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A traumatic brain injury (TBI) occurs when an external force affects normal brain function or pathology. TBIs can range in classification from mild to severe but all classifications pose a risk for neurological decline in the first 24 hours. Accurate and rapid monitoring of the TBI patient allows for early detection of neurological worsening resulting in timely intervention and more predictable outcomes.
In this guide, you can explore medical procedures, technologies, and diagnostic considerations that can help you improve patient care and neurological outcomes for patients with traumatic brain injury. This guide includes:
⇒ Traumatic brain injury definition
⇒ Etiology
⇒ What are the symptoms of sleep apnea?
⇒ Diagnosing sleep apnea with polysomnography
⇒ How to diagnose traumatic brain injury
⇒ Neurological bedside assessment for TBI
⇒ How to treat traumatic brain injury
⇒ Diagnostic considerations for traumatic brain injury
Traumatic brain injury (TBI) is defined as an alteration in brain function or pathology changes caused by an external force.1
Primary injury from TBI occurs at the time of impact. Secondary injury is the sequelae that occurs after the primary injury. The goal of traumatic brain injury treatment and management in all settings is to prevent worsening of the primary injury and decrease the severity of secondary injury. In the acute setting of the intensive care unit (ICU) the two primary brain monitoring techniques are: intracranial pressure (ICP) monitoring and continuous electroencephalogram (cEEG). These technologies assist the health care provider in their role to anticipate and prevent secondary injury; early detection and rapid intervention is essential in preventing irreversible brain damage and even death.²
The Centers for Disease Control (CDC) estimate 2.5 million people are diagnosed with traumatic brain injury each year in the United States.
Of those, 283,000 are hospitalized, 52,000 die and 5 million live with a disability. It is estimated that sixty-nine million individuals worldwide sustain a TBI each year.² Falls are the number one cause of traumatic brain injury, followed by firearm-related suicide, motor vehicle crashes and assaults.³ Blast injuries from explosives is the number one cause of TBI in the military population.4
Traumatic brain injury can be divided into three categories:
TBI can also be classified by diagnosis including subdural hematoma, intracerebral hemorrhage, epidural hematoma, diffuse axonal injury, traumatic subarachnoid hemorrhage and diffuse swelling. It is feasible to have more than one diagnostic classification in a single trauma; multicompartmental hemorrhages carry higher risk of brain compression and herniation as hemorrhagic expansion occurs in about 50% of cases.
Traumatic brain injury is diagnosed as a known trauma in a patient experiencing neurological symptoms. TBI patient may be found at the scene or present to the emergency room reporting a traumatic injury with external findings such as facial lacerations or skull fractures.
Important patient history includes mechanism of injury, medications (in particular antiplatelet or anticoagulant), alcohol or drug use, loss of consciousness, post trauma amnesia and post-traumatic seizure. After the patient is stabilized and a primary survey is complete, neuroimaging is the next step in a traumatic brain injury diagnosis.
Computerized Tomography (CT) is most common neuroimaging modality as it is fast, accessible and reliable to detect acute blood. Imaging, such as a CT, will help to identify both location and severity of hemorrhage. Repeating a CT scan at six hours is strongly recommended to re-evaluate stability. A neurosurgical consult will establish whether observation or the need for emergent neurosurgical intervention is appropriate.
Neurological bedside assessments are crucial in detecting early neurological decline. This assessment should be done both frequently and consistently to identify changes. All classifications of TBI are at high risk for neurological decline in the first 24 hours – primarily due to secondary injury.
Immediate assessment should include airway, breathing and circulation (ABC’s). Hemodynamics and oxygenation must be restored and maintained as a top priority. Hypotension and hypoxia are the largest contributing factors to secondary injury and as a result greatly increases risk of mortality. The Glasgow Coma Scale (GCS) is used to rate the severity of injury post-resuscitation. Drugs, alcohol and sedation may alter the GCS score. The GCS ranges from 15 (awake, alert and oriented) to 3 (unresponsive to noxious stimuli).
A patient with a score of 13-15 would be classified as having a mild traumatic brain injury, 9-12 is a moderate injury and 3-8 is a severe injury. Patients with a moderate to severe traumatic brain injury diagnosis should be admitted to the ICU, monitored hourly and followed by specialists including neurosurgery, trauma and neurocritical care experts. Any decline in GCS greater than or equal to 2 or decrease of 1 in the GCS motor score is critical to recognize. A decline in GCS may indicate increased secondary brain injury including hematoma expansion, increased cerebral edema, herniation or seizures. It is important to note that factors such as drugs, alcohol or sedation may alter the GCS score and must be taken into account during traumatic brain injury assessment.
