Brain (1989), 112, 1019-1037

ANTERIOR CALLOSAL HAEMORRHAGE
A PARTIAL INTERHEMISPHERIC DISCONNECTION

SYNDROME

by RAMON LEIGUARDA, SERGIO STARKSTEIN1 and MARCELO BERTHIER
(From the Instituto de Investigaciones Neurologicas Dr R. Carrea-Fleni, Buenos Aires, Argentina)

SUMMARY
The interhemispheric disconnection syndrome secondary to a callosal haemorrhage is exceedingly
uncommon. In the present study, 3 patients with haemorrhages restricted to the corpus callosum
are presented. All 3 developed a partial anterior interhemispheric disconnection syndrome: unilateral
tactile anomia, unilateral agraphia, unilateral apraxia, difficulty in copying drawings, dyscalculia
as well as abnormalities of somaesthetic transfer and the 'alien hand' sign. The study of these cases
allowed a close examination of the association between deficits in the transfer of specific
neuropsychological information and the precise topography of callosal damage. Variability in the
lateralization of cognitive functions, and possible mechanisms underlying the production of callosal
haemorrhages after the rupture of saccular aneurysms are also discussed.
INTRODUCTION

Knowledge concerning the neurological and psychological effects of callosal
disconnection stems mostly from observations of patients whose neocortical
commissures were sectioned as treatment for severe epilepsy (Sperry et al., 1969;
Bogen, 1985). Since damage to the corpus callosum rarely occurs in isolation,
and damage of adjacent structures may mask symptoms pertaining to callosal
involvement, the callosal disconnection syndrome is seldom the result of naturally
occurring lesions. Clinical cases contributing to the interpretation of the callosal
disconnection syndrome have fallen mainly in two groups: (1) those with occlusion
of the anterior cerebral artery or one of its branches; and (2) those with invasive
neoplasms of the corpus callosum (for review, see Brion and Jedynak, 1975).
Haemorrhages into the corpus callosum are relatively rare and mainly found
within the context of more extensive cerebral damage, often secondary to bleeding
from a vascular malformation (Crompton, 1962; Brion and Jedynak, 1975;
Escourolle et al., 1975; Yock and Larson, 1980; Lau et al., 1984). Only 9 cases of
interhemispheric disconnection syndrome due to callosal haemorrhages have so
far been reported. Five cases had haemorrhages in the posterior portion of the
Correspondence to: Dr R. Leiguarda, Instituto de Investigaciones Neurologicas Dr R. Carrca-Fleni, Ayacucho
2166, 1112 Buenos Aires, Argentina.
1
Present address: Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of
Medicine, Meyer Building 4-119, Baltimore, MD 21205, USA.
© Oxford University Press 1989

1020

R. LEIGUARDA AND OTHERS

callosum (4 secondary to an arteriovenous malformation (Brion and Jedynak,
1975; Gersh and Damasio, 1981; Yamadori et al., 1983) and 1 of traumatic origin
(Alexander and Warren, 1988)), whereas 4 had haemorrhages secondary to
ruptured saccular aneurysms involving the anterior half of the callosum (Sweet,
1945; Brion and Jedynak, 1975; Poncet et al., 1978; Graff-Radford et al., 1987).
We report 3 patients with haemorrhages restricted to the corpus callosum who
developed a partial callosal disconnection syndrome as the main complication of
the haemorrhagic lesions.
PATIENTS
Case I

A 57-yr-old right-handed male (+100 on Handedness Inventory, Oldfield, 1971) suddenly
developed severe bilateral frontotemporal headache, nausea and vomiting. Two weeks later he was
admitted to our unit complaining of headache, gait difficulties and urinary incontinence. On
neurological examination the patient was alert and fully orientated; his digit span was 6 numbers
forward and 3 backwards. General information for past events was unaffected; he showed no
impairment in learning new material and no confabulation was observed spontaneously or in
response to specific questions. Although spontaneous speech was well articulated and grammatical,
he experienced difficulties in initiating conversation and showed long response latencies as well as
hypophonia. Naming, repetition, auditory and reading comprehension were normal. He had signs
of callosal dysfunction {see Neuropsychological Assessment). Mild neck stiffness was present.
Cranial nerve examination proved normal and there was no evidence of hemianopia or visual

FIG. 1. Case I. Postcontrast CT scan showing a resorbing callosal haemorrhage with peripheral enhancement
(pseudotumoral pattern). Arrow indicates a saccular aneurysm.

