Risk factors for delayed neuro-surgical intervention in patients with acute mild traumatic brain injury and intracranial hemorrhage

Mild traumatic brain injury is a common presentation at the emergency department. Brain CT is the standard diagnostic tool for detecting the intracranial condition of patients with acute TBI. The incidence of associated intracranial abnormalities is 0.7–20 % [1‐4]. Some patients with large intracranial hematoma will undergo surgical management initially following guidelines for the surgical management of traumatic brain injury [5]. Repeat brain CT scans after admission and monitoring the neurologic status [6, 7] are used for the early detection of progressive hematoma and increasing intracranial hypertension (IICP) [6, 8‐10] in patients without initially surgical intervention. Surgical intervention is used for evacuation of the hematoma and failure of medical treatment of IICP. Several studies have focused on risk factors of intracranial lesion and delayed hemorrhage and intensive care unit (ICU) monitoring to prevent poor outcome of mild TBI patients [1‐4, 6]. Few studies have given attention to the risk of surgical intervention [11] after initial neurosurgeon assessment. Because there is a need for better delineation of potential risk factors and clinical features in this specific subgroup, this study aimed to analyze the clinical features, neuro-imaging findings, and measurements to determine the potential risk factors predictive of surgical intervention in patients with mild TBI and tICH on admission.

Patient with acute mild TBI constitute a significant number of patients in the emergency department. Regular follow-up brain CT, monitoring in the intensive care unit, and financial difficulties have all been discussed. Surgical intervention is the most important consideration. In the current study, the failure rate of non-operative management is 3.8 % (13/340). Such figures are consistent with those of five recent studies, with a range of 1–8.7 % [6, 10, 17‐19]. The rate and number of patients with acute mild TBI undergoing neurosurgical intervention is low. The rate of craniotomy is 0.9–5.8 % and ICP monitor insertion is 0.2–2.9 %. In 2009, Bee et al. reported the largest number and rate of neurosurgical intervention in mild TBI with tICH [6]. Thomas et al. reported the largest number of patient with mild TBI with tICH [10]. Their number of neurosurgical intervention was 18 and 14, respectively. Both studies focused on repeat brain CT, progressive hemorrhage, and ICU monitor. We identified the risk of factors of mild TBI with initial tICH and delayed neurosurgical intervention including volume of EDH.

In the initial brain CT, only volume of EDH was the risk of delayed neuro-surgical intervention. The median volume of EDH was larger than volume of SDH and IPH. Patients can tolerate the larger volume of EDH without neurologic deficit than others of hemorrhage. Chen et al. reported that an EDH volume >30 ml, thickness >15 mm, and midline shift >5 mm tended to require surgery [20]. In this series, there is no successful non-operative management in patients with EDH >26 ml on initial brain CT. All of them had signs of progressive IICP during non-operative management. Moreover, any increase of one cubic centimeter (cm [3]) increased the presence of delayed neurosurgical intervention by 16.0 % (p = 0.011; OR: 1.190, 95 % CI: 1.041–1.362). Larger volume of initial EDH tended to have higher risk of delayed neuro-surgical management.

Previous reports found that progressive hemorrhage occurred in approximately 15–28 % of patients with acute mild TBI [6, 16, 21]. Most developed early (within one day after the injury) during the clinical course [22‐24]. In this study, 20.5 % of patients had larger hematoma seen in following up brain images. The median time of repeated brain CT is 65.9 (10.1, 128.4) hours in delayed neurosurgical intervention. Most patients (12/13, 92.3 %) had neurologic deficit. The median time of neurologic deterioration and neurosurgical intervention was 51.8 (9.9, 92.9) hours and 67.7 (31.5, 125) hours in delayed neuro-surgical intervention.

In the current study, neurologic deterioration in acute mild TBI accounts for 7.3 % (25/340) of all episodes, including 48 % (12/25) who underwent neuro-surgical intervention. The study by Sifri et al. had 161 patients with mild traumatic brain injury and intracranial bleed on initial cranial CT. Due to abnormal neurologic findings on repeat CT scan, 6 % of these patients underwent emergency craniotomy [17]. In another study, 3.7 % (21/565) had acute neurologic deterioration and 29 % (6/21) led to neuro-surgical or medical intervention [18]. Washington et al. reported 321 patients with mild TBI and abnormal head CT, including four patients (1 %) with neurologic decline and three who underwent neurosurgical intervention [19]. In the present series, there was a higher incidence of neurologic deterioration in the delayed neuro-surgical intervention group.

In terms of laboratory data, higher WBC count is a risk of delayed neurosurgical intervention. Leukocytosis is associated with the severity of injury and outcome [25, 26]. Although the mechanism is still controversial, catecholamines increase the leukocyte count by releasing marginated cells into the circulating pool. Corticosteroids increase the neutrophil count by releasing cells from the storage pool in the bone marrow. In this study, leukocytosis is significantly different in the two groups of non-operative management and delayed neurosurgical intervention. There were thirteen patients received anti-coagulation therapy in our study, but only ten patients had coagulopathy at the time of injury. However, no patient with coagulopathy needs delayed neurosurgical intervention. In our clinical practice, we corrected those patients with coagulopathy as soon as possible after intracranial hemorrhage was diagnosed. Furthermore, we only enrolled patients with mild traumatic brain injury. This could be why no patient with coagulopathy needs delayed neurosurgical intervention in this study.

This study has several limitations. First, the study is retrospective. Second, following brain images during non-operative management are irregular, and that could be a confounding factor. The real rate of progressive intracranial hemorrhage is also unknown. Lastly, there is the short-term follow-up period and relatively small sample size. A larger cohort is necessary to generate more powerful conclusions and to refine predictors of neuro-surgical interventions.

Larger volume of EDH on initial brain CT had higher risk of delayed neuro-surgical intervention after neurosurgeon assessment. Longer and closer neurological function monitor and repeated brain image is required for those patients had initial larger EDH. A large-scale, multi-centric trial with a bigger study population should be performed to validate the findings.