Overview of Traumatic Brain Injury

Original Editor - Wendy Walker and Anna Ziemer

Lead Editors - Wendy Walker, Naomi O'Reilly, Kim Jackson, Rachael Lowe, Vidya Acharya, Lucinda hampton, Kalyani Yajnanarayan, Stacy Schiurring, George Prudden, Shaimaa Eldib, Nicole Hills, Lauren Lopez, Mande Jooste, 127.0.0.1, Tony Lowe, Nupur Smit Shah, WikiSysop, Simisola Ajeyalemi, Karen Wilson and Uchechukwu Chukwuemeka

Introduction

Acquired brain injury or head injury are broad terms describing an array of injuries that occur to the scalp, skull, brain, and underlying tissue and blood vessels in the head. Acquired brain injury does not include damage to the brain resulting from neurodegenerative disorders like Multiple Sclerosis or Parkinson’s Disease. Acquired brain injuries are broadly classified into; Traumatic brain injury derived from an external source and non-traumatic brain injury derived from either an internal or external source.

Traumatic Brain Injury	Non-Traumatic Brain Injury
Falls	Stroke e.g. Haemorrhage, Clot
Assaults	Infectious Disease e.g. Meningitis, Encephalitis
Motor Vehicle Accidents	Seizure
Sport / Recreation Injury	Electric Shock
Abusive Head Trauma e.g Shaken Baby Syndrome	Tumours
Gunshot Wounds	Toxic Exposure
Workplace Injury	Metabolic Disorders
Child Abuse	Neurotoxic Poisoning e.g. carbon monoxide, lead exposure
Domestic Violence	Lack of Oxygen e.g. drowning, choking, hypoxic & anoxic injury
Military Actions eg. Blast Injury	Drug Overdose

Traumatic Brain Injury

Traumatic Brain Injury is “an alteration in brain function, or other evidence of brain pathology, caused by an external force”. It occurs when an external force impacts the brain, and often is caused by a blow, bump, jolt or penetrating wound to the head. However, not all blows or jolts to the head cause traumatic brain injury: some just cause bony damage to the skull, without subsequent injury to the brain. Mild traumatic brain injury are also more commonly referred to now as Concussion.

Whole-brain tractography in an aged-matched control and in a case of 26-year-old patient, 15 months post-traumatic brain injury. Tracts are represented in a scalar mode (0.4–0): regions with higher FA values are colored in red (0.4) and the ones with lower FA (0) in blue. A diffuse reduction of FA values is evident in the TBI patient (blue prevalence), and quantified on the right column.

Traumatic brain injury does not always have to be demonstrated by motor impairment but hidden non-motor like symptoms related to cognition and behaviour are altered in all forms of traumatic brain injury. This phenomenon and the nature of the population living with traumatic brain injury not being outspoken either demanding in their rights enforcement as well as the lack of insight into real impact of traumatic brain injury on society earned the traumatic brain injury the “silent epidemic” name.

Neurorehabilitation is an effective form of post traumatic brain injury treatment following the life-saving and critical care procedures and financially cost-effective approach to reducing the motor and non-motor impairment. Despite the vast supporting evidence, it is not commonly accessible. The strict algorithm-based treatment approach to Emergency and Intensive Care Medicine successfully saving lives of people sustaining traumatic brain injury has not been introduced to intermediate either community Neurorehabilitation. The lack of systematic approach to Neurorehabilitation, general underfunding or difficulty accessing the services demonstrate the lack of financial efficiency following ever growing cost of live saving procedures and acute care. This also prevents the people living with traumatic brain injury to capitalise on the most valuable time for rehabilitative treatment and impacts on early achievements. Resultant severely increased care costs, unemployability and loss of income by the traumatic brain injury survivors but also often by family members providing care are other factors contributing to the widely underestimated social cost of traumatic brain injury.

Causes

The two most common causes of traumatic brain injury are Falls and Road Traffic Accidents, which includes vehicle collisions, pedestrians being hit by a vehicle, vehicle-cyclist and car-motorcyclist collisions as well as bicycle and motorbike crashes which do not involve another vehicle. Until recently, road traffic accidents were the primary cause of traumatic brain injury, but an international study published in 2013 reported that "falls have now surpassed road traffic incidents as the leading cause of this injury".

