Traumatic Brain Injury: A Review on Some Important Clinical Notes

Abstract

Traumatic brain injury results from any impact on the head, which could disrupt the normal function of the brain. The aim of this review is to evaluate traumatic brain injury from a clinical perspective by pointing to some important clinical notes about traumatic brain injury. The main target groups that this study is designed for are the clinicians who are dealing with patients suffering from traumatic brain injury and also scholars who would like to review some important notes about traumatic brain injury and may want to increase their knowledge about that. This review is designed in a way that would be as concise and informative as possible. This would be of help to review some important notes about the topic in a short period of time.

1. Introduction

Traumatic Brain Injury is a common cause of referring patients to the emergency wards and the intensive care units. Head injuries leading to cause damage to the brain tissue and surrounding structures are among the main causes of morbidity and mortality in the communities. Using motor vehicles and machines increases the risk of the occurrence of trauma. This includes causing trauma to the brain and surrounding structures either.

The trauma-related deaths are common in early middle age and youth, and traumatic brain injury contributes in a significant way to the outcome of affected patients. Traumatic brain injury has a wide spectrum, from mild concussions to severe forms of brain injury.

Traumatic brain injuries may be classified into two main groups: the primary and the secondary ones. Treatment strategies may be taken based on this classification. However, new pathophysiology-related studies and relevant findings suggest that in case of necessity, the treatment should be started as soon as possible regardless of considering such classification. In fact, as long as the initial treatment starts earlier, the outcome would become better unless the initial condition of the affected patients is bad enough, which even early initializing the treatment, would not affect the patient’s outcome. This is mostly pronounced in the cases of severe traumatic brain injuries and in the persistence of the possible concomitant pathologies that may cause organ failure and death. The same would be pronounced in polytraumatized patients.

The pathologies that may cause traumatic brain injuries include direct trauma to the brain tissue and surrounding structures, brain swelling or cerebral edema, intracerebral shearing, cerebral contusion, intracerebral hemorrhage and hydrocephalus development.

Traumatic brain injuries comprise a wide range of topics. This review tries to point to some of the relevant topics and important notes about traumatic brain injuries.

2. Body

2.1 Some notes about the initial approach to the patients suffering from traumatic brain injuries

The occurrence of traumatic brain injury has different causes like motor vehicle accidents, falls, blunt trauma, etc.

There are various factors that should be considered in the evaluation of patients suffering from traumatic brain injury. Depending on the general condition of the patient and by considering the fact that in which grade the patient would be categorized including mild, moderate or severe, the neurological examination should be done for all of the patients.

In the patients who are categorized in moderate to severe form of injury and ones whose general conditions are unstable and require immediate intervention, first of all, resuscitative efforts should be done including evaluation of the airway, breathing, circulation, disability, exposure and necessary interventions should be done accordingly. After stabilizing the general condition of the patients, evaluation of the traumatic brain injuries should be done.

Neuroimaging including simple Radiography, computed tomography scanning and magnetic resonance imaging is of importance in the initial examination of stabilized patients. Emergency laboratory tests should also be done for all of the admitted patients. In polytraumatized patients, depending on the general condition of the patient, a quick general assessment should be done in search of finding other traumas and fractures, the possible sources of bleeding and obscure blood loss in the patients with hemodynamic instability. In case of possibility, a brief history about the presence of other concomitant disorders in the affected patients should also be done.

In the traumatic brain injury settings, the patients with higher Glasgow coma scale (GCS) generally have better outcomes. A worse outcome may be predicted if the systolic blood pressure is lower than 90 millimeters of mercury or the partial pressure of oxygen is lower than 60 millimeters of mercury. Maintaining the cerebral perfusion pressure in ranges that are higher than 70 millimeters of mercury and trying to keep the intracranial pressure lower than 20 millimeters of mercury should be considered in the affected patients. Controlling the intracranial pressure is an important factor in the management of the patients suffering from traumatic brain injuries. This goal can be achieved by employing various strategies like using paralytics and sedatives, draining the cerebrospinal fluid, coma induction with pentobarbital and administering the mannitol. Administration of mannitol can be done by giving 1 gram per kilogram as a bolus dose and continuing the administration with a route of 0.25 gram per kilogram every 6 hours. In patients suffering from renal failure or congestive heart failure, mannitol should not be administered.

