0.600e3.128)
0.455
ASDH
1.213 (0.196e7.519)
0.835
Motor deficit
1.754 (0.656e4.691)
0.263
IVH
1.029 (0.989e1.071)
0.502
OR, odds ratio; CI, confidence interval; GCS, Glasgow Coma Scale; DSF, depressed skull fracture; ICH, intracerebral hematoma; LOC, loss of consciousness; AEDH, acute epidural hematoma; ENT, ear, nose, throat; ASDH, acute subdural hematoma; IVH, intraventricular hemorrhage.
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Table 4. Multivariate Analysis for Predictors of Dural Tear in Patients with Compound Depressed Skull Fracture (N ¼ 128) 95% CI for OR B
Wald c2
0.256
16.983
0.000 1.292
1.144
1.459
Pneumocephalus
0.897
4.248
0.039 2.452
1.045
5.755
Brain Contusion/ICH
1.313
8.871
0.003 3.717
1.567
8.819
4.207
23.984
0.000 0.015
1.051
17.132
Predictors Depth of depression
Constant
P
OR
Upper Lower
OR, odds ratio; CI, confidence interval; ICH, intracerebral hematoma.
predicting dural tear were not evaluated.10 In the present study, we evaluated all potential predictive factors that might correlate with dural tear in patients with compound DSF, including pneumocephalus, brain contusions/ICH, and depth of fracture depression. Furthermore, we developed a logistic regression model (diagnostic test) to predict the probability of dural tear from the predictive factors (available on preoperative CT) and validated the model (diagnostic test) using the ROC curve and area under the curve (0.835).17-19 We also determined the cutoff value for a positive test giving the highest accuracy to be 30% with a corresponding sensitivity of 93.0% and specificity of 43.9%. To the best of our knowledge, there is no study in the literature that reports a model (diagnostic test) to detect dural tear. This model is the first of its kind, and we believe that it will have clinical application. Moreover, the sample size (n ¼ 128) in the present study was fairly large enough to allow generalizable conclusions. We believe that knowledge of the status of the dura mater (whether it is torn or not) based on preoperative CT, is important to guide treatment decision making in resource-limited settings where the risk of extensive cranial surgery outweighs the benefit. On one hand, the absence of dural tear may mandate conservative treatment to avoid more extensive cranial surgery.15,16 On the other hand, the presence of dural tear requires immediate surgical repair to reduce cranial infections.11,13
REFERENCES 1. Haagsma JA, Graetz N, Bolliger I, Naghavi M, Higashi H, Mullany EC, et al. The global burden of injury: incidence, mortality, disability-adjusted life years and time trends from the Global Burden of Disease study 2013. Inj Prev. 2016;22: 3-18. 2. Global Burden of Disease 2013 Collaborators. Global, regional, and national disability-adjusted life years (DALYs) for 306 diseases and injuries and healthy life expectancy (HALE) for 188 countries, 1990-2013: quantifying the epidemiological transition. Lancet. 2015;386:2145-2191.
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Figure 3. Receiver operating characteristic (ROC) curve showing the overall ability of the model to classify dural status. The area under the curve ¼ 0.835.
CONCLUSIONS Based on results of this study, there is a statistically significant correlation between the predictor variables (i.e., depth of fracture depression, pneumocephalus, and brain contusion/ICH) and the intraoperative finding of dural tear in patients with compound DSF. Dural tear in compound DSF can be predicted with 93.0% sensitivity using preoperative CT findings, and this may help guide treatment decision making in resource-limited settings where the risk of extensive cranial surgery outweighs the benefit. ACKNOWLEDGMENTS The authors thank the neurosurgical teams in all the hospitals that participated in this study for their great support.
3. Global Burden of Disease 2015 Collaborators. Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet. 2016;388:1545-1602. 4. Hyder AA, Wunderlich CA, Pavanachandra P, Gururaj G, Kobusingye OC. The impact of traumatic brain injuries: a global perspective. Neurorehabilitation. 2007;22:341-353. 5. Heary RF, Hunt CD, Krieger AJ, Schulder M, Vaid C. Nonsurgical treatment of compound depressed skull fractures. J Trauma. 1993;35: 441-447.
