Sunday, 18 November 2012

When it's raining? .........

I had the strangest experience last evening. It had been a funny sort of day for weather, a mixture of sunshine and light showers with a brisk breeze. Around 9pm I left home in the car to meet John from transport bringing him back from a 3-day golfing trip. It was twilight and I parked the car and began what was to be quite a long wait. I started to wish that I had brought a book with me, but sat and amused myself by watching the rain falling instead.

The rain was coming down quite fast - very tiny drops, some of which swirled around a little like tiny snowflakes. After several minutes I realised that the windscreen did not appear to be wet, so I began looking all around through the windows and, Yes, I could see the fine drizzle from every angle. Puzzled I got out of the car only to find that it was not raining at all. Although I could still see it falling as I had whilst inside no drops were landing on me or anywhere else!!

I found this really quite scary as I realised that what I was seeing was some sort of hallucination. In due course John arrived and as I started to drive home I asked him if it was raining and he said it wasn't. Once inside I looked out of the window (by now it was completely dark) and could still see the rain and then, having settled quietly in a chair, I found it was raining inside as well! And it continued until I went to bed.

I woke up this morning to a bright and sunny day and found that I could only see the mysterious rainfall if I looked into the shadows.

Naturally enough I have been looking on the Internet for an explanation of the phenomenon of visual hallucinations and it appears that there are a number of types which vary according to cause. One type which occurs in psychologically healthy people is called Charles Bonnett syndrome which has been extensively studied by neurologist and author Oliver Sacks.

'His studies have determined that over the course of a person’s life, there are subtle changes that can occur within the structural set up of the visual cortex, causing one to hallucinate. “There is a special form of hallucinations that could go along with deteriorating vision or blindness… As the visual parts of the brain are no longer getting any input, they become hyperactive…they begin to fire spontaneously and you start to see things,” said Sacks'

Charles Bonnett syndrome usually affects those with impaired sight, who may start to have strange, visual hallucinations, sometimes just of patterns but often more elaborate visions of complex scenes or ranks of people in exotic dress. Perhaps 20 percent of those losing their vision or hearing may have such hallucinations.

Other causes of visual hallucinations include Parkinsons disease, dementia with Lewy bodies (DLB), posterior cortical atrophy, seizures, migraine, certain drugs, errors of metabolism and tumours. 

Features of Visual Hallucination/Most Likely Causes

Simple patterns, spots, shapes, or lines; 

unilateral distribution; associated with headache:               
Migraine, seizure, tumor

Macropsia, micropsia, metamorphopsia:                              

Seizure, Creutzfeldt-Jakob disease

Associated with going to, or waking from, sleep:

Hypnagogic or hypnopompic hallucinations                           

Confabulation of all vision:  

Anton's syndrome

Frightening content:

Psychotic disorder, delirium, hallucinogenic drug

Good insight:

Charles Bonnet syndrome, migraine, peduncular hallucinosis

Nothing I have found so far really fits in with my hallucination of continuous rainfall ........ just another thing to ask the doctor about along with the toothache, tingly lip, pains in ear ....... !!

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