The general consensus to optimize the care for severe TBI patients is management at specialized neurotrauma centers with neurosurgical and neurocritical care support and the use of guidelines-based standardized protocols. Over the last decade, significant efforts have been made to define neurotrauma treatment guidelines. However, it is important to recognize the heterogeneity of TBI and that the “one-size-fits-all approach” may not always be appropriate for these patients. Knowledge synthesis activities in neurotrauma are important to define future research agendas. Clinical and research advances have influenced neurotrauma as it continues to mature into a distinct subspecialty of neurosurgery.
Key points
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The general consensus to optimize the care for severe TBI patients is management at specialized neurotrauma centers with neurosurgical and neurocritical care support and the use of guidelines-based standardized protocols.
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It is important to recognize the heterogeneity of TBI and that the “one-size-fits-all approach” may not always be appropriate for all TBI patients.
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Knowledge synthesis activities in neurotrauma are important to define future research agendas. Advances have influenced neurotrauma as it continues to mature into a distinct subspecialty of neurosurgery.
Traumatic brain injury epidemiology and cranial surgery rates
In the United States, there were 2.5 million emergency department (ED) visits, hospitalizations, and deaths attributed to traumatic brain injuries (TBI) in 2010 alone, either as an isolated injury or in combination with extracranial injuries. Approximately 2% of those patients (>50,000) died, accounting for approximately 40% of all deaths from acute injuries in the United States. The major causes of TBI-related hospitalizations were falls, assaults, and motor vehicle traffic incidents. TBI also remains the most common cause of disability among people younger than 40. An estimated 3.2 million to 5.3 million persons in the United States are living with disabilities acquired from a TBI-related event. Since 2007, the number of TBI-related ED visits has increased by 56%. This increase did not apply to TBI-related hospitalizations and deaths. TBI-related crude mortality rates slightly decreased from 18.2 to 17.1 per 100,000 persons from 2007 to 2010. Although the exact cause for this decrease has not been established, it is thought to follow a continued reduction in motor vehicle traffic incidents. In addition, advances in prehospital and neuro–intensive care in specialized trauma centers led to improved care quality and health outcomes for TBI patients. A study conducted using the National Trauma Data Bank (NTDB) found that craniotomies were performed in 3.6% of all head-injured patients. More than 95% of patients with head injuries in the NTDB received conservative/nonoperative management. However, the NTDB included patients with both mild and moderate head injuries, and the absolute number of emergency cranial surgical procedures has not been established firmly. It remains important to track these rates to assess practice patterns, implementations of guidelines, and impact on patient outcome.
Traumatic brain injury epidemiology and cranial surgery rates
In the United States, there were 2.5 million emergency department (ED) visits, hospitalizations, and deaths attributed to traumatic brain injuries (TBI) in 2010 alone, either as an isolated injury or in combination with extracranial injuries. Approximately 2% of those patients (>50,000) died, accounting for approximately 40% of all deaths from acute injuries in the United States. The major causes of TBI-related hospitalizations were falls, assaults, and motor vehicle traffic incidents. TBI also remains the most common cause of disability among people younger than 40. An estimated 3.2 million to 5.3 million persons in the United States are living with disabilities acquired from a TBI-related event. Since 2007, the number of TBI-related ED visits has increased by 56%. This increase did not apply to TBI-related hospitalizations and deaths. TBI-related crude mortality rates slightly decreased from 18.2 to 17.1 per 100,000 persons from 2007 to 2010. Although the exact cause for this decrease has not been established, it is thought to follow a continued reduction in motor vehicle traffic incidents. In addition, advances in prehospital and neuro–intensive care in specialized trauma centers led to improved care quality and health outcomes for TBI patients. A study conducted using the National Trauma Data Bank (NTDB) found that craniotomies were performed in 3.6% of all head-injured patients. More than 95% of patients with head injuries in the NTDB received conservative/nonoperative management. However, the NTDB included patients with both mild and moderate head injuries, and the absolute number of emergency cranial surgical procedures has not been established firmly. It remains important to track these rates to assess practice patterns, implementations of guidelines, and impact on patient outcome.
