Analysis of Factors Affecting Outcome of Acute Extradural Hematoma—Our Observation in Dhaka Medical College and Hospital

Abstract Background  Extradural hematoma (EDH) is a leading cause of death in young population. Timely intervention gives dramatic recovery but often fatal if not treated in time. The surgical outcome of EDH depends on many variables that strongly affect the prognosis of the disease, which are preoperative Glasgow coma scale (GCS), overlying skull fracture, time interval between injury and surgery, other associated intracranial injuries (like cerebral contusion, subdural hematoma, or intracerebral hematoma), pupillary abnormalities (anisocoria), and hematoma volume. But no correlation was found between surgical outcome of EDH and age, sex, etiology, and site of hematoma. Objective  We want to identify the factors affecting the surgical outcome of EDH that will help us in preoperative prioritization of the cases for intervention, adequate resuscitation, and counselling the attendant regarding the outcome. Our ultimate goal was to reduce the mortality and morbidity from this disease. Methods  This study was conducted on the patients admitted through neuroemergency and diagnosed as EDH by computed tomography scan of head, in the department of Neurosurgery of Dhaka medical college and hospital from January 1, 2017 to December 31, 2019. This is three-year prospective interventional study where all the patients underwent surgical evacuation of EDH on emergency basis and outcome was measured by Glasgow outcome scale (GOS) after 48 hours of admission and at discharge. Results  Outcome was divided into good (GOS 4,5) and poor (GOS 1–3) groups. Pre-operative GCS, overlying skull fracture, time interval between injury and surgery, associated intracranial injuries, anisocoria and hematoma volume were the factors affecting the surgical outcome significantly. Conclusion  Good surgical outcome is associated with EDH volume less than 40cc, preoperative GCS more than 8, absence of anisocoria, overlying skull fracture, no associated intracranial injury and surgery within 12 hours of injury. But age, sex and site of EDH has no definite correlation with outcome.


Introduction
Accumulation of blood in the potential space between dura matter and skull is called extradural hematoma (EDH). 1 Fractures on the skull bone having rupture of middle meningeal artery or its branches are present in approximately 85% of cases and the rest occur by ruptured venous sinuses and fractured diploic bone. 1,2EDHs have three classical presentations.First, a brief period of post-traumatic loss of consciousness; second, a lucid interval for several hours; and lastly obtundation, contralateral hemiparesis, and ipsilateral mydriasis. 3,4DHs are a very common clinical condition among traumatic brain injury counting around 2.7 to 4%. 5 It is the leading cause of death in the age group of 16 to 40 years. 6ith the availability of computed tomography (CT) scan of head almost everywhere in Bangladesh and economic solvency of the people, EDH can be diagnosed immediately after trauma.Temporal region is most prone for developing EDH in head injury, followed by frontal, parietal regions, and posterior fossa 7 as people of our country are very reluctant to use helmet while riding motor bike.Most of the patients present with headache, vomiting, altered sensorium, and lucid interval. 8,9espite advancement in neurosurgical management and increasing health care costs within the United States and other countries including Bangladesh, EDH remains a major cause of significant morbidity and mortality. 1EDH is a neurosurgical emergency and timely surgical intervention for significant EDH is the gold standard. 10Craniotomy and evacuation of the hematoma are the treatment of choice. 3he Brain Trauma Foundation has recommended that any EDH more than 30 mL should be surgically evacuated regardless of the patient's Glasgow coma scale (GCS) score. 11,12The GCS score on admission is one of the most important predictors of eventual prognosis, with the outcome being better when the initial GCS score is high. 12he level of consciousness before surgery had been correlated with mortality rate by Wells et al 12,13 as follows: (1) no mortality for patients who are awake/ conscious at the time of presentation in the hospital, (2) mortality of 9% for obtunded patients, and (3) mortality of 20% for comatose patients.
The surgical outcome of EDH depends upon many variables, in which the following six have special importance: (1) Preoperative GCS, (2) time between injury and surgery, 14 (3) overlying skull fracture, (4) associated intracranial injuries (like contusion, subdural or intracerebral hematoma), (5) pupillary abnormality (anisocoria), and 6) Hematoma volume. 8Outcome was measured during second postoperative day and at discharge from hospital by using GOS. 15In GOS good outcome was defined as GOS of 4 to 5 and poor as GOS of 1 to 3. 15,16 The patients having GCS of 13 to 15 at admission have a good outcome in 85% of cases, while those with GCS of 9 to 12 and 3 to 8 have 67 and 39%, respectively. 8Mortality rate of 23.5% in patients having surgery later than 6 hours of injury can be reduced to 18.5%, if surgery is performed within 6 hours of injury. 17Associated intracranial injuries are found in 32.46% of cases of EDH and are important to prognosticate the outcome, as 15 out of 45 patients (33.3%) who expired with EDH had associated brain injuries. 7,9,18These injuries may be subdural hematoma, contusion, and intracerebral hemorrhage.About 15 to 22% of patients have anisocoria prior to surgical evacuation of EDH. 7,9Time between injury and surgery and the hematoma volume are important factors affecting the surgical outcome. 19,20he rationale of this study is to determine the effects of said factors on the surgical outcome that will help in preoperative counseling and selecting the operative candidates earlier to reduce mortality and morbidity among the young population.