Traumatic brain injury in sport has become a burning problem with clearly emerging long-term consequences. Many professionals have become involved in developing the evidence about complexity of symptoms, impact of its repetitive nature on brain health and long-term prognosis of sport related concussion. The evidence of its assessment and treatment as well as role in brain degenerative diseases is emerging and enhancing safety of those participating in sports like rugby, football, boxing, horse riding and racing, American football or ice hockey.

Global conflicts like the Global War on Terror had expose the military population to new pathomechanisms, but also enhance the development of subacute care and life-saving and neurosurgical procedures. With the speed of global information share being faster than ever, the civil services benefit from military good practice dissemination.

Incidence

Traumatic brain injury has been a public health problem for many years, and for years to come will still be a main source of death and severe disability. According to World Health Organisation by 2020 traumatic brain injury will surpass many diseases as the major cause of death and disability.

We are currently observing increasing number of traumatic brain injury due to medical advances in emergency medicine and intensive care but also due to decreasing fatalities as a result of safety and preventative measures such as decreased speed limits, use of helmets or development in army amours.

Traumatic brain injury continues to be critical health and socio-economic problem worldwide across low and high-income countries due its life-long consequences and can affect people at any age. Socioeconomic change of low and middle-income countries drives an increase in traumatic brain injury due to urbanisation and mechanisation.

One study found that TBI was "a major cause of death and disability on the United States, contributing to about 30% of all injury deaths". A 2010 study looked at data from several nations, and reported that:"each year 235 000 Americans are hospitalised for non-fatal TBI, 1.1 million are treated in emergency departments, and 50 000 die. A report from Victoria, Australia of traumatic brain injury numbers from 2006-2014 found a decline in the incidence of motor vehicle-related severe traumatic brain injury, suggesting that road injury prevention measures have been effective, but targeted measures for reducing the incidence of major head injuries from falls should be explored as in the over 65 age bracket these are on the rise. The Northern Finland birth cohort found that 3.8% of the population had experienced at least 1 hospitalisation due to traumatic brain injury by 35 years of age, while the Christchurch, New Zealand birth cohort found that by 25 years of age 31.6% of the population had experienced at least 1 traumatic brain injury, requiring medical attention including hospitalisation, emergency department, or physician office. An estimated 43.3% of Americans have residual disability 1 year after a traumatic brain injury, with the most recent estimate of prevalence of US Civilian residents living with disability following hospitalisation with traumatic brain injury is 3.2 million".

We are witnessing a change in traumatic brain injury distribution for age groups with childhood and aging being the highest risk population; gender with males being the most at risk between 10 and 20 years old and females between 70 and 80 , as well as mechanism contributing to injury with falls increasingly contributing to traumatic brain injury and blast related injury being most popular mechanism of battlefield sustained traumatic brain injury.

The incidence amongst children creates new challenges in the field of traumatic brain injury often overlooked like behavioural change or educational difficulties. Vulnerability to criminalisation amongst adolescents and young people with traumatic brain injury has been becoming another problem. Accessible housing and complex care needs follow the traumatic brain injury increasing incidence amongst elderly (Time for Change).

The access to emergency services as well as neurosurgical services determines mortality and recovery outcomes after traumatic brain injury across the world regions. In lower-income countries the access is scarce and determines higher numbers of severe disability post traumatic brain injury.

Mechanism of Injury

Closed Head Injury

• Often occurs as a result of RTA, or a blow to the head, or a fall where the head strikes the floor or another hard surface..
• In closed head injury, the skull is not penetrated, but it is frequently fractured.
• Generally there is both focal and diffuse axonal damage.

Open Head Injury

• This is caused by a penetrating wound, eg. by a weapon or from a bullet.
• In these cases the skull is penetrated.
• The brain injury is usually largely focal axonal damage.

Deceleration Injury

• This frequently occurs in RTA, when rapid deceleration occurs as the skull meets a stationary object, causing the brain to move inside the skull.
• Mechanical brain injury occurs due to axonal shearing, contusion and brain oedema.

