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CONCUSSION; Where are we now?
- Dec 15, 2022
- Latest Journal
Mr M J Potts, Consultant Neuro ophthalmologist – Bristol
The awareness of concussion has come a long way in the past decade. We are much better at recognising it. We have some tools for measuring it and we are more aware of its potential for long term damage and injury. Preventing it is more difficult and we are developing guidelines in sport and other fields to recognise and manage it; so as to prevent long term damage.
Some people are more susceptible to it and genetics and long term research may help explain this. We recognise unconsciousness is not obligatory for its occurrence merely a marker of potential risk.
There are many definitions of concussion but largely a direct or indirect blow to the head results in initial temporary loss of orientation (only 25% may have actual loss of consciousness) with disturbed vision and balance. Concussion only becomes obvious after 10 minutes which is why players leave the field for a HIA (Head Injury Assessment) tests.
If concussion is confirmed by HIA assessment then individual and personalized guidelines come into play for management and return to activities.
Long term and/or recurrent concussion results in loss of function in 4 domains; Cognition, Physical malaise and headaches, sleep changes and mood changes.
The visual system remains a highly sensitive system with which to detect concussion. Why? ; well because over half the brain pathways! are directly or indirectly connected to the visual system. 80% of patients have visual or vestibulo ocular symptoms. Eye movements are affected in a high (30% to 60%) proportion and/or complaints of blurred vision, double vision and photophobia.
Vestibular and vestibulo ocular symptoms are also commonly affected. Most symptoms resolve in 1 – 3 weeks with rest but some will persist with disabling symptoms. A second concussion during the early recovery is very bad especially in the first 10 days.
Testing for concussion has evolved; early tests of rapid number naming were 86% sensitive and 90% specific, they have evolved to rapid word and picture naming. (Maddocks Questions).
Immediate examination of vision and eye movements is still often used in the field. (I suggest a picture here of a rugby player recovering from a head injury with the medics attending and using their finger to perform eye movement testing).
We have developed better more sensitive HIA tests both at the scene and in the immediate post injury examination. There are now national and sports specific guidelines for the management and return to activity in place.
Long term recurrent episodes result in Chronic Traumatic Encephalopathy (CTE) and boxers have been shown to have reduced Retinal Nerve fibre layer thickness although it is not seen after 1 concussion.
We have some treatment options; largely around preventing recurrence especially early after the first injury. Vitamins B complexes may help. Guidelines for the safe return to activities are in place for both amateur and professional sports. We now are aware that 3 or more concussions is very ill advised and may be career ending.
New detection techniques including gumshield accelerometers and saliva or blood based shock proteins are being trialled.
Medico-legally there are more cases being pursued due to the increased awareness and assessment. However, it is recognized that there are some challenging issues here. Most of the assessment techniques are subjective tests making them vulnerable to bias and variable reproduceability.
Individual susceptibility to concussion is a factor we do not fully understand although probably will have a genetic component. It has been long known and recognised that the motivation to recover from concussion is another factor affecting long term outcomes. How and why Valantino Rossi was able to crash at such high speeds over such a long period with such a high risk of concussion and yet be able to jump back on his bike with ‘rubber like’ enthusiasm is amazing. Unfortunately, Marc Marquez, a much younger fellow Moto GP rider, has been less fortunate and has recently succumbed to recurrent double vision as a complication of his recurrent crashes.
The final problem for medico-legal aspects of concussion comes in proving Causation. Many of the 1960’s and 1970’s football and rugby players now affected by Chronic Traumatic Encephalopathy now considering claims for concussion after effects also drank prodigiously and smoked heavily making the assessment of Causation problematic. Assessment and guidelines were not in place then either.
No doubt “Concussion” will continue to evolve and we will begin to have some more answers to these complex questions, and especially to the genetic predisposition components.
