Neuro Flashcards
What are the causes of monocular vision loss?
Ipsilateral retinal or optic nerve lesion
Retinal - central retinal artery / vein occlusion, retinal detachment
Optic nerve - optic neuritis, optic atrophy, glaucoma
What visual field defect does a pituitary adenoma cause?
Bitemporal hemianopia - compression of the chiasm
Where would the lesion be in a homonymous hemianopia?
Contralateral optic tract (or whole optic radiation) lesion e.g. middle cerebral artery occlusion (stem)
What are the potential causes of a homonymous superior quandrantanopia?
Contralateral lesion of the inferior optic tract (temporal lobe) e.g. tumour or middle cerebral artery occlusion (inferior branch)
Where would the lesion be in a homonymous inferior quandrantanopia?
Contralateral lesion of the superior optic tract (parietal lobe) e.g. parietal lobe tumour or middle cerebral artery occlusion (superior branch)
What causes a homonymous hemianopia with macular sparing and why?
Contralateral occipital lobe lesion e.g. posterior cerebral artery occlusion, the macular cortex receives dual blood supply from PCA and MCA.
What are the two classifications of a third nerve palsy? How would you differentiate between the two? What is the pathology behind this?
Surgical and medical
Medical = pupil sparing, painless
Surgical = fixed dilated pupil
Pathology: pupil fibres run along the outside of the nerve so are affected first by compression (POCM) whereas in a medical palsy the inside is affected first and the outside (pupillary fibres) spared.
What are the signs of a complete third nerve palsy?
Complete ptosis, ‘down and out’ eye, fixed dilated pupil (mydriasis)
What is Horner’s syndrome and what are the signs?
Disruption of the sympathetic nerve supply to the face
Miosis (fixed constricted pupil), anhydrosis, ptosis (partial)
Normal light and accommodation reflexes and eye movements.
What are the three main causes of Horner’s syndrome?
Central - MS, SOL, syringomyelia, stroke / lateral medullar syndrome
Pre-ganglionic - Pancoast tumour, cervical rib
Post-ganglionic - carotid artery dissection, radical neck dissection.
What are the causes of bilateral ptosis?
Myasthenia Gravis
Myotonic dystrophy (frontal balding, facial muscle wasting, distal weakness)
Congenital
Neurosyphilis (Argyll Robertson pupil - accommodation reflex present, pupillary reflex absent).
What muscles are supplied by the 4th (trochlear) and 6th (abducens) nerves?
Superior oblique and Lateral rectus
What are the signs of a 4th nerve palsy?
Difficulty reading - moving the eye down and in
Affected eye will be slightly raised compared to other
Patient tilt head away from the side of the affected lesion (e.g. right nerve palsy, head tilted to the left).
What is the pathological process behind internuclear ophthalmoplegia (INO)?
Lesion in the medial longitudinal fasciculus - connects the III’d, IV’th and VI’th nerves’ nuclei to coordinate movements.
What are the features of background diabetic retinopathy?
Dot haemorrhages / microaneurysms, hard exudates (can see vessels through hard exudates)