ANTERIOR CALLOSAL H A E M O R R H A G E

1021

inattention. There was mild weakness in both lower limbs with increased tendon reflexes. An
extensor plantar response was elicited on the left, and a tonic foot response was present on the
right. There was also a right hand grasping reflex, but no other motor deficit in either arm. Sensation
was normal and the patient could adequately identify single or double tactile simultaneous
stimulation on either limb. Two weeks after onset, a CT scan revealed a lesion of increased
attenuation involving the corpus callosum from the dorsal-rostral portion of the genu to the most
caudal part of the body (fig. 1). After the injection of intravenous contrast material an irregular
peripheral enhancement of the lesion was observed, a finding consistent with the 'pseudotumoral
pattern' characteristic of a reabsorbing callosal haemorrhage (Lau el al., 1984).
There was no radiological evidence of extracallosal damage. CT measurement of skull asymmetries
demonstrated the typical left occipital 'petalia' (Hadziselimovic and CuS, 1966) normally observed
in right-handed individuals (Pieniadz el al., 1983). While mean occipital widths and lengths were
+ 20 and + 10, respectively, frontal region measurements showed symmetric widths and lengths.

FIG. 2. Case 1. Digital subtraction angiography demonstrating a saccular aneurysm (arrow) at the right
pencallosal bifurcation, displacement of the callosomarginal artery towards the left, and stretching and
straightening of the pericallosal artery with mild vasospasm.

Digital subtraction angiography showed a bilobulated saccular aneurysm at the right pericallosal
bifurcation. The callosomarginal artery was slightly displaced towards the left, and the pericallosal
artery was stretched and straightened, showing mild vasospasm (fig. 2). The patient refused surgery
and died a week later, presumably due to massive rebleeding. No postmortem examination was
available.
Case 2
A 51-yr-old ambidextrous male ( + 40 on Handedness Inventory, Oldfield, 1971) with a family
history of sinistrality suffered a sudden severe frontal headache and immediately fainted. He
recovered consciousness after 25 min but felt dizzy and was admitted to hospital. Past history was
unremarkable. On examination the patient was alert and orientated in time, place and person.
Attention and memory were normal. His spontaneous speech was abnormally sparse with long
pauses but with preserved articulation and grammar. Naming, repetition, and auditory and reading
comprehension were also normal. He had signs of callosal disconnection (see Neuropsychological

1022

R. L E I G U A R D A AND OTHERS

Assessment). Cranial nerve examination was normal with no hemianopia. He had left crural
hyperreflexia with a left extensor plantar response and forced grasping in both hands. Sensation
and coordination were normal and there was no neck rigidity. A CT scan showed blood in the
anterior interhemispheric fissure and a circumscribed haemorrhage extending from the dorsal part
of the genu to the caudal third of the callosal body (fig. 3).

FIG. 3. Case 2. Postcontrast CT scan showing callosal haemorrhage. Arrow indicates a saccular aneurysm.

FIG. 4. Case 2. Digital subtraction angiography showing a saccular aneurysm (arrow) of the left pericallosal
artery and stretching of the pericallosal artery with moderate vasospasm.

ANTERIOR CALLOSAL HAEMORRHAGE

1023

CT measurements of skull asymmetries (Pieniadz et al., 1983) showed an 'atypical' pattern with
a larger left frontal region (widths —40 and lengths — 10) and a larger right occipital region (widths
— 30 and lengths —10). Digital subtraction angiography showed a saccular aneurysm of the left
pericallosal artery at the junction with the callosomarginal artery. Stretching of the pericallosal
artery as well as moderate vasospasm were also observed (fig. 4). The aneurysm was successfully
clipped and the patient made a gradual recovery.

FIG. 5. Case 3. Postcontrast CT scan showing callosal haemorrhage. Arrow indicates a saccular aneurysm.

FIG. 6. Case 3. Digital subtraction angiography demonstrating a saccular aneurysm (arrow) of the anterior communicating artery and stretching of the pericallosal artery due to the intracallosal lesion with mild distal
and segmented vasospasm.

