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Parietal Lobe SIgns 24_7_18
- 1. Parietal Lobe Signs Dr. Mandeep Singh Kataria
- 2. Anatomy • Limits • Anteriorly – Central Sulcus • Posteriorly • Parieto-occipital sulcus superiorly • Preoccipital notch inferiorly • Inferiorly – Sylvian fissure • Parts • Two sulci • Post-central sulcus • Interparietal sulcus • Inferior Parietal Lobule • Supramarginal Gyrus (Area 40) • Angular Gyrus (Area 39) • Superior Parietal Lobule • Bound by the post central gyrus, interparietal gyrus and extends onto the medial surface (areas 5 and 7) • Post central gyrus • Brodmans areas 1, 2 and 3
- 4. Brodman Areas In the Parietal Lobe • Area 1, 2 and 3 – Postcentral Gyrus • Primary sensory cortex • Area 5 – Somatosensory association cortex • Area 7 – Somatosensory association cortex • Together form the superior parietal lobule • Area 39 – Wernicke’s area – Angular Gyrus • Area 40 – Supramarginal Gyrus
- 6. Unilateral Parietal Lobe Disease • On either side • Cortical Sensory syndrome • Sensory extinction • Homonymous hemianopia with visual inattention • Contralateral neglect • Abolition of optokinetic nystagmus to one side
- 7. Dominant lobe lesion • Aphasias • Broca’s • Wernicke’s • Global • Conduction • Alexia without agraphia (pure word blindness) • Bilateral astereognosis • Gerstmann’s syndrome • Agraphia without alexia • Right-left confusion • Acalculia • Finger agnosia • Bilateral Ideomotor apraxia
- 8. Cortical Sensory Syndrome • Loss of position sense and passive movement sense • Inability to localize touch, temperature or pain • Astereognosis • Agraphesthesia • Loss of two-point discrimination • Easy fatigability of sensory perceptions • Difficulty in distinguishing simultaneous stimulations • Hyperpathia • Touch hallucinations • Preservation sensations – Pain, Pressure, Touch, Temperature, Vibration (when the postcentral gyrus is not involved in the lesions)
- 9. Exceptions • Cortical lesion presenting as a thalamic syndrome • Dejerine and Mouzon’s sensory syndrome • touch, pressure, pain, thermal, vibratory, and position sense are lost on one side of the body or in a limb • Typically seen with thalamic lesions • May occur with acute lesions involving the central and subcortical region of the parietal lobe • Cortical lesion presenting as radiculopathy or peripheral neuropathy • May be cause by smaller lesions – glancing blows to the skull • Pseudothalamic Pain Syndrome • Pain on the side deprived of sensations
- 10. Character of Parietal Sensory Defects • Easy fatigability • Inconsistent response to stimuli • Tactile extinction – disregard of stimuli on affected side when both sides are stimulated simultaneously • Hyperpathia
- 11. Anton Babinski Syndrome • Anosognosia (anos- disease, agnosia – lack of knowledge) • Apathy • Allocheria • Dressing apraxia • Extinction • Contralateral visual field inattention
- 12. • Anosognosia • Lesion lies in the cortex and white matter of Superior Parietal lobule • Rarely lesion of ventrolateral thalamus and adjacent parietal lobe white matter may show similar symptoms • Unilateral Astomatognosia is more often associated with Nondominant lesions than with Dominant parietal lesions • In respect to spatial attention, the right parietal lobe is truly dominant • Unilateral Spatial Neglect • Ask the patient to draw a clock, copy a flower • Rejection Behaviour • Loss of exploratory and orienting behaviour with the contralateral arm • Tendency to avoid tactile stimuli • Release of grasp reflex – • Frontal – self grasp not present • Parietal – self grasp present
- 14. Motor disturbances with parietal lobe lesions • Mild hemiparesis – significant contribution to the corticospinal tract • May simulate a hemiplegia because of inability to move the limb • Reduced movements of opposite side – Parietal lesions have been reported to cause contralateral muscular atrophy and trophic skin changes • Optic ataxia – inability to grasp an object under visual guidance • Pseudocerebellar syndrome – intention tremor and incoordination • Pseudoathetosis – random finger movements in an outstretched hand • Apraxias
- 15. Apraxia • Loss of the ability to execute previously learned activities in the absence of weakness, ataxia, sensory loss, or extrapyramidal derangement that would be adequate to explain the deficit. • Planned or commanded action is normally first conceptualized in the parietal lobe of the language-dominant hemisphere, where visual, auditory, and somesthetic information is integrated – The space-time plan
- 16. Apraxia • Ideational apraxia – What to do? • The failure to conceive or formulate an action to command • Areas 5 and 7 in dominant parietal lobe + supplementary and premotor cortex of bilateral frontal lobe • Ideomotor apraxia – How to do? • Impaired performance of skilled motor acts despite intact sensory, motor, and language function. • Patient may know how to do a task but is unable to execute it. • Oral-buccal-lingual apraxia • Inability to carry out facial movements on command • May be able to imitate them • Left supramarginal gyrus or the left motor association cortex • Limb-kinetic apraxia • Clumsiness due to inability to fluidly connect the various movements of the hand or limbs.
