EWJ Dec 2023 - Journal - Page 56
practice but there has always been difficulty in
establishing exactly what symptoms are referred to.
Since the revision of the major diagnostic taxonomies,
it no longer exists as a diagnosis.
a claimant fulfils criteria for MTBI or not is not
particularly relevant; persistent symptoms are likely to be
functional, whether there has been an insult directly to the
head or not" (2021, p.3).
DSM-V (May 2013 & TR version March 2022,
American Psychiatric Association)
Post-concussion syndrome was considered to be
a controversial and (scientifically) poorly defined entity. PCS was used by clinicians to describe and refer
to all sorts of different symptoms and presentations.
The DSM-IV criteria for PCS were for research use,
not clinical use, and were never generally accepted.
DSM-V, therefore, dropped the diagnostic construct
and indicated that persistent symptoms after a concussion should lead to consideration of neurocognitive impairment, somatic symptom disorder, or
non-psychiatric causes.
What is the evidence for long-term or
permanent consequences of MTBI?
Carroll et al (2014) review the literature and conclude
that complete recovery may take six months or even
up to a year but that full recovery would be expected.
However, other researchers (Dean et al, 2012;
McInnes et al, 2017; Nelson et al, 2019;
and, Machamer et al, 2022) all attempt build a case
for incomplete recovery up to and over a year after
MTBI. But, there are several issues to consider:
1. The term MTBI is an over-inclusive descriptor
which includes those who did not lose consciousness
after a bump on the head and have clear CT and
MRI scans, through to those who lost consciousness
and have positive neuroradiological evidence of underlying brain injury: "one should consider subgroups of
patients likely to vary in prognosis" (Nelson et al
2019 p.1050)
ICD-11 (World Health Organisation, January 2022)
What was previously referred to as PCS is now
classified as "mild neurocognitive disorder due to
TBI". There needs to be less than one month between
injury and symptom onset and the symptoms should
not be sufficiently severe to significantly interfere
with independence or activities of daily living.
2. Most research or review studies have small sample
sizes (eg: Dean et al, 2015, claim evidence of permanent white and grey matter changes after MTBI
based on a sample size of 16).
What is the evidence for long-term or permanent
consequences of MTBI?
There are researchers and clinicians who are seeking
the "holy grail" of pathophysiological evidence within
the brain to explain those with MTBI who report
persistent symptoms for months or even years after
injury – often in the face of no biological evidence
of injury. They refer to published evidence of
blood biomarkers (inflammatory markers; tau proteins, neurofilament light – the latter is an axonal protein) in support of this position. However, as recently
as 2022, Mayer & Quinn critically examined the
strengths and limitations of neuroimaging for establishing TBI related microstructural changes, neuroinflammation, proteinopathies, blood-brain barrier
damage and disruptions in cellular signalling. They
concluded that, “neuroimaging biomarkers do not yet
exist for the definitive in vivo diagnosis of cellular
pathology”(p.459). Rajesh et al (2023) call for further
research into the potential role of biomarkers in
prognosis following head injury.
3. Many studies use self-report measures such
as the Rivermead Postconcussion Questionaire (RP
Q) to positively diagnose MTBI yet it has weak content
and construct validity. The RPQ lists symptoms which
as non-specific such that a person with a chronic pain
condition or an orthopaedic injury who has never
sustained a head injury would score positively for
symptoms of post-concussion.
4. Where comprehensive neuropsychological testing
takes place, many commentators are unaware that
inter-test scatter of scores occurs in the normal
(healthy) population. Iverson & Gaetz (in Lovell et al,
2004) remind researchers that the more tests that are
administered, the greater the probability that an individual will score in the “abnormal” range for one or
more scores, even in the absence of a brain injury. This
is a necessary caution as it avoids one pathologizing
what is essentially a normal test profile.
The Lancet supports this position and states that:
"when compared with more severe TBI, biomarkers were less
predictive of outcomes in mild TBI and of incomplete recovery overall" (2022, p.1025). Other researchers are also
unconvinced. Huovinen et al, (2021) found that, “in
MTBI, traumatic microbleeds do not seem to be a significant
prognostic factors of RTW (return to work)”
5. McInnes et al (2017) argued that half the individuals with a diagnosis of MTBI have cognitive impairments on formal neuropsychological testing at 3, 6 or
12 months post-injury…BUT Iverson et al (2019)
thoroughly debunked this paper concluding that, the
impact of MTBI is undetectable on testing at 3 months
post injury also arguing that McInnes et al “has the potential to misinform scientists, clinicians and the
public…Clinicians who review and accept the findings of
McInnes et al will be misinformed” (p.13).
Those who argue for long-term consequences of
MTBI suggest that there is a need for increasingly sophisticated brain imaging, suggesting that they just
need to look harder and they will find the biological
basis of perpetuating symptoms following such injuries. Bunnage had urged caution in that such a link
has yet to be established, "to what extent (imaging abnormalities) can actually explain the disability experienced
by patients" (2013, p.72) even where they exist. More
In summary, there is no established evidence of
objective, measurable, long-term adverse cognitive
effects in a single MTBI.
So, what about Post Concussion Syndrome?
This term used to be used frequently in clinical
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