Materials and Methods
Patients with traumatic EDH diagnosed on plain CT scan of brain admitted through emergency at department of neurosurgery, Dhaka Medical College and Hospital, fulfilling the inclusion criteria for surgical evacuation were included in this study.After initial resuscitation in emergency, conservative management was decided for the patients who had all of the following: (1) volume less than 25 cm 2 , thickness less than 10 mm, 3 midline shift less than 5 mm, (4) GCS more than 8 and (5) no focal neurological deficit. 21Those who were selected for emergency operation were taken to operating room after blood arrangement and consent was documented.Surgical evacuation was performed within first 24 hours in all patients.Under general anesthesia or regional block, after all aseptic measures, craniotomy and evacuation of hematoma were performed.Hemostasis was secured and hitch sutures were applied prior to wound closure.Postoperatively some of the patients were shifted to neurosurgical intensive care unit (ICU) or high-dependency care unit as per need.Surgical outcome was measured by the GOS after 48 hours of surgery and at discharge from hospital.
Our sample size was very large.Detail of sample size is shown in ►Table 1 that is documented unit wise and was published as "Year Book" of the Department of Neurosurgery in Dhaka Medical College and Hospital in the year of 2017, 2018, and 2019.

Results
Out of 1,978 patients, 1,543 (78%) patients were male and female were 435 (22%) with M:F¼ 3.5:1.Majority of the patients were around 30 years of age with a mean age of 30.2 years (►Figs. 1 and 2).
►Table 3 shows analysis of factors affecting the outcome of surgery of the study population.Preoperative GCS of the patient showed significant effect on final outcome.Thirty percent patients had GCS of 14 to 15, 563 (95%) patients had good surgical outcome, while those (57%) with GCS of 9 to 13,1038 (92%) had good outcome.Thirteen percent patients were with poor GCS of 3 to 8, while 180 (70%) cases had poor surgical outcome.Anisocoria is associated with poor surgical outcome in 249 (84%) of the patients.Seventy-six (64%) patients with hematoma volume more than 60 mL had good outcome, but those with 21 to 40 mL and 41 to 60 mL had good surgical outcome in 759 (96%) and 856 (92%) cases following surgical evacuation.When EDH was associated with other intracranial injuries in 25% (495) cases on CT scan, 296 (60%) had poor surgical outcome, while those having no such injuries (only 119 out of 1,484; 8%) showed poor outcome.The patients having skull fractures had good outcome in 1,378 (82%) cases, while patients with no fracture (297; 15%) showed good outcome in only 125 (42%) cases.Good surgical outcome was reported in 100% cases with surgical evacuation within 12 hours of injury (475; 24%), while outcome was good in 1,116 (94%) and 202 (64%) cases when operated in 12 to 24 hours and more than 24 hours, respectively.So, delayed surgery beyond 24 hours caused poor outcome (GOS 1-3) in 114 (36%) of case (►Figs. 5and 6).

