54ournal of Neurology, Neurosurgery, and Psychiatry 1995;59:548-551

SHORT REPORT

Callosal disconnection syndrome and knowledgeof the body: a case of left hand isolation from thebody schema with names

Toyoko Nagumo, Atsushi Yamadori

AbstractA patient is described who presented witha disturbance of body cognition confinedto the left side of the body. She showeddifficulties in naming the left fingers andin moving the named left fingers. She alsoshowed great difficulty in pointing tonamed parts of the body with her lefthand. Earlier in the course of the diseaseshe showed a personification phenome-non of the left hand. Brain MRI showedinvolvement of the entire corpus calo-sum, probably due to occlusion of abranch of the anterior cerebral artery. Itis speculated that this syndrome is causedby disconnection of the right hemispherefrom the left hemispheric body schema.

(7 Neurol Neurosurg Psychiatry 1 995;59:548-55 1)

Keywords: callosal disconnection syndrome, bodyschema, autotopagnosia, tactokinesthetic two wayanomia.

Department of SpeechTherapy, NiigataPrefectualMuikamachi Hospital,Niigata, JapanT NagumoSection ofNeuropsychology,Division of DisabilityScience, TohokuUniversity GraduateSchool ofMedicine,Sendai, JapanA YamadoriCorrespondence to:Ms Toyoko Nagumo,Department of SpeechTherapy, NiigataPrefectural MuikamachiHospital, Muikamachi636-2, Minamiuonuma-Gun,Niigata, 949-66, Japan.Received 23 August 1994and in final revised form26 June 1995Accepted 5 July 1995

We encountered a patient who showed anarray of disconnection syndromes after aninfarction of the corpus callosum. We havealready reported the left sided avoiding reac-tion of this patient and discussed the symptomin terms of possible disconnection of the asym-metrically organised manual spatial function.'Other intriguing symptoms of this patient werea left sided alien hand sign 2 3in the earlycourse of the disease and persistent difficultyin identifying body parts with the left hand. Toour knowledge, reports of unilateral auto-topagnosia associated with the callosal discon-nection syndrome have not appeared in themedical literature.We studied the symptoms in detail and

speculate on an underlying mechanism interms of lateralisation of a body recognisingsystem-that is, a body schema.

Case presentationThe details of this 56 year old right handedhousewife have already been reported.' InMarch 1988 she had a cerebral infarction,most likely a thrombosis of a branch of the leftanterior cerebral artery. Neuroimaging studiesincluding CT and MRI confirmed anischaemic lesion confined to the left half of thecorpus callosum from the genu through theentire length of the body (fig 1).

Subsequently, she showed various typicaldisconnection syndromes including alien lefthand sign, diagonistic apraxia, self grasping bythe left hand, left hand tactile anomia, lefthand agraphia, left ideomotor apraxia, leftsided motor initiation difficulty, left sidedcrossed avoiding,4 and left unilateral neglectwhen drawing with the right hand.5 This leftunilateral spatial neglect was never seen withtasks involving the left hand. General behav-ioural neglect toward the left was not seen indaily activities.On 20 December 1988 she was alert and

cooperative. Cranial nerves were normalincluding the visual fields. Movements of theleft upper and lower limbs were clumsy in fin-ger to nose and heel to shin tests, but no clearweakness or ataxia was present. Muscle tonewas normal. Deep tendon reflexes wereincreased bilaterally but no pathologicalreflexes were detected. Superficial sensationwas normal. Joint position sense was impairedin the fingers of the left hand. Vibration was

slightly decreased bilaterally. For stereognosis,the right hand was normal and the left hand

Figure 1 CT of the brain showing circumscribed lowabsorption areas in the corpus callosum and the adjacentmedial area of the leftfrontal lobe consistent with adiagnosis of infarction of the left anterior cerebral artery.

