Corticosensory syndrome and sensory extinction (or total hemianesthesia with large acute lesions of white matter)

1. Parietal Lobe Anatomy
Ashish Sharma

2. Boundaries of parietal lobe

3. Mesial surface

4. SULCI AND GYRI
GYRI
Post central gyrus
Supeior Patietal lobule
Inferior Parietal lobule
SULCI
Post central sulcus
Inter parietal sulcus

5. NP/MG
Paracentral lobule
Superior Temporal gyrus
Middle Temporal gyrus
Inferior Temporal gyrus
Central Sulcus
Postcentral gyrus
Cingulate gyrusIntraparietal sulcus
Fusiform gyrus
Collateral sulcus
Parahippocampal gyrus
Supramarginal gyrus
Intraparietal sulcus

6. BLOOD SUPPLY

9. Parietal lobe
Anterior
zone 1,2,3
Posterior
zone
PE PF PG

10. Connections of the Parietal Lobes
Somatosensory
Strip
To area PE- Tactile
recognition
To motor regions-
sensory information
about limb position
and movement

11. Area PE
• Inputs from the
somatosensory strip
• Outputs to primary
motor cortex,
supplementary motor
cortex, premotor
regions, and area PF
Area PF
• Input from
somatosensory,
primary motor cortex,
premotor cortex, and
small visual input
through area PG
Area PG
• Receives complex
connections including
visual, somesthetic,
proprioceptive,
auditory, vestibular,
oculomotor, and
cingulate connections

12. Deficit: Proprioception, Tactile
sensation, Two point
discrimination, Astereognosis,
Outputs: primary motor cortex,
contralateral S1,association
somatosensory cortex(area 5 &
7), thalamus
Location : Post central gyrus on
lateral surface and dorsal
aspect of paracentral lobule on
medial surface. area (3 ,1, 2)
Representation : contralateral
half of body inverted
Function: reception center for
afferent impulses,touch ,
pressure, and position
sensations.
Afferent connections:
VP nucleus of
thalamus
Primary
somatosensory

13. Somatosensory Homunculus

14. Function: not well
described, ? Involved in
less discriminative aspects
of sensation.
Lesions: none ascribed,
rarely inability to appreciate
pain(asymbolia)
Location : superior lip of
lateral fissure (parietal
operculam)
Representation
:contralateral side
dominant, Bilateral
representation
Afferent: Intralaminar
nuclei and posterior
group of nuclei of
thalamus

15. Location : superior parietal
lobule. broadmann’s
area(5,7)
Afferent: primary
somato-sensory area
astereognosis, agraphesthesia,
two-point discrimination, and
tactile localization , poor hand
eye coordination
FUNCTION
Integration of visual and
somato-sensory stimuli, Hand-
eye coordination, reaching and
grasping,

16. Function:
Left hemisphere –
language ,maths, reading,
writing, understanding
of symbols.
Right hemisphere—visuo-
spatial orientation.
• Location:
supramarginal
gyrus (40) and
angular gyrus
(39)
Lesions
Aphasia, agnosia, and
apraxia and visuspatial
defects

17. LESIONS OF PARIETAL LOBE
– Post central gyrus
• Simple somatosensory disturbances
– Contra lateral sensory loss (object
recognition > position sense > touch >
pain and temperature, vibration);
tactile extinction
– Contra lateral pain, paresthesias

18. LESIONS OF PARIETAL LOBE
• In general,
– left hemisphere is dominant for thought
and reasoning, analytic and mathematical
skills
– the right hemisphere is dominant for tasks
requiring spatial and constructional skills, as
well as for directed attention and body
image

19. LESIONS OF UNLATERAL PARIETAL LOBE
(LEFT OR RIGHT)
– Corticosensory syndrome and sensory
extinction (or total hemianesthesia with
large acute lesions of white matter)
– Homonymous hemianopia or inferior
quadrantanopia or visual inattention
– Neglect of the opposite side of external
space (far more prominent with lesions of
the right parietal lobe).

20. LESIONS OF NON DOMINANT
PARIETAL LOBE
– Topographic memory loss
– Anosognosia
– Hemisomatognosia
– Left sided hemispatial inattention
– Dressing apraxia
– Constructional apraxias
– Allesthesia

22. LESIONS OF DOMINANT PARIETAL
LOBE
– Gerstmann syndrome
– Ideomotor apraxia
– Ideational apraxia
– Disorders of language (especially alexia)
– Tactile agnosia (bimanual astereognosis)

23. Thank You