6. Graham DI, Gennareli TA. Pathology of brain damage after head injury. In: Cooper P, Golfinos G, eds. Head Injury. 4th ed. New York: Morgan Hill; 2000. 7. Braakman R. Depressed skull fracture: data, treatment and follow up in 225 consecutive cases. J Neurol Neurosurg Psychiatry. 1972;35:395-402. 8. Ali M, Ali L, Roghani IS. Surgical management of depressed skull fracture. J Postgrad Med Inst (Peshawar-Pakistan). 2003;17:116-123. 9. Rolekar NG. Prospective study of outcome of depressed skull fracture and its management. Int J Med Sci Public Health. 2014;3:1540-1544.
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10. Shokouhi G, Sattarnezhad N, Motlagh PS, Mahdkhah A. Correlation of fracture depression level and dural tear in patients with depressed skull fracture. Neurosurg Q. 2014;24:84-86.
11. Al-Hadad SA, Kirollos R. A 5-year study of the outcome of surgically treated depressed skull fractures. Ann R Coll Surg Engl. 2002;84: 196-200.
12. Hossain MZ, Mondle MS, Hoque MM. Depressed skull fracture: outcome of surgical treatment. J Teach Assoc. 2008;21:140-146.
PREDICTING DURAL TEAR IN COMPOUND DEPRESSED SKULL FRACTURE
14. Kalyanaraman S. Scalp and skull injuries. In: Textbook of Neurosurgery. 2nd ed. New Delhi: Churchill Livingstone; 1996:259-262.
19. Kumar R, Indrayan A. Receiver operating characteristic (ROC) curve for medical researchers. Indian Pediatr. 2011;48:227-287.
15. Katikar DB, Jaykar RD, Rahul G, Shivprasad L, Vikas K. A prospective randomized study of operative and conservative management for compound depressed fracture skull. MedPulse Int Med J. 2014;1:689-693.
Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
16. Van Den Heever CM, Van Der Merwe DJ. Management of depressed skull fractures selective conservative management of nonmissile injuries. J Neurosurg. 1989;71:186-190. 17. Hosmer DW, Lemeshow S, Sturdivant RX. Applied Logistic Regression. Hoboken, NJ: Wiley; 2013.
13. Jennett B, Miller J. Infection after depressed fracture of skull: implications for management of nonmissile injuries. J Neurosurg. 1972;36: 333-339.
18. Hajian-Tilaki K. Receiver operating characteristic (ROC) curve analysis for medical diagnostic test evaluation. Caspian J Intern Med. 2013;4:627-635.
WORLD NEUROSURGERY 114: e833-e839, JUNE 2018
Received 31 January 2018; accepted 12 March 2018 Citation: World Neurosurg. (2018) 114:e833-e839. https://doi.org/10.1016/j.wneu.2018.03.095 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2018 Elsevier Inc. All rights reserved.
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Predicting Dural Tear in Compound Depressed Skull Fractures: A Prospective Multicenter Correlational Study Shemsedin Musefa Salia1, Hagos Biluts Mersha2, Abenezer Tirsit Aklilu2, Abat Sahlu Baleh2, Morten Lund-Johansen3
BACKGROUND: Compound depressed skull fracture (DSF) is a neurosurgical emergency. Preoperative knowledge of dural status is indispensable for treatment decision making. This study aimed to determine predictors of dural tear from clinical and imaging characteristics in patients with compound DSF.
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METHODS: This prospective, multicenter correlational study in neurosurgical hospitals in Addis Ababa, Ethiopia, included 128 patients operated on from January 1, 2016, to October 31, 2016. Clinical, imaging, and intraoperative findings were evaluated. Univariate and multivariate analyses were used to establish predictors of dural tear. A logistic regression model was developed to predict probability of dural tear. Model validation was done using the receiver operating characteristic curve.
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RESULTS: Dural tear was seen in 55.5% of 128 patients. Demographics, injury mechanism, clinical presentation, and site of DSF had no significant correlation with dural tear. In univariate and multivariate analyses, depth of fracture depression (odds ratio 1.3, P < 0.001), pneumocephalus (odds ratio 2.8, P [ 0.005), and brain contusions/ intracerebral hematoma (odds ratio 5.5, P < 0.001) were significantly correlated with dural tear. We developed a logistic regression model (diagnostic test) to calculate probability of dural tear. Using the receiver operating characteristic curve, we determined the cutoff value for a
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Key words Black Lion score - Brain contusion - Depressed skull fracture - Dural tear - Neurosurgery - Pneumocephalus - Skull fracture -
Abbreviations and Acronyms CI: Confidence interval CSF: Cerebrospinal fluid CT: Computed tomography DSF: Depressed skull fracture ICH: Intracerebral hematoma
positive test giving the highest accuracy to be 30% with a corresponding sensitivity of 93.0% and specificity of 43.9%. CONCLUSIONS: Dural tear in compound DSF can be predicted with 93.0% sensitivity using preoperative findings and may guide treatment decision making in resource-limited settings where risk of extensive cranial surgery outweighs the benefit.