Invasive brain monitoring
Monitoring of intracranial pressure (ICP), clinical neurologic examination, and computed tomography (CT) scanning are currently the primary methods to guide treatment of patients with TBI during neurointensive care. Unconscious or unstable patients are often sedated, therefore, limiting the utility of clinical examinations. In these cases, ICP monitoring is traditionally used to guide management to maintain adequate cerebral perfusion and oxygenation and avoid secondary injuries. The BEST TRIP study provided evidence that patients may be treated without ICP monitoring. However, the Brain Trauma Foundation guidelines and a recent consensus conference held in Milan recommend ICP monitoring in salvageable severe TBI patients with abnormal CT finding (mass lesions, swelling, herniation, or compressed basal cisterns).
Measurement of ICP can be done in several ways. Many consider intraventricular catheters as the gold standard method of ICP monitoring. This method allows both measurement of ICP and the possibility to treat raised ICP via drainage of cerebrospinal fluid (CSF). Intraventricular catheters can be connected with fluid-coupled catheter to an external strain gauge or available with an integrated micro strain gauge or fiber-optic–tipped catheter. As with all intraventricular catheters, there is chance of drain-related infections that increase the longer a catheter is in place. In addition, in a trauma setting it can be technically challenging to insert an intraventricular catheter in a patient with cerebral edema, midline shift, or small/compressed ventricles.
Intraparenchymal ICP monitoring devices use fiber-optic catheters to measure the ICP without CSF diversion. Compared with intraventricular catheters, parenchymal monitors are a less-invasive alternative to measure ICP and carry a lower risk of infection and hemorrhage. However, this method does not allow CSF drainage for therapeutic purposes. There are varying reports on the drift of parenchymal monitors, although this drift is not deemed a clinical concern. Subdural, subarachnoid, and epidural monitors are also described and are currently considered less accurate than intraventricular or intraparenchymal devices. In TBI cases with mass lesions, it has been known that ICP is not transmitted equally throughout the intracranial space. Studies suggest that expanding mass lesions are associated with ICP gradients, in particular, acute subdural hematomas. Greater than 10–mm Hg differences have been described between hemispheres. Further research is needed to define the optimal ICP measurement location to guide ICP management for these cases.
Multimodality neuromonitoring, including ICP, partial pressure of oxygen, and cerebral microdialysis can provide a more comprehensive monitoring of the injured brain than ICP monitoring alone. These methods allow individualized management of secondary cerebral insults targeting patient-specific pathophysiology. Current cranial access devices enable multiple catheters and sensors to be transmitted into the brain parenchyma, to allow for ICP, cerebral microdialysis (monitoring of chemistry of the extracellular space), and partial pressure of oxygen (monitoring of cerebral oxygen metabolism) catheters to be monitored continuously at the bed-side.
Evacuation of intracranial hematomas
The role of surgery in traumatic intracranial hematomas is to prevent irreversible brain injury or death caused by hematoma expansion, increased ICP, and herniation of the brain. An initial assessment of neurologic deficits, pupil abnormalities, degree of midline shift, hematoma volume, and the presence/severity of associated trauma are required to determine the necessity for emergency cranial surgery. For neurosurgeons, one of the most complicated decisions is whether moderate-sized mass lesions should be evacuated or observed. On one hand, surgical intervention might be unnecessary; on the other hand, neurologic deterioration with possible secondary insults to the brain may negatively impact the patient’s outcome. Current guidelines and recommendations are available but principally drawn up by experts and the (limited) evidence that is available.