1024

R. LEIGUARDA AND OTHERS

Case 3
This case was extensively described in a previous report (Starkstein el a!., 1988) and only the
main features will be presented here. A 35-yr-old right-handed male ( + 100 on Handedness Inventory,
Oldfield, 1971) was admitted to hospital complaining of loss of speech fluency and antagonistic
movements of the left hand (e.g., after having picked up a pen with his left hand, he could not
transfer it readily to the right hand and was forced to take it with an effort). He also noticed that
his left hand behaved in a noncooperative way (e.g., when he tried to open a drawer with his right
hand, the left tried to close it). This behaviour was so astonishing and uncontrollable that he
occasionally hit his left hand with the right one. All these symptoms had a sudden onset 15 days
before his admission and were accompanied by headache, nausea, vomiting, dizziness and urinary
incontinence, all of which cleared in 36 h. A month before hospitalization, however, the patient
noticed a sudden and intense frontal headache that lasted a few hours. There was no personal
history of neurological illness during infancy and no family history of left-handedness. On physical
examination he was attentive, cooperative and fully orientated, but he had signs of callosal
disconnection (see Neuropsychological Assessment). Memory was normal. His spontaneous speech
was sparse, monotonous, agestural, and showed long response latencies. Naming, repetition, auditory
and reading comprehension were all normal. Cranial nerves were normal. He had a mild paraparesis
with bilateral flexor plantar responses, brisk tendon reflexes and forced grasping with his right hand.
On double simultaneous tactile stimulation, extinction was found on the right side (upper limb).
Coordination was normal and he had a slight nuchal rigidity. A CT scan showed an extensive
haemorrhage involving the callosum from the rostral portion of the genu to the dorsal splenium
(fig. 5). After contrast enhancement a small hyperdense mass was observed in the anterior portion
of the suprasellar cistern. CT measurements of skull asymmetries (Pieniadz et al., 1983) showed
an 'atypical' pattern with a larger right occipital region (widths —20 and lengths —10), but with
symmetric widths and lengths in the frontal region.
Digital subtraction angiography revealed a saccular aneurysm of the anterior communicating
artery with stretching of the pericallosal artery due to the intracallosal lesion; mild distal and
segmental vasospasm was also observed (fig. 6).
Neuropsychological assessment of callosal functions
A detailed neuropsychological evaluation of callosal function was performed in all 3 patients as
follows.
Somaesthetic transfer. While blindfolded, one of the patients' upper limbs was put in a fixed
position and they were asked to copy this position with the other limb. Later, both palms were
placed upwards and the tip of one finger was slightly touched by the examiner; patients were asked
to touch the corresponding finger of the contralateral hand using the thumb of that same hand.
Five right-handed male normal controls (mean age 48.6 yrs) were also examined and their
performance compared with the patient group.
Tactile naming. While blindfolded, patients were asked to palpate and name 10 common objects.
Each hand was tested separately, and after each trial, patients were asked to recognize the object
after it had been mingled with other unrelated ones.
Visual naming and reading (in each half visual field). Patients were asked to name 10 common
objects to confrontation and to read aloud 10 words presented in either the left or right half visual
fields.
Writing. Patients were asked to write and typewrite simple words and short sentences spontaneously, from copy, and to dictation. Left and right hands were tested separately.
Drawing. Patients were presented with four different geometric figures (cube, square, triangle and
hexagon) and were asked to copy them. Each hand was tested separately.
Calculation. Patients were asked to carry out additions, subtractions, multiplications and divisions,
both written and mentally.

