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Mild Traumatic Brain Injury in

Military Service Personnel:

Key Issues and Considerations

Silviya Doneva PhD

King Edward VII’s Hospital and Medical Advisory

Committee (MAC)

Prepared by The Health of Veterans Research Team (HVRT)

30.03.2017

1

1. Purpose of the Review

This report on the health of military personnel considers mild traumatic brain injury

(mTBI) and in particular, the one related to blunt head trauma. It aims to set out the

current picture of mTBI amongst military personnel, including its definition and

classification, prevalence rates, markers and possible long-term consequences,

comorbidity with other disorders and approaches to treatment. Information has been

drawn from the most current reports published by the UK Ministry of Defence (MoD),

the World Health Organization (WHO) Collaborating Centre Task Force on Mild

Traumatic Brain Injury, as well as high-impact academic research in the field, mainly

making use of US and UK military data1. Furthermore, the present report also

includes exclusive data on the number of mTBI cases among the UK military for the

period between the 1 April 2008 and the 31 March 2016 that we received with

permission from the Department of Defence Statistics at the MoD (discussed in

Section 7d)).

Being the most controversial form of TBI in terms of its cause and nature, mTBI

continues to raise ardent debates among researchers and clinicians. The review

recognises the lack of universal agreement in the field, and thus it attempts to

incorporate as many of the different perspectives as possible. It should be noted that

although in the past ‘concussion’ has been considered synonymous for mTBI, the

present review abstains from using this term to refer to mTBI, in accordance to more

recent literature on the topic (1).

2. Definitions

a) mTBI

Traumatic Brain Injury is a very common condition resulting in over 1 million cases

being registered in UK emergency departments each year (2). The majority (80% to

90%) are characterised as mild (1,3,4). More specifically, mTBI has been defined as

‘a traumatically induced physiological disruption of brain function’ (5) (p. 86) that is

characterised by at least one array of symptoms (See Section 3 for more detail).

1 For completeness, this report also incorporates research, based on civilian data, as well as data from other countries, such as Australia and Canada.

2

MTBI in military settings is believed to most often follow from a blunt force trauma

to the head, in particular, blast injury secondary to improvised explosive devices

(6,7). In view of the large numbers of service personnel being exposed to a blast

during the recent conflicts in Iraq and Afghanistan, mTBI has been referred to as a

‘service-related mental disorder’ ((8), p. 1) and a ‘signature war injury’ for those

returning from these theatres of operation (9,10). Importantly, mTBI also occurs in

non-combat situations such as during contact sports activities and road accidents.

For example, in civilians it is usually caused by falls and motor vehicle collisions

(11,12). MTBI is also one of the most common sports-related injuries, and as a

consequence has been extensively studied among sportsmen (See Section 5 for

details). Furthermore, this is where much of the guidance for best practice in

managing mTBI comes from (See Section 8c)). Finally, mTBI is normally considered

relatively innocuous with its effects disappearing within minutes (1,13). As a

consequence, many patients, diagnosed with the condition, are not taken to hospital

nor are they encouraged to seek medical help.

b) mTBI as an unexplained condition

According to Rona (6), the majority of mTBIs in military settings are caused by

exposure to improvised explosive devices (IED). Explosives, however, are not unique

to the recent war conflicts. Instead, exposure to bombarding is believed to be one of

the causes of the signature injury during the First World War known as the ‘shell

shock’ epidemic (6,14). Some other examples of similar conditions with unexplained

aetiology and unclear diagnostic criteria, reported amongst military personnel in past

wars, are the ‘effort syndrome’ that emerged during the Second World War (15) and

the 1991 Gulf War Syndrome (16).

Finally, there is no consensus regarding the definition of mTBI or what it entails, with

some authors using concussion interchangeably with mTBI and some making a

difference, which does not necessarily agree with the distinction that others have

made between the two terms (1). Furthermore, because of the diversity in

symptoms, recovery rates, long-term effects and susceptibility to treatment within

the condition, some have proposed that mTBI should be subdivided into categories

and viewed as a heterogeneous condition (1,17) (see Section 3).

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c) Postconcussive symptoms

Several evidence-based reviews of the literature have suggested that symptoms of

mTBI usually resolve spontaneously within about 2 weeks (18–20). If unresolved

within 3 months, however, these evolve into what is known as persistent

postconcussive symptoms (or postconcussional syndrome, PCS) (21–23). The WHO’s

International Statistical Classification of Diseases and Health-Related Disorders 10th

edition (ICD-10; (24))2 classifies postconcussional syndrome under ‘Mental and

behavioural disorders (F00-F99)’ and more specifically under ‘Personality and

behavioural disorders due to brain disease, damage and dysfunction (F07)’. PCS

could be grouped into three categories: somatic (physical), psychological (emotional

and behavioural) and cognitive (thinking). Please, refer to Table 1 for all possible

symptoms in each category.

Table1. Postconcussive symptoms, usually reported following mTBI. The displayed

information has been based on Bagalman (26), Thompson (20), Thompson, Scott &

Dubinsky (27) and Rona (6).

Symptom Type Expression

Somatic

Headache, dizziness, ringing in the ears, visual

disturbances, sensitivity to light and noise, disturbed sleep,

lethargy, fatigue.

Cognitive

Psychological

Confusion, problems with thinking, decision making,

memory, attention, concentration, abstract reasoning,

information processing.

Depression, anxiety, mood swings, irritability, impulsivity,

loss of interest, agitation, relationship difficulties.

2 We refer to the ICD-10 manual as the latter is used by the MoD Specialist Mental Health Services to diagnose and assess the mental health of service personnel (e.g., (25)).

