Traumatic Brain Injury
Traumatic brain injury (TBI) occurs when external forces cause damage to the brain. Depending on the extent of damage and clinical findings (including duration of unconsciousness and post-traumatic amnesia as well as the Glasgow Coma Scale Score, GCS), TBI is classified as mild, moderate or severe. All forms of TBI can result in a variety of significant disorders, which may persist for a prolonged time or even permanently. Such disorders include headache, nausea, convulsions, blurred vision, personality and emotional disorders, cognitive deficits, sleep disorders or different forms of motoric impairment.
Severe traumatic brain injury (TBI), characterized by a GSC <9, prolonged unconsciousness and substantial structural brain damage, is the leading cause of death following trauma and is a leading cause of death and permanent disability in the population under 45 years in industrialized nations. Severe TBI imposes a considerable burden on the individual patients and their relatives, but also on the society through lifetime costs of care and loss of productive life years.
Epidemiology and mechanisms of injury
Due to inconsistencies in definition, classification, reporting and documentation, only few reliable data on the incidence of TBI are available. In industrialized nations, the incidence of TBI is estimated to be approximately 150-250 per 100,000 population per year. No recent data are available for the Netherlands, however incidence is estimated to be about 25,000 cases per year, leading to about 14,000 hospital admissions. The vast majority of these cases are mild TBI.
The BRAIN-PROTECT research project focusses on patients with severe TBI, and accurate epidemiological data are lacking for this patient group. The following data are estimates based on regional data in the Netherlands, extrapolated to the country as a whole. While the BRAIN-PROTECT database primarily focusses on prehospital treatments and their relationship to outcome, it will also provide first reliable data on the incidence of severe TBI in the Netherlands.
About 500 to 700 patients with severe TBI are admitted annually to a hospital in the Netherlands, however no data are available on how many patients die at the accident scene. About 70% of patients are male, and the mean (SD) age is 45 (20) years. The two most common injury mechanisms are traffic accidents and fall from height.
TBI results from primary and secondary injuries. Primary injury, including direct destruction of brain tissue, damage to blood vessels and axonal shearing, occurs during the initial trauma by external mechanical forces and cannot be influenced by prehospital treatment. In contrast, secondary injuries evolve over time and lead to degeneration of neurons and glia cells that have not been destroyed during the primary impact. Pathophysiological mechanisms of secondary injury are complex and involve release of excitatory amino acids and tissue factor, disturbance of cellular calcium hemostasis, production of nitric oxide and free oxygen radicals as well as lipid peroxidation. These mechanisms trigger a variety of signal transduction pathways, resulting in disruption of the blood-brain barrier, cytotoxic and vasogenic edema, rises in intracranial pressure, ischemia, micro-thrombi, inflammation as well as necrotic and apoptotic cell death.
Secondary injury is a direct consequence of the primary insult, however its intensity is modulated by subsequent events. Several factors influencing cerebral oxygenation, perfusion and metabolism, such as hypotension, hypoxia, hyper- and hypocapnia, hyper- and hypothermia, hyper- and hypoglycemia, acidosis, coagulopathy and seizures, are believed to aggravate secondary injury and to deteriorate outcome. Since effective treatments targeting at biomolecular pathways of secondary injury are not available, early management focuses on prevention and treatment of those factors known to aggravate secondary injury. Hence, optimal prehospital treatment could likely have a significant impact on overall survival and outcome. Unfortunately, optimal prehospital treatment is largely unknown and based on expert consensus rather than on rigorous scientific evidence. BRAIN-PROTECT will allow extensive analyses of current prehospital treatment approaches and their effects on outcome, with the goal to identify prognostic factors and and to suggest effective treatment approaches.
Treatment of patients with severe trauma / TBI
Prehospital treatment focuses on rapid rescue of entrapped patients (e.g. from car wrecks), on rapid medical treatment to stabilize vital functions and prevent secondary injury, and on rapid transport to definite medical treatment in a trauma centre. Since our research project especially focusses on prehospital treatment, we dedicated an own page to this topic here. The rest of the section briefly describes in-hospital treatment.
In the Netherlands, patients with severe TBI are usually transported directly to a level 1 Trauma Centre, which is capable of providing 24/7 high level neurosurgical, traumatologic and intensive care treatment. 11 such centers are available, and some other larger hospitals are also capable of treating selected TBI patients. In exceptional cases, extremely unstable patients may be first presented to a regional hospital for initial stabilization and damage control surgery before they are secondarily transferred to a trauma centrum. Because the Netherlands are a rather small country and trauma centers are quickly accessible, patients are usually transported by ground ambulance and often reach the emergency room within one hour after the accident. Patients in remote locations may be transported by helicopter if time can be saved compared to ground transport.