ANTERIOR CALLOSAL

1025

HAEMORRHAGE

Praxis. Patients were asked to carry out transitive (involving direct manipulation of an object)
and intransitive (not involving direct manipulation of an object) movements on command, then to
imitate the examiner's movement and finally to demonstrate the use of an actual object. Whole
body and buccofacial movements were also examined.
RESULTS

Results of the neuropsychological evaluation of callosal functions are listed in
the Table and only the main findings will be described.
Somaesthetic transfer. On the first test (copy of the position of the contralateral
upper limb), 4 normal controls performed flawlessly (10/10 correct), while 1 made
1 error (normal control group mean ±SD = 9.8 + 0.4). All 3 patients performed
below chance and more than 4 SD below normal. On the contralateral finger
recognition task, 3 normal controls performed flawlessly (10/10 correct), while
2 normal controls made 1 error (9/10 correct) (normal control group mean
+ SD = 9.6 + 0.55). All 3 patients scored below chance level and more than 4 SD
below the normal control group mean.
TABLE. RESULTS OF NEUROPSYCHOLOGICAL EVALUATION OF CALLOSAL FUNCTIONS
Somaesthetic transfer
Cross-replication
of hand postures
Cross-localization
of finger tips
Tactile naming
Right hand
Left hand
Visual naming
Writing
Right hand
Left hand
Reading
(in each half visual field)
Drawing
Right hand
Left hand
Calculation
Written
Mental
Praxis
Right hand
Left hand
Alien hand sign
Autocriticism

Case 1

Case 2

Case 3

2/10

6/10

3/10

3/10

5/10

4/10

10/10 correct
0/10 correct
Normal

10/10 correct
10/10 correct
Normal

0/10 correct
10/10 correct
Normal

Normal
Apraxic agraphia

Aphasic agraphia
Normal

Aphasic agraphia
Normal

Normal

Normal

Normal

0/4 correct
4/4 correct

4/4 correct
0/4 correct

0/4 correct
4/4 correct

Impaired
Normal

Impaired
Normal

Impaired
Impaired

Normal
Ideomotor apraxia
Present
Absent

Normal
Normal
Absent
Absent

Ideomotor apraxia
Normal
Present
Present

At the bottom of each patient column, the diagrams illustrate the rostrocaudal extent of the callosal
haemorrhage based on CT sagittal reconstructions.

1026

R. LEIGUARDA AND OTHERS
Left hand, dictation
'No creo que Ilueva' (I don't think it will rain)

Left hand, typewriting
'El dia amanecio lluvioso' (It was raining at dawn)
El dia amanec io lluvioso

Right hand, dictation
'No creo que Ilueva' (I don't think it will rain)

QMtf
FIG. 7. Case I. Left hand apraxic agraphia.

Tactile naming. Unilateral tactile anomia was demonstrable for the left hand in
Case 1 and for the right hand in Case 3; they were unable to name any of the
objects properly with these hands although they were able to recognize adequately
all 10 objects by touching when they were mingled with 10 unrelated ones.
Writing. While all the patients showed unilateral agraphia, this was either an
apraxic agraphia (e.g., an illegible scrawl) in Case 1 (fig. 7) or an aphasic agraphia
(e.g., letters or syllable repetitions, distortions, omissions and inversions) in Cases
2 and 3 (figs 8, 9).
Drawing. All 3 patients showed unilateral copying difficulties, but none had any
evidence of spatial neglect.
Calculation. Written calculation was impaired in all patients mainly due to
difficulty in aligning columns of numbers, particularly in Case 1 (fig. 10). Mental
calculation was preserved in Cases 1 and 2 but mildly impaired in Case 3.
Praxis. Only Cases 1 and 3 showed a unilateral ideomotor apraxia. On verbal
command, Case 1 showed slow responses with his left hand characterized by
irrelevant gestures. Errors were mainly observed in distal movements, particularly
in those requiring the use of single digits. When performing movements that

ANTERIOR CALLOSAL HAEMORRHAGE

1027

Right hand, spontaneous writing
'Manana iremos al campo' (Tomorrow we will go to the countryside)

Left hand, spontaneous writing Mapicera' (pen)

FIG. 8. Case 2. Right hand aphasic agraphia; left hand graphomotor disturbances attributable to left hand
grasping.

Right hand, spontaneous writing
'El interior' (The inside)

Right hand, dictation
'El interior de la habitacion mostraba.
(The inside of the room showed..)

•ft
Left hand, dictation
'El interior de la habitacion mostraba.
(The inside of the room showed..)

FIG. 9. Case 3. Right hand aphasic agraphia.