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Furthermore, PCS are often referred to as ‘nonspecific’ as these are not strictly

associated with mTBI. For example, these have sometimes been reported to occur

prior to mTBI (14), or have been detected to a similar extent in patients with mTBI

and controls suffering from a trauma without a history of such an injury (28) also

see (29,30). Therefore, it has been argued that PCS could also stem from a variety

of mental and physical health conditions such as potential exposure to depleted

uranium (31) or acute stress response (32). Still, it is important to note that white

matter abnormalities have been detected in some mTBI patients, suggesting that

one needs to be careful when making assumptions that PCS are purely

psychological. In fact, there is evidence that in certain cases mTBI can result in

serious long-term effects (See Section 5).

3. Challenges to Classification

TBI severity is classified according to single indicators such as the Glasgow Coma

Scale (GCS), duration of post-traumatic amnesia (PTA), and duration of loss of

consciousness (LOC). For example, mTBI is traditionally diagnosed by at least one of

the following: amnesia for less than 24 hours post-injury, loss of consciousness for

30 minutes or less, GCS score between 13 and 15, as well as confusion or

disorientation and some transient neurological abnormalities (e.g., focal signs,

seizures; (14,27)). Importantly, however, research has shown that single indicators

may be influenced by factors, unrelated to TBI severity. For example, as described

by Malec et al. (33) ‘systemic or psychologic shock as well as organ system failure

and fractures associated with polytrauma can extend PTA and may affect acute

assessment of GCS and LOC’ (p. 1418). Therefore, the Mayo classification has been

developed as a more reliable system that uses only positive, objective evidence for

categorisation, rather than on lack of information in the patient’s record. According

to this classification, mTBI should be split into two subcategories – mild (probable)

and symptomatic (possible; for the full criteria of the Mayo classification please refer

to Appendix 1). The latter division accounts for the heterogeneity of mTBI that has

been acknowledged by many academics and clinicians (e.g., (1,17,34)).

Finally, another factor that further complicates the diagnosis of mTBI in military

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settings is that the latter is normally based on self-reporting of the injury in a

retrospective (See (6,14) for a discussion). Furthermore, research has demonstrated

that the temporal gap between the accident and the sufferers’ self-report could vary

considerably from research to research, and it could span between several months to

several years (6,35).Thus, the latter raises questions about the reliability of such

diagnosis. This is so as delayed self-reporting is subject to memory distortions which

could lead to erroneous reporting, underreporting or exaggeration of the symptoms.

Recently, researchers have started to recognise these problems and to encourage

the use of contemporaneous data (14).

4. Neuroimaging and Biochemical Markers of mTBI

As explained earlier, mTBI symptoms are often considered of a transient nature so

that the patient is most often not referred to undergo neuroimaging or further

examination (1). Moreover, mTBI symptoms are not always reliable indicators to

determine the patient’s recovery, as although they might look free of the initial

symptoms, the condition might have resulted in a still undiagnosed neurological

damage (See Section 5 for more details). As discussed in the previous section,

because of the considerable clinical heterogeneity within mTBI, advanced

neuroimaging and biochemical markers are needed to identify and correctly classify

mTBI, as well as to make predictions about its course.

Neurological abnormalities associated with mTBI normally remain undetected by

conventional Computed Tomography (CT) and Magnetic Resonance Imaging (MRI)

techniques (36). Thus, these have started to be discovered only recently with the

use of newer imaging methods such as Diffusion Tensor Imaging3 (DTI; (37)). DTI

relies on the principle that water diffuses differently in white matter depending on its

integrity, type of tissue, presence of barriers etc., which allows quantifying patterns

of water diffusion with white matter damage (38). Research using the technique has

shown that the most typical abnormalities associated with mTBI are traumatic axonal

3 Two other novel neuroimaging techniques to detect white matter pathology associated with mTBI are Diffusion MRI and Susceptibility-Weighted Imaging (SWI; see (1,7) for more

details).

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injury (TAI; and especially diffuse axonal injury4), and vascular injury (1).

Furthermore, the amount of discovered TAI has been found to be a good predictor of

the impairments following mTBI (7). Finally, there is also some evidence that fluid

biomarkers of neuronal, axonal and astroglial5 pathology can be used to diagnose

mTBI (41). However, cerebrospinal fluid (CSF) markers are normally preferred over

blood markers, as CSF ‘is in direct contact with the extracellular matrix in the brain,

and its composition reflects biochemical changes that occur in this organ’ ((41), p.

4).

The possible long-term consequences of mTBI and their respective markers are

discussed in the next section.

5. Possible Long-Term Effects of mTBI

Although ‘once thought to be trivial in terms of [its] consequences … there is now

substantial evidence that [mTBI] can lead to a number of neuropathological,

neurophysiological, and neurocognitive changes’ ((13), p. 310). Thus, in some cases

PCS have been discovered to last for years and lead to a permanent disability

(42,43). Therefore, it is of vital importance to acknowledge the long-term effects of

the disorder. As mentioned earlier, because of being particularly spread among

sportsmen, much of the research into mTBI comes from this population. For

example, most of what is known about the long-term effects of the condition has

been derived exactly by studying sportsmen who have sustained an mTBI. Details of

some of the most serious long-term consequences of the condition are given below,

as reported in the literature.

a) Chronic Traumatic Encephalopathy (CTE)

Chronic traumatic encephalopathy (CTE) was first identified in boxers who sustained

a repetitive head injury and later in other athletes participating in contact sports.

The disorder is associated with progressive neurological deterioration, it usually

starts in mid-life and develops years to decades following a recovery from the head

4 Diffuse axonal injury is a widespread damage to the white matter which can disrupt communication between axons. Therefore, the most common clinical outcome following diffuse axonal injury is cognitive impairment (39). 5 Astroglia are a collection of astrocytes, which are cells essential for brain homeostasis and communication between neurons and other cells (40).