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INTRODUCTION
I
njuries are substantial causes of morbidity and mortality affecting 973 million people worldwide and resulting in 4.8 million deaths in 2013. According to the World Health Organization, by 2020, head injury will surpass many diseases as a major cause of death and disability.1-4 Depressed skull fracture (DSF) is a serious injury that occurs in up to 6% of all head injuries and 11% of severe head injuries. Approximately 68%e86% of DSFs are compound fractures, and dural tear, which has a significant association with cranial infections, occurs in a great proportion of these (10%e52%).5-12 The incidence of infection in compound DSF can reach 10.6% and infection is associated with a significantly higher incidence of persistent neurologic deficit, late-onset epilepsy, and death. Operative management reduces the incidence of infection to 4.6%.11,13 Therefore, these fractures warrant immediate treatment, which may vary in complexity from simple skin débridement and wound closure to fracture
OR: Odds ratio ROC: Receiver operating characteristic From the 1Neurosurgery Unit, Department of Surgery, Hawassa University Comprehensive Specialized Hospital, Tabor Sub-city, Hawassa, Ethiopia; 2Neurosurgery Unit, Department of Surgery, Addis Ababa University Tikur Anbessa Specialized Hospital, Lideta Sub-city, Addis Ababa, Ethiopia; and 3Department of Neurosurgery, Haukeland University Hospital, Bergen, Norway To whom correspondence should be addressed: Shemsedin Musefa Salia, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2018) 114:e833-e839. https://doi.org/10.1016/j.wneu.2018.03.095 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2018 Elsevier Inc. All rights reserved.
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PREDICTING DURAL TEAR IN COMPOUND DEPRESSED SKULL FRACTURE
elevation, débridement of contused brain, and closure of a dural defect.14 The decision regarding the need for extensive surgery may be a difficult one. In particular, it may be difficult to predict whether or not the dura mater is torn. The presence of dural tear mandates immediate surgical repair to avoid bacterial meningitis, subdural empyema, and brain abscess.11 The absence of dural tear may mandate conservative treatment to avoid more extensive cranial surgery.11,15,16 Few studies have explored the clinical and computed tomography (CT) scan findings to predict dural tear in a patient with a compound DSF.10 In this prospective study, using a logistic regression model, we investigated whether preoperative findings might predict dural tear in patients who underwent surgery for compound DSF.
MATERIALS AND METHODS This prospective, multicenter, correlational study to determine the predictors of dural tear in patients with compound DSF was approved by the Research Ethics Committee of the Department of Surgery, Addis Ababa University, Ethiopia. Informed consent was obtained from all individual participants included in the study and/or their legal caregivers. The study was conducted from January 1, 2016, to October 31, 2016, in 4 hospitals in Addis Ababa, Ethiopia, that provide neurosurgical service—Addis Ababa University Tikur Anbessa Specialized Hospital, African Leprosy Research Training Hospital, Zewditu Memorial Hospital, and Myungsung Christian Medical Center, with surgical bed capacity of 300, 53, 45, and 40 beds. Eight consultant and 35 resident neurosurgeons work in these hospitals on a rotational basis. Patients were included in the study if they had consented to undergo surgery, had received a CT scan of the head, and had consented to be involved in this research. Patients who did not undergo surgery, patients with penetrating head injury, and patients with obvious dural tear (cerebrospinal fluid leakage or oozing brain tissue) on clinical examination were not included. Clinical findings on admission, cause and site of injury, and detailed CT findings were recorded. On review of admission CT scans, the maximum depth of fracture depression in millimeters was measured