1028

R. L E I G U A R D A AND O T H E R S

involved proximal and distal parts of the upper limb (e.g., throwing a ball)
proximal movements proved to be more accurate, and in every instance the
examiner could discern that the patient was trying to make the appropriate
movement. Although on imitation and with the actual object, performance
improved, he still made many temporospatial errors. No apraxia was observed in
facial or whole-body movements. Case 3 also showed temporospatial errors on
command, imitation and with use of actual objects when using the right upper
limb.

FIG. 10. Case 1. Spatial dyscalculia.

Dissociative phenomena. These were clearly present in Cases 1 and 3. Case 1
showed uncooperative and oppositional movements with the left hand, such as
putting his glasses on his nose with the right hand and removing them with the
left. During examination of Case 3, involuntary and antagonistic behaviour of his
left hand was clearly observed (e.g., while the patient was trying to open a case
with his right hand, the left prevented him). Although less frequent, some
involuntary and oppositional movements of the right hand were also seen without
the patient being conscious of this fact (e.g., when asked to write with his left
hand, his right one took the sheet of paper and dropped it to the floor; when
asked why he had done that, he denied having performed such an act).
Follow-up. Case 2 was reevaluated 3 months after the operation. He had full
recovery of callosal functions without any clinical evidence of interhemispheric
disconnection. A control CT scan showed a small hypodense lesion involving the
dorsocaudal portion of the genu and the rostral third of the body of the callosum
with minimal involvement of the anterior left cingulate gyri with no further
evidence of extracallosal damage (fig. 11).

A N T E R I O R CALLOSAL H A E M O R R H A G E

1029

FIG. 11. Case 2. Unenhanced CT scan
3 months after operation showing damage
affecting the dorsal portion of the genu and
the anterior part of the body of the corpus
callosum; a small lesion is observed in the left
anterior cingulate gyms.

DISCUSSION
Three patients are presented who developed a partial interhemispheric disconnection syndrome as the main neurological manifestation of an anterior callosal
haemorrhage secondary to rupture of a saccular aneurysm. We will now examine
the clinical features relevant to the extracallosal damage, the presence of atypical
lateralization of neuropsychological functions, the interhemispheric disconnection
signs and their association with the specific portion of the corpus callosum involved
by the lesion, and new aspects of the pathogenesis of callosal haemorrhages
secondary to ruptured aneurysms.
Clinical features of extracallosal damage
All 3 patients presented abnormal neurological findings such as mild corticospinal signs in the lower limbs, abnormal reflexes, tactile extinction and urinary
incontinence. These 'extracallosal' signs may result from pressure of the haemorrhage on the descending precentral and frontal fibres producing the corticospinal
signs and the grasp reflex (Fisher, 1982) and on the anterior cingulate gyrus and
adjacent frontal regions producing tactile extinction and urinary incontinence
(Andrew el ai, 1966; Heilman and Valenstein, 1972). Despite the fact that 2 out
of our 3 patients (Cases 1, 2) had angiographic evidence of vasospasm, it seems
most unlikely that an ischaemic lesion contributed to the development of the
extracallosal symptomatology, since none of the patients presented features
commonly seen with ischaemia in the territory of the anterior cerebral artery, such
as persistent disturbances of consciousness, amnesia, confabulation, personality
and psychiatric disorders, eye movement abnormalities, hypometria, bradykinesia,
catatonia, neglect and aphasia (Critchley, 1930; Alexander and Freedman, 1984;
Eslinger and Damasio, 1984; Brust, 1986; Meador et ai, 1986). CT studies likewise
failed to reveal ischaemic changes in the anatomical regions surrounding the
corpus callosum.

1030

R. LEIGUARDA AND OTHERS

At the onset, all 3 patients showed similar speech difficulties, characterized by
paucity of speech, long latencies and hypophonic but normally articulated verbal
output. Transient mutism is a common finding after complete commissurotomy
(Bogen, 1985) and during the recovery period, speech production is limited to a
few short grammatically correct and well articulated sentences. Although these
speech disturbances may be attributed to damage in the anterior cingulate gyrus,
they may also reflect callosal dysfunction (Sussman et al., 1983), since electrical
stimulation of the genu may produce inhibitory effects on speech output
(Schaltenbrand et al., 1972).