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injury (37,44). CTE has a varied clinical profile, however several reports have

suggested that it commences with behavioural changes such as significant irritability

and aggression, memory loss, depression or apathy and in some cases increased

suicidality (37,44). Moreover, normally the next stage is marked by neurological

changes such as parkinsonism, gait and speech abnormalities. Furthermore,

according to several reports, in its late stage, CTE may clinically resemble

Alzheimer’s disease or dementia (37,45). A recent post-mortem cohort study of 64

athletes and 21 military veterans, who had a history of mTBI, shed more light on the

link between mTBI and CTE (37). The results revealed that 63% of the participants

in this study were diagnosed with CTE. CTE was also found to be associated with a

number of neurological abnormalities – abnormally aggregated proteins,

neurofibrillary tangles6 in the frontal neocortex, multifocal axonal varicosities7,

axonal loss and hyperphosphorylated tau pathology8 that varied depending on

severity (37). Thus, despite considered harmless, repetitive mTBI can be extremely

dangerous and in some cases lead to ‘severe and devastating long-term

consequences’ ((37) p. 62). Still, as outlined by Rosenfeld (50), more research on

the topic is required to determine the nature of the risk factors contributing to the

association between CTE and mTBI.

b) Other neurodegenerative diseases

Several studies have reported that mTBI may also increase the risk of other

neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease, as well as

speed the progression of parkinsonian signs in general (37,51,52). For instance, in

the study explained above, McKee (37) found that 16% of their mTBI patients had

Lewy body disease9, while 11% had Alzheimer’s disease. Interesting insights can

also be derived from a very recent study that focused on non-athlete civilians that

had a TBI with loss of consciousness (LOC; (51)). The research included data from

6 Neurofibrillary tangles in the front area of the brain are an accumulation of tau, a protein which is a primary marker for Alzheimer’s disease and other neurodegenerative diseases associated with abnormal clusters of protein tau (46,47). 7 Axonal varicosities are swellings which appear in along the length of an axon at the point of injury (48). 8 Hyperphosphorylated tau pathology is when there is abnormal mitosis of tau, which can result in neurofibrillary tangles and neurodegeneration (49). 9 Lewy body disease is a type of dementia, caused by Lewy body protein deposits on nerve cells which results in a decline in cognition (37).

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three longitudinal studies with a combined sample of 7130 individuals and examined

the association between TBI and a number of late-life effects, such as dementia and

Alzheimer’s disease, Parkinson’s disease, the progression of parkinsonian signs and

mild cognitive impairment. For the purposes of the present review, only the results

relevant to mTBI are discussed. It was found that TBI sufferers with a LOC of 1 hour

or less had an increased risk for developing Lewy bodies10 in the frontal and

temporal cortex of the brain. Moreover, this was also one of the types of TBI

associated with the progression of parkinsonian signs. Finally, a large proportion

(more than one third) of those who sustained a TBI with a LOC of 1 hour or less

acquired the injury early in life (when they were no older than 25 years), although

the condition only produced long-term neuropathological consequences in this group

in more severe TBI cases (with a LOC longer than 1 hour).

c) Cognitive impairment

In some cases mTBI can also lead to cognitive impairment, causing memory loss,

executive dysfunction and the slowing of one’s information processing (39,54,55).

Research has demonstrated an array of neurological abnormalities associated with

cognitive impairment in mTBI. For example, using diffusion MRI, Niogi et al. (56)

examined the microstructural white matter integrity and connectivity of mTBI

patients and matched controls. Their results illustrated damage in the attentional

and memory tracts of the brain which was associated with a deficit in the respective

cognitive domain. Furthermore, Tremblay et al. (57) compared 15 former male

university-level athletes who sustained an mTBI in early adulthood with 15 male

control athletes with no history of head injury. Importantly, the comparison took

place 30 years after the last recorded mTBI, which allowed examining whether a

relationship could be established between brain function abnormalities found in some

asymptotic athletes at young age and cognitive decline as they grow older. Tremblay

et al. (57) discovered a number of anomalies in the mTBI group such as aberrant

ventricle enlargement11, neurometabolic imbalance and lastly, cortical thinning in the

10 Lewy bodies are neuropathological deposits of protein in the brain cells associated with dementia and Parkinson’s disease (53). 11 Ventricle enlargement is often found in patients with schizophrenia and most likely indicates brain shrinkage (58).

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frontal, temporal and parietal lobes which also correlated with episodic memory12

decline in this group. Thus, it was demonstrated that mTBI can also lead to abnormal

aging marked by cognitive decline and disruption of white matter integrity.

Still it should be noted that the association between cognitive abnormality and white

matter damage in mTBI is not confirmed by all studies, which once again reflects the

heterogeneity of mTBI. To illustrate, Kinnunen et al. (55), for instance, found a

progressive increase in axial diffusivity in their mTBI sample which is a protective

factor that predicts axonal recovery. However, at the same time three of the eight

mTBI patients in the same study were discovered to have microbleeds (tiny

haemorrhages within the white matter) in the inner cerebral cortex which is a

marker of diffuse axonal injury (55).

