In this study, we evaluated the impact of primary DC and craniotomy on sTBI with mass lesions. As expected (given the greater severity), patients undergoing primary DC had higher 6-month mortality than the remainder of the cohort. However, in the surviving patients, the favorable GOSE rate was similar in primary DC patients and craniotomy patients indicated that primary DC might improve outcomes of subgroup patients of sTBI. We further identified that patients either with both pupillary light reflex absent or with closed basal cisterns, the primary DC decreased the mortality and increased the favorable GOSE proportion. Furthermore, we developed a multivariate logistic regression equation for decision making and to determine whether the primary DC should be done or not for sTBI with mass lesion.
TBI is one of the leading causes of death and disability worldwide, with a global annual incidence of more than 50 million cases[22]. With a population of 1.4 billion, the number of patients with TBI in China exceeds that of most other countries, causing an enormous burden to society and families[1]. Among patients who are hospitalized with severe TBI, 60% either die or survive with severe disability[18]. In China, the proportion of patients with severe TBI is around 20%,and the mortality of sTBI is also around 20%[2, 13].
After severe TBI, medical and surgical therapies are performed to minimize secondary brain injury[18]. The treatment goal of severe TBI is to reduce and prevent intracranial hypertension (ICH), a pathologic increase in ICP can lead to brain ischemia by reducing CPP and lead to neurologic deficit and fatal brain herniation syndromes. To achieve this goal, several medical and surgical therapies can be performed, including head-of-bed elevation, pharmacologic sedation and analgesic, improved blood flow, external ventricular drain, surgical evacuation of hemorrhagic lesions, and DC[23]. Despite recommendations by the Brain Trauma Foundation supporting the use of these therapies for sTBI, there is no level I evidence demonstrating improvement in patient outcomes through definitive, surgical management of TBI [17, 24]. DC has been performed for the purpose of relieving elevated intracranial pressure with outcome improvement in specific TBI patients[25].DC holds the promise of reduced mortality, but long term neurological outcomes and indications remain controversial[10].
Recently, in The Lancet Neurology, the results of the Chinese sister study—the CENTER-TBI China registry study including 13138 patients from 52 centers showed that surgical interventions, including insertion of the intracranial pressure device, decompression, external ventricular drainage, and hematoma removal show therapeutic benefits in patients with signs of brain herniation[2]. Moreover, this finding probably reflects the high proportion of patients with severe injury, but from a clinical perspective preemptively treating impending brain herniation is preferable, rather than waiting for the condition’s full development[2]. The effectiveness of these surgical interventions in this cohort is of particular relevance given the lack of benefit reported in the overall TBI population in previous clinical trials[26-28]. The identification of subgroups who are most likely to benefit from these interventions should be a priority[2].
In China, the indications for unilateral or bilateral large DC include progressive neurological deterioration, intracerebral hematoma, contusion or edema with midline shift more than 5 mm and cisternal compression on CT, and intracranial pressure higher than 30 mm Hg for longer than 30 min[13]. However, these indication variables alone do not define the patient who should undergo DC intervention. Although, intracranial pressure monitoring is widely used to evaluate the intracranial status of patients with TBI. And, in the past two decades, the addition of ICP monitoring has markedly improved decision making and management of patients with severe TBI[13]. But, most patients admitted to the ICU with severe TBI in China did not receive an ICP monitoring device, thus implying that in many centers treatment decisions are made on the basis of clinical and radiological findings[2]. Instead, in China, CT scans are done for patients with TBI in all hospitals with departments of neurosurgery[1]. Primary DC is most often performed for clinical and radiographic evidence of herniation, rather than for refractory ICP elevation[29].Moreover, we found that DC in TBI was performed in Chinese centers more often than that in European centers[2, 15].