Discussion
In our study, majority of patients were in the most acute period of life with mean age of 30.2 years that is comparable with the age mentioned in studies of Ozkan et al and Cheung et al, who found the mean age of patients with EDH as 26.9 and 37.7 years, respectively, in their series.series of 1,978 patients, 1,543 (78%) were males and 435 (22%) were females with a male to female ratio 3.5:1.Much higher male predominance of 13:1 was reported in a Pakistani study on 38 patients at Pakistan Institute of Medical Sciences, Islamabad by Mushtaq and Khaleeq. 23atients with traumatic EDH frequently present with altered state of consciousness 9 that is measured by GCS.In our study, 593 (30%), 1,128 (57%), and 257 (13%) patients presented with a GCS of 14 to 15, 9 to 13, and 3 to 8, respectively, 20,[22][23][24] which is majority (57%) of patients presented with GCS of 9 to 13.This is in contrary to the results of Cohen et al and Cheung et al in which the GCS of the majority of patients was in 13 to 15 range, that is, 67 and 70%, respectively. 8,24The reason of more patients with decreased GCS in our series is due to the inclusion of the very cases who underwent neurosurgical evacuation of hematoma as compared with the studies mentioned in which patients who needed conservative management only were also included.
In literature, approximately 15 to 22% of patients have anisocoria prior to surgical evacuation of EDH. 7,9Our result of 297 (15%) patients with anisocoria is comparable with these studies.One of the most important prognostic factors in EDH is its volume. 23Chowdhury et al and Ayub et al also explained the importance of volume in surgicaloutcome. 9,19n our series, there were four groups with respect to EDH volume: less than or equal to 20ml, 21 to 40ml, 41 to 60ml, and more than 60ml.Majority of the patients (930; 47%) presented with volume between 41 and 60 mL, followed by 791 (40%) cases with 21 to 40 mL volume.Only 138 (7%) and 119 (6%) of patients had volume of less than or equal to 20 and more than or equal to 60 mL, respectively.
Cheung et al in his study in Hong Kong showed that 5 patients out of 89 (5.6%) have associated intracranial injuries in traumatic EDH cases. 8In the relatively larger series of 300   patients, Babu et al got a higher (14.3%) cases with associated injuries along with EDH. 7 Later in 2008, Chowdhury et al published still a higher percentage of 32.4% (in 610 patients) for associated injuries. 9While comparing our result of 494 (25%) associated traumatic injuries was somewhat in between these two larger series.Our result is very comparable with the study at Saudi Arabia, in which 73% had EDH alone and 27%had additional intradural injury. 9In our study, skull fracture was found in 1,681 (85%) of cases on CT scan of head and preoperative findings that somehow reduce intracranial pressure and give better outcome in comparison to those who did not a fracture.9,25 In our series, the surgical outcome of EDH was measured by GOS. 15 After surgery, 1,642 (83%) of patients with EDH had good surgical outcome (GOS 4 and 5).The remaining (336; 17%)patients were in poor surgical outcome group (GOS 1-3).Mushtaq al got comparable postsurgical outcome in which, 86.8% cases were in good scale and the remaining 13.2% were in poor scale. 23Similarly, Cheung et al experienced postsurgical good and poor outcome in 76.6 and 23.3%, respectively. 5The mortality rate of 3% in our study was  comparable to the 2.63% of Mushtaq's series. 23Cheung et al reported a higher mortality of 13.3%. 8n our study, GCS of 14 to 15 and 9 to -13 had good surgical outcome in majority of cases (i.e., 100 and 95%, respectively); while the GCS of 3 to 8 had poor outcome in majority (70%) of patients.This result was supported by the Hong Kong series, in which GCS of 13 to 15 and 9 to 12 had good final outcome in 90.5 & 100% cases, respectively, and GCS 3 to 8 had poor outcome in 71.4% cases. 8The Pakistani study published better outcome of 100% for GCS of either 13 to 15 or 9 to 12, with only 55.5% poor outcome for GCS 3 to 8. 23 We also found that anisocoria is associated with poor surgical outcome in 249 (84%) patients and patients with bilateral equal pupil (1,681; 85%) had good GOS in 1,597 (95%) cases.