from the inner table of the normal calvaria to the inner table of the depressed fragment. For purposes of this study, any air inside the cranial cavity close to the DSF was defined as pneumocephalus. Hyperdense areas on posttrauma CT scan measuring >10 mm were arbitrarily defined as intracerebral hematoma (ICH), whereas smaller lesions were categorized as brain contusion. In all surgical procedures, the dura mater was carefully inspected, and the status of dural patency was noted. A structured questionnaire was used for data collection. A convenience sampling method was used. A sample size estimation method for the proportion of binary (dichotomous) outcome was used: pð1 pÞ (1) d2 where N is the size of sample, Z is the z score for the desired level of confidence, p is the estimate of expected proportion with the variable of interest in the population, and d is the half-width of the desired interval (precision). N ¼ Z2
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A prospective study on compound skull fractures conducted by Rolekar9 reported the proportion of dural tear in operated DSF cases to be 10%. Hence, taking 10% as the estimate of expected proportion, 1.96 as the value of Z for 95% confidence level (CI), and 0.05 as the value of d, the calculated sample size was 139. However, 128 patients who fulfilled the inclusion criteria were identified during the study period, which constituted 92.1% of the estimated sample size. Baseline demographic and clinical data were compared using statistical tests based on the characteristics of the variables. Mean age and mean depression levels were compared using t test. Univariate analysis and multivariate analysis were used to establish predictors of dural tear. Logistic regression analysis was employed to predict the probability of dural tear from the predictor variables. A regression model was developed to predict the natural log of the odds of having dural tear: Y lnðoddsÞ ¼ ln ¼ a þ bx þ . (2) 1Y odds ð1 þ oddsÞ
(3)
odds ¼ eaþbxþ.
(4)
Y ¼
eaþbxþ. (5) 1 þ eaþbxþ. where Y is the predicted probability of torn dura, 1 Y is the predicted probability of intact dura, x is the predictor variable, and e is the base of the natural logarithm (e ¼ 2.718 .). The Hosmer-Lemeshow goodness-of-fit test was used to check that the predictions made by the model fit perfectly with the observed data.17 Model validation was done using the receiver operating characteristic (ROC) curve.18,19 Statistical significance was set at P < 0.05. Data were analyzed using IBM SPSS Version 20 (IBM Corp., Armonk, New York, USA). Y ¼
RESULTS There were 128 patients (114 men; 89.1%) who fulfilled the inclusion criteria and were included. Fourteen patients were excluded because they presented with oozing brain tissue, cerebrospinal fluid leakage, or penetrating injury. Most patients (116; 90.7%) were <45 years old (mean age, 26.0 years; range, 3e65 years). Physical assault was the mechanism of injury in 77 (60.2%) cases. Of the assault cases, a stone was used in 44 (47.3%) cases, a stick was used in 33 (35.5%) cases, and other objects were used in 16 (17.2%) cases. Headache occurred in 108 (84.4%) patients, and loss of consciousness occurred in 98 (76.6%) of patients. Based on Glasgow Coma Scale score, 99 (77.3%) patients had mild head injury (Table 1). Frontal or parietal fractures accounted for 81 (63.3%) cases. Pneumocephalus was present in 74 (57.8%) cases, brain contusion/ICH was present in 79 (61.7%) cases, acute epidural hematoma was present in 34 (26.6%) cases, acute subdural hematoma was present in 5 (3.9%) cases, and intraventricular hemorrhage was present in 2 (1.6%) cases. The mean depth of fracture depression as measured from the inner table of the normal calvaria was 12.7 0.4 mm (range,
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PREDICTING DURAL TEAR IN COMPOUND DEPRESSED SKULL FRACTURE
Table 1. Demographic and Clinical Characteristics and Intraoperative Dural Status of Patients with Compound Depressed Skull Fracture (N ¼ 128) Dural Status
Characteristics
