A middle-aged lady had her hair washed seven times (this much because the stylist was trying to get the colouring right), while leaning back over the edge of the sink.
Many mechanisms and factors might lead to a ‘vascular event’ in this situation, potentially causing a stroke.
What do we mean by a vascular event? Well, the vertebral arteries (which connect the aorta’s freshly oxygenated blood to the base of the brain) have to wind their way up through the vertebrae of the neck and then loop – in quite an odd way – around the top vertebrae before going up into the brain. See this diagram.
Any direct pressure on the artery – especially likely to happen at this loop level – can cause a reflex contraction of the muscular coat of the artery. Temporary stress like this won’t usually cause a problem – perhaps just momentary dizziness?
But what if this pressure combined with excessive stretching, torsion or abrasion? This might just happen when the neck twists and tightens around the artery.
It’s all probably a bit more likely if there is weak muscular control over the neck (a common problem in our current office lifestyle) and if there is any degenerative change in the neck due to trauma or age.
A small tear – which can sometimes lead to a dissection – in the inner muscular coat of the artery can, apart from causing pain, potentially rupture into the internal space of the artery where the high-pressure blood flows. A stroke might just develop from this – generally after some delay (at least a few hours).
The moral of the story? Always have your hair washed leaning forward over the sink. Never backwards.
Important: the risks of this are still very low. So please don’t worry about going to hairdressers in the slightest! But a very tiny risk multiplied by such a potentially serious outcome requires awareness and understanding.