sensory disturbances at the level of thalamus and cortex
DESCRIPTION
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SENSORY DISTURBANCES AT THE LEVEL OF THALAMUS
AND CORTEX
SENSORY DISTURBANCES
NEUROLOGICAL
• PN, NR,SpC,BS, Thalamus, Cortex
NON NEUROLOGICAL
• HYSTERICAL
SOMATIC SENSATIONSSUPERFICIAL DEEP COMBINED/ CORTICAL
PAIN VIBRATION TWO POINT DISCRIMINATION, TACTILE LOCALISATION
TEMPERATURE POSITION STEREOGNOSIS , GRAPHAESTHESIA
TOUCH PASSIVE MOVT DOUBLE SIMULTANEOUS STIMULATION
PATHWAYS
SPINOTHALAMIC
• ANT- crude touch
• LAT- pain, temperature
DORSAL COLUMN
• Fine touch• Position sense
• Vibration
Figure 26.18 The main somatic sensory pathways.
Downloaded from: StudentConsult (on 5 July 2011 01:13 AM)© 2005 Elsevier
THALAMUS
Forms the lateral wall of 3rd ventricleSupply: POST. CEREBRAL A
SENSORY RELAY CENTRE- ‘HEAD GANGLION OF ALL SENSORY SYSTEMS’
PROCESSING OF SENSATIONS- ‘Fnl gateway of cerebral cortex’
PARTS
1.Ant. Nuclei
2.Med. Nuclei
3.Lat. Nuclei [Largest;neothalamus]4.Intralaminar N
LATERAL NUCLEI
DL VM
ANT INT POST
LAT[VPL] MED[VPM]
VPL VPM
SPINAL,MEDIAL
LEMNISCITRIGEMINAL
LEMNISCI
AREA 3,1,2
THALAMIC LESIONS
C/L loss of all sensationsTHALAMIC SYNDROME:- Lacunar infarction1. c/l sensory loss2. Thalamic/ athetoid hand3. Intention tremor4. Choreoathetosis
5. Thalamic over-reaction eg; DEJERINE ROUSSY SYNDROME- agonizing pain in the affected areaRx: frontal lobotomy6. Amelognosis7. Thalamic phantom limb 8.Mild hemiparesis
CORTEX
PARIETAL CORTEXCORTICAL Br of MCA n ACAPrimary sensory area-3,1,2Sec sens areaSensory assosn area-5,7,40
CORTICAL LESIONS
c/l Cortical sensations are lost Hemi neglect,hemi inattention Simulate paralysis
Pseudothalamic syndrome- Cortical lesion with c/l loss of sensationsAnt. Parietal infarctionSimulate thalamic lesion
LAT MED
Thalamic lesion
Cortical lesion
pain + _
Tingling n numbness + _
Perception of sensation
_ +Loss of discrimination
_ +