6. Comorbidity with Psychological Conditions

Although persistent PCS are often found to co-occur with a psychological disorder, it

is difficult to reconcile which condition came first. Therefore, these have been

included in the following section, labelled as ‘comorbid’13 with (rather than resultant

from) mTBI.

a) PTSD

Academic research has consistently reported an association between persistent PCS

and PTSD in both US and UK samples (14,29,61,62). One example is a study done

on a sample of 2525 US Army soldiers who were surveyed 3 or 4 months after

returning from Iraq (61). It was found that 43.9% of those who reported an injury

involving loss of consciousness, also met the criteria for PTSD. Furthermore, when

the effects of PTSD and depression were controlled for, an mTBI episode was no

longer associated with the postconcussive symptoms reported by the soldiers, except

for headache.

b) Stress

There are many similarities between the symptoms of persistent mTBI/PCS and

12 Episodic memory involves being able to remember and recall life experiences, and is referred to as autobiographical memory (59). 13 Comorbidity refers to the co-occurrence of two or more disorders in an individual. It has important implications for identifying the aetiology and diagnostic criteria of conditions, as well as for how healthcare should be provided to see an improvement (60).

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acute stress reaction14 (ASR; (32,62–64)). According to Bryant (32), ‘there are no

reliable means to differentiate between symptoms involving impaired awareness that

are caused by severe stress or mild traumatic brain injury’ (p. 526). In support, a

very recent study on the effects of blast-related mTBI reported a significant

association between mTBI and ASR in their sample of US military members (64).

c) Depression

After PTSD, depression is the second most reported comorbid condition with mTBI,

particularly because of the attentional and memory problems identified in both

disorders (65). For instance, in the study by Hoge et al. (61) mentioned above,

22.9% of the soldiers in their sample who incurred an injury involving loss of

consciousness, also met the criteria for depression. Finally, many studies conducted

with civilians have suggested that TBI, in general, increases the risk for developing

depression (66–68).

7. The Size of the Problem – Prevalence Rates

a) US

According to the US Defense Medical Surveillance System and the Theater Medical

Data Store, about 58% of all traumatic brain injuries occur in US Army personnel,

while the remainder is evenly spread among the Navy, Marines, and Air Force (69).

An overall high prevalence15 of persistent PCS has been identified in US Armed

Forces returning from the Iraq and Afghanistan wars. Although the exact percentage

of those affected by mTBI post-deployment remains unclear, research has suggested

that this is between 15% (61) and 22% (70). Furthermore, a substantially higher

percentage of those sustaining an mTBI are combat personnel (71), as might be

expected as combat roles increase the risk of exposure to blast and therefore an

increased risk of sustaining mTBI (72).

b) UK and Canada

Much lower prevalence rates of mTBI have been reported among UK service

14 Acute Stress Reaction involves an initial state of daze, amnesia, narrowing of attention and disorientation (ICD-10; (24)). 15 Prevalence gives a measure of how widespread a particular condition is at a single point of time.

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personnel as compared to those in the US. For example, according to Rona et al.

(73) the overall prevalence for those returning from Afghanistan and Iraq is 4.4%,

rising to 9.5% for combat personnel. Furthermore, more recently Jones et al. (14)

reported an even lower yearly rate of 3.2% with no significant difference between

combat and other military personnel. Finally, a similarly low prevalence rate of mTBI

has been identified in a recent study based on the responses of 16,193 Canadian

military who were sent to Afghanistan between 2009 and 2012 (5.2%, (10,74)16.

c) Prevalence vs incidence

Importantly, it should be noted that comparing the frequency of mTBI cases among

different samples of Armed Forces is not necessarily best expressed with prevalence

proportions, as the latter do not take into account the length of deployment for each

cohort. Furthermore, Rona et al. (75) suggested that a more appropriate estimate

when cross-sectional data17 is used, would be adjusting the rates for ‘person-years’

to account for the length of deployment and therefore be able to obtain an estimate

of incidence18 instead. By applying this method to a data set of 3763 UK personnel,

who have been deployed to Iraq and Afghanistan, Rona et al. (75) identified an

mTBI incidence rate of 10.2 (per 100 person-years) in the UK Army and Marines and

9.0 (per 100 person-years) for all UK Armed Forces in the sample. Therefore,

although still lower than those in the US, these incidence rates were higher than the

prevalence rates of mTBI previously reported amongst similar UK samples. Thus,

overall comparisons between different military populations in terms of the relative

frequency of the condition should be applied with caution. As Garber et al. ((10),

p.6), suggested ‘… there is no single prevalence estimate of mTBI in a deployed

military population. This highlights the need for all militaries to estimate the risk

based on the nature and duration of the deployment.’

16 Both studies make use of the same data. 17 Cross-sectional design refers to studying the sample of interest at a single point in time. Cross-sectional data is used to provide an estimate of the prevalence of a certain outcome

(e.g., mTBI) in the study population. Longitudinal studies, on the contrary, involve following the same group of individuals over a period of time and therefore are used to provide an incidence estimate (75). 18 Incidence gives a measure of the risk of contracting a condition (i.e., how many new cases occur and how the pattern changes). Thus, to determine the incidence rate, one needs to examine the study population for a period of time.

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d) Current mTBI rates according to the MoD

Following a request by the HVRT, the Department of Defence Statistics at the MoD

revealed the number of mTBI cases in the UK Armed Forces for the period between

the 1 April 2008 and the 31 March 2016 (Reference of the request:

FOI2016/07678). The data had been collated from four datasets – the Joint Trauma

and Theatre Register (JTTR); the Neurology Rehabilitation Group at the Defence

Medical Rehabilitation Centre, Headley Court (NRG DMRC Database); mTBI Database

(maintained by the mTBI cell at DMRC Headley Court) and the Defence Medical

Information Capability Programme (DMICP).

As reported in Table 2, in the above period, 967 UK Service Personnel were identified

as having ‘a possible or definite’ mTBI, while roughly one third of those, 343, met

the official diagnostic criteria for mTBI, as described in Section 3 of the present

report. Importantly, in both occasions the cited figures represent the minimum

number of cases as in some occasions it was not possible to classify the severity of

the injury or data could not have been retrieved/was not available (See Appendix 2

for full details). Furthermore, as it could be seen from the data, most of the mTBI

cases have been reported in Army personnel (748 people with a possible or definite

mTBI) which makes 77% of the total cases; the proportions for the Royal Navy and

Royal Marines (Naval Service) and the Royal Air Force are 13% and 10%,

respectively.

