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Alasdair - Neurology > Visual fields > Flashcards

Flashcards in Visual fields Deck (11):
1

Visual pathway

Retina
Optic nerve
Optic chiasm: nasal fibres decussate
Optic tract
Lateral geniculate nucleus of thalamus
Optic radiation (superior field: temporal, inferior field: parietal)
Visual cortex

2

investigations for visual field defects

Perimetry
CT/MRI brain

3

Anatomical site of lesion in homonymous hemianopia

Retrochiasmatic
Greater defect = larger lesion or closer to chiasm
Contralateral

4

Extra examinations in homonymous hemianopia

Examine for ipsilateral hemiparesis
Examine for cerebellar signs
Right: test for neglect
Left: test for aphasia

5

Specific history in homonymous hemianopia

Speed of onset
Vascular risk factors

6

Differentiating MCA versus PCA stroke in homonymous hemianopia

MCA stroke:
MCA supplies the optic radiation in the temporal and parietal lobes
Hemiparesis
Higher cortical dysfunction: neglect, aphasia
PCA stroke:
PCA supplies occipital lobe and visual cortex
Homonymous hemianopia with macula sparing (branch of MCA supplies this part of visual cortex)
No hemiparesis
May have cerebellar signs

7

Causes of homonymous hemianopia

Vascular: ischaemia or haemorrhage
SOL: tumour, abscess
Demyelination: MS

8

Lesion site in bitemporal hemianopia

Chiasmatic lesion

9

Specific history in bitemporal hemianopia

Endocrine disease: acromegaly, prolactinoma, Cushing's

10

Causes of bitemporal hemianopia

Pituitary tumour:
Compresses from below - descending visual loss
Craniopharyngioma:
Compresses from above - ascending visual loss
Benign suprasellar tumour originating from Rathke's pouch
Calcified as arises out of odontogenic epithelium

11

Monocular blindness lesion site

Lesion proximal to optic chiasm
Optic nerve affected i.e. optic neuropathy