The serum level of the potassium should be kept in the normal range and the patient should be in the normovolemic condition. The occurrence of acute tubular necrosis may be possible during administration of the mannitol, and enough care should be taken to avoid its occurrence by regular checking of the osmolarity of the patient’s serum, preferably every 6 hours. In case the osmolarity of the serum falls under 320, administration of the mannitol should be discontinued and be held. Coma induction may be of help to decrease the amount of free radicals, the amount of the cerebral metabolic rate of oxygen and the intracranial pressure. Also, such induction causes myocardial depression, sympathetic tone reduction and hypotension.

Prophylactic measures should be taken against the occurrence of deep vein thrombosis, and the patient’s possible high temperature should be controlled. In the epidural hematoma settings, in case the total volume would be lower than 30 cubic centimeters and the thickness would be lower than 15 millimeters with the midline shift, which would be lower than 5 millimeters and in the condition which the patient has a high measured GCS score, the patient can be observed. In such circumstances, neuroimaging should be repeated and the neurological condition of the patient should be examined on a regular basis. Any changes in the patient’s condition and new findings in the neuroimaging studies suggesting that the patient’s condition is becoming worse should be considered as an emergency, and the neurosurgical intervention should be done as soon as possible [1, 2, 3].

There are some classification systems for traumatic brain injuries. Glasgow coma scale or GCS, Mayo and Marshall, are three classification systems that may be used in the evaluation of patients who are suffering from traumatic brain injuries.

In the Glasgow coma scale system, which is commonly used in emergency settings, the patients with traumatic brain injuries would be classified into three main groups including mild, moderate and severe ones.

In the Mayo classification system, traumatic brain injury may be classified into three main groups including possible, mild and moderate to severe ones.

In the Marshall classification system, traumatic brain injury may be classified into six main categories [4, 5, 6].

Having knowledge about these three classification systems for evaluation of the patients with traumatic brain injuries can be of help to approach the affected patients with more precision, and this would result in taking an appropriate treatment strategy for the patients based on their conditions and the severity of the traumatic brain injuries.

2.2 Some notes about the respiratory functions and the mechanical ventilation in the patients suffering from traumatic brain injuries

Management of ventilation and oxygenation in traumatic brain injury settings is an important note to be considered at the bedside. Trying to manage the conditions of ventilation and oxygenation in patients suffering from traumatic brain injuries in the first stages is important to reduce the risks for the occurrence of secondary injuries. Also, this management would help improve patient outcomes.

Increased intracranial pressure in patients with traumatic brain injuries is an important problem that these patients encounter. The occurrence of hypocapnia because of the hyperventilation and vasoconstriction in the blood vessels of the brain causes a reduction in the blood flow. As a result, the risk of the occurrence of secondary injuries because of ischemia and hypoperfusion will be increased. In these settings, the recommendation would be to keep the levels of the partial pressure of carbon dioxide in a range between 35 and 40.

Minimizing the bag ventilation of the intubated patients suffering from traumatic brain injuries is an important note which should be kept in mind in reduction of the risk of hyperventilation in these patients. The mechanical ventilator should be employed as early as possible in these patients. Seven to 8 liters per minute may be a reliable starting minute ventilation in these settings. It is because of this fact that there would be a possibility of the existence of the hypermetabolic state in patients suffering from traumatic brain injuries. Since these patients are at risk for developing acute respiratory distress syndrome, permissive hypercapnia is not an appropriate strategy to be taken in these settings.

In such settings, arterial blood gas and capnography should be considered to correlate the end-tidal carbon dioxide with the partial pressure of carbon dioxide. In such circumstances, normoxia is another important parameter. It prevents the occurrence of secondary injury and improves the outcome of the affected patients. About 15–20 minutes after intubation, the arterial blood gas should be checked.

In different cases and based on the curve of the oxygen-hemoglobin dissociation, the ranges for the partial pressure of oxygen in the arterial blood, the fraction of inspired oxygen and the oxygen saturation should be defined.

