lørdag 9. januar 2010

Hunden som ikke gjenkjenner foten sin - et tilfelle av asomatognosia?

Jeg har tidligere skrevet om hunden i videoen under, hvor jeg spekulerte i om den hadde et tilfelle av Proprioception Deficit Disorder (PDD). Denne sykdommen kjennetegnes av mangel på kontakt med kroppsdeler og problemer med å gjenkjenne dem korrekt.

Jeg lurer nå på om ikke det rette begrepet kan være asomatognosia, som skyldes en defekt i høyre isselapp i hjernen. Dette gir seg utslag i at man får problemer med å gjenkjenne sine egne kroppsdeler på venstre side av kroppen.

Oliver Sacks har beskrevet et tilfelle i sin bok "The Man Who Mistook His Wife For A Hat":

When I was a medical student many years ago, one of the nurses called me in considerable perplexity, and gave me this singular story on the phone: that they had a new patient - a young man - just admitted that morning. He had seemed very nice, very normal, all day - indeed, until a few minutes before, when he awoke from a snooze. He then seemed excited and strange - not himself in the least. He had somehow contrived to fall out of bed, and was now sitting on the floor, carrying on and vociferating, and refusing to go back to bed. Could I come, please, and sort out what was happening?
     When I arrived I found the patient lying on the floor by his bed and staring at one leg. His expression contained anger, alarm, bewilderment and amusement - bewilderment most of all, with a hint of consternation. I asked him if he would go back to bed, or if he needed help, but he seemed upset by these suggestions and shook his head. I squatted down beside him, and took the history on the floor. He had come in, that morning, for some tests, he said. He had no complaints, but the neurologists, feeling that he had a 'lazy’ left leg - that was the very word they had used - thought he should come in. He had felt fine all day, and fallen asleep towards evening. When he woke up he felt fine too, until he moved in the bed. Then he found, as he put it, 'someone’s leg’ in the bed - a severed human leg, a horrible thing! He was stunned, at first, with amazement and disgust - he had never experienced, never imagined, such an incredible thing. He felt the leg gingerly. It seemed perfectly formed, but 'peculiar’ and cold. At this point he had a brainwave. He now realised what had happened: it was all a joke! A rather monstrous and improper, but a very original, joke! It was New Year’s Eve, and everyone was celebrating. Half the staff were drunk; quips and crackers were flying; a carnival scene. Obviously one of the nurses with a macabre sense of humour had stolen into the Dissecting Room and nabbed a leg, and then slipped it under his bedclothes as a joke while he was still fast asleep. He was much relieved at the explanation; but feeling that a joke was a joke, and that this one was a bit much, he threw the damn thing out of the bed. But - and at this point his conversational manner deserted him, and he suddenly trembled and became ashen-pale -when he threw it out of bed, he somehow came after it - and now it was attached to him.
     'Look at it!’ he cried, with revulsion on his face. 'Have you ever seen such a creepy, horrible thing? I thought a cadaver was just dead. But this is uncanny! And somehow - it’s ghastly - it seems stuck to me!’ He seized it with both hands, with extraordinary violence, and tried to tear it off his body, and, failing, punched it in an access of rage.
     'Easy!’ I said. 'Be calm! Take it easy! I wouldn’t punch that leg like that.’
     'And why not?’ he asked, irritably, belligerently.
     'Because it’s your leg,’ I answered. 'Don’t you know your own leg?’
     He gazed at me with a look compounded of stupefaction, incredulity, terror and amusement, not unmixed with a jocular sort of suspicion, 'Ah Doc!’ he said. 'You’re fooling me! You’re in cahoots with that nurse - you shouldn’t kid patients like this!’
     'I’m not kidding,’ I said. 'That’s your own leg.’
     He saw from my face that I was perfectly serious - and a look of utter terror came over him. 'You say it’s my leg, Doc? Wouldn’t you say that a man should know his own leg?’
     'Absolutely,’ I answered. 'He should know his own leg. I can’t imagine him not knowing his own leg. Maybe you’re the one who’s been kidding all along?’
     'I swear to God, cross my heart, I haven’t… A man should know his own body, what’s his and what’s not - but this leg, this thing’ - another shudder of distaste - 'doesn’t feel right, doesn’t feel real - and it doesn’t look part of me.’
     'What does it look like?’ I asked in bewilderment, being, by this time, as bewildered as he was.
     'What does it look like?’ He repeated my words slowly. 'I’ll tell you what it looks like. It looks like nothing on earth. How can a thing like that belong to me? I don’t knowwhere a thing like that belongs…’ His voice trailed off. He looked terrified and shocked.
     'Listen,’ I said. 'I don’t think you’re well. Please allow us to return you to bed. But I want to ask you one final question. If this - this leg - is not your left leg’ (he had called it a 'counterfeit’ at one point in our talk, and expressed his amazement that someone had gone to such lengths to 'manufacture’ a 'facsimile’) 'then where is your own left leg?’
     Once more he became pale - so pale that I thought he was going to faint. 'I don’t know, he said. 'I have no idea. It’s disappeared. It’s gone. It’s nowhere to be found…’

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