Finally, when the number of cases are broken down by type of Service and yearly

period and compared to the total strength of each Service for the respective year, it

could be seen that the relative incidence of mTBI is extremely low (See Table 3).

Furthermore, the increased number of mTBI cases seen in 2009-2010 corresponds

to the high operational tempo in Iraq and Afghanistan in this period, whereas the

decreased numbers seen in later years coincide with the end of the UK operation in

Afghanistan (Operation HERRICK began 1 April 2006 and ended on 30 November

2014; (76)). Full detail of the response provided by the Department of Defence

Statistics could be found in Appendix 2.

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Table 2. UK Service Personnel Mild Traumatic Brain Injury by Service and financial

year, 1 April 2008 – 31 March 2016, Numbers1,2,3,4. Table reproduced from the

Department of Defence Statistics response to request FOI2016/07678. Please refer

to Appendix 2 for the full details.

Source: JTTR, NRG DMRC Database, mTBI Database, DMICP

1. Numbers presented are a minimum, please see Advice and Assistance for more

information.

2. Patients have been counted the first time they appear on any one of the four

datasets. If they later appear on a separate data source they have not been counted

again.

3. JTTR data was based on date of injury, the NRG data was based on date of

admittance, the mTBI data was based on date of referral and DMICP was based on

date the READ code was entered.

4. In line with JSP 200 (April 2016), and in keeping with the Office for National

Statistics Guidelines, all numbers less than five have been suppressed and presented

as ‘~’ to prevent the inadvertent disclosure of individual identities.

All Royal Navy

and Royal

Marines

Army RAF All Royal Navy

and Royal

Marines

Army RAF

All 967 126 748 93 343 52 239 52

2008-09 110 20 81 9 36 6 25 5

2009-10 201 17 174 10 41 ~ 34 ~

2010-11 158 15 132 11 36 ~ 26 ~

2011-12 124 28 85 11 40 ~ 24 ~

2012-13 105 12 84 9 39 ~ 31 ~

2013-14 90 9 70 11 21 ~ 13 ~

2014-15 83 13 55 15 53 9 32 12

2015-16 96 12 67 17 77 8 54 15

Record possible or definite mTBI

Financial Year

mTBI that met the

concussion/mTBI criteria outlined

in JSP 950 Leaflet 2-4-3

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Table 3. Incidence proportion of possible or definite mTBI per financial year.

Strength of UK Armed Forces* at the 1st of April of each respective financial year.

Financial Year

UK Forces

Strength*

a

Possible or

definite mTBI

b

Incidence

proportion of

mTBI

(b/a)x100

(%)

2008-09

192 230 110 0.057

2009-10

195 500 201 0.103

2010-11

190 240

158 0.083

2011-12

183 620 124 0.068

2012-13

174 220 105 0.060

2013-14

162 680 90 0.055

2014-15

156 590 83 0.053

2015-16

153 860

96 0.062

* Please, note that the presented totals comprise of UK Regular Forces and Gurkhas

only. This is so as the statistical reports on the total strength of the UK Armed Forces

released by the MoD prior to 2011 included ‘Full Time Reserves’ while after 2011,

these included ‘Volunteer Reserves’. Therefore, the presented totals have been

provided for comparison purposes only, these are lower than the actual totals and do

not strictly reflect all UK Service Personnel, meaning that the actual incidence

proportion of mTBI per year is even lower than the one reported.

Sources: (77,78).

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8. Current Practices in Approaching and Managing mTBI

a) In the US (Armed Forces)

mTBI is treated through early screening and intervention programs, including in-

theatre services for those in close proximity to explosion. Both the US Department

of Defense (DoD) and the Veterans Health Administration (VHA) have developed

stepped population-based screening tools. For example, the Military Acute

Concussion Evaluation (MACE) has been extensively adopted in the recent Iraq and

Afghanistan theatres of operation as a rapid, easy-to administer test, used to screen

especially for blast injury secondary to improvised explosion devices (79). MACE

consists of two parts – in the first part the patient is asked questions to determine

the historical context of the condition and the diagnosis. In the second part, their

orientation, immediate memory, concentration, and delayed recall are examined to

screen for any neurocognitive deficits that might have occurred (80). However,

despite commonly used in the military head trauma population, MACE showed poor

reliability as a screening tool for mTBI in a recent study conducted with civilians

(80). Furthermore, some have raised concerns about the sensitivity of such tools in

general (the screen misses 30%-60% of TBI cases; (40) and whether population

screening is really necessary, given the nonspecific nature of PCS (81).

b) In the UK

Armed Forces: In the UK, health treatment is instead provided only to those who

have experienced a moderate or severe TBI or exhibit persistent PCS following a

head trauma (14). Several research reports, based on UK military data, have shown

support for the latter policy. For example, based on the identified very small

incidence rate of mTBI in their sample, Jones et al. (14) advised against the

adoption of US–like in-theatre interventions, in view of the potential for inflating the

rates of symptom reporting.

General primary care and recommendations: In the UK, clinical care is usually

provided either in general practices or in emergency departments, however, patients

with mTBI often receive inconsistent advice depending on the awareness of the

practitioner. As mentioned earlier, the majority of patients diagnosed with mTBI are

not referred to a specialist which however, is recommended especially when PCS

develop (1,2). In view of the heterogeneity of the condition and the possibility of

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developing PCS, researchers have suggested that even mTBI patients might benefit

from primary survey and simultaneous resuscitation, receiving care from

interdisciplinary teams, as well as being followed up at specified intervals after the

injury (1,2). Although there is no agreed standard on the management and

treatment of mTBI, The UK National Institute of Health and Care Excellence (NICE)

has come up with guidelines on the assessment and early management of head

injury (36). However, more recently NICE started their ‘NICE Pathways’ series which

represent interactive, flowchart guides that make the information even more

accessible. These incorporate all NICE guidance, quality standards and other NICE

information, are updated on a regular basis and are easily accessible online.