Intact Torn (% within Group) (% within Group)
Total (%)
24.1 1.7
27.5 1.7
26.0 1.2
13.1
14.0
13.7
49 (43.0)
65 (57.0)
114 (89.1)
8 (57.1)
6 (42.9)
14 (10.9)
Assault
34 (44.2)
43 (55.8)
77 (60.2)
Road traffic accident
10 (50)
10 (50)
20 (15.6)
Mean age, years SD Sex Male Female Mechanism of injury
Fall
4 (44.4)
5 (55.6)
9 (7.0)
Other mechanism
9 (40.9)
13 (59.1)
22 (17.2)
Headache
46 (42.6)
62 (57.4)
108 (84.4)
Vomiting
22 (36.7)
38 (63.3)
60 (46.9)
Seizure
4 (30.8)
9 (69.2)
13 (10.2)
Loss of consciousness
42 (42.9)
56 (57.1)
98 (76.6)
ENT bleed
12 (38.7)
19 (61.3)
31 (24.2)
7 (33.3)
14 (66.7)
21 (16.4)
10 (52.6)
9 (47.4)
19 (14.8)
Mild
45 (45.5)
54 (54.5)
99 (77.3)
Moderate
11 (44.0)
14 (56.0)
25 (19.5)
1 (25.0)
3 (75.0)
4 (3.1)
Clinical presentation
Motor deficit Language deficit
Univariate analysis was performed for each of the variables to determine their predictive statistical significance, odds ratio (OR), and 95% CI (Table 3). The P value for significance of correlation was set at P ¼ 0.05. Brain contusion/ICH (OR 5.519; 95% CI, 2.536e12.011; P < 0.001), pneumocephalus (OR 2.851; 95% CI, 1.380e5.891; P ¼ 0.005), and depth of fracture depression (OR 1.318; 95% CI, 1.179e1.475; P < 0.001) had statistical significance in predicting dural tear. These variables were included in the multivariate analysis (Table 4). In the multivariate analysis, the criterion for statistical significance was set at P ¼ 0.05. Depth of depression, pneumocephalus, and brain contusions/ICH were significant predictors of dural tear by ORs ranging from 1.3 to 5.5 (Table 3). Table 4 shows the logistic regression coefficients, Wald test, OR, and 95% confidence level for each of the predictors of torn dura. Using this output and entering it into the regression equation (Equation 2) generates the model for predicting torn dura as follows: lnðoddsÞ ¼ 4:207 þ 0:256 D þ 0:897 P þ 1:313 CH (6) where D is depth of fracture depression (in millimeters), P is pneumocephalus (1 ¼ present, 0 ¼ absent), and CH is brain contusion/ hematoma (1 ¼ present, 0 ¼ absent).
Table 2. Fracture Characteristics and Intracranial Findings and Intraoperative Dural Status of Patients with Compound Depressed Skull Fracture (N ¼ 128) Dural Status
Severity of head injury
Severe
None of the variables distributed showed significant difference between groups. ENT, Ear, nose, throat.
3e24 mm; SD 4.4). Mechanisms of injury and clinical characteristics of the study population are summarized in Table 1, and imaging characteristics are summarized in Table 2. At surgery, a dural tear was found in 71 (55.5%) patients, and intact dura was confirmed in 57 (44.5%) patients. The mean depths of fracture depression in the groups with torn dura and intact dura were 14.55 0.5 mm (SD 4.26) and 10.36 0.4 mm (SD 3.35), respectively (Table 2). The independent sample t test showed a statistically significant difference (t126 ¼ 6.079, N ¼ 128, P < 0.001) in the mean depths of fracture depression in the 2 groups. The observed distribution of dural status with respect to the independent variables is summarized in Tables 1 and 2. Demographics, injury mechanism, clinical presentation, and site of DSF were not significantly different between the 2 groups. Figures 1 and 2 show CT images of 2 patients with intraoperative findings of dural status.
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Characteristics
Intact Torn (% within Group) (% within Group)
Total (%)
Location Frontal
18 (38.3)
29 (61.7)
47 (36.7)
Parietal
19 (55.9)
15 (44.1)
34 (26.6)
Temporal
3 (33.3)
6 (66.7)
9 (7.0)
Occipital
4 (80.0)
1 (20.0)
5 (3.9)
13 (39.4)
20 (60.6)
33 (25.8)
10.36 0.4
14.55 0.5
12.7 0.4
3.35
4.26
4.4
Pneumocephalus
25 (33.8)
49 (66.2)
74 (57.8)
Contusions/ICH
23 (29.1)
56 (70.9)
79 (61.7)
AEDH
17 (50.0)
17 (50.0)
34 (26.6)
ASDH
2 (40.0)
3 (60.0)
5 (3.9)
IVH
0 (0.0)
2 (100)
2 (1.6)
2 bones involved Mean depth of depression, mm SD
Intracranial findings are based on head computed tomography scan. ICH, intracerebral hematoma; AEDH, acute epidural hematoma; ASDH, acute subdural hematoma; IVH, intraventricular hemorrhage.