Hematoma volume is calculated on CT scan brain by measuring the three dimensions (i.e., transverse, anteroposterior, and craniocaudal) in mm and using the formula: 0.5 Â transverse diameter × anteroposterior diameter × craniocaudal diameter.Many studies included this variable while determining the factors affecting outcome in EDH patients. 23In our series, volume of more than or equal to 60 mL had poor outcome in 36% of cases with 64% good outcome, while volume of 21 to 40 mL and 41 to 60 mL had good surgical outcome in majority of cases (i.e., 96 and 92%, respectively).This observation is partly supported by Mushtaq et al, with 90% good outcome when hematoma volume is less than 50 mL.On the contrary, Mushtaq et al reported good outcome in still 83.3% of cases even when the volume was more than 50 mL. 23n this study, EDH coexisted with other intracranial injuries on CT scan head in 494 (25%) cases.Of which, 296 (60%) patients had poor surgical outcome, while in patients with no associated intracranial injuries 1484 (75%) with EDH only 119 (08%) showed poor outcome. 26Good surgical outcome was reported in 100% cases with surgical evacuation within 12 hours of injury (475; 24%), while outcome was good in 1,116 (94%) and 202 (64%) cases when operated in 12 to 24 and more than 24 hours, respectively.So, delayed surgery beyond 24 hours caused poor outcome (GOS 1-3) in 114 (36%) of case.
Ozkan et al in his retrospective analysis published that mortality rate of 23.5% in patients having surgery later than 6 hours of injury can be reduced to 18.5%, if surgery is performed within 6 hours of injury. 17In our study, all the patients (1978) who were operated within 12 hours of injury achieved good outcome (i.e., GOS 4 and 5); while the patients in whom the surgery was done between 12 and 24 hours achieved GOS of 4 to 5 (94% cases) and those who were operated beyond 24 hours ended up with GOS 4 to 5 (64% cases).Fifty-nine (3%) patients expired in our series, all of whom had time between injury and surgery of more than 12 hours specially more than 24 hours.So, if we can evacuate all EDH within 12 hours of injury, if we can provide ICU support to all patients and if evacuation can be done under general anesthesia, eventually mortality can be reduced close to nil.

Conclusion
Preoperative GCS, anisocoria, time interval between injury and surgery, hematoma volume, overlying skull fracture, and associated intracranial injuries affect the surgical outcome significantly.
Good surgical outcome is associated with patients with solitary extra dural hematoma of:

Fig. 1
Fig. 1 Distribution of study population by age.

Fig. 2
Fig. 2 Distribution of study population by gender.

Fig. 3
Fig. 3 Distribution of study population by mode of injury.RTA, road traffic accident.

Fig. 4
Fig. 4 Distribution of study population by volume of extradural hematoma.

Fig. 5
Fig. 5 Distribution of study population by types of lesions.EDH, extradural hematoma.Fig. 6 Distribution of study population by timing of surgery.

• Preoperative GCS ! 8 •
Absence of anisocoria • Absence of overlying skull fracture • Absence of associated intracranial injury • Undergoing surgical evacuation within 12 hours of injury • Volume of EDH less than 60 mL Note This work should be attributed to the Department of Neurosurgery, Dhaka Medical College Hospital, Dhaka, Bangladesh.

Table 1
Distribution of study population by admitting neurosurgical units (NSUs; n ¼ 1,978)