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Can the mind believe what the eye sees
1. The sign wasn’t placed there
By the Big Printer in the sky
Prof. A.V. SRINIVASAN.
Prof. A.V. SRINIVASAN.
M.D, D.M, PhD, F.I.A.N, F.A.A.N ,,
M.D, D.M, PhD, F.I.A.N, F.A.A.N
EMERITUS PROFESSOR OF NEUROLOGY
EMERITUS PROFESSOR OF NEUROLOGY
FORMER HEAD AND PROFESSOR OF NEUROLOGY
FORMER HEAD AND PROFESSOR OF NEUROLOGY
Institute of Neurology
Institute of Neurology
Chennai
Chennai
4. Shri Uttambhai Nathalal Mehta
1924 - 1998
A visionary par excellence
The pioneer of neuropsychiatry in
India
The mind behind some of the
blockbuster drugs in the
neuropsychiatry segment; the
founder and guiding force behind
Torrent Group
A perfect epitome of business
excellence, scientific integrity and
benevolence unparalleled
SHRI US MEHTA ORATION
5. Thomas Elbert
Basic Principles
Cortical representation expands linearly with use.
Synchronous inputs lead to fusion of cortical zones
Asynchronous inputs lead to segregation of cortical
zones.
Disuse
or De-afferentation leads to invasion of
unused cortical area by nearby neurons.
6. Sensory modulation in spatial neglect
Novel Techniques
Peripheral somatosensory- Magnetic
stimulation
Repetitive optokinetic stimulation
Neck Vibration training
Drug Treatment is currently unsuccessful
7. Sensory modulation and Stroke
Rehabilitation aimed to increase use of
paretic hand
Virtual reality
Motor imagery
Prof. V.S..Ramachandran’s virtual reality box
Phantom limb phenomenon
8. Other techniques
Caloric tests for balance
Brings awareness of illness to patient.
Kinesthetic, visual, and auditory cues to
improve Parkinsonian gait.
10. BACKGROUND
Allesthesia and extinction of referral
sensation in brachial plexus lesions
A.V. Srinivasan and V.S. Ramachandran et al (1998)
Intermanual referral of sensations after
central lesions of the somato sensory
system
K. Sathian et al (2000)
11. METHODS
8 patients (19-51 years)
Brachial plexus lesion – one
Amputation – two
Stroke – five
Patients were video filmed in the movement
disorder clinic. Pinprick, cold, vibration and
kinesthesis were tested
MRI & ENMG in all cases
12. CENTRAL LESION
Stroke
Thalamicstroke - three
Temparo parietal - two
Three to four months later
Ipsilateral arm - no referral
to leg
13. STROKE Contd…
Intense pressure on the normal hand resulted
in extinction of pain in the stroke side
Pain returned within one
minute of the pressure
Intense pressure improved
sensory and motor
phenomenon
14. AMPUTATION
Both the patients (below
elbow & knee amputation)
showed intermanual referral
of sensation within 10 days.
The referred sensations of
touch and vibration lacked
spatial organization and poor
localization with a relatively
high threshold
15. CASE VIGNETTE (BRACHIAL PLEXUS
LESION)
21 year old girl, after total
brachial plexus lesion was
examined 6 months, 1 ½ &
2 ½ years after the lesion
She had sensations
intermanually referred in a
topographically organized
manner in the phantom limb
16. INTERMANUAL REFERAL AND EXTINCTION OF PAIN
SENSATION
Hemiparesis with Brachial
hemisensory deficit Amputation plexus
Spatial organi- Poor Poor Excellent
sation
Localisation Good Poor Excellent
Time of occurance After 3 to 4 months Immediate Immediate
with in 7 days with in 7days
Pain After a delay of Immediate Immediate
Extinction 3 - 5 seconds
17. DISCUSSION
Anatomical facts
1. Primary somato sensory area 3b
2. A. Primary somato sensory area 1 & 2
2. B. Second somato sensory cortex and
parietal operculum
In 2a & 2b the receptive fields are larger
bilateral and callosal connection are
abundant
18. DISCUSSION Contd…
Contralateral referral of sensations was not
found in normal subjects or in hemiparetic
patients without hemi sensory loss
Neural mechanisms for perceptual alteration
not clear
19. DISCUSSION Contd…
It appears that a decrease in
somatosensory input to one
cerebral hemisphere from the
contralateral hand allows
responsiveness of neurons in
this hemisphere to
moderately intense tactile
stimuli on the ipsilateral hand
to exceed perceptual
threshold (which does not
normally occur).
20. CONCLUSION
Intermanual referral & extinction of pain
occurred immediately in amputation and
brachial plexus lesions and after a delay in
stroke
Intermanual referral of sensation occurred
topographicaly organised manner in brachial
plexus lesions but not in amputation and stroke
22. Can the mind believe
what the eye sees ?
On vision, visuospatial dysfunction
and body image perception in
right hemispherical dysfunction
Dr.K.Bijoy Menon (Senior Resident)
Dr.Sundar, Dr.Saravanan, Dr.Ramakrishnan
Dr.Nithyanandan (Asst.Prof) ,
Prof. A.V.Srinivasan
23. We thank
Prof.
V.S.Ramachandran, M.D., Ph.D., Direct
or
Centre for Brain and Cognitive Sciences
University of California, San Diego, USA
24. Indrani. 50 year old female
Presents with sudden onset of weakness
of left upper and lower limb
O/E.
Conscious, oriented to time, place and person
Mild left UMN facial paresis
Left hemiplegia
All peripheral pulses palpable
25. CT Brain – P – Shows a (R) Occipitotemporal
infarct
26. Higher mental function evaluation
MMSE : 28/30
She was very attentive and quite clear in her
conversation with us, though she would be
complaining of a vague left sided shoulder pain
On lobar testing, she had
Left visual neglect with (L) hemianopia
No auditory neglect
Absent sensory perception in (L) upper limb and
(L) tactile neglect in the lower limb
36. On Anosognosia, Body neglect
(Hemisomatognosia) and somatoparaphrenia
Anosognosia – our patient has it
Body neglect by Bisiach’s test – our patient
does not have it
Somatoparaphrenia – our patient has it
39. On Allesthesia, tactile neglect and ‘blind touch’
‘Touch your left arm’ Bisiach’s test of body
neglect.
Absent proprioception and touch in the left
upper limb
Patient is still able to touch her left arm
whatever position the examiner keeps the arm
in.