Most sTBI patients with intracranial hypertension attribute to mass lesions, such as contusion and acute subdural hematoma (ASDH)[17]. Severe primary injury and worsening condition necessitate emergent surgical intervention. The available type of operation is either craniotomy or DC. Generally, there are three distinct scenarios in which DC is performed for TBI: firstly, as a ‘‘primary’’ procedure following evacuation of a mass lesion; secondly, as emergent treatment for neurological deterioration attributable to worsening mass effect in patients who previously were not considered to have an indication for ICP monitoring; and thirdly, as treatment for raised ICP that is refractory to medical therapy[29].
In this study, in contrast to DECRA and RESCUE-ICP[18, 27], we performed DC as primary procedure following evacuation of a mass lesion. Our data supported the hypothesis that some specific TBI patients would benefit from primary DC. Our results in line with some studies which suggesting primary DC proposed that early aggressive intervention could mitigate the secondary damages of increased ICP[30]. In Europe, a retrospective study of 729 patients revealed that one-third of patients with STBI who received emergency surgery still needed DC even after hematoma evacuation[31]. In a retrospective cohort comparison study of 91 patients who had an operation for an ASDH, 56% received a primary DC, while the rest a craniotomy[32]. This study supports the hypothesis that a primary DC (i.e. bone flap left out after ASDH evacuation) may lead to better outcomes compared to a craniotomy (i.e. bone flap is replaced) due to better control of brain swelling and intracranial hypertension in the post-operative period. This hypothesis is also supported by a two-center non-experimental comparative effectiveness research (CER), which found that post-operative ICP was better controlled and patient outcomes were better in the center with greater utilization of primary DC[33, 34]. Given the potential benefit from primary DC on TBI, there are several prospective randomized trials are going on. The primary DC for patients with ASDH is being systematically evaluated in the context of the RESCUE-ASDH trial in UK[33]. And, the effect of primary DC in sTBI with mass lesions is being evaluated in a prospective, randomized, assessor-blind, single center clinical trial named prospective, randomized evaluation of therapeutic decompressive craniectomy in sTBI with mass lesions (PRECIS) in China[35].
When comparing DC with craniotomy patients, it shows DC patients have a lower mean preoperative GCS (p = 0.01); more patients with GCS of 6 (p=0.007);more unresponsive pupillary light reflex (p< 0.001); more closed basal cisterns (p< 0.001); and more patients with diffuse injury (p=0.025). These results seem to support the notion that the perioperative neurological status in decompressive craniectomy patients is more severe than in craniotomy. To explore the factors involved in decision marking for DC, in addition to the single factor analysis and multi-factorial prognostic analysis, in our study, we further combined an ROC curve and the multivariate logistic regression equation to evaluate the predictive accuracy of two variables in choosing of DC. In line with previous reports demonstrated that the effacement of the basal cisterns and the absent of pupil reaction are strongly associated with poor outcomes and that calling for DC[36]. These results disclosed two variables, which had previously been shown to be related to survival, as having strong accuracy in prognostic judgment with sensitivity 81.6% and specificity 84.9% in predicting of DC. Since these two variables in the scoring model are clinically simple to attain in the acute stage after TBI, we consider therefore, that the derived equation is clinically useful to make decision on whether DC or not in daily practice.
There are limitations of the present study must be considered because of the nature of the retrospective, nonrandomized design of this study. It is a retrospective analysis of a 5-year cohort of sTBI patients with mass lesion requiring primary DC or craniotomy. The decision of operation procedure was nonrandom that may be affected by experience of surgeons and patients’ condition. The perioperative neurological status in patients with DC is more severe than in craniotomy. This issue needs to be addressed in prospective studies. Another limitation of this study is lacking preoperative ICP monitoring. Although, all the patients in this study need operation, without preoperative ICP, we could not analyze the ICP factors in decision making. Additional limitation of the present study includes the heterogeneity of the patient population. Despite all patients in present study with mass lesions, the different types of TBI such as epidural hematoma, subdural hematoma and contusion hemorrhage will result in different outcomes and might vary in operation style. In future, the subgroup analysis of an enriched population of different types of TBI patients is needed to clarify the issue.