Traumatic brain injury: Imaging, operative and nonoperative care, and complications

Traumatic brain injury (TBI) represents a major burden to trauma centers and the health care infrastructure. Heart disease, cancer, and stroke remain the leading cause of mortality year after year in the United States and in various locations abroad. Unlike TBI, these diseases generally affect a much older population with fewer life years lost. TBI on the other hand is most prevalent in the age group spanning 18 to 45 years with billions of dollars of resultant cost to health care systems around the world.

Specialty collaboration

Surgeons across all specialties are involved in the care of TBI patients at some point in their career. These patients require long-term care for the myriad of associated injuries that represent the norm in TBI. General surgeons, and more specifically trauma surgeons, play an integral role in the triage and care of these patients from arrival to discharge. This care is coordinated across multiple specialties to optimize the prognosis for each patient. The role that trauma surgeons play in the care and outcome of TBI patients simply cannot be overstated. There are key modifiable factors, such as hypoxia and hypotension, which can be optimized by the trauma surgery team prior to neurosurgical evaluation. The previous chapter reviewed pathophysiology, epidemiology, and prehospital management of patients with TBI. This chapter will serve as a guide to help trauma surgeons navigate the initial management of trauma patients with associated TBI.

Initial management

Initial management of TBI patients is no different than that of other trauma patients. The primary survey and stabilization with a focus on airway, breathing, and circulation are integral. The key components to this stabilization from a brain injury perspective share a common goal of cerebral perfusion optimization to prevent secondary brain injury. This goal can be achieved in parallel with the initial trauma stabilization via early avoidance of hypotensive and hypoxic episodes.

Oxygenation

The most effective way to avoid hypoxia is a low threshold for intubation, especially with borderline oxygen saturation and propensity to suffer further decline based on constellation of injuries. Intubation should be completed before any hypoxic episodes, as these episodes have been associated with doubling the mortality rate. Paralytics and sedatives are commonly utilized for rapid sequence intubation in trauma patients. Possible short-acting medications should be used to avoid prolonged obscuration of the neurologic examination over and above that of intubation alone.

Blood pressure management

Hypotension is another common sequela of severe traumatic injury. This is mitigated with aggressive resuscitation utilizing at times massive transfusion protocols including crystalloid, colloid, and various blood products. Avoidance of hypotension in general is more important than the exact fluids utilized with specific regard to subsequent brain injury. The classic definition of hypotension in the TBI population is systolic blood pressure (SBP) <90 mm Hg. Research over the last decade actually suggests avoidance of SBP <100 mm Hg and even <110 mm Hg in patients over 70 years old. This increase in the goal SBP to prevent secondary injury has been suggested with brain injury secondary to ischemic and hemorrhagic stroke as well. While these are different mechanisms of injury, ongoing research suggests the recommendations for each may share similarities with regards to risks from systemic hypotension.

Monro-Kellie doctrine

The Monro-Kellie doctrine states that the intracranial compartment is a fixed volume within the confines of the skull. This compartment consists of brain matter, cerebrospinal fluid (CSF), cerebral blood volume, and mass lesions. In this context, mass lesions include cerebral contusions, traumatic infarcts, as well as other intra-axial and extra-axial hemorrhages as a result of traumatic injury. Treatment aimed toward modification of any of these parameters can make a significant impact on intracranial pressure (ICP). Simple alteration of patient position can optimize (ICP) along the lines of this doctrine by maximizing cerebral venous return and thus decreasing the overall cerebral blood volume. This can be accomplished by keeping the cervical spine in neutral position while elevating the head. If there is concern for a cervical spine injury, this can be performed via reverse Trendelenburg positioning. Placement of an external ventricular drainage catheter can measure ICP and remove CSF to decrease ICP. Direct evacuation of traumatic intracranial hemorrhage is the surgical treatment of choice in many instances, especially with failure of nonsurgical management to lower ICP.

Coagulopathy reversal

Anticoagulants and antiplatelet medications are now common due to the increasing population of elderly patients in the United States. Reversal of pharmacologically induced coagulopathy is also paramount during the initial evaluation. In many cases no family will be available to document exact anticoagulation/antiplatelet medications. Early evaluation for coagulopathy should be completed via standard laboratory evaluation including prothrombin time, activated partial thromboplastin time, and international normalized ratio. Thromboelastography is a commonly utilized clot assay in the trauma surgery patient population to measure several parameters of clot formation at the bedside. Many institutions will have an up-to-date protocol in place for coagulopathy reversal. This requires constant update given the ever-changing availability of new anticoagulant/antiplatelet agents and associated specific reversal agents in some cases. The pharmacy takes primary responsibility for updating this protocol in many cases.

