How a dip in the sea wiped out my memory

DR MICHAEL MOSLEY reveals a frightening drama last weekend that left his wife fearing he’d had a stroke

LAST weekend my wife Clare and I went to stay with my older brother John, who lives by the coast in Cornwall.

The weather was terrible. But, as readers of my regular Mail on Sunday column may remember, I enjoy swimming in the sea as often as possible, not least because of the health

benefits. And so – despite it being cold and also raining – Clare and I decided we’d go for a dip in the ocean.

We’re well used to it, but after swimming around for a few minutes, we reckoned it was too chilly even for us – and challenged each other to a race back

to the shore. I remember thinking: ‘I am definitely going to be able to beat Clare to the land.’ And then it all went blank.

The next thing I remember is being in A&E at hospital in Truro, with Clare sitting beside me looking extremely concerned.

As we waited to be seen, she told me that after I emerged from the water, I looked perplexed.

I was not particularly distressed and in many ways appeared to be completely normal.

I was able to talk but apparently I kept asking her the same two questions over and over again: ‘Is it 2017?’ and ‘Did I pass out?’

I also kept reminding myself, out loud, that I had four children, and saying their names, as though I was frightened I would otherwise forget them. For obvious reasons, this alarmed her. With my brother’s help, Clare had got me dressed and drove me straight to hospital.

It was in the A& E department about two hours after the swim that my memory started to slowly come back and I became aware of my surroundings.

CLARE, who is a GP, was obviously very worried that I might have had a mini-stroke – what is known as a transient ischaemic attack, or TIA. This is when the blood flow is temporarily cut off to an area of the brain – usually the result of a blood clot that has formed elsewhere in the body and travelled to the neck, causing a blockage.

The disruption results in a lack of oxygen to the brain and this can lead to sudden symptoms that are similar to a stroke, such as problems with speech and vision, and numbness or weakness in the face, arms and legs.

A TIA doesn’t last as long as a stroke and its effects can often last only a few minutes or hours and fully resolve themselves within 24 hours.

But it’s a warning shot: a TIA means you are at high risk of a full-blown stroke. Strangely enough, I wasn’t that worried.

In fact, as we sat there, I told Clare my main concern was that going into hospital in the early weeks of August wasn’t a great idea, as this is when junior doctors start their new jobs.

When I was at medical school, we called it ‘the killing season’ – and studies have since shown, statistically, that patients may be slightly more likely to die if they are admitted to hospital in the first week of August than in the weeks before.

The fact that I could remember something I’d learnt at medical school was, I suppose, a reassuring sign.

Fortunately, I was soon seen by a young doctor who clearly knew what she was doing.

She did a full neurological examination, which consists of testing things such as co-ordination and grip strength.

I didn’t have any obvious signs of physical or facial weakness, nor was my speech slurred – both telltale signs of a TIA and a stroke.

By this point I was lucid and the only thing that was obviously wrong with me was the fact that I had no memory of how I’d got there, or what had happened to me.

Puzzled, the junior doctor went off to fetch a more senior colleague. He did a further examination and gave me the good news that whatever was wrong with

me, I had not had a stroke or epileptic attack.

Instead he said that I had almost certainly experienced something called transient global amnesia, and that it was brought on by coldwater swimming.

He said it was like a migraine attack, and although my memory had been badly affected, he fully expected it to return to normal within 24 hours. BACK in t he car on our way home, as anyone would, I immediately started to Google my new diagnosis. As the consultant had explained, although it is very scary, global ( meaning total) transient (meaning that it passes) amnesia ( the medical term for total or partial memory loss) also appears to be entirely benign.

It is rare – affecting about one in 10,000 people in the UK every year – and it typically happens to people over the age of 50.

The average age that someone has an attack is 62, I discovered, which happens to be my age.

People who experience this kind of memory loss don’t normally have high blood pressure or high cholesterol – both of which are major risk factors for strokes. Nor is the condition linked to a head injury, which could trigger epilepsy. In fact, the only thing it is associated with is a history of migraine attacks, which I have sometimes suffered.

The most common triggers of transient global amnesia are coldwater swimming, vigorous exercise, sexual intercourse or being under extreme stress.

Later I asked Dr Paul Jarman, a consultant neurologist at the National Hospital for Neurology and Neurosurgery, London: why?

He told me patients have actually been filmed in a brain scanner during such an episode.

So doctors know it’s due to a swelling in the area of the brain responsible for short-term memory, the hippocampus.

And this swelling can be caused by a certain type of breathing – known as valsalva maneuver, essentially holding your breath while trying to forcefully exhale (hence the association with swimming in very cold water).

‘ This kind of st rain rapidly increases the blood pressure in the chest, which can force the circulation to momentarily move in the wrong direction, up through the veins in the neck,’ he explained,

KNOW THE TRIGGERS – HEAT, COLD AND SEX