Lateralization of cognitive functions
Case 1 developed the typical clinical manifestations of anterior interhemispheric
disconnection observed in right-handed patients with left hemisphere dominance
for language and praxis (i.e., agraphia, tactile anomia and ideomotor apraxia for
the left hand; Bogen, 1985). On the other hand, Cases 2 and 3 presented with an
atypical lateralization pattern of neuropsychological function and, in both, CT
scan measurements of the occipital and frontal 'petalias' lend support to such an
atypical cerebral dominance pattern.
The lateralization of the disconnection signs in our ambidextrous patient (Case
2) suggests that his right hemisphere was dominant for writing (he had a right
hand agraphia) whereas the left hemisphere was dominant for visuospatial skills
(he had difficulties in copying with the left hand). Similar cases of atypical
lateralization of neuropsychological functions in patients with the callosal disconnection syndrome are not unknown. The left-handed patients of Gazzaniga and
Freedman (1973), Poncet et al. (1978) and Gur et al. (1984) behaved as righthanders with left hemisphere dominance for language and right hemisphere
dominance for visuospatial skills, whereas the right-handed patient of Trescher
and Ford (1937) developed disconnection signs compatible with right hemisphere
dominance for language. Lastly, Schott et al. (1975) reported an ambidextrous
patient with a callosal tumour who presented with right aphasic agraphia and
tactile alexia, bilateral constructional apraxia and a partial left ear extinction on
dichotic listening.
Our Case 3 showed right hemisphere dominance for language (he had a right
hand agraphia), skilled motor movements (he had a right ideomotor apraxia) and
visuospatial skills (he had difficulties in copying with the right hand), thus showing
a hemisp'here dissociation between dominance for handedness and dominance for
language and praxis. A similar dissociation of handedness and praxis has been
recently reported in right-handed patients with right hemisphere strokes (Rapcsak
-et al., 1986; Berthier et al., 1987) but to our knowledge, Case 3 is the first case of
a right-handed person with a callosal disconnection syndrome and crossed
lateralization of praxis, language and handedness.

ANTERIOR CALLOSAL HAEMORRHAGE

1031

Clinical features ofinterhemispheric disconnection
The most striking clinical features in our patients were due to interhemispheric
disconnection and included disturbances of somaesthetic transfer, tactile anomia,
agraphia, ideomotor apraxia, difficulties in copying, spatial dyscalculia and the
'alien hand' sign.
Disturbance of somaesthetic transfer
All 3 patients showed an impaired ability to cross-replicate hand postures and to
cross-localize stimulation of finger tips, which constitute the hallmark of the
interhemispheric disconnection syndrome (Bogen, 1985). In monkeys, the interconnecting callosal fibres responsible for the transfer of somaesthetic information are
localized in the rostral portion of the caudal half of the callosal body (Pandya et
al., 1971). As the transfer of such information, whether proprioceptive, tactile or
stereognostic, is not dependent on hemispheric dominance, dysfunction regularly
occurs when the lesion affects that portion of the callosal body (Jeeves et al., 1979;
Bentin et al., 1984). This region was involved by the haemorrhage throughout.
However, damage was probably partial in Case 2, since the deficit in somaesthetic
transfer reverted to normal and tactile naming was preserved.
Unilateral tactile anomia
This deficit is the result of the failure to transfer somaesthetic information
across the callosum from the (nonverbal) nondominant hemisphere to the intact
naming mechanism of the (verbal) dominant hemisphere. Brion and Jedynak
(1975) proposed that unilateral tactile anomia is most frequent with callosal lesions
extending from the splenium caudally to the junction of the anterior and medial
portions of the callosal body rostrally. Tactile anomia was present in Cases 1 and
3, both with extensive damage in the callosal body but without involvement of
the splenium. It was absent in Case 2, in whom the caudal third of the callosal
body was not involved by the haemorrhage. Therefore, fibres transferring this
complex somaesthetic information may be primarily located in the most caudal
part of the callosal body, posterior to those transmitting other somaesthetic
modalities. In support, Degos et al. (1987) reported the case of a patient with
posterior callosal infarction who had tactile anomia but partially preserved
somaesthetic transfer for other modalities.
Unilateral agraphia
Apraxic and aphasic agraphia of the nondominant hand have been reported in
patients with callosal lesions (Bogen, 1969; Watson and Heilman, 1983; Roeltgen,
1985) and it was speculated that the type of unilateral agraphia may be related to
lesions of a specific part of the corpus callosum (Watson and Heilman, 1983).
The cases described by Sweet (1945) and Watson and Heilman (1983), as well
as our Case 1, are examples of apraxic agraphia of the left (nondominant) hand.
In all of them, the lesion involved the callosal body, sparing most of the genu and