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Callosal disconnection syndrome and knowledge of the body: a case of left hand isolation from the body schema with names

was correct for 80% in non-verbal responsetasks.No appreciable change was detected in the

neurological signs at a re-examination threeyears after the onset. In this examination wetested for the first time left-right transfer oftactile localisation and finger pattern. Transferfrom the right to the left often elicited stiffnessof the left hand. Even when the left-righttransfer was feasible, it ended in errors.

Brain CT taken four years after the onsetshowed an advance of the cortical atrophy inthe left frontal area. The anterior horn of theleft hemisphere was enlarged and the damageof the corpus callosum at this level was clear.

Studies on body identificationPERSONIFICATIONFor three months after the onset she showed apronounced personification phenomena6 ofthe left, non-paralysed, hand. She oftenbehaved as if the left hand were a real person.The personification usually occurred when shecould not control her left hand voluntarily.Here is an example:When she was being tested for apraxia, the

left hand grasped the right hand performing atask. She tried to let the left hand go to noavail. Then she started talking towards the lefthand, "Grandma, would you please let me go.You are warm, but my hand is sweating anduneasy."

IDENTIFICATION OF THE PATIENT'S OWNBODYBased on the method described by Benton7,extensive tests of body identification were per-formed over a two year period one year afterthe onset. During this period no personifica-tion phenomena were seen. The table sum-marises the test results.

For naming of fingers three methods wereemployed, visual naming and two non-visualmethods of naming a finger touched by anexaminer with the patient blindfolded andwith the hand behind the patient's back. Forcomprehension of finger names, two methodswere used: pointing to a named finger with thecontralateral hand and moving a named finger.For non-verbal identification of fingers thepatient was asked to move a touched finger.For identification ofbody parts the patient wasasked to name a touched part, point to anamed part, and to point to a touched part.The patient's performance was perfect for

visual naming of the fingers and the body.Non-visual naming, and naming of the bodyparts and the right fingers were perfect; how-ever, the patient performed very poorly fornon-visual naming of the left fingers. Thepatient performed accurately for pointing to anamed left finger with the right hand with theeyes open or closed, but was poor in pointing tothe right fingers with the left hand, beingmuch worse when blindfolded. Pointing to anamed body part with the right hand was per-fect (fig 2), but it was poor with the left handboth with the eyes closed and open.

Identification of a named finger by movingit was perfect for the right hand with the eyes

'' W11-''^ IFigure 2 Identification ofbody parts: patient was askedto point to her abdomen. The right hand always respondedaccurately.

open, the eyes closed, and the hand behind thebody. It was remarkably poor for the left hand,being much worse when blindfolded. With thenon-verbal identification task of moving atouched finger, the left fingers responded cor-rectly in both visual and non-visual conditions.Body part identification by pointing to atouched part was fairly good with the lefthand, even when non-visual.

IDENTIFICATION OF THE EXAMINER'S BODYVisual naming of the examiner's body partsincluding the fingers was perfect. Pointing tothe named parts of the examiner's body wasalso without error if performed with the righthand. Correct pointing rate with the left hand,however, fell to 79%.

POINTING TO OBJECTSFinally we tested pointing ability of the lefthand with objects. Five objects were placed ona desk, the patient pointed to a named objectwhen able to see and when blindfolded. Underthe visual condition, the patient's responsewas good. With 10 trials (50 pointings) shewas 97% correct. Under the non-visual condi-tion, the response became slow and poor, butthe performance improved after she memo-rised the location of objects. With 10 trials (50pointings) she was 67% correct. We testedvisual pointing capacity of her left hand for sixobjects, placed on her forehead, ear, shoulder,breast, navel, and knee.8 With the total of fivesessions (30 pointings) she was 80% correct.When the task was switched to pointing to anamed body part she was correct in only 37%of 30 pointings. For both tests the perfor-mance of the right hand was normal.

