The sign wasn t placed there By the Big

The sign wasn’t placed there By the Big Printer in the sky Prof. A. V. SRINIVASAN. M. D, D. M, Ph. D, F. I. A. N, F. A. A. N, EMERITUS PROFESSOR OF NEUROLOGY FORMER HEAD AND PROFESSOR OF NEUROLOGY Institute of Neurology Chennai

Neu. Con CONTROVERSIES IN NEUROLOGY APRIL 3 -4, 2010 G. ARJUNDAS

SHRI US MEHTA ORATION

Thomas Elbert Basic Principles l Cortical representation expands linearly with use. l Synchronous inputs lead to fusion of cortical zones l Asynchronous inputs lead to segregation of cortical zones. l Disuse or De-afferentation leads to invasion of unused cortical area by nearby neurons.

Sensory modulation in spatial neglect Novel Techniques l Peripheral somatosensory- Magnetic stimulation l Repetitive optokinetic stimulation l Neck Vibration training Drug Treatment is currently unsuccessful

Sensory modulation and Stroke l Rehabilitation aimed to increase use of paretic hand l Virtual reality l Motor imagery l Prof. l V. S. . Ramachandran’s virtual reality box Phantom limb phenomenon

Other techniques l Caloric tests for balance l l Brings awareness of illness to patient. Kinesthetic, visual, and auditory cues to improve Parkinsonian gait.

INTERMANUAL REFERRAL OF SENSATION AND EXTINCTION OF PAIN IN PERIPHERAL AND CENTRAL LESIONS OF SOMATO SENSORY SYSTEM

BACKGROUND l Allesthesia and extinction of referral sensation in brachial plexus lesions A. V. Srinivasan and V. S. Ramachandran et al (1998) l Intermanual referral of sensations after central lesions of the somato sensory system K. Sathian et al (2000)

METHODS 8 patients (19 -51 years) l Brachial plexus lesion – one l Amputation – two l Stroke – five l Patients were video filmed in the movement disorder clinic. Pinprick, cold, vibration and kinesthesis were tested l MRI & ENMG in all cases

CENTRAL LESION Stroke l Thalamic stroke l Temparo parietal - three - two Three to four months later l Ipsilateral to leg arm - no referral

STROKE Contd… l Intense pressure on the normal hand resulted in extinction of pain in the stroke side l Pain returned within one minute of the pressure l Intense pressure improved sensory and motor phenomenon

AMPUTATION l 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

CASE VIGNETTE (BRACHIAL PLEXUS LESION) l 21 year old girl, after total brachial plexus lesion was examined 6 months, 1 ½ & 2 ½ years after the lesion l She had sensations intermanually referred in a topographically organized manner in the phantom limb

INTERMANUAL REFERAL AND EXTINCTION OF PAIN SENSATION Hemiparesis with hemisensory deficit Amputation Spatial organisation Poor Excellent Localisation Good Poor Excellent Immediate with in 7 days Immediate with in 7 days Immediate Time of occurance After 3 to 4 months Pain Extinction After a delay of 3 - 5 seconds Brachial plexus

DISCUSSION Anatomical facts 1. Primary somato sensory area 3 b 2. A. Primary somato sensory area 1 & 2 2. B. Second somato sensory cortex and parietal operculum In 2 a & 2 b the receptive fields are larger bilateral and callosal connection are abundant

DISCUSSION Contd… l Contralateral referral of sensations was not found in normal subjects or in hemiparetic patients without hemi sensory loss l Neural mechanisms for perceptual alteration not clear

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).

CONCLUSION l Intermanual referral & extinction of pain occurred immediately in amputation and brachial plexus lesions and after a delay in stroke l Intermanual referral of sensation occurred topographicaly organised manner in brachial plexus lesions but not in amputation and stroke

Hemineglect An Interesting Case from Prof. A. V. Srinivasan’s Unit

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

We thank l Prof. V. S. Ramachandran, M. D. , Ph. D. , Director Centre for Brain and Cognitive Sciences University of California, San Diego, USA

Indrani. 50 year old female l Presents with sudden onset of weakness of left upper and lower limb l O/E. l Conscious, oriented to time, place and person l Mild left UMN facial paresis l Left hemiplegia l All peripheral pulses palpable

l CT Brain – P – Shows a (R) Occipitotemporal infarct

Higher mental function evaluation l MMSE : 28/30 l 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 l Left visual neglect with (L) hemianopia l No auditory neglect l Absent sensory perception in (L) upper limb and (L) tactile neglect in the lower limb

On cold caloric tests and its effect on neglect

Video of Neglect

Video of caloric test and Nystagmus

Video of disappearance of neglect

On ‘ Mirror Agnosia’ Mirror Agnosia on the Right

After caloric test, Mirror Agnosia on the Left

‘Mirror Agnosia’ to front

l On Anosognosia, Body neglect (Hemisomatognosia) and somatoparaphrenia l Anosognosia – our patient has it l Body neglect by Bisiach’s test – our patient does not have it l Somatoparaphrenia – our patient has it

Somatoparaphrenia

On the somatophrenic arm and mirrors

l On Allesthesia, tactile neglect and ‘blind touch’ l ‘Touch your left arm’ Bisiach’s test of body neglect. l Absent proprioception and touch in the left upper limb l Patient is still able to touch her left arm whatever position the examiner keeps the arm in.

Blind Sight Vs Blind Touch

l On visual imagery, neglect and caloric tests l Visual imagery l Bisiach’s test l Our test

Results

Unconscious awareness in a person with Blind Sight And Blind Touch Conscious mind and unconscious mind Theories of consciousness and the soul.