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PREDICTING DURAL TEAR IN COMPOUND DEPRESSED SKULL FRACTURE
Figure 1. Axial computed tomography scan of the head of a 29-year-old man revealed fracture depression depth of 17 mm and pneumocephalus.
Intracerebral bleeding or contusions were not seen. The probability of dural tear according to the formula was 75.4%. A torn dura was found during surgery.
From Equation 6, a formula to calculate the probability of dural tear (Y) in patients with compound DSF can be derived. We decided to name this formula Salia’s formula (Equations 7 and 8) and its output the Black Lion score. Y ¼
eð4:207þ0:256Dþ0:897Pþ1:313CHÞ 1 þ eð4:207þ0:256Dþ0:897Pþ1:313CHÞ
(7)
After rounding, simplification, and inserting the value of e (¼ 2.72) into Equation 7, the formula becomes: D 2:72ð4þ4þPþCHÞ Y ¼ D 1 þ 2:72ð4þ4þPþCHÞ
(8)
A test of the full model versus a model with intercept only was statistically significant (c23 ¼ 47.469, N ¼ 128, P < 0.001). The Hosmer-Lemeshow goodness-of-fit test showed insignificant c2 test (c28 ¼ 6.737, P ¼ 0.565), indicating that predictions made by the model fit perfectly with the observed data. The ROC curve was used to evaluate the goodness of fit of the logistic regression model based on the simultaneous measurement of sensitivity and specificity for all possible cutoff points. The ROC curve for the present model (Figure 3) was located closer to the left upper corner (area under the curve ¼ 0.835; 95% CI, 0.766e0.904; P < 0.001), indicating that the model classifies the group with dural tear significantly better than by chance. The optimal cutoff point for positivity was determined by maximizing the sum of sensitivity and specificity (1.369) and using the maximum Youden index (0.369) across various cutoff points. The cutoff value for positivity giving the highest accuracy was 30% with a corresponding sensitivity of 93.0% and specificity of 43.9%. Based on this cutoff value, the minimum depth of fracture depression to predict dural tear was 13.2 mm if both of the other predictors were absent, 10.0 mm if only
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pneumocephalus was present, 8.0 mm if only brain contusion/ ICH was present, and 5.0 mm if both of the other predictors were present. An Excel sheet calculator was developed based on the formula for ease of practical application (see Supplement 1). DISCUSSION In the present study, 90.7% of patients were <45 years old, which is a higher percentage than reported by other studies (75%).7,9,11 This study also showed a male predominance of 89.1%, which agrees with other studies in the literature.7,10,11 Some studies reported physical assault to be the most common cause of DSF (30%e75%), as was the case in the present study (60%), whereas other studies reported road traffic accident as the most common cause of DSF.7,9-12 Headache (84.4%) and loss of consciousness (76.6%) were the most common presenting symptoms in this study, which is similar to other studies.9,10 Most studies reported the frontal or parietal bones to be the most common sites of DSF, which is in agreement with the present study.7-9 Although there are a few studies that report the incidence of brain contusions/ ICH, we found no literature depicting the incidence of pneumocephalus in this study population.8 DSF is a serious type of head trauma, with 68%e86% of cases being compound fractures.5-12 These fractures warrant immediate treatment, which may vary in complexity from simple skin débridement and wound closure to fracture elevation, débridement of contused brain, and closure of a dural defect.14 The decision regarding the need for extensive surgery may be a difficult one. In particular, it may be difficult to predict whether or not the dura mater is torn. The present study showed intraoperative findings of dural tear in 55.5% of cases with compound DSF; this percentage is similar to reports by Al-Haddad and Kirollos11 and Braakman,7 but it is higher than reported by Husien et al.12 and Rolekar.9 Pneumocephalus and
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PREDICTING DURAL TEAR IN COMPOUND DEPRESSED SKULL FRACTURE
Figure 2. Axial computed tomography scan of the head of a 55-year-old man revealed fracture depression depth of 5 mm, pneumocephalus, and
brain contusions/ICH were shown in the present study to have significant correlation with intraoperative finding of dural tear. To the best of our knowledge, there is no literature evaluating these imaging findings and dural status in such a study population. The present study also revealed the mean depths of fracture depression in the groups with torn dura and intact dura to be 14.55 4.26 mm and 10.36 3.35 mm, respectively. According to Shokouhi et al.,10 there is a significant correlation between depth of fracture depression and dural tear with the cutoff value for predicting dural tear being 14 mm with 77% sensitivity.
brain contusion. The probability of dural tear according to the formula was 32%. A torn dura was found during surgery.