Antiplatelet agents

The primary antiplatelet therapy classes encountered in trauma patients are COX-1 (aspirin) and P2Y12 inhibitors (Plavix, Ticlopidine, Prasugrel). Transfusion of platelets is recommended immediately prior to any neurosurgical procedure with history of antiplatelet therapy from either of these classes. Platelets can be held if a platelet function analysis (aspirin) or whole blood aggregation test (Plavix, Ticlopidine, Prasugrel) is normal and/or if there is no evidence of persistent hemorrhage or plan for operative intervention. Platelet function analysis is more sensitive for aspirin platelet defect than thromboelastography, but can be significantly impacted by the anemia seen in many trauma patients. The generally accepted hold period for these medications prior to elective neurosurgical procedures is 5 days for COX-1 and 5–7 days for P2Y12 inhibitors.

Anticoagulants

The primary anticoagulants affecting most trauma patients are vitamin K dependent (warfarin), parenteral (enoxaparin and heparin), and the growing list of direct oral anticoagulants (apixaban, rivaroxaban, etc.). International normalized ratio evaluation is the best way to evaluate for warfarin effect. Reversal historically was completed with vitamin K and fresh frozen plasma. The protocol at most institutions now involves vitamin K and a prothrombin complex concentrate. This allows for faster reversal of warfarin effect in the face of active traumatic bleeding. Enoxaparin and heparin reversal is completed with protamine in urgent situations, despite its incomplete effect with the former. The direct oral anticoagulant category has benefited from the recent Food and Drug Administration approval of two direct binding inhibitors, idarucizumab and andexanet, in recent years. Further detailed discussion of these reversal protocols is outside of the scope of this chapter.

Managing expectations

The last point on initial management relates to setting the tone for expected recovery. Many times as surgeons we are pulled from one patient to the next as each is initially stabilized. Neurologic injury follows a complicated recovery paradigm that many are constantly attempting to decipher. Unfortunately, the prognostication of each of these patients is nowhere near a perfect science and relies on the interaction of multiple factors. There is current research underway to look at a variety of parameters through the use of artificial intelligence to predict outcomes. It is important to update these families early on the severity of any neurologic injuries. They should expect a long road to recovery over months to years with the goal of treatment to minimize additional injury and speed recovery. The timeline and degree of recovery is not usually readily apparent during initial management and may remain elusive throughout their recovery. Younger age is associated with a faster and more optimal recovery in many cases. Family understanding of this concept will ease interactions as their loved ones navigate the complicated road to recovery following TBI.

Imaging evaluation

Protocols are in place at most institutions that dictate the order and type of imaging evaluation for each trauma patient. The mainstay of initial imaging evaluation for trauma patients remains computed tomography (CT). This many times includes intravenous contrast to look for vascular injury in the head and neck. The addition of these angiographic studies aims to identify patients early with blunt cerebrovascular injury to prevent secondary injury from occlusive or embolic cerebral ischemia.

Computed tomography

CT imaging is very sensitive for the diagnosis of acute hemorrhage, but not for any ischemic injury due to trauma within approximately 48 hours. This imaging modality of the chest, abdomen, pelvis, head, and neck can be acquired in minutes. Early determination of the extent of potential injury to the spine can also be completed via CT evaluation. Bone and acute hemorrhage are hyperdense (bright) on CT versus more chronic hemorrhage, which becomes more iso- to hypodense in the weeks following initial injury. Significant injuries noted on in the brain or spine may prompt follow-up with magnetic resonance imaging (MRI). CT imaging should also be repeated to demonstrate stability of any intracranial hemorrhage as well as with any neurologic decline. CT head and neck angiography should be completed following the initial imaging evaluation to evaluate for blunt cerebrovascular injury. Early diagnosis of cerebrovascular injury can help mitigate secondary stroke injury.

Magnetic resonance imaging

MRI can be employed in a more subacute fashion following initial trauma evaluation and stabilization. This imaging modality relies on the water content of various tissues and their polarity in a magnetic field to provide an image. This imaging provides high levels of detail for many soft tissues in the body, especially the brain and spine. It is the best modality to determine ischemic injury within the first 48 hours of injury, and intrinsic injury as well as shear injury within the deep portions of the brain. MRI is many times used to help determine the extent of injury, especially in those patients whose clinical examination is worse than their CT imaging would otherwise suggest. There is a growing interest in looking at MRI TBI scoring criteria and special sequences such as diffusion tensor imaging with regards to outcome across multiple metrics following TBI.

Ultrasound

The final imaging modality worth mentioning is ultrasound. There is limited utility for ultrasound with regards to TBI or blunt cerebrovascular injury in the acute setting to date. Ultrasound can be utilized to evaluate for cerebral vasospasm, which may place a patient at risk for ischemic infarct. Duplex ultrasonography is also well established to screen for extremity deep venous thrombosis. Ultrasound functionality continues to advance, and it may play an even larger role in the ongoing evaluation of trauma patients soon.

Nonoperative care

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