NEUROLOGY:

Normal function of the brain:

Signs and symptoms related to specific areas of a brain lesion:

Parietal lobe lesions

· sensory inattention

· apraxias

· astereognosis (tactile agnosia)

· inferior homonymous quadrantanopia

· Gerstmann's syndrome (lesion of dominant parietal): alexia, acalculia, finger agnosia and right-left disorientation

Occipital lobe lesions

· homonymous hemianopia

· cortical blindness

· visual agnosia

Temporal lobe lesion

· Wernicke's aphasia

· superior homonymous quadrantanopia

· auditory agnosia

· prosopagnosia (difficulty recognising faces)

Frontal lobes lesions

· expressive (Broca's) aphasia: located

· disinhibition

· perseveration

· anosmia

· inability to generate a list

Visual field defects:

Visual field defects (Main points):

• left homonymous hemianopia means visual field defect to the left, i.e. lesion of right optic tract
• homonymous quadrantanopias: PITS (Parietal-Inferior, Temporal-Superior)
• incongruous defects = optic tract lesion; congruous defects= optic radiation lesion or occipital cortex

Homonymous hemianopia

• incongruous defects: lesion of optic tract
• congruous defects: lesion of optic radiation or occipital cortex
• macula sparing: lesion of occipital cortex

Homonymous quadrantanopias

• superior: lesion of temporal lobe
• inferior: lesion of parietal lobe
• mnemonic = PITS (Parietal-Inferior, Temporal-Superior)

Bitemporal hemianopia

• lesion of optic chiasm
• upper quadrant defect > lower quadrant defect = inferior chiasmal compression, commonly a pituitary tumour
• lower quadrant defect > upper quadrant defect = superior chiasmal compression, commonly a craniopharyngioma