In patients suffering from traumatic brain injuries, the hemodynamics should be managed appropriately. Any abnormal changes in the blood pressure of these patients should be corrected to prevent further complications [7, 8, 9].

The clinicians who are dealing with patients suffering from traumatic brain injuries should have enough knowledge about ventilation and oxygenation management as an important factor in determining the outcome of the patients.

One of the important factors in the management of the patients with traumatic brain injuries, specifically the severe forms of such injuries, would be employing mechanical ventilation. Having enough knowledge to work with the ventilator and relevant terms and physiology is important in traumatic brain injury settings. It is recommended that clinicians who are dealing with patients suffering from traumatic brain injuries, specifically ones who are required to be put on the ventilator, to gain enough knowledge about the lung physiology and details to work with the ventilator [10, 11, 12].

2.3 Evaluation of the polytraumatized patients including the traumatic brain injuries with the trauma score

Paying attention to a score called trauma score is of importance in patients suffering from traumatic brain injuries, since the affected patients may have traumas in different parts of the body. So, considering the trauma score would be of help in evaluating the affected patients in a more comprehensive way. Polytraumatized patients with traumatic brain injuries may be evaluated with the trauma score more comprehensively. Having knowledge about the trauma score is of importance to assess polytraumatized patients including those with traumatic brain injuries [13, 14, 15].

2.4 Some notes about the skull base fractures in traumatic brain injuries

The patients suffering from traumatic brain injuries may have skull base fractures, which such fractures are of importance and require taking certain strategies in the management of the patients.

Temporal bone skull base fractures are among this category of fractures. Facial palsy, otorrhea, tinnitus, vertigo, postauricular hemorrhage and hemotympanum are the signs of the middle cranial skull base fractures. To classify the temporal bone fractures, the long axis of the petrous pyramid would be used.

The skull base fractures that traverse the middle ear or the paranasal sinuses can be associated with the occurrence of tearing in the dura and may be accompanied by a cerebrospinal fluid fistula. The occurrence of the cerebrospinal fluid fistula can be seen in about 10–20 percent of the patients with skull base fractures. In young children the formation of the cerebrospinal fluid fistula is not common because of the late maturation and development of the paranasal sinuses.

In comparison with the middle and posterior cranial fossae, the anterior fossa where cerebrospinal fluid leaks commonly happen. In the skull base trauma settings there are some indications for surgical repair of the cerebrospinal fluid fistula.

In spite of lumbar drainage, in case the cerebrospinal fluid leakage lasts for more than 7–10 days after the occurrence of the injury, conservative therapy would not be effective and surgical repair should be done for the cerebrospinal fluid leakage.

Having a high risk for meningitis development, the presence of the pneumocephalus and the large dural tear, delayed cerebrospinal fluid leakage, penetrating injuries and external brain herniation are the indications for early surgical intervention.

The swelling of the frontal lobe will be decreased in a time period of about 10 days after the occurrence of the trauma. It allows enough retraction to expose the anterior skull base. Traumatic otorrhea will be resolved in about 14 days after the time of the injury, and therefore, surgical repair is usually not necessary in such circumstances. Therefore, the conservative management of the cerebrospinal fluid otorrhea should be considered for longer periods after the injury. Just in case conservative management fails, the surgical intervention can be considered.

In the traumatic brain injury settings, skull base injuries are important and should be focused on in the treatment of patients suffering from traumatic brain injuries [16, 17, 18, 19, 20, 21].

3. Conclusion

Traumatic brain injury, as a neurological insult due to trauma, is a common cause of referring patients to the emergency wards and the intensive care units. It is important for clinicians, specifically neurosurgeons, neurologists, intensivists and emergency medicine physicians to have enough knowledge about various aspects of traumatic brain injuries. Having such knowledge is important to approach the affected patients with more precision at the bedside.

In the management of patients with traumatic brain injuries, paying enough attention to details is crucial. Traumatic brain injury comprises a wide range of topics, and any of them includes important notes.

Considering these, it is recommended to study more about the traumatic brain injuries and relevant topics from other sources until getting familiar with various aspects of traumatic brain injuries and the relevant important notes.

Conflict of interest

The author declares no conflict of interest.