In Dutch trauma centers, the severely injured patient is initially assessed in the shock-room of the emergency department (ED) by a so-called „trauma team“, usually consisting of an anesthesiologist, (trauma-)surgeon, radiologist, neurologist/neurosurgeon and nursing staff, supplemented by additional specialists as required. Initial assessment includes assessment of the vital functions according to the „ABCDE“ scheme (Airway, Breathing, Circulation, Disability, Exposure), lab testing and emergency radiology to detect and treat life-threatening disorders and injuries at the most early possible stage. All involved specialties work closely together as a team, where each specialist contributes his own special expertise:
The anesthesiologist is primarily responsible for the „A“ as well as non-surgical „B“ and „C“ management and monitoring. The anesthesiologist assesses the airway for obstruction and performs endotracheal intubation as required to secure the airway and to allow uncompromized ventilation. Assessment of breathing (breath sounds and thorax excursions, oxygenation, capnometry) as well as mechanical ventilation („B“) are also core competencies of the anesthesiologist. Moreover, monitoring of the patients circulatory status („C“), if necessary invasively by using arterial and central venous catheters, belong to the tasks of the anesthesiologist, who also stabilizes the circulation using fluid infusions, transfusion of blood and blood products and vasoactive or inotropic drugs. Patients with severe trauma and patients who are unstable and/or require mechanical ventilation are monitored continuously by the anesthesiologist throughout the diagnostic process and subsequent surgical interventions, until the patient is transferred to the intensive care unit. During this phase, the anesthesiologist also provides anesthesia and analgesia to protect the patient from painful and noxious stimuli.
The (trauma-)surgeon usually coordinates the trauma team, gathers all relevant information and prioritizes diagnostic and therapeutic actions. The surgeon also initially assesses, together with the anesthesiologist, the airway, breathing and circulation, and is responsible for the urgent surgical treatment of any life-threatening injury. A common finding in trauma patients is a pneumothorax (collapsed lung), which can significantly impair respiration and oxygenation („B“) but also the circulation (tension-pneumothorax, „C“), and which is usually surgically treated in the emergency department by insertion of a thoracic drain. Other surgical interventions are mostly performed in the operating room after initial stabilization and diagnostic workup. Only in exceptional instances, when for example an exsanguinating patient cannot be stabilized and transported to the operating room, emergency surgery is attempted in the emergency room.
The radiologist and neurologist initially have a primarily diagnostic function in the process of trauma care in the emergency department. The radiologist plays a key role in the early diagnosis of life threatening injuries in the shock room by performing and assessing x-ray and ultrasound imaging. The neurologist focusses on the neurologic status and injuries of the patient, including assessment of consciousness, pupil size and reactivity, and reflexes.
The nursing staff do not only play an important role in assisting the medical specialists, but also connect the patient to monitoring facilities, administer oxygen in spontaneously breathing patients, obtain blood samples, establish venous access, document vital parameters and treatments, maintain close contact with patient‘s relatives in the ED, and perform basic life support when cardiopulmonary resuscitation becomes necessary.
After initial assessment and stabilization, a computed tomography (CT) of the brain is usually done immediately in patients with suspected TBI to detect intrancranial injuries, but also other CT diagnostics may be performed as required (e.g. spinal column, thorax, abdomen or pelvis) to detect accompanying extracranial injuries. Herein, the radiologist, the neurologist/neurosurgeon and (trauma-)surgeon assess and discuss the pattern of injuries to determine further surgical treatment.
Further treatment and outcome
Further treatment depends on the pattern of injuries and the clinical condition of the patient and follows the dogma „treat first what kills first“. Internal hemorrhage, for example, may require urgent laparotomy or thoracotomy before surgical treatment of cerebral injuries. In other cases, when TBI is the leading injury or in cases of isolated TBI, a neurosurgical intervention will be performed first and treatment of other injuries are deferred until later. Many patients with severe TBI will require some form of neurosurgical intervention, which can range from placement of a probe to measure intracranial pressure to decompressive craniectomy. Following surgery, patients are usually transferred to an intensive care unit. Intensive care therapy in the Netherlands is provided by „intensivists“, who are mostly specially qualified anesthesiologists or internists. Critical care treatment of TBI patient is complex and may involve treatment of all organ systems. This may include, just to name some of the most important tasks of intensive care treatment, mechanical ventilation and weaning from the respirator, cardiovascular support with vasoactive and inotropic drugs and fluids, maintaining or reestablishing homeostasis, treatment of coagulation disorders, renal replacement therapy, enteral and parenteral nutrition, and treatment of infections and sepsis.
Following intensive care therapy, the patient is usually treated on a traumatologic or neurosurgical ward, depending on the leading type of injury. Subsequently, most patients who have survived until now will need an intense rehabilitation program before they can be discharged home, and about one half of the patients who survive are still moderately or severely disabled at one year following the accident.