Mild Traumatic Brain Injury

A Science and Engineering Perspective

Mark A. Mentzer

• Publisher: CRC Press
• Year: 2020
• ISBN:
  9781000207712
• Edition: 1
• Topic: Medicina
• Subtopic: Teoría, práctica y referencia médicas

Mild traumatic brain injury (mTBI), directly related to chronic traumatic encephalopathy, presents a crisis in contact sports, the military, and public health. Mild Traumatic Brain Injury: A Science and Engineering Perspective reviews current understanding of mTBI, methods of diagnosis, treatment, policy concerns, and emerging technologies. It details the neurophysiology and epidemiology of brain injuries by presenting disease models and descriptions of nucleating events, characterizes sensors, imagers, and related diagnostic measures used for evaluating and identifying brain injuries, and relates emerging bioinformatics analysis with mTBI markers. The book goes on to discuss issues with sports medicine and military issues; covers therapeutic strategies, surgeries, and future developments; and finally addresses drug trials and candidates for therapy. The broad coverage and accessible discussions will appeal to professionals in diverse fields related to mTBI, students of neurology, medicine, and biology, as well as policy makers and lay persons interested in this hot topic.

Features

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• Summarizes the entire scope of the field of mTBI

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• Details the neurophysiology, epidemiology, and presents disease models and descriptions of nucleating events

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• Characterizes sensors, imagers, and related diagnostic measures and relates emerging bioinformatics analysis with mTBI markers

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• Discusses issues with sports medicine and military issues

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• Covers therapeutic strategies, surgeries, and future developments and addresses drug trials and candidates

Dr Mark Mentzer earned his PhD in Electrical Engineering from the University of Delaware. He is a former research scientist at the US Army Research Laboratory where he studied mild traumatic brain injury and developed early-detection brain injury helmet sensors. He is a certified test director and contracting officer representative. He possesses two Level-III Defense Acquisition University Certifications in Science and Technology Management and in Test and Evaluation. During his career, he developed a wide range of sensors and instrumentation as well as biochemical processes to assess brain trauma. Mentzer currently teaches graduate systems engineering and computer science courses at the University of Maryland University College.

1 Clinical Sequelae and Functional Outcomes

Definitions of mTBI

Following are some common definitions for TBI. These provide an overview of the concerns and varied stakeholder perspectives.

Centers for Disease Control

A traumatic brain injury is caused by a bump, blow, or jolt to the head or a penetrating head injury that disrupts the function of the brain. (CDC, 2016)

National Institute of Neurological Disorders and Stroke

TBI, a form of acquired brain injury, occurs when a sudden trauma causes damage to the brain. TBI can result when the head suddenly and violently hits an object, or when an object pierces the skull and enters brain tissue. (NINDS, 2012)

Department of Defense

A traumatically induced structural injury or physiological disruption of brain function as a result of external force that is indicated by new onset or worsening of at least one of the following clinical signs, immediately following the event:

• any alteration in mental status (e.g., confusion, disorientation, slowed thinking)
• any loss of memory for events immediately before or after the injury
• any period of loss or a decreased level of consciousness, observed or self-reported.

External forces may include any of the following events: the head being struck by an object, the head striking an object, the brain undergoing an acceleration/deceleration movement without direct external trauma to the head, or forces generated from events such as blast or explosion, including penetrating injuries. (Dept. of Defense, 2014)

American Psychiatric Association

TBI is the injury sustained and can be the nucleating factor for a host of neurological disorders. Neurocognitive disorder (NCD) due to TBI is termed a DSM-5 diagnosis regarding cognitive symptoms of impairments following a TBI. About 80% of cases are mild, 10% moderate, and 10% severe, but “at a minimum, TBI produces a diminished or altered state of consciousness. TBI results in a diverse, idiosyncratic constellation of cognitive, neurological, physical, sensory, and psychosocial symptoms” (American Psychiatric Association, 2013).

National Academy of Sciences

The National Academy of Sciences (National Academies of Science, Engineering, and Medicine, 2019) defines traumatic brain injury as

an insult to the brain from an external force that leads to temporary or permanent impairment of cognitive, physical, or psychosocial function. TBI is a form of acquired brain injury, and it may be open (penetrating) or closed (non-penetrating) and can be categorized as mild, moderate, or severe, depending on the clinical presentation.

Brain Injury Association of America

• TBI: “alteration in brain function, or other evidence of brain pathology, caused by an external force.”
• Acquired brain injury (ABI): “injury to the brain which is not hereditary, congenital, degenerative, or induced by birth trauma … an injury to the brain that has occurred after birth.”

American Congress of Rehabilitation Medicine

A patient with mild traumatic brain injury is a person who has had a traumatically induced physiological disruption of brain function as manifested by at least one of the following (Ashley and Hovda, 2018; Kay et al., 1993)

• Any period of loss of consciousness
• Any loss of memory for events immediately before or after the accident
• Any alteration in mental state at the time of the accident (e.g., feeling dazed, disoriented, or confused)
• Focal neurological deficit(s) that may or may not be transient, but where the severity of the injury does not exceed the following:
  • Loss of consciousness of approximately 30 minutes or less
  • After 30 minutes, an initial Glasgow Coma Scale (GCS) of 13–15
  • Posttraumatic amnesia (PTA) not greater than 24 hours

Carney et al. Definition

Carney et al. (2014) provided a definition:

• A change in brain function after a force to the head that may be accompanied by temporary loss of consciousness
• Indicators of concussion, identified in an alert individual after a force to the head that include the following:
  • Observed and documented disorientation or confusion immediately after the event
  • Slower reaction time within 2 days postinjury
  • Impaired verbal learning and memory within 2 days postinjury
  • Impaired balance within 1 day postinjury

American Association of Neurological Surgeons

The AANS (2020) defined concussion as “A clinical syndrome characterized by immediate and transient alteration in brain function, including alteration of mental status and level of consciousness, resulting from mechanical force or trauma.”

