what is the cause - bededoktorem

[ArchivalUser]

of right homonymous inferior quadrantanopia?

[ArchivalUser]

occlusion of branch of posterior cerebral art that supplies the non-meyer's loop fibres in the visual radiation

[ArchivalUser]

I can tell the mechanism for inf quadranopia:
Optic radiation from lateral geniculate usually spilt into
Superior loop of fibres crossing parietal lobe and
Inferior loop of fibres crossing temporal lobe(also called Meyer's loop)

Damage to some extreme temporal fibres will cause Supirior Quadranopia
Damage to some extreme parietal fibres will cause Inferior Quadranopia

But it will be bilateral in most of the case and depend on which side you have lesion.
Cause can be stoke.

[ArchivalUser]

thanks



there is a branch of posterior cerebral artery occlusion of which gives inferior quadrantanopia

and occlusion of posterior cerebral artery gives hemianopia

my problem is, how to distinguish them, where is the point here?

what have to happen to cause hemianopia versus inferior quadrantanopia?

thanks

[ArchivalUser]

A lesion in the antero-superior parietal lobe projection of the optic radiation produces a contra-lateral congruous, partial or complete homonymous inferior quadrantopia
The more lesion located posteriorily, more it is towards hemianopia.

So the branch supplying the antero-superior parietal lobe will cause inferior quadrantopia but if main branch of post cerebral artery is involved it will cause hemianopia.

I think this will help.

[ArchivalUser]

bededoktorem, I think (not sure) if lesion:

1-Optic tract----->hemianopia

2-Optic radiations----->quadrantanopia

Now to remember superior vs inferior(Optic radiations) lesions :

P I T S:

Parietal is Inf (lower) homonymous quadrantanopia ----> MCA

Temporal is Sup (upper) homonymous quadrantanopia ---> PCA


Now to make the difference between left and right you need more Infos.......

Correctly if wrong.

[ArchivalUser]

Sorry for typo, I mean correct me if wrong

[ArchivalUser]

Thanks for clearing, I like this mnemonic
P I T S:


but here a typo:


Parietal is Inf (lower) homonymous quadrantanopia ----> MCA

Temporal is Sup (upper) homonymous quadrantanopia ---> PCA



Should be opposite, right?


Parietal is Inf (lower) homonymous quadrantanopia ----> PCA

teMporal is Sup (upper) homonymous quadrantanopia ---> MCA

[ArchivalUser]

thanks okt3 and drangina for help

[ArchivalUser]

oh my bad I was expecting the correction)

Thanks