1032

R LEIGUARDA AND OTHERS

splenium. Unilateral apraxic agraphia may therefore be due to interference of
transcallosal transmission of graphomotor engrams from the (verbal) dominant
parietal lobe to the nondominant hemisphere through the body of the callosum.
Aphasic agraphia, on the other hand, has been described in patients with callosal
lesions of variable extent and location. Thus in some patients (as in our Case 3)
the lesion roughly involved the anterior four-fifths of the corpus callosum
(Liepmann and Mass, 1907; Geschwind and Kaplan, 1962; Yamadori et al., 1980;
Goldenberg et al., 1985; Graff-Radford et al., 1987) while in our Case 2, as well
as Case D in Brion and Jedynak (1975), it spared the splenium, most of the genu
and the caudal third of the callosal body. Alternatively, aphasic agraphia has also
been correlated with callosal lesions involving the caudal portion of the body and
the splenium (Brion and Jedynak, 1975, Case D; Gersh and Damasio, 1981;
Yamadori et al., 1983; Degos et al., 1987). As illustrated by our patients, the
anterior form of aphasic agraphia can coexist with ideomotor apraxia (Case 3) or
be dissociated from it (Case 2), depending on how posteriorly the callosal lesion
extends. In contrast, the posterior form is rarely accompanied by apraxia but
usually presents with clinical findings resulting from the disruption of the
interhemispheric transfer of visual information such as double hemianopia,
hemialexia and unilateral visual naming defects (Bogen, 1985).
Unilateral ideomotor apraxia
Apraxia of the nondominant limb in patients with callosal lesions may have
different characteristics. Similar to the patients reported by Liepmann and Mass
(1907), Sweet (1945), Klein and Ingram (1958), Schott et al. (1969), Barbizet et
al. (1978), Watson and Heilman (1983) and Goldenberg et al. (1985), our Cases
1 and 3 had an ideomotor type of apraxia, since they could not use their hand on
command, on imitation or while holding an object. As some of these previously
reported cases also had extensive hemisphere damage, it was speculated that the
extracallosal lesions, particularly in the supplementary motor area, may be
important for the production of apraxia (Gazzaniga et al., 1967; Goldenberg et
al., 1985). In our Cases 1 and 3, however, as well as in those described by Sweet
(1945), Watson and Heilman (1983) and Graff-Radford et al. (1987), the lesion
was restricted to the callosum, supporting the hypothesis that unilateral ideomotor
apraxia may be primarily the result of disconnection of the area containing
the visuokinaesthetic motor engrams in the dominant from the nondominant
hemisphere (Liepmann and Mass, 1907) by a lesion restricted to the callosal body
through which these engrams are presumably transmitted (Watson and Heilman,
1983). Like Case D in Brion and Jedynak (1975), our Case 2 failed to develop
unilateral apraxia of the nondominant limb despite a callosal haemorrhage. It is
possible that these patients had bilateral representation of visuokinaesthetic motor
engrams, as well as verbal comprehension abilities in their nondominant hemisphere
(Heilman and Gonzalez Rothi, 1985). Alternatively, callosal damage may not have

ANTERIOR CALLOSAL HAEMORRHAGE

1033

been extensive enough to interrupt the fibres responsible for the interhemispheric
transmission of these engrams.
Unilateral copying difficulty and dyscalculia

Our 3 patients had difficulty in copying drawings with the hand ipsilateral to
their 'minor' hemisphere; in addition, Case 1 had such a severe spatial dyscalculia
as to interfere with solving written arithmetic problems. The appearance of certain
disorders of visuospatial function in our patients are evidence of the callosal
impairment in the transfer of information from the minor nonlanguage dominant
hemisphere to the dominant one, in keeping with previous reports (Bogen, 1969;
LeDoux et ai, 1978). The clinicopathological study of Degos et al. (1987) has
demonstrated that at least part of the interhemispheric parietal connection
responsible for the transfer of some visuospatial functions travel through the
caudal part of the callosal body and splenium. Since the splenium was intact in
our patients, as well as in the patient of Graff-Radford et al. (1987), we may
assume that these fibres in man course through the posterior half of the callosal
body in agreement with thefindingsof Pandya et al. (1971) in nonhuman primates.
Dissociative phenomena