- 17. Apraxia • The exact lesion - Variable • Supramarginal gyrus • Superior parietal lobe (areas 5 and 7) • Subcortical or cortical • Majority of lesions – Left hemisphere
- 18. Testing for Apraxia 1. Observe the actions of a patient while he engages in simulated tasks 2. Ask he patient to carry out symbolic acts • Wave goodbye • Salute • Blow a kiss 3. Ask the patient to imitate such acts if he cannot perform them on command 4. Ask him to do more complex tasks – simulate taking out comb from pocket and comb hair, brush teeth, hammer a nail…
- 19. Gerstmann Syndrome • Left-Right Confusion • Dysgraphia • Finger agnosia • Acalculia • Lesion in inferior parietal lobule – angular gyrus and subjacent white matter • Spatial knowledge mediated by the language has been proposed as a basic underlying deficit
- 20. • The right angular gyrus clearly participates in visuospatial processing, and damage to it results in severe hemi-spatial neglect. • The left angular gyrus participate in calculation abilities, reading/ writing, naming, and some type of body-knowledge (somatognosis).
- 21. Visual Disorders in Parietal Lobe Lesion • Visual Field Defects • Homonymous hemianopia • Homonymous inferior quadrantanopia • Visual neglect • Posterior parietal lesions • More prominent on the right side • Loss of optokinetic nystagmus • Abolished when following objects towards the lesion side
- 22. • Posterior Parietal Lesions • Deficits in localization of visual stimuli • Inability to compare the sizes of objects • Failure to avoid objects when walking • Inability to count objects • Disturbances in smooth-pursuit eye movements • Loss of stereoscopic vision • Blepharospasm • Disinclination to open eyelids when addressed • Intense blepharospasm precluding ocular examination • Topographagnosia • Patients are unable to orient themselves to abstract space • Loss of topographical memory
- 23. Auditory Neglect • Less apparent than is visual neglect • Displacement of the direction of the perceived origin of sounds toward the opposite side • Lesion in right superior lobule.
- 24. Balint Syndrome • Visual-spatial Imperception – Simultagnosia • Unable to percieve more than a single object at a time • Optic Apraxia • Difficulty in directing gaze to an object • Optic Ataxia • Difficulty in reaching out to an object under vision
- 25. Aphasias seen with Parietal Lobe Lesions • Wernicke’s Aphasia • Temporal, supramarginal and angular gyri • Fluent aphasia – neologism, lacks meaning • No repetition • Greatly impaired comprehension • Transcortical Sensory Aphasia • Similar to Wernicke’s but repetition is preserved • Lesion is near the Wernicke’s area • Conduction Aphasia • Lesion in supramarginal gyrus or insula • Fluent aphasia where comprehension and is preserved but repetition is lost
- 26. Summary • Unilateral Parietal Lobe Syndrome • Sensory disturbances • Homonymous hemianopia • Abolition of optokinetic nystagmus with target moving toward side of the lesion • Contralateral Hemineglect • Dominant Parietal Lobe Lesion • Language dysfunction (Alexia) • Gerstmann syndrome • Bilateral astereognosis • Bilateral apraxia
- 27. Summary • Nondominant Parietal Lobe Lesion • Visuospatial disorders • Topographic memory loss • Anosognosia • Blepharospasm • Confusion • Bilateral Parietal Lobe Lesions • Balint syndrome