As soon as a stroke strikes within minutes brain cells – neurons and glial cells – begin to die; each second costs as many as 32,000 neuron cells, 230 million synapses, and 200 meters of axonal fibers. In terms of minutes, each passing minute costs 1.9 million neuron cells, 13.8 billion synapses, and 12 kilometers of axonal fibers (Saver J.L. 2005).
So, every second
“Time is Brain”, but only as a general rule
As far back as in 1993, Dr. Camilo R. Gomez coined this exhortation – “Time is Brain” – in an editorial to the Journal of Stroke and Cerebrovascular Diseases.
Wait; there is a caveat.
In 2018, Dr. Gomez updated his “Time is Brain” slogan!
That brain cells’ dying speed is not linear. It depends on the affected person’s collateral system. What does that mean? We all have a backup blood supply mechanism, just in case. When the main supply route blocks, our alternate support system gets activated. We still do not know how wide this mechanism operates. What we do know is that it’s spread varies from person to person.
In other words, while acknowledging that the “Tims is Brain” is still a valid slogan, we still proceed to act on the F.A.S.T. even the golden hour is elapsed.
The critical time of no return
How long neurons can survive without blood?
This is a very important question I had when I was writing this post. As far back as 1981, Jones and a team of researchers attempted to find an answer to this question using monkeys. They found no irreversible damage when the blood supply was restored within 30 minutes (Jones et al. 1981).
There was another interesting finding.
When the blood supply was not completely blocked out – only reduced to 12 – 18ml/100g/min (mild-moderate ischemia) – even after 2 – 3 hours, the affected cells survived! That means only when the blood supply reduced to less than 10-12ml/100g/min, the damage became irreversible (Jones et al. 1981).
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Within the first 3 – 8 days after a stroke, the affected area swells more than the volume of this area. Then, re-organisation and retraction remove the dead tissues resulting in a volume smaller than the pre-affected brain area within the next 2 weeks to 3 months time (Saver J.L. 2005).