CSTE and BU School of Medicine

The Center for the Study of Traumatic Encephalopathy (CSTE) and Boston University School of Medicine defined chronic traumatic encephalopathy (CTE) as:

a progressive neurodegenerative disease caused by repetitive trauma to the brain … characterized by the build-up of a toxic protein called Tau in the form of neurofibrillary tangles (NFT’s) and neuropil threads (NT’s) throughout the brain. The abnormal protein initially impairs the normal functioning of the brain and eventually kills brain cells. Early on, CTE sufferers may display clinical symptoms such as memory impairment, emotional instability, erratic behavior, depression and problems with impulse control. However, CTE eventually progresses to full-blown dementia.

Concussion in Sport Conference

The Fourth Annual Conference on Concussion in Sport (McCrory et al., 2013) provided a consensus statement:

Concussion is a brain injury and is defined as a complex pathophysiological process affecting the brain, induced by biomechanical forces. Several common features that incorporate clinical, pathologic, and biomechanical injury constructs that may be utilized in defining the nature of a concussive head injury include

1. Concussion may be caused either by a direct blow to the head, face, neck, or elsewhere on the body with an “impulsive” force transmitted to the head.
2. Concussion typically results in the rapid onset of short-lived impairment of neurological function that resolves spontaneously. However, in some cases, symptoms and signs may evolve over a number of minutes to hours.
3. Concussion may result in neuropathological changes, but the acute clinical symptoms largely reflect a function disturbance rather than a structural injury and, as such, no abnormality is seen on standard neuroimaging studies.
4. Concussion results in a graded set of clinical symptoms that may or may not involve loss of consciousness. Resolution of the clinical and cognitive symptoms typically follows a sequential course. However, it is important to note that, in some cases, symptoms may be prolonged.

NCAA

The National Collegiate Athletic Association (NCAA) defines concussion or mild traumatic brain injury as “a complex pathophysiological process affecting the brain, induced by traumatic biomechanical forces.”

In each of the definitions the forces applied to the head may result from forces applied elsewhere and transmitted through the body to the head. Each of the definitions states or implies that symptoms may not necessarily be transient. Factors specific to each patient may contribute to disposition toward a response to mechanical insult, thereby complicating prognostication. Most individuals experience resolution of symptoms within 90 days of injury (Alexander, 1995). There is also lack of understanding of the relationship between activity and rest levels and how these factors influence symptom persistence (Ashley and Hovda, 2018).

World Health Organization (WHO, 1995)

A case of traumatic brain injury (craniocerebral trauma) is either:

• An occurrence of injury to the head (arising from blunt or penetrating trauma or from acceleration–deceleration forces) with at least one of the following:
  • Observed or self-reported alteration of consciousness or amnesia due to head trauma
  • Neurologic or neuropsychological changes or diagnoses of skull fracture or intracranial lesions that can be attributed to the head trauma
• Or an occurrence of death resulting from trauma with head injury or traumatic brain injury listed on the death certificate, autopsy report, or medical examiner’s report in the sequence of conditions that resulted in death

Examples of neurologic changes include abnormalities of motor function, sensory function, or reflexes; abnormalities of speech (aphasia or dysphasia); or seizures acutely following head trauma. Examples of neuropsychological abnormalities include amnesia as described previously; agitation or confusion; and other changes in cognition, behavior, or personality.

Severity Classification of TBI and Screening Tools

The severity of TBI is classified using the Glasgow Coma Scale (GCS), Loss of Consciousness (LOC), and post-traumatic amnesia (PTA), along with a variety of other screening tools such as ANAM (Automated Neuropsychological Assessment Metrics), the Repeatable Battery for Assessment of Neuropsychological Status, the Concussion Management Algorithm (CMA), the King-Devick concussion test (North et al., 2012; Marshall et al., 2012), the Sport Concussion Assessment Tool (SCAT3), and the Acute Concussion Evaluation (Ontario Neurotrauma Foundation, 2013; Gioia and Collins, 2006). And no single classification embraces all the features of mTBI (clinical, pathological, cellular/molecular). The severity does not directly equate to neurocognitive disorder (NCD) or the potential for rehabilitation. Many factors such as injury specifics, age, prior history, and substance abuse relate to the effects of a TBI (Relias Academy, 2020). Edition 5 of the Diagnostic and Statistical Manual for Mental Disorders (DSM-5) describes the neurocognitive sequelae following TBI. NCD encompasses the group of acquired disorders wherein the primary clinical deficit is disrupted cognitive functioning (American Psychiatric Association, 2013). DSM-5 is the standard classification of mental disorders used by mental health professionals in the United States.

Symptoms often...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Foreword
• Acknowledgments
• Author
• Introduction
• Chapter 1 Clinical Sequelae and Functional Outcomes
• Chapter 2 Sensing and Assessment of Brain Injury
• Chapter 3 Instrumentation for Assessing mTBI Events
• Chapter 4 mTBI in the Military and Contact Sports
• Chapter 5 Therapeutic Strategies and Future Research
• Appendix 1: US Patent 9080984 Blast, Ballistic, and Blunt Trauma Sensor
• Appendix 2: Significance of the NMDA Cell Surface Receptor
• Appendix 3: Neuroproteomics, Protein Folding, Transcription Factors, and Epigenetics for TBI Research
• Appendix 4: Rhodopsin and Signal Transduction
• Index