Other relevant clinical findings in our Cases 1 and 3 were the presence of
intermanual conflict and the 'alien hand' sign. Brion and Jedynak (1972, 1975)
described the presence of the alien hand sign in 6 patients with callosal disconnection
syndrome and found that the damge invariably involved the cllosum from the
splenium caudally to the middle of the body rostrally. This portion of the callosum
was also damaged in our Case 1 and 3, as well as in the cases reported by Watson
and Heilman (1983) and Graff-Radford et al. (1987). On the other hand, this
portion of the callosum was partially spared in our Case 2, and in Case D described
by Brion and Jedynak (1975), who also failed to show the alien hand sign.
The alien hand sign has also been observed in patients with hemisphere lesions,
either in the medial frontal cortex (Goldberg et al., 1981; Watson et al., 1986;
Magnani et al., 1987) or in the posterior cerebral artery territory, sparing the
callosum (Levine and Rinn, 1986). One difference between the 'callosal' and the
'hemisphere' types of alien hand sign is that in patients with the callosal type, the
alien hand sign appears in the hand ipsilateral to the language and motor-dominant
hemisphere, whereas in the hemisphere type, the alien hand sign develops in the
hand contralateral to the lesion, regardless of the pattern of cerebral dominance.
Pathogenesis of callosal haemorrhages secondary to ruptured aneurysms

Crompton (1962) suggested that the direct jet from the ruptured anterior
communicating artery aneurysm or the secondary dissection of an interfrontal
subarachnoid haematoma would cause the blood to pass beneath the rostral
callosal fibres and progress upwards into the septum pellucidum producing a
septal or caval haematoma. From here, the blood may progress into the lateral
ventricle or, more rarely, into the callosum. Less frequently, blood may pass

1034

R LE1GUARDA AND OTHERS

over the dorsum of the callosum, producing a supracallosal or intercingulate
subarachnoid haematoma which may then burst laterally into the parietal white
matter or down into the callosum. None of these mechanisms, however, can
explain the development of the callosal haemorrhage in our Case 3, since the CT
scan showed neither a septal nor a supracallosal or intercingulate haematoma.
We believe that this patient developed a small interfrontal subcallosal haematoma
as a result of the first bleeding and by the time of the second bleed, this haematoma
may have partially resolved, leaving subarachnoid adhesions which may have
provided a route through which the jet of blood reached the callosal genu. A
similar mechanism may apply to Sweet's case (1945) in which a saccular aneurysm
located below the callosal rostrum (in the proximal portion of the anterior cerebral
artery) was surrounded by coagulated blood and projected upwards into the
substance of the callosum. Whatever the mechamsm may be, it would be rather
exceptional, since callosal haematomas after the rupture of anterior communicating
artery aneurysms have invariably presented in association with haemorrhages in
other locations (Crompton, 1962; Yock and Larson, 1980) and not as a single
lesion as in our Case 3.
Bleeding from a pericallosal aneurysm may initially cause an intercingulate
haematoma which later ruptures downwards into the callosum (Crompton, 1962).
Alternatively, the callosal haematoma may be produced by the direct rupture of
the aneurysm into the callosal substance since neither in our Cases 1 and 2 nor
in those reported by Brion and Jedynak (1975) (Case D) and Graff-Radford et
al. (1987) was there any evidence of extracallosal haemorrhage. Two anatomical
features may readily account for the direct bleeding of a pericallosal aneurysm
into the callosum: (1) these aneurysms are usually located at the pericallosal
bifurcation above the genu, where the pericallosal artery often makes a sharp
bend (Laitinen and Snellman, 1960) and (2) these aneurysms are closely attached
to the callosal surface, where there is no subarachnoid cistern into which they can
bleed (Mann et al., 1984).
ACKNOWLEDGEMENTS
This research was supported in part by a grant from the Institute Di Telia. Dr Starkstein was a
recