17/03/2015 13:26 GMT | Updated 17/05/2015 06:12 BST

Subdural Haematoma or a Trip to 'Planet Zembar'

I am often in my own world of dreams and daydreams. I appear to be engaging in conversations when, in fact, I'm somewhere else. My wife, Anne Aylor, recognised this long ago. She coined a phrase for it. She says I'm on the Planet Zembar.

In late November 2014 I journeyed there for an extended visit. Strange things were happening. I'd look at my computer keyboard and forget how to type. Use my mobile phone to exit the tube instead of my travel card. What I had was a bleed on the brain and I survived only because of surgery. (Thank God for the Neurological Hospital at Queen Square, London and for the NHS)

My diagnosis was not a stroke or an aneurysm. It was a condition I'd never heard of: subdural haematoma. (US spelling is hematoma) There are two types, acute and chronic. The most serious, the former, is caused by trauma when rapid bleeding fills the area between the outer layer of the brain - the meninges - and the brain itself. This occurs as a result of severe concussion such as car or cycle accidents or smashing against a tree on the ski slopes. We have all heard about Michael Schumacher and Natasha Richardson.

You don't have to be a racing driver, skier or cyclist to get subdural haematomas. It can occur after a minor head injury, especially among the elderly. I am about to turn 70 so I am now in the category of the Grey Panthers. With all haematomas, small veins between the surface of the brain and its outer covering - the dura - stretch and tear and blood collects. The dura is a lining of tissue immediately below the skull that encloses the brain. It is tough and has been compared to a piece of kevlar.

This bleed presses down on the brain through the dura. There is a competition between blood and brain and when blood wins, the brain is moved off-centre. In severe cases, the lower part of the brain can be pushed where the spinal cord is attached. This is very dangerous because the brain stem is where the impulse to breathe is located.

As we get older, we shrink, and this includes our brain which makes it more susceptible to haematomas because the veins are stretched. But there still has to be a cause and, in hospital, I was repeatedly asked if I had recently bashed my head. We live in a small flat and our bedroom has a sloping ceiling so I guess I can blame Zembar. But another cause is alcohol, which thins the blood and therefore allows ease of bleeding. I have given up on the booze.

If a person exhibits any of the known symptoms: drowsiness, confusion, personality changes, speech problems, impaired vision, vomiting- they need to get to A&E and, like me, have a CT (brain scan).

If an operation is then required the blood has to be drained from the skull.

Douglas Katz, assistant Professor of Neurology at Boston School of Medicine, has said "the person may appear fine initially because the mass of blood in the head is expanding and there isn't too much pressure on the brain yet." He refers to this as 'Talk and Die' syndrome. Others call it 'Walk and Die'.

I was doing both at the time I was advised to get to A&E quickly. You can read about my experience in my soon-to-be published memoir, Left Field.

I am trying hard not to take any more trips to Planet Zembar.