OTHER TESTS RELATED TO THE BODY IMAGEWe asked 14 verbal questions describing arelation of the various body parts. For

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Nagumo, Yamadori

Naming and identification of body parts

Naming of fingers (% correct):Visual namingName a touched finger

With eyes closedWith hand behind body

Identification of fingers:Point to a named finger

With the right handWith eyes openWith eyes closed

With the left handWith eyes openWith eyes closed

Move a named fingerWith eyes openWith eyes closedWith hand behind body

Move a touched fingerWith eyes openWith eyes closed

Naming of body parts (% correct):Name a touched part

Identification of body partsPoint to a named part

With the right handWith the left hand

Point to a touched partWith the right handWith the left hand

Rightfingers

100

100100

Left fingers

100

3213

10097

6426

100100100

100100

Eyes open

100

9941

10097

52240

9898

Eyes closed

95

10030

10085

Body parts included head, ear, forehead, eye, cheek, nose, mouth, chin, neck, shoulder, chest,breast, arm, elbow, hand, abdomen, navel, back, loin, buttock, foot, thigh, knee, calf, and heel.The number of tests were: finger test; 5 fingers times 10 for each; body part naming; 30 sitestimes 3; body parts pointing; 30 sites times 5; right and left hands were tested alternately.

instance, we asked the correctness of the fol-lowing statement: "The mouth is situatedabove the eyes." She scored 27 points out ofexpected 28. We also asked her to draw a

human figure. Her drawing was clumsy. Thelengths of the arms and legs were short relativeto the trunk, but the spatial relation betweenvarious body parts was well preserved.According to MacDonald's scoring method9the right hand's score was 8 of 10 and the lefthand's score was 7.

DiscussionThe present case presented a unique combina-tion of signs confined to the left hand.Essentially there were two core symptoms.One was the difficulty of left finger identifica-tion. She could neither name the left fingersnor move the named left fingers when visionwas excluded. Under visual conditions thesetasks were perfectly conducted. The other wasthe difficulty of pointing to the named bodyparts with the left hand. The difficulty coveredthe whole body including the right fingers.Again the right hand showed no difficulty.

Autotopagnosia was first described by Pickin 1909 and defined as patients' inability tolocalise and name the parts of their own bodycorrectly.'0 Finger agnosia, described byGerstmann in 1924," belongs to this categoryof autotopagnosia. Typical patients would notbe able to name or move the parts of their ownbodies touched by an examiner, or move or

indicate the parts named by the examiner. Thedisorder was always bilateral. Drawing of a

human figure may be abnormal.The present case can be placed in this broad

category of autotopagnosia but with excep-tional features. Thus we have a case of tac-tokinesthetic autotopagnosia confined to the

left fingers associated with left hand disorien-tation for named body parts.

Tactokinaesthetic left finger agnosia can beexplained in terms of modality specific as wellas category specific two way anomia. Two wayanomia was first described by Geschwind andFusillo in the colour domain.'2 Their patienthad difficulty naming colours and pointing tothem but preserved the ability to sort coloursaccording to hues, match colours, and recallcolour names in response to verbal questions.They explained the symptoms as a disconnec-tion of the linguistic system from the righthemispheric colour system because of com-bined damage to the left occipital visual sys-tem and the corpus callosum, through whichthe colour information of the right hemispherepasses to the left language area. The identicalargument is feasible in the present case.Suppose a reference system for the locationand the names of the body-call it the bodyimage with names-is lateralised in the lefthemisphere. If this body image with nameswas separated from the right hemisphere by anappropriately placed callosal lesion, anomia aswell as comprehension difficulty for the namesof parts of left side of the body wouldinevitably result. Tactospatial informationfrom the left finger area must be firstprocessed in the contralateral right hemisphereand subsequently have to pass to the left hemi-sphere for reference for a body part identifica-tion and a name. When a name of the leftfingers was provided, the left hemisphericbody image with names was activated, butcould not transmit this exact localising infor-mation to an appropriate area of the rightmotor area. Axial body information may reachthe left hemisphere ipsilaterally resulting in nodifficulty in identification. As the right somes-thetic processing area is essentially intact, tac-tile localisation of a touched finger by movingthe same finger should be possible.How can we reconcile the peculiar left hand