Furthermore, the NICE ‘Pre-hospital management’19 and ‘Assessment in the

emergency department’20 pathways identify the conditions when a patient who has

sustained an mTBI is likely to be at risk and therefore requires further examinations

and a specialist review. For example, according to these ‘patients presenting to the

emergency department with impaired consciousness (GCS less than 15) should be

assessed immediately by a trained member of staff’ and ‘patients who return to an

emergency department within 48 hours of transfer to the community with any

persistent complaint relating to the initial head injury should be seen by or discussed

with a senior clinician experienced in head injuries, and considered for a CT scan.’

((36), p.20-21).

Guidelines for best practice in contact sports: The US National Football League

has come up with best practice guidelines for handling mTBI in contact sports. For

example, the Concussion Evaluation and Management Protocol is a procedure

guideline, designed for all Clubs that stipulates simple, easy to follow instructions

regarding the provision of educational material to players, baseline testing,

identification, evaluation, and management of the condition. Importantly, the

protocol also features a thorough list of signs and symptoms outlining when a player

19 ‘Pre-hospital management’ can be accessed at http://pathways.nice.org.uk/pathways/head-injury/pre-hospital-management-for-patients-with-head-injury. 20 ‘Assessment in the emergency department’ can be accessed at http://pathways.nice.org.uk/pathways/head-injury/assessment-in-the-emergency-department-for-patients-with-head-injury.

17

should be removed from play for an acute evaluation, as well as clear return to play

rules. Additionally, the US Centers for Disease Control and Prevention publish

guidelines, specifically designed for young athletes of different age groups, parents,

coaches and sports officials (82). Despite the latter, best practice clinical pathways

from injury to return to play have generally been difficult access and find in the UK

and only recently such have started to emerge. For example, the Scottish Sport

Concussion Guidelines for the general public and participants in grassroots sports

were only launched in 2015 (83). Finally, the need for ‘a cross-sports consensus on

the recognition and management of concussion with consistency across all sporting

bodies and in conjunction with education and healthcare systems’ has recently been

recognised by the UK Faculty of Sport and Exercise Medicine (FSEM, (83)). The

FSEM, together with UK National Sporting Bodies and Medical Royal Colleges are

currently working towards creating common guidelines for consistent best practice

for handling mTBI.

Educational therapy: The evidence suggests that participation in early educational

intervention programs can be particularly beneficial for alleviating PCS following

mTBI. In a review of the literature on non-surgical interventions for mTBI, (84)

found that simple educational interventions, where patients are reassured about the

recovery and are encouraged to slowly return to normal activity, were more effective

than an intensive intervention. Moreover, administering even a single educational

session to patients with mTBI was found to be as effective as more in-depth

assessment and therapy (See (84)). Furthermore, patient education is also at the

basis of the rehabilitation programme, devised by the UK Defence Medical

Rehabilitation Centre (DMRC) Headley Court. There is evidence that the programme,

consisting of four phases, including psychological treatment for more persistent

cases, could be beneficial for helping military personnel to regain their stability after

the injury (85). Finally, there is evidence that educational therapy could be effective

for reducing PCS even if done via telephone (86,87).

Psychological therapy: Considering the significant associations between mTBI and

other disorders such as PTSD and depression, several authors have proposed that

psychological treatment could alleviate persistent PCS by addressing the comorbid

conditions PCS co-occurs with (63,65,85). Some of these approaches include

18

modified cognitive behavioural therapy (CBT) and cognitive restructuring and

behavioural activation. Research has suggested that modified cognitive behavioural

therapy (CBT), in particular, might be successful in addressing persistent PCS

following mTBI (88,89). Furthermore, CBT has been recommended as a therapeutic

method by the US Department of Veterans Affairs and the DoD (90).

Medication: Research has indicated that certain drugs can have a positive effect on

mTBI. For example, methylphenidate, which is also used for the treatment of ADHD

in children, has been shown to alleviate mental fatigue by increasing the levels of

dopamine and noradrenalin in the body (91). Furthermore, there is evidence that it

can improve patients’ impaired cognitive function (information processing speed,

working memory and attention) following TBI (92,93), including mTBI (91).

Moreover, according to findings from animal studies, methylphenidate can also have

a positive psychological impact by reducing aggression and promoting psychosocial

function (See (94) for a meta-analysis). Finally, in the context of military setting,

acetylcysteine has proven efficacious in reducing the constellation of PCS and

cognitive dysfunction symptoms in 81 US Service Personnel who sustained a blast-

related mTBI (95). Furthermore, no side effects were reported in this study seven

days after the administration of the drug. Acetylcysteine is known for its

neuroprotective21 effects in ‘animal ischemia-reperfusion22 cerebral stroke models,

rodent closed head trauma model, sensory nerve axotomy23 model and inner ear

neuronal death after noise exposure’ ((95), p. 2).

9. Conclusion

The aim of this report was to provide a review of mTBI in military personnel by

drawing information from key research studies, government reports and relevant

literature on mTBI in contact sports. Although identified as the ‘signature injury’ of

the recent Afghanistan and Iraq conflicts, mTBI seems to vary considerably in

prevalence among UK and US service personnel. There is still no agreement on the

21 Neuroprotective refers to helping to reduce the rate of neuronal loss. 22 Ischemia-reperfusion is tissue damage, caused by restriction of blood flow to the heart. 23 Axotomy refers to the cutting of the axon.

