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 NEUROLOGYFORMER HEAD AND PROFESSOR OF NEUROLOGYFORMER HEAD AND PROFESSOR OF NEUROLOGY Institute of Neurology Chennai Chennai
Thomas Elbert Basic PrinciplesCortical 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.
Sensory modulation in spatial neglect Novel Techniques Peripheral somatosensory- Magnetic stimulation Repetitive optokinetic stimulation Neck Vibration training Drug Treatment is currently unsuccessful
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
Other techniques Caloric tests for balance Brings awareness of illness to patient. Kinesthetic, visual, and auditory cues to improve Parkinsonian gait.
INTERMANUAL REFERRAL OFSENSATION AND EXTINCTION OFPAIN IN PERIPHERAL ANDCENTRAL LESIONS OF SOMATOSENSORY SYSTEM
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)
METHODS8 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
CENTRAL LESIONStrokeThalamic stroke - threeTemparo parietal - twoThree to four months laterIpsilateral arm - no referral to leg
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
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
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
INTERMANUAL REFERAL AND EXTINCTION OF PAIN SENSATION Hemiparesis with Brachial hemisensory deficit Amputation plexus Spatial organi- Poor Poor Excellent sation Localisation Good Poor ExcellentTime 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
DISCUSSIONAnatomical facts 1. Primary somato sensory area 3b 2. A. Primary somato sensory area 1 & 2 2. B. Second somato sensory cortex and parietal operculumIn 2a & 2b the receptive fields are largerbilateral and callosal connection areabundant
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
DISCUSSION Contd…It appears that a decrease insomatosensory input to onecerebral hemisphere from thecontralateral hand allowsresponsiveness of neurons inthis hemisphere tomoderately intense tactilestimuli on the ipsilateral handto exceed perceptualthreshold (which does notnormally occur).
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
HemineglectAn Interesting Case from Prof.A.V.Srinivasan’s Unit
Can the mind believewhat 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 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 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
CT Brain – P – Shows a (R) Occipitotemporal infarct
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 painOn 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
On cold caloric tests and its effect on neglect
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
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.