Disconnection syndrome

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1. Disconnection Syndrome Dr Gulab Soni

2. White matter connection 3 types of white matter fibre: Commissural fibre: interhemispheric Association fibre: intrahemispheric Projection fibre- Vertical Horizontal

3. Disconnection syndrome: Introduction Defined as symptoms and sign, which are arises due to white matter disconnection 1965 - Norman Geschwind , US neurologist Usually two types- Interhemispheric disconnection syndrome : due to involvement of commissural fibres Intrahemispheric disconnection syndrome : due to association fibres involvement

4. Disconnection syndrome Fibre type Tract involved Symptoms Association Arcuate fasciculus Conduction aphasia, ideomotor apraxia Inferior longitudinal fasciculus Visual object agnosia Pure alexia Prosopagnosia (B/L) Commissural Corpus callosum Left hand apraxia , left hand agraphia , pure alexia etc Projection Corticospinal tract Locked in syndrome, hemiparesis

5. Apraxia

6. Visual object agnosia Inability to recognize object by sight Based on lesion: Lateral occipital cortex (cortical): apperceptive visual agnosia Associative fibre connections ( transcortical ): associative visual agnosia - disconnection syndrome DORSAL STREAM-VISUALY GUIDED ACTION VISUAL INFORMATION VENTRAL STREAM-VISUAL RECOGNITION

7. Visual object Agnosia

8. Alexia Acquired inability to read Alexia without agraphia /pure alexia / pure word blindness/visual verbal agnosia - disconnection syndrome Alexia with agraphia - lesion at angular gyrus Third alexia/ alexic agraphia - seen with brocas aphasia

9. Pure Alexia

10. Conduction aphasia

11. Conduction aphasia The lesions of conduction aphasia usually involve either the superior temporal or inferior parietal region. Conduction aphasia plus limb apraxia : parietal lesions Conduction aphasia without apraxia : temporal lesions

12. Callosal Disconnection Syndrome Verbal Disconnection Motor Disconnection Left visual anomia Crossed optic ataxia Left hemialexia Left unilateral motor apraxia Left auditory anomia Agraphia of the left hand Left tactile anomia Right unilateral construnctional apraxia Right olfactory anomia Alien hand syndrome Mainly due to -Posterior callosal lesion Mainly due to -Anterior callosal lesion

13. A) Verbal disconnection disorders Verbal output is exclusively sub served by the left hemisphere So in callosal lesion patient have difficulty in communicating from right hemisphere

14. 1. Left visual anomia Image seen in right visual field (left hemisphere) are normally named or described, while those shown in the left hemi field (right hemisphere) cannot. Lesion site: Posterior and dorsal portion of splenium

15. 2. Left hemialexia Special case of anomia for words shown in the left visual field, patient unable to report aloud or write down those presented on the left side Lesion site: Ventral and anterior portion of splenium

16. 3. Left auditory anomia Repetition of verbal material (syllables, words and numbers) or naming of auditory stimuli (sound and voices) are normal when presented to each ear separately- due to the bilateral projection of cortical auditory pathway Bilateral simultaneous stimulation of both ear, results in deficit from left ear i.e right hemisphere Lesion site: Posterior inferior trunk/isthmus

17. 4. Left tactile anomia Patient can describe and name objects palpated with the right hand (without vision)but not with the left hand Also k/a pseudoastereognosis Lesion site: posterior trunk

18. 5. Right olfactory anomia Odors presented to right nostril (right hemisphere) are not named, while those presented to left nostril (left hemisphere) are—olfactory inputs project ipsilaterally . No anosmia : patient winces in response to unpleasant odours

19. B) Motor disconnection disorders Difficulty in coordinating bimanual gesture due to lack of sensory motor transfer, ex- difficulty in tie shoelaces in absence visual inspection Rapid alternating movement of both hand also impaired, ex-hand clapping/tapping Lesion: anterior corpus callosum

20. 1. Right unilateral constunctional apraxia Difficulty in drawing and constructive abilities when using right hand Due to disconnection of the left motor cortex from right hemisphere visuospatial skills

21. 2. Alien hand syndrome “Feeling that one limb is foreign or “has a will of its own,” together with observable involuntary motor activity Depending upon the site of lesion, 3 types of alien hand syndrome described

22. Alien hand syndrome Frontal variant Callosal variant Sensory variant Clinical features Reflexive grasping, groping and compulsive manipulation of tools Intermanual conflict Levitation Lesion site Medial prefrontal cortex Anterior corpus callosum Parietal cortex Affected side of hand Dominant hand Nondominant hand Nondominant hand Associated finding Transcortical motor aphasia, Sensory ataxia, Optic ataxia, neglect Cause ACA territory stroke Callosal surgery in epilepsy Head injury CBGD Posterior cortical atrophy (AD)

23. Geschwind’s disconnection syndromes Disconnections between sensory areas and limbic cortex Disconnections between sensory areas and Wernicke’s area Disconnections between sensory areas and motor cortex Disconnection between the hemispheres Pain asymbolia (no response to pain in the presence of normal tactile discriminatory function) Tactile aphasia/ anomia / agnosia : (the inability to name a held object in the presence of preserved speech and naming in other sense modalities Conduction aphasia/central aphasia: disconnections of Broca’s area from Wernicke’s area Callosal disconnection syndrome Verbal learning impairment examples- autism, schizophrenia Pure word deafness( auditory verbal agnosia ): inability to understand spoken words in the presence of preserved hearing Apraxia : disconnections of the hand motor cortex from posterior sensory area Pure word blindness: (visual verbal agnosia or alexia)

24. Thank-u References: Adams and victors-text book of neurology, 10 th edition Bradleys text book of neurology, 6 th edi Stroke Syndromes, 3ed . By Louis R. Caplan , Jan van Gijn Marco Catani and Dominic H. The rises and falls of disconnection syndromes. Brain (2005), 128, 2224–2239 Developmental Neuropsychology ( Otfried Spreen , Anthony H. Risser , Dorothy Edgell ) The American Psychiatric Publishing Textbook of Geriatric Neuropsychiatry ( Norman L. Foster)

25. Limb kinetic apraxia : localises lesion at premotor cortex or adjacent centrum semiovale /corona radiata Ideomotor apraxia : not follow command, pantomime and imitation of object, how they are used but when object given to patient the demonstrate there use Ideational apraxia : deficit in the execution of a goal-directed sequence of movements of a tool Alien hand phenomenon: severe form of sympathetic apraxia , characterized by additional features of motor disinhibition on the left hand

26. Dressing and construction apraxia : bilateral (or right-sided) dorsal parietal lobe lesions, denotes disturbance in spatial orientation In callosal apraxia when lesion extends towards medially it may be associated with trancortical aphasia