Epidural Hematomas
Epidural hematomas (EDH) usually develop in young adults after traffic-related accidents, falls, and assaults. In TBI patients, the incidence of surgical and nonsurgical EDH cases has been estimated between 2.7% to 4%. EDH are thought to result from a direct blow to head and are usually found on the same side impacted by the blow. Typically, the source of bleeding is arterial after a trauma to the sphenoid or temporal bone with subsequent tearing of the middle meningeal artery and hematoma formation in the middle of the cranial fossa. EDH may also occur in the frontal, occipital, and vertex regions and are usually associated with the anterior ethmoidal artery, transverse or sigmoid sinuses, and superior sagittal sinus, respectively. EDH originating from venous sources are thought to expand more slowly compared with their arterial counterparts. EDH specific mortality has been described to be around 10% in adult patients. The role of surgery is to prevent irreversible brain injury or death caused by hematoma expansion, increased ICP, and herniation of the brain. Patients presenting with (progressive) focal neurologic signs or symptoms or hematoma growth must be considered as emergency cases. Evidence and expert-based recommendations for evacuations of EDH are surgery for all adult patients with a hematoma volume greater than 30 cm 3 (>30 mL) regardless of the Glasgow Coma Scale (GCS) score and comatose patients (GCS <9) with pupillary abnormalities. Evacuation should be performed through a craniotomy window fashioned according to the location of the hematoma, providing adequate access to the hematoma margins. If the brain appears tight, it is important to inspect the subdural space for additional clots. When the bone flap is replaced, several tenting sutures should be placed to minimize the epidural space. Bone flaps are not generally left out for isolated EDH with no parenchymal injuries. Close observation and conservative management are appropriate for patients with no focal neurologic deficits, with a small hematoma (<30 cm 3 ), a clot thickness less than 15 mm, and midline shift less than 5 mm on imaging.
Acute Subdural Hematomas
Acute subdural hematomas (aSDH) usually develop from motor vehicle accidents (MVA), falls, or assaults. In younger patients (18–40 years), 56% of the aSDH were caused by MVA and only 12% were caused by falls. Unlike the young patients, those 65 years and older had, in 22% of the cases, an MVA and 56% had a fall. Unlike EDH, the source of bleeding is usually venous caused by torn bridging veins under acceleration conditions, with arterial bleeding sources reported for approximately 20% to 30% of aSDH cases. Mortality rates for aSDH patients requiring surgery is between 15% and 60%. Evidence and expert-based recommendations for evacuations of aSDH are surgery for all adult patients with a hematoma thickness greater than 10 mm, midline shift greater than 5 mm, GCS score decreased by ≥2 points from injury to hospital admission, or patients presenting with pupillary abnormalities. Because advanced age has been associated with increased rates of adverse outcome, age should be taken into account when deciding to perform surgery. TBI patients presenting with an aSDH frequently have significant parenchymal injury and swelling on imaging. Patients with aSDH that require surgery to remove the clot are treated either with a craniotomy or a decompressive craniectomy (DC). However, there is often uncertainty as to whether the bone flap should be replaced. The RESCUE-ASDH trial is currently recruiting aSDH patients and aims to compare craniotomy versus DC for adult patients undergoing evacuation of an aSDH. The results of this trial will inform surgical decision making in the management of aSDH patients. Close observation and conservative management is appropriate for patients that are neurologically stable and have hematoma thickness less than 10 mm, midline shift less than 5 mm, no pupillary abnormalities, and no intracranial hypertension on ICP monitoring. Conservatively managed aSDH resolve gradually and are usually absorbed over weeks although in elderly patients may turn into a chronic subdural hematoma.