Coup-Contracoup Injury

Coup Injury

This occurs beneath the point of impact - may be associated with a skull fracture at the site of impact

Contracoup Injury

This occurs when the impact is sufficient to cause the brain to move within the skull; the brain moves in the opposite direction, and hits the opposite side of the skull, causing bruising.

Coup-Contracoup Injury

This is a frequent occurrence - opposite poles of the brain suffer injury.

Pathological Process

Classification

There are various classification determinants utilized to classify traumatic brain injury. The clinical presentation and prognosis depend on the individual nature of the injury with often coexisting types of TBI. The classification is important for acute management, treatment and prognosis as well as neurorehabilitation requirements.

Mechanical Damage

AKA Primary Damage and Primary Insult. Primary mechanical brain injury is the direct injury to the brain cells caused by the initial impact.

The mechanical forces can cause intracranial haematoma [ defined as "a localised swelling that is filled with blood caused by a brea in the wall of a blood vessel"] and/or vascular injury, as well as injury to cranial nerves.

Intracranial haematomas are categorised in the following way:

• Epidural haematomas
• Subdural haematomas
• Subarachnoid haematomas

In the CT scan image shown here, skull fractures are visible, as well as multiple frontal, parietal and emporal lobe contusions with a subdural haematoma on the left side as well as associated interhemispheric haemorrhages.

Delayed non-mechanical Damage

AKA Secondary Damage. Non-mechanical brain injury is caused by ischaemic, cytotoxic and inflammatory processes.

One of the most significant factors is the excessive release of glutamate and aspartate, which alter cell wall permeability which ultimately leads to destruction of axons.

Clinical Presentation

The presentation depends on the areas of the brain which have been damaged.

Spasticity if one of the early signs of TBI. This often develops a week after the injury. Symptoms include hypertonicity and spasm of the affected muscles and an increase in deep tendon reflexes; it's severity can range from mild stiffness of the muscles to severe (and painful) muscle spasms.

Classification of TBI

There are 3 ways of classifying head injury:

1. Patho-anatomic ie. what damage has occurred where in the brain, for instance, subdural haemorrhage
2. Injury severity, typically using the Glasgow Coma Scale [GCS] as the measure, where a score of 8 or less is defined as Severe TBI
3. Physical mechanism causing the injury, categorised as contact or "impact" loading when the head is struck or strikes an object, as oppsed to non-contact or "inertial" loading (which is when the brain moves within the skull).

Signs & Symptoms

• Loss of consciousness: In Moderate brain injury, loss of consciousness [LOC] ranges from 30 minues to 6 hours, and generally the patient will have a GCS score between 9 and 12. In Severe brain injury, loss of consciousness occurs for more than 6 hours and the GCS score is 8 or lower.
• Cognitive issues: These may include problems with concentration, attention, memory, speed of processing, language comprehension, confusion, impulsive behaviour
• Speech and language issues: Receptive aphasia (ie. not understanding the spoken word), Expressive aphasia (difficulty with/inability to talk), Slurred speech
• Vision: Blindness or partial blindness, blurred vision, double vision (diplopia), Photophobia, light sensitivity
• Hearing: Deafness, or reduction in hearing, Tinnitus (ringing in the ears), increased sensitivity to sounds (hyperacusis, phonophobia)
• Smell and taste: Reduced or loss of sense of smell and/or taste, reduced appetite
• Emotional and Social Irritability, aggression, depression, apathy, inhibition, lack of insight, reduced motivation, mood swings

Diagnostic Procedures

Post acute TBI, all patients are encouraged to undergo an urgent neurological examination in addition to a surgical examination. Magnetic Resonance Imaging (MRI) and Computerised Tomography (CT) scanning are frequently used in order to image the brain. CT scanning is indicated in the very early stages post injury. The EFNS guidelines confirmed that the use of CT scans can be limited to patients with Mild TBI that present with certain clinical signs and symptoms. The CT scan can show potential fractures and can detail haemorrhages and haematomas in the brain, as well as contusions and swelling. MRI is often used once the patient is medically stable to give a more detailed view of the brain tissue.

