07/01/2023
CONCUSSION - Part 2 🧠
Concussions are a traumatic brain injury caused by 2 primary mechanisms.
1.) A neuronal shear force, in the midbrain, cerebellum or basal ganglia etc. This is where our cortex accelerates on a stationery midbrain.
2.) A coup, contrecoup injury created from direct impact of the brain on the inside of the skull .
In addition to these 2 mechanisms, often a secondary ischaemic penumbra can occur, which is the area around the affected brain tissue that is also damaged by the acute inflammatory response.
The pathophysiology of concussion is one of diffuse axonal depolarisation of multiple anatomically neighboring axons, in turn leaving neural networks temporarily disrupted. ( In layman’s terms: a cellular network outage - or in South African terms: load shedding to a certain area of the brain! 😂🙃)
This abrupt mass depolarisation leaves the brain in a large metabolic deficit, which normalises a lot later than symptom resolution. This partly explains why a 2nd concusssion shortly following the 1st is much slower to recover, and emphasises the need to have time out after a concussion. **Patients with concussion will present with slower reaction rates and lower cerebral blood flow, especially in the association centers of the brain, until full physiological recovery, which is often months post incident**
so how do we identify concussion?
Most of us would expect to witness a head clash, bad fall, collision etc. However, as we now know, axonal shear is also a common mechanism. So for this, we need to include any sudden, unexpected rapid deceleration type injury such as whiplash.
The common symptoms we need to be looking out for are indicated in the table below.
Knowing that there are subtypes of concussion is very useful, as it allows one to know what type of activity may bring on the symptoms, and where you should focus your rehab.
Remember - you don’t need to test for everything. Just LISTEN to what the patient is telling you and let their subjective experience guide you.
I know this all sounds quite scary 🙃 - but concussion is often not taken seriously enough and then this leads to long term medical and performance issues. So on a more cheerful note, I’ll do a part 3 to look at recovery success, with proper rehab measures put in place.