19

classification and the aetiology of the disorder, which most likely stems from the

existent heterogeneity within the condition. Furthermore, despite being characterised

by non-specific postconcussive symptoms that can manifest even in the absence of a

traumatic head injury, in a minority of cases mTBI results in a serious disability,

marked by clear psychical abnormalities. Future work should focus on identifying

optimal strategies to bridge the gaps in the management and treatment of mTBI;

how much follow up is needed to detect PCS and whether more serious long-term

effects are likely to develop; as well as on identifying reliable markers to distinguish

between the different subcategories within the condition.

20

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32

Appendix

2

Appendix 1

Table 1. The Mayo TBI Severity Classification System (taken from (33)).

A. Classify as Moderate-Severe (Definite) TBI if one or

more of the following criteria apply:

1. Death due to this TBI

2. Loss of consciousness of 30 minutes or more

3. Post-traumatic anterograde amnesia of 24 hours or

more

4. Worst Glasgow Coma Scale full score in first 24 hours

<13 (unless invalidated upon review, e.g., attributable

to intoxication, sedation, systemic shock)

5. One or more of the following present:

• Intracerebral hematoma

• Subdural hematoma

• Epidural hematoma

• Cerebral contusion

• Hemorrhagic contusion

• Penetrating TBI (dura penetrated)

• Subarachnoid hemorrhage

• Brain Stem Injury

B. If none of Criteria A apply, classify as Mild (Probable)

TBI if one or more of the following criteria apply:

1. Loss of consciousness of momentary to less than 30

minutes

2. Post-traumatic anterograde amnesia of momentary to

less than 24 hours

3. Depressed, basilar or linear skull fracture (dura intact)

2

C. If none of Criteria A or B apply, classify as Symptomatic

(Possible) TBI if one or more of the following symptoms

are present:

• Blurred vision

• Confusion (mental state changes)

• Dazed

• Dizziness

• Focal neurologic symptoms

• Headache

• Nausea

3

Appendix 2

Defence Statistics (Health)

Ministry of Defence

Oak 0 West (#6028)

Abbey Wood North

Bristol BS34 8JH

United Kingdom

Telephone

[MOD]:

Facsimile

[MOD]:

E-mail:

+44 (0)30679 84423

+44 (0)1179 319634

DefStrat-Stat-Health-PQ-

FOI@mod.uk

Reference: FOI2016/07678

SilviyaDoneva@kingedwardvii.co.uk

4

28 September 2016

Dear Dr Doneva,

Thank you for your email of 31 August 2016 requesting the following

information:

“I am interested in mTBI statistics and more specifically the percentage of

mTBI cases in the UK Armed Forces (Navy, Air Force and Army), ideally for

the period between 2001 and 2016, in years:

2001/2002

2002/2003

2003/2004

2004/2005

2005/2006

2006/2007

2007/2008

2008/2009

5

2009/2010

2010/2011

2011/2012

2012/2013

2013/2014

2014/2015

2015/2016

However, if not possible for as many years in that period as possible”.

I am treating your correspondence as a request for information under the

Freedom of Information Act 2000.

A search for the information has now been completed within the Ministry of

Defence, and I can confirm that the information in scope of your request is

held by the MOD.

However, I have to advise you that we will not be able to fully answer your

request without exceeding the appropriate limit. This is because to locate,

retrieve and extract information in scope of your request, specifically relating

6

to identifying the number of personnel who had a Mild Traumatic Brain Injury

(mTBI) prior to 2008/09 and to identify if the injuries sustained were mild or

moderate/severe would exceed the cost of compliance limit.

Section 12 of the Act makes provision for public authorities to refuse

requests for information where the cost of dealing with them would exceed

the appropriate limit, which for central government is set at £600. This

represents the estimated cost of one person spending 3.5 working days in

determining whether the department holds the information, and locating,

retrieving and extracting it.

In your request you asked the MOD to provide as many years of information

as possible in order to bring the cost of compliance for your request under

the limit. Please find the information you requested below for the time period

1 April 2008 to 31 March 2016.

Section 40(2) has been applied to some of the information in order to protect

personal information as governed by the Data Protection Act 1998. This is

also in line with Joint Service Publication 200 (JSP) in which numbers fewer

than five are suppressed in order to reduce the possible inadvertent

disclosure of individual identities. Section 40 is an absolute exemption and

there is therefore no requirement to consider the public interest in making a

decision to withhold the information.

7

Between 1 April 2008 and 31 March 2016, a minimum of 967 UK Service

Personnel had a record of having a possible or definite mild traumatic brain

injury (mTBI). Of these, a minimum of 343 met the concussion/mTBI criteria

outlined in JSP 950 Leaflet 2-4-3 :

Patients with concussion/mTBI can present to medical personnel with a

variety of symptoms which normally manifest immediately following an

event. Whilst most resolve quickly within minutes to hours some may persist

longer. To make a diagnosis of concussion/mTBI all three of the following

criteria must be met:

a. A history of related head injury or involvement in a blast.

b. Glasgow Coma Scale (GCS) no lower than 13 at thirty minutes

post-injury.

c. One or more of the following:

i. Alteration of consciousness (AOC) / mental state - this may

present as a variety of transient physical, cognitive or

emotional symptoms. Commonly this will include confusion,

disorientation, feeling or looking dazed and difficulty

concentrating.

ii. Loss of consciousness (LOC) - for no more than 30 minutes

duration post-injury.

iii. Post-traumatic amnesia (PTA) - for no more than 24 hours

duration post-injury.

8

iv. Transient neurological abnormalities - such as focal signs or

seizures.

