Parietal lobe signs

The parietal lobe is the principal sensory area of the cerebral cortex. The manifestations of damage may be specific to the dominant or non-dominant hemisphere, or it may be general:

Disease of either dominant or non-dominant hemisphere post-central gyral sensory cortex produces contralateral disturbance of cortical sensation:

• impairment of postural sensation and sensation of passive movement
• impairment of tactile sensation - accurate localisation of light touch, two point discrimination
• agraphism, astereognosis
• sensory and visual inattention

Dominant hemisphere lesions:

• involving Wernicke's speech area - receptive dysphasia
• Gerstmann's syndrome
• dyslexia

Non-dominant lesions:

• neglect of contralateral limb, even if densely hemiplegic
• denial of weakness - anosognosia
• spatial neglect
• disappreciation of three dimensional sense - dressing dyspraxia, constructional dyspraxia
• geographical agnosia - e.g. unable to find defined places

Involving the optic radiation deep in the parietal lobe:

• lower homonymous quadrantanopia