Table 1: Classification of Traumatic Brain Injury and indication for immediate CT scan

Classification	Characteristics	Referral for CT?
Mild	- Hospital admission -GCS 13-15 - LOC (if present) <30min	No
Category 1	- GCS 15 - 0-1 minor risk factor (CHIP rule) - Head Injury, no TBI	No
Category 2	- GCS 15 - >1 Major risk factors/ >2 minor risk factors (CHIP rule)	Yes
Category 3	-GCS 13-14	Yes
Moderate	- GCS 9-12	Yes
Severe	- GCS <8	Yes
Critical	- GCS 3-4 with reduced/absent pupillary and motor reactions	Yes
Glascow Coma Scale (GCS), Canadian CT in Head Injury Patients prediction rule (CHIP rule)

Management / Interventions

Surgical Interventions

Emergency surgery is often required to minimise brain damage:

• surgery to remove haematoma and thus reduce pressure on brain tissue
• removal of part of the skull in order to relieve pressure
• surgical repair of severe skull fractures, and/or removal of skull fragments from brain tissue

Medical Interventions

Medication may be used to limit secondary damage to the brain:

• Coma-inducing medication may be given, as a brain in coma requires far less oxygen so if there is reduced oxygen and nutrient supply due to blood vessels being compressed by increased pressure, being in coma is therapeutic
• Diuretics (given intravenously) can be used to reduce the amount of fluid in soft tissues and thus help reduce pressure in the brain
• Anti-epileptic medication is often provided in the early stages to avoid any additional brain damage which might be caused if a seizure were to occur.

Resources

BrainLine is an American multimedia website providing information and resources about treating and living with TBI; it includes a series of webcasts, written online resources and an electronic newsletter. It has a version in Spanish too.

Headway is a UK charity for TBI which has a comprehensive website, with information on the different aspects of TBI and its rehabilitation. It has a number of useful written resources for patients on the website, including ones on Brain injury and Epilepsy, Loss of taste and smell after Brain injuryand Balance problems and Dizziness after Brain injury

Symptoms

Traumatic brain injury can have wide-ranging physical, cognitive, psychological and physiological effects occurring immediately or elapsed. The symptoms might differ depending on the severity of TBI, but some are not specific to the type of injury.

Mild TBI

Physical Symptoms	Sensory Symptoms	Cognitive Symptoms
With or without loss of consciousness. If loss of consciousness: a few seconds to a few minutes	Blurred Vision	State of being dazed, confused or disoriented
Headache	Ringing in the Ears	Memory or concentration deficits
Nausea or Vomiting	Bad taste in the mouth or changes in the ability to smell	Mood changes or mood swings
Fatigue or Drowsiness	Sensitivity to light or sound	Irritability
Problems with speech		Feeling depressed or anxious
Difficulty sleeping or sleeping more than usually		Fatiguability
Dizziness or loss of balance

Moderate to Severe TBI

Physical Symptoms	Sensory Symptoms	Cognitive Symptoms
Loss of consciousness from several minutes to hours or days	Blurred vision	Coma and other disorders of consciousness
Persistent headache or headache that worsens	Double vision	Profound confusion
Repeated vomiting or nausea	Ringing in the ears	Irritability
Convulsions or seizures	Bad taste in the mouth or changes in the ability to smell	Agitation, combativeness or other unusual behaviour
Dilation of one or both pupils of the eyes	Sensitivity to light or sound	Sad or depressed mood
Clear fluid or blood draining from the nose or ears		Fatiguability
Sudden swelling or bruises behind the ears or around eyes
Inability to awaken from sleep
Weakness or numbness
Loss of coordination or balance
Irregular breathing
Difficulty speaking

Summary

With the complexity of the traumatic brain injury and its consequences there is no speciality capable to deal with them alone. In traumatic brain injury management the role of Multidisciplinary Team is invaluable with Physiotherapist / Physical Therapist role at its heart form acute to chronic stages.

The currently growing insight into devastating impact of traumatic brain injury on individual’s, families’ and society’s life initiates widespread change in research and evidence implementation resulting in prevention, services design, legislation and funding. We are seeing developments in neuroprotective and neurorestorative treatments and therapeutic approaches driving the neuroplastic change at cell and network levels. We are accessing more precise diagnostic enabling more effective treatment choices. We are capitalising on gains of more advanced medical and rehabilitation centres with knowledge and evidence being widely shared. We are living in truly exciting times when more than ever can be done for traumatic brain injury survivors.

References