Pupillary assessment can give good insight as to development or evolvement of cerebral swelling. Inconsistencies of pupillary size, symmetry and or reactivity can be an indication of increased cerebral edema. Patients with asymmetric pupils of > 1 may be indicative of brain herniation and imminent death.
Trained clinicians are essential in the management and treatment of traumatic brain injury and in the prevention of secondary injury. Several significant references exist to help guide treatment and management decisions: Emergency Neurological Life Support (ENLS), Brain Trauma Foundation Guidelines and Seattle International Severe Traumatic Brain Injury Consensus Conference (SIBICC). Being that 50% of all deaths related to TBI occur within the first few hours of injury, having guidance starting with pre-hospital evaluation and management is critical.
ENLS is a certification course aimed at improving care for neurological emergencies in the first hours after injury – from prehospital to emergency room to ICU admission. ENLS provides a standardized approach to diagnosis, stabilization and management. Special attention is given to relative data and effective communication through the continuum of acute care.
The Brain Trauma Foundation TBI Guideline provides recommendations based on available supporting evidence leaving space for clinical judgement when a lack of evidence exists. The Fourth Edition intends to be a living guideline that will only be revised when new evidence is available that supports a revision. These TBI guidelines provide recommendations on traumatic brain injury treatment, monitoring and thresholds. Adherence to these TBI guidelines improves neurological outcomes.
Many providers find management algorithms useful to clinical practice. SIBICC used a consensus approach to develop a management algorithm for Severe Traumatic Brain Injury (sTBI) patients admitted to the ICU with an ICP monitor. A total of 18 traumatic brain injury interventions were established as fundamental and 10 traumatic brain injury treatments were determined not to be used. The 3-tier algorithm is based on treating elevated ICP with the higher tiers involving therapies with greater risk.
Seventy-five percent of patients diagnosed with severe traumatic brain injury present with elevated ICP which leads to secondary brain injury, increased mortality and worse neurological outcomes. Although head CT findings may indicate mass effect or diffuse swelling, intracranial hypertension cannot be reliably diagnosed by clinical examination and brain imaging alone. According to the Brain Trauma Foundation, ICP monitoring is recommended to reduce in-hospital mortality and 2-week post-injury mortality.5
ICP Monitoring is indicated for sTBI with a GCS of less than or equal to 8 with an abnormal CT. ICP monitoring may be considered in patients with a normal head CT, GCS <8 with 2 or more of the following: age > 40, motor posturing, systolic blood pressure less than 90 mmHg. Treatment is recommended for ICP > 22 mmHg in adults and >20 in pediatrics.
CP Monitoring is indicated for sTBI with a GCS of less than or equal to 8 with an abnormal CT. ICP monitoring may be considered in patients with a normal head CT, GCS <8 with 2 or more of the following: age > 40, motor posturing, systolic blood pressure less than 90 mmHg. Treatment is recommended for ICP > 22 mmHg in adults and >20 in pediatrics. Adequate cerebral perfusion pressure (CPP) is an important parameter for brain injured patient and required for maintaining cerebral blood flow. CPP is a calculation – mean arterial pressure (MAP) minus ICP equals CPP. Target CPP in adults is 60 – 70 mmHg; CPP in pediatrics is based on age.
Adequate cerebral perfusion pressure (CPP) is an important parameter for brain injured patient and required for maintaining cerebral blood flow. CPP is a calculation – mean arterial pressure (MAP) minus ICP equals CPP. Target CPP in adults is 60 – 70 mmHg; CPP in pediatrics is based on age.
Intracranial Pressure is measured invasively with either an external ventricular drain (EVD) attached to an external transducer or with an advanced system using fiber optic catheters to monitor inside the skull most commonly in the parenchyma but also can be in the ventricle or subdural space. EVDs allow for therapeutic cerebral spinal fluid (CSF) drainage but carries an 8 – 10% risk of infection and 5% risk of hemorrhage complication during insertion. Parenchymal catheters carry a <1% risk of complication.1
Both external and parenchymal catheters require zeroing. An EVD requires frequent zeroing and accuracy relies on variables such as clinician skill for leveling and zeroing as well as age and precision of transducer with an inevitable drift over time. An EVD is also limited to either draining or monitoring as they cannot be done simultaneously. Unlike the EVD, these advanced catheters are zeroed one time to atmospheric pressure prior to placement. These advanced catheters provide a continuous numeric value as well as waveform to monitor compliance. One unique catheter provides the benefits of an advanced catheter while simultaneously being open to drain. The drift rate in these catheters is nominal with little to no clinical significance.