Traumatic Intracerebral Hemorrhage
Traumatic intracerebral hemorrhage (ICH) is also referred to as traumatic intraparenchymal hemorrhage and (hemorrhagic) contusion . Posttraumatic contusions are usually multiple and are located in the basal surface of the frontal and temporal lobes. In the acute stages, the ICH consists of a (semi-)liquid mass of blood with surrounding edema. These mass lesions evolve over days and change consistency while edema begins to recede. Mortality secondary to traumatic ICH is related to the location and size of the lesion(s). Surgical interventions are aimed at preventing secondary damage, brainstem compression, and herniation of the brain. Unfortunately, the only trial investigating the role of early surgery versus initial conservative treatment to anticipate and prevent secondary damage in traumatic ICH was halted early. Although the evidence is limited because of the low sample size resulting from premature termination, it appears that the STITCH(Trauma) Trial observed reduced mortality with early surgery. However, patients in this trial were mostly recruited in resource-limited settings in which ICP monitoring was not usually available. Current evidence and expert-based recommendations for evacuations of traumatic ICH involving the cerebral hemispheres recommend surgery for patients with focal lesions and the following indications: progressive neurologic deterioration, medically refractory raised ICP, a hematoma volume greater than 50 cm 3 (>50 mL), GCS score of 6 to 8 in a patient with a frontal or temporal hemorrhage greater than 20 cm 3 (>20 mL) with either midline shift of greater than 5 mm, or cisternal compression on CT scan. Patients with diffuse injuries developing medically refractory posttraumatic cerebral edema and intracranial hypertension may be considered for a bifrontal DC within 48 hours of injury. DCs may also be considered for patients with refractory intracranial hypertension and diffuse injuries with clinical and radiographic evidence for transtentorial herniation. Evacuation of a traumatic ICH in the posterior fossa is recommended when there is evidence of neurologic dysfunction/deterioration and significant mass effect on the basal cisterns, fourth ventricle, or signs of obstructive hydrocephalus. Intensive monitoring and serial imaging are appropriate for patients with no focal neurologic deficits and nonsignificant mass effect on imaging.
Decompressive craniectomy in traumatic brain injury
Management of refractory raised ICP after severe TBI consist of medical and surgical treatments. DC is generally considered a surgical treatment of diffuse brain swelling or expanding contusions/hematomas refractory to medical treatment and impending herniation. In recent years, the role of DC has been discussed as a primary treatment in the acute phase, leaving out the bone flap after evacuation of a mass lesion or as a second- or third-tier therapeutic measure for diffuse brain injury and edema, commonly named secondary or protocol-driven DC. The expansion of a swollen brain outside the skull can potentially lead to a reduction in ICP and risk of herniation. The physiologic improvements described in severe TBI patients after DC, include improvement in brain tissue oxygenation, cerebral perfusion, and neurochemistry. The risk of complications should also be considered, as early or delayed complications can occur after DC. Expansion of (contralateral) mass lesions, wound infections and healing problems, subdural or subgaleal collections, hydrocephalus, syndrome of the trephined, and complication related to the subsequent cranioplasty have been recognized as DC-related complications. Because the risk of severe disability and death in severe TBI remains relatively high, several trials have explored the use of DC to improve patient outcomes. However, defining the indications, timing, techniques, and optimal outcome measures for DC is difficult, and good-quality evidence linking efficacy to outcome is lacking.
Decompressive Craniectomy Methods
Decompressive craniectomy is an umbrella term for a group of procedures in which part of the skull is removed. In severe TBI, the most frequently described DC procedures in adults are bifrontal DC and unilateral frontotemporoparietal craniectomy, also termed hemi(spherical)-craniectomy or unilateral DC . For unilateral conditions with midline shift and (potential) swelling (eg, aSDH with parenchymal injuries), a hemicraniectomy can be useful. Evidence and expert-based recommendations for adequate hemi-craniectomies suggest that the bone flap should be large with a minimum anteroposterior diameter of 11 to 12 cm to achieve an adequate reduction of ICP and reduce the risk of transcalvarial herniation that is associated with parenchymal injuries at the bone edge. Bifrontal DC is a treatment option for diffuse (bihemispheric) injuries with medically refractory intracranial hypertension. A bifrontal DC extends from the floor of the anterior cranial fossa to the coronal suture posteriorly and to the temporal floor bilaterally. A widely opened dura mater is required to allow the brain to sufficiently expand. Different techniques are described for the dura (left open with onlay of hemostatic material, pericranium, or temporalis fascia or closure with dural expansion grafts) and sagittal sinus sectioning or sparing. Reports also describe bilateral hemicraniectomies as an approach for patients with diffuse injuries, although an improvement over the bifrontal DC approach has not been investigated. For patients with temporal lesions or edema causing brainstem compression, extension of the DC to the floor of the middle cranial fossa is essential.
Evidence Base for Decompressive Craniectomy in Traumatic Brain Injury
The DECRA trial failed to find an improvement in functional outcome by performing early bifrontal DC over medical management for patients with diffuse TBI. The study found that patients treated with DC had shorter duration of ventilation and length of stay in the intensive care unit. The RESCUEicp trial aimed to examine the clinical and cost effectiveness of secondary DC (unilateral or bifrontal DC) for severe TBI patients with refractory intracranial hypertension as a last-tier therapy. The target sample size of 400 patients was achieved, and the study is currently in the analysis/write-up phase, results are expected in 2016. In contrast to the aforementioned trials, the RESCUE-ASDH trial is an ongoing randomized trial comparing primary unilateral DC with craniotomy (bone flap out vs bone flap replaced) for patients with aSDH. Information from these studies will define the role of secondary and primary DC in future TBI treatment guidelines. Based on the current available evidence, neurosurgeons and neurointensivists must weigh the potential risks and benefits faced by their individual patients when deciding to perform a DC.
External ventricular drainage in traumatic brain injury
External ventricular drainage not only allows for measurement of ICP but also drainage of CSF at the bedside to control increased ICP. This method is fast, minimally invasive, and effective for patients with intracranial hypertension even without hydrocephalus. However, this procedure also carries certain risks and potential complications. Complications of external ventricular drain (EVD) placement include the risk of infection, increasing with the length of drainage, and the risk of hemorrhages, increased by posttraumatic clotting derangements. Image guidance can facilitate safe placement of the catheter in TBI patients with diffuse brain swelling that often have small ventricles. Optical and electromagnetic neuronavigation systems can be used, with the latter not requiring rigid pinning cranial fixation. There is no class I evidence on the use of EVD as a first-tier or second-tier intervention in severe TBI patients, and there is also clinical uncertainty regarding continuous drainage of CSF (open EVD system) versus intermittent opening as necessary to drain CSF (closed EVD system). Although the latter method would allow for real-time measurement of ICP, it can potentially expose patients to elevations of ICP between drainage periods. The theoretic benefit of an open EVD system is tighter and stable ICP control; however, there is a risk of overdraining with potential subsequent collapse of the ventricles.
Surgical management of skull fractures
Skull fractures most frequently involve the parietal bone, followed by the temporal, occipital, and frontal bones. TBI patients usually present with linear fractures and less frequently with depressed and skull base fractures. The force of the trauma to the skull required to cause fractures is significant; therefore, patients are at significant risk of underlying brain injury. Evidence and expert-based recommendations for skull fractures are elevation and washout for patients with open skull fractures depressed more than the thickness of the cranium or more than 5 mm below the adjacent inner table. The rationale is reducing the risk of infection for these cases with early surgery, especially in the presence of dural tears, pneumocephalus, frontal sinus involvement, or contaminated wounds. Emergent surgery is also indicated for fractures with an underlying (expanding) hematoma. Elevation of the fracture also improves cosmesis for cases of significant displacement of the bone. Reconstruction can usually be achieved by using the bone fragments; if this is not feasible, implants can be used to cover the skull defect. Antibiotics are usually administered to patients with open skull fractures; currently routine prophylaxis for all skull fractures is not supported by the available evidence.
Related posts:
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Concussion—Mild Traumatic Brain Injury
Cerebral Metabolism and the Role of Glucose Control in Acute Traumatic Brain Injury
Cerebral Edema in Traumatic Brain Injury
Past, Present, and Future of Traumatic Brain Injury Research
Role of Metabolomics in Traumatic Brain Injury Research
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