The present study confirmed the significant correlation between depth of fracture depression and dural tear but with different cutoff values for predicting dural tear based on the presence or absence of other predictor variables. Although the study by Shokouhi et al.10 indicated the depth of fracture depression to be a predictor of dural tear, it displayed an average depth of fracture depression of 23.5 8.9 mm and 14.7 4.6 mm for the group with torn dura and for the group with intact dura, respectively. These findings are quite different compared with the findings of our study. Additionally, that study had a sample size about one third of ours (n ¼ 40), and other factors potentially important in
Table 3. Univariate Analysis for Predictors of Dural Tear in Patients with Compound Depressed Skull Fracture (N ¼ 128) Variable
OR (95% CI)
P
Sex
0.565 (0.184e1.736)
0.319
Dysphasia
Age
0.981 (0.956e1.008)
0.165
GCS
Mechanism
Variable
OR (95% CI) 0.682 (0.257e1.813)
P 0.443 0.735
0.829
DSF location
Headache
1.078 (0.274e4.239)
0.914
Depth of depression
1.318 (1.179e1.475)
0.458 0.000
Vomiting
1.832 (0.902e3.720)
0.094
Pneumocephalus
2.851 (1.380e5.891)
0.005
Seizure
1.923 (0.560e6.604)
0.299
Contusions/ICH
5.519 (2.536e12.011)
0.000
LOC
1.333 (0.587e3.027)
0.492
AEDH
0.741 (0.337e1.627)
0.455
ENT bleed
1.370 (0.600e3.128)
0.455
ASDH
1.213 (0.196e7.519)
0.835
Motor deficit
1.754 (0.656e4.691)
0.263
IVH
1.029 (0.989e1.071)
0.502
OR, odds ratio; CI, confidence interval; GCS, Glasgow Coma Scale; DSF, depressed skull fracture; ICH, intracerebral hematoma; LOC, loss of consciousness; AEDH, acute epidural hematoma; ENT, ear, nose, throat; ASDH, acute subdural hematoma; IVH, intraventricular hemorrhage.
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Table 4. Multivariate Analysis for Predictors of Dural Tear in Patients with Compound Depressed Skull Fracture (N ¼ 128) 95% CI for OR B
Wald c2
0.256
16.983
0.000 1.292
1.144
1.459
Pneumocephalus
0.897
4.248
0.039 2.452
1.045
5.755
Brain Contusion/ICH
1.313
8.871
0.003 3.717
1.567
8.819
4.207
23.984
0.000 0.015
1.051
17.132
Predictors Depth of depression
Constant
P
OR
Upper Lower
OR, odds ratio; CI, confidence interval; ICH, intracerebral hematoma.
predicting dural tear were not evaluated.10 In the present study, we evaluated all potential predictive factors that might correlate with dural tear in patients with compound DSF, including pneumocephalus, brain contusions/ICH, and depth of fracture depression. Furthermore, we developed a logistic regression model (diagnostic test) to predict the probability of dural tear from the predictive factors (available on preoperative CT) and validated the model (diagnostic test) using the ROC curve and area under the curve (0.835).17-19 We also determined the cutoff value for a positive test giving the highest accuracy to be 30% with a corresponding sensitivity of 93.0% and specificity of 43.9%. To the best of our knowledge, there is no study in the literature that reports a model (diagnostic test) to detect dural tear. This model is the first of its kind, and we believe that it will have clinical application. Moreover, the sample size (n ¼ 128) in the present study was fairly large enough to allow generalizable conclusions. We believe that knowledge of the status of the dura mater (whether it is torn or not) based on preoperative CT, is important to guide treatment decision making in resource-limited settings where the risk of extensive cranial surgery outweighs the benefit. On one hand, the absence of dural tear may mandate conservative treatment to avoid more extensive cranial surgery.15,16 On the other hand, the presence of dural tear requires immediate surgical repair to reduce cranial infections.11,13
REFERENCES 1. Haagsma JA, Graetz N, Bolliger I, Naghavi M, Higashi H, Mullany EC, et al. The global burden of injury: incidence, mortality, disability-adjusted life years and time trends from the Global Burden of Disease study 2013. Inj Prev. 2016;22: 3-18. 2. Global Burden of Disease 2013 Collaborators. Global, regional, and national disability-adjusted life years (DALYs) for 306 diseases and injuries and healthy life expectancy (HALE) for 188 countries, 1990-2013: quantifying the epidemiological transition. Lancet. 2015;386:2145-2191.