The number of personnel with a record of an mTBI were a minimum because:

• There were 97 personnel with a record of a traumatic brain injury

where it was not possible from the electronic data held to classify

the injury into mild, moderate and severe.

• If information was entered as free text in the electronic patient

record then it is not available in the data warehouse and will not be

retrieved using the search for mTBI.

The number of personnel with a record of an mTBI who met the

concussion/mTBI criteria outlined in JSP 950 Leaflet 2-4-3 were a minimum

as not all of the data sources used within this response contained the level of

detail required to identify if the criteria had been met.

Table 1 presents the number of UK Service Personnel who had a

record of having a possible or definite mild traumatic brain injury

(mTBI) and of these the number that met the concussion/mTBI

criteria outlined in JSP 950 Leaflet 2-4-3. Service personnel are

included once in the year where the mTBI was first identified in one

of the four datasets (see Advice and Assistance section).

Table 1: UK Service Personnel Mild Traumatic Brain Injury by

9

Service and financial year, 1 April 2008 – 31 March 2016,

Numbers1,2,3,4

Source: JTTR, NRG DMRC Database, mTBI Database, DMICP

1. Numbers presented are a minimum, please see Advice and Assistance for more

information.

2. Patients have been counted the first time they appear on any one of the four datasets. If

they later appear on a separate data source they have not been counted again.

3. JTTR data was based on date of injury, the NRG data was based on date of admittance, the

mTBI data was based on date of referral and DMICP was based on date the READ code was

entered.

4. In line with JSP 200 (April 2016), and in keeping with the Office for National Statistics

Guidelines, all numbers less than five have been suppressed and presented as ‘~’ to

prevent the inadvertent disclosure of individual identities.

Under Section 16 (Advice and Assistance) you may find it helpful to note the

All Royal Navy

and Royal

Marines

Army RAF All Royal Navy

and Royal

Marines

Army RAF

All 967 126 748 93 343 52 239 52

2008-09 110 20 81 9 36 6 25 5

2009-10 201 17 174 10 41 ~ 34 ~

2010-11 158 15 132 11 36 ~ 26 ~

2011-12 124 28 85 11 40 ~ 24 ~

2012-13 105 12 84 9 39 ~ 31 ~

2013-14 90 9 70 11 21 ~ 13 ~

2014-15 83 13 55 15 53 9 32 12

2015-16 96 12 67 17 77 8 54 15

Record possible or definite mTBI

Financial Year

mTBI that met the

concussion/mTBI criteria outlined

in JSP 950 Leaflet 2-4-3

10

following:

The information contained within this response has been compiled from four

data sources:

a. Data held on the Military Audit of Clinical Effectiveness (MACE)

database on the Joint Trauma and Theatre Register (JTTR).

b. Data held by the Neurology Rehabilitation Group (NRG) at the Defence

Medical Rehabilitation Centre (DMRC), Headley Court.

c. Data held on the mTBI database which is maintained by the mTBI cell

at DMRC Headley Court.

d. Defence Medical Information Capability Programme (DMICP) has a

centralised data warehouse of coded information. It is the source of

electronic, integrated healthcare records for primary healthcare and

some MOD specialist care providers.

Personnel have been counted once overall and in Table 1 in the year of the

earliest record of an mTBI. Please note that these are live databases. This

means that occasionally patient records can be updated which may change

the figures presented in this response.

Please note the inclusion of patients who have subsequently died. Patients

may sustain other injuries alongside their mTBI/TBI and providing that the

patients were alive at the point that they left the Royal Centre of Defence

Medicine (RCDM) they have been included in the response whether or not

11

they have subsequently died of connected or unconnected causes.

JTTR

An extract of the JTTR data was taken in September 2016 and was based on

the following criteria: surviving UK Service personnel who sustained an injury

that contained the body region ‘head’. The list of Service personnel with

Abbreviated Injury Scale codes that would indicate they may have a TBI were

reviewed by the Clinical Information Exploitation Team who advised on their

inclusion in the TBI statistics.

DMICP

An extract of data held on DMICP deployed was taken in September and a

search for the following TBI Read codes was conducted:

• DMSRC 132 – ‘Traumatic brain injury’

• DMSRC 133 – ‘Mild traumatic brain injury’ (as indicated in JSP 950

Leaflet 2-4-3)

The information presented in this response have been structured to release

information into the public domain in a way that contributes to the MOD

accountability to the British public but which doesn’t risk breaching

individual’s rights to medical confidentiality. In line with JSP 200 (April

2016), and in keeping with the Office for National Statistics Guidelines, all

12

numbers less than five have been suppressed and presented as ‘~’ to

prevent the inadvertent disclosure of individual identities. Where there is only

one cell in a row or column that is less than five, the next smallest number

(or numbers where there are tied values) has also been suppressed so that

numbers cannot simply be derived from totals.

If you are not satisfied with this response or you wish to complain about any

aspect of the handling of your request, then you should contact me in the

first instance. If informal resolution is not possible and you are still

dissatisfied then you may apply for an independent internal review by

contacting the Information Rights Compliance team, 2nd Floor, MOD Main

Building, Whitehall, SW1A 2HB (e-mail CIO-FOI-IR@mod.uk). Please note

that any request for an internal review must be made within 40 working days

of the date on which the attempt to reach informal resolution has come to an

end.

If you remain dissatisfied following an internal review, you may take your

complaint to the Information Commissioner under the provisions of Section

50 of the Freedom of Information Act. Please note that the Information

Commissioner will not investigate your case until the MOD internal review

process has been completed. Further details of the role and powers of the

Information Commissioner can be found on the Commissioner's website,

http://www.ico.gov.uk.

13

I hope this is helpful.

Yours sincerely

Defence Statistics (Health) Head (B1)