difficulty of pointing to the named body partsbilaterally with this two way anomia theory?When given a name, the left hand showed dis-orientation and could not arrive at a correctdestination. But the performance was betterwhen visual than when blindfolded. Whengiven tactile information (touch), the samehand localised the point fairly well under bothconditions. This left hand performance couldnot be due to apraxia or visuomotor ataxia, asthe spatial reaching at an object outside thepatient's own body was good as shown by herability in pointing to the body parts of theexaminer and pointing to objects even on herown body. The left hand, under right hemi-spheric control, was unable to relate its spa-tiomotor information with the left hemisphericbody image with names through the corpuscallosum.

This theory is consistent with previous ones.Gerstmann,'3 for instance, argued that thebody schema should be lateralised to the lefthemisphere. From a study of "pure" auto-topagnosia in which verbal and non-verbalidentification of body parts is impaired,Semennza and Goodglass postulated the exis-

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Callosal disconnection syndrome and knowledge of the body: a case of left hand isolation from the body schema with names

tence of a conceptual representation of bodyparts and their spatial and fimctional interrela-tions in the left hemisphere.'4 Based on studiesof anosognosia Yamadori also argued that thebody schema is still a relevant neurologicalconcept in interpreting symptoms related todifficulty in identifying parts of the body and ismost likely to be lateralised in the left hemi-sphere.'5 The present case seems to reinforcethese arguments.Was her left alien hand and personification

episode consistent with this callosal discon-nection theory of the body image with names?After Yamadori'5 an argument can bepresented. In the acute phase with a wide-spread callosal disconnection, the bodyschema principally organised in the lefthemisphere would be thrown into imbalanceand tend to be activated. The activation of thebody schema would mean an autonomousactivity of the body schema even in theabsence of supporting information, in this par-ticular case somesthetic information from theright hemisphere concerning the left half of thebody. The autonomous body schema activa-tion in the left hemisphere would generate anexperience of a perfect body image. A suddenmovement of the left hand driven by thedisconnected right hemisphere would beperceived and appreciated as a movement. Butit is disconnected from a feeling of thepatient's having a complete body. A consciousleft hemisphere'6 would very likely interpretthis hand movement as something outside itsown body, resulting in alien hand sign.Some might argue that the phenomenon

could be interpreted as a partial symptom ofthe left sided neglect. It was true the patientshowed left unilateral neglect with the righthand5, but not with the left hand. No spatialinattention toward the left side was seenbehaviourally. If there was a problem, it wastoward the right.' Thus it is difficult tointerpret the symptoms in terms of left side

neglect. Even the personification phenomenonseen in the present case was different from thesimilar phenomenon often seen in associationwith anosognosia.6 The first is seen in responseto a moving left hand, whereas the second isseen in association with a paralysed left hand.

We thank Dr Yoshiaki Soma, Dr Takeo Kuwabara at theNiigata University, Dr Yokichi Hayashi, and Ms Mari Hoshinofor help in preparation of the manuscript. We also thank DrMasakazu Ito, Director of Niigata Prefectural MuikamachiHospital for supporting our study. Last but not least are thanksto the patient, whose willing cooperation made this studypossible.

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4 Lechevalier B, Andersson JC, Morin P. Hemispheric dis-connection syndrome with a "crossed avoiding" reactionin a case of Marchiafava-Bignami disease. J NeurolNeurosurg Psychiatry 1977;40:483-97.

5 Kashiwagi A, Kashiwagi T, Nishikawa T, Tanabe H,Okuda J. Hemispatial neglect in a patient with callosalinfarction. Brain 1990;113:1005-23.

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16 Sperry RW, Gazzaniga MS, Bogen JE. Interhemisphericrelationships: the neocortical commissures; syndromes ofhemispheric disconnection. In: Vinken PJ, Bruyn GW,eds. Handbook of clinical neurology. Vol 4. Amsterdam:North-Holland, 1969;273-90.

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