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Figure 3. Receiver operating characteristic (ROC) curve showing the overall ability of the model to classify dural status. The area under the curve ¼ 0.835.
CONCLUSIONS Based on results of this study, there is a statistically significant correlation between the predictor variables (i.e., depth of fracture depression, pneumocephalus, and brain contusion/ICH) and the intraoperative finding of dural tear in patients with compound DSF. Dural tear in compound DSF can be predicted with 93.0% sensitivity using preoperative CT findings, and this may help guide treatment decision making in resource-limited settings where the risk of extensive cranial surgery outweighs the benefit. ACKNOWLEDGMENTS The authors thank the neurosurgical teams in all the hospitals that participated in this study for their great support.
3. Global Burden of Disease 2015 Collaborators. Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet. 2016;388:1545-1602. 4. Hyder AA, Wunderlich CA, Pavanachandra P, Gururaj G, Kobusingye OC. The impact of traumatic brain injuries: a global perspective. Neurorehabilitation. 2007;22:341-353. 5. Heary RF, Hunt CD, Krieger AJ, Schulder M, Vaid C. Nonsurgical treatment of compound depressed skull fractures. J Trauma. 1993;35: 441-447.
6. Graham DI, Gennareli TA. Pathology of brain damage after head injury. In: Cooper P, Golfinos G, eds. Head Injury. 4th ed. New York: Morgan Hill; 2000. 7. Braakman R. Depressed skull fracture: data, treatment and follow up in 225 consecutive cases. J Neurol Neurosurg Psychiatry. 1972;35:395-402. 8. Ali M, Ali L, Roghani IS. Surgical management of depressed skull fracture. J Postgrad Med Inst (Peshawar-Pakistan). 2003;17:116-123. 9. Rolekar NG. Prospective study of outcome of depressed skull fracture and its management. Int J Med Sci Public Health. 2014;3:1540-1544.
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10. Shokouhi G, Sattarnezhad N, Motlagh PS, Mahdkhah A. Correlation of fracture depression level and dural tear in patients with depressed skull fracture. Neurosurg Q. 2014;24:84-86.
11. Al-Hadad SA, Kirollos R. A 5-year study of the outcome of surgically treated depressed skull fractures. Ann R Coll Surg Engl. 2002;84: 196-200.
12. Hossain MZ, Mondle MS, Hoque MM. Depressed skull fracture: outcome of surgical treatment. J Teach Assoc. 2008;21:140-146.
PREDICTING DURAL TEAR IN COMPOUND DEPRESSED SKULL FRACTURE
14. Kalyanaraman S. Scalp and skull injuries. In: Textbook of Neurosurgery. 2nd ed. New Delhi: Churchill Livingstone; 1996:259-262.
19. Kumar R, Indrayan A. Receiver operating characteristic (ROC) curve for medical researchers. Indian Pediatr. 2011;48:227-287.
15. Katikar DB, Jaykar RD, Rahul G, Shivprasad L, Vikas K. A prospective randomized study of operative and conservative management for compound depressed fracture skull. MedPulse Int Med J. 2014;1:689-693.
Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
16. Van Den Heever CM, Van Der Merwe DJ. Management of depressed skull fractures selective conservative management of nonmissile injuries. J Neurosurg. 1989;71:186-190. 17. Hosmer DW, Lemeshow S, Sturdivant RX. Applied Logistic Regression. Hoboken, NJ: Wiley; 2013.
13. Jennett B, Miller J. Infection after depressed fracture of skull: implications for management of nonmissile injuries. J Neurosurg. 1972;36: 333-339.
18. Hajian-Tilaki K. Receiver operating characteristic (ROC) curve analysis for medical diagnostic test evaluation. Caspian J Intern Med. 2013;4:627-635.
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Received 31 January 2018; accepted 12 March 2018 Citation: World Neurosurg. (2018) 114:e833-e839. https://doi.org/10.1016/j.wneu.2018.03.095 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2018 Elsevier Inc. All rights reserved.
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