Post-traumatic seizures are common in moderate and severe traumatic brain injury and occur in about 10% – 50% of the patients 6, 7. Seizures may be clinically visible or subclinical and detected on cEEG. These seizures are classified as: Immediate – within 24 hours of injury; Early – 24 hours up to 7 days; Late – greater than 7 days from injury.
Prophylactic antiseizure medication is recommended for 7 days following severe TBI. Despite this medication, seizures occur in 30% of patients with moderate to severe TBI. These early post-trauma seizures may lead to secondary brain injury, metabolic crisis, increased intracranial pressure and cerebral edema. The use of non-invasive EEG monitoring to continuously record the electrical activity in the cerebral cortex allows for a constant assessment of the cerebral activity in these critically ill patients.
Literature supports the use of cEEG that allows for accurate temporal and spatial resolution. Nowadays, EEG quantitative analysis assist in data interpretation using algorithms that analyze, compress and rectify large amounts of data in graphical trends representing the raw EEG in which it’s possible to identify significant changes in pattern such as increased amplitude compatible with seizures in the TBI population.8
SIBICC tier-one recommendation is to consider EEG monitoring for subclinical seizures that can cause intracranial hypertension. The Consensus statement from the Neurointensive care section of the European Society of Intensive Medicine (ESICM) also recommends EEG monitoring in traumatic brain injury patients being cared for in the ICU.9 Moderate to severe comatose TBI patients need cEEG monitoring for early identification of seizures to allow for immediate intervention. There are several multi-center studies underway (TrackTBI, Centre TBI, BOOST, etc.) whose outputs will inform decision making in the field. These will help to continue to advance our understanding of TBI and improve care for patients who sustain it.
Bibliography
1. Zimmermann LL, Tran, DS, Lovett, ME, Mangat, HS. Emergency Neurological Life Support: Traumatic Brain Injury. Neurocritical Care. 2019.
2. Dewan MC, Rattani A, Gupta S, et al. Estimating the global incidence of traumatic brain injury [published online ahead of print, 2018 Apr 1]. J Neurosurg. 2018;1-18. doi:10.3171/2017.10.JNS17352
3. Traumatic Brain Injury . Centers for Disease Control and Prevention. https://www.cdc.gov/traumaticbraininjury/. Published May 13, 2021. Accessed June 17, 2021.
4. Meaney DF, Morrison B, Dale Bass C. The Mechanics of Traumatic Brain Injury: A Review of What We Know and What We Need to Know for Reducing Its Societal Burden. Journal of Biomechanical
Engineering. 2014;136(2). doi:10.1115/1.4026364
5. Brain Trauma Foundation. http://braintrauma.org/guidelines/guidelines-for-the-management-of-severe-tbi-4th-ed. Accessed June 17, 2021.
6. Ding K, Gupta PK, Diaz-Arrastia R. Epilepsy after Traumatic Brain Injury. In: Laskowitz D, Grant G, editors. Translational Research in Traumatic Brain Injury. Boca Raton (FL): CRC Press/Taylor and Francis
Group; 2016. Chapter 14. Available from: https://www.ncbi.nlm.nih.gov/books/NBK326716/
7. MD ABEK, 07/2020 A. Traumatic Brain Injury and Epilepsy. Epilepsy Foundation. https://www.epilepsy.com/learn/epilepsy-due-specific-causes/structural-causes-epilepsy/specific-structural-epilepsies/traumatic-brain-injury-and-epilepsy. Accessed June 17, 2021.
8. Haneef Z, Levin HS, Frost JD Jr, Mizrahi EM. Electroencephalography and quantitative electroencephalography in mild traumatic brain injury. J Neurotrauma. 2013;30(8):653-656.
doi:10.1089/neu.2012.2585
9. laassen J, Taccone FS, Horn P, et al. Recommendations on the use of EEG monitoring in critically ill patients: consensus statement from the neurointensive care section of the ESICM. Intensive Care Med.
2013;39(8):1337-1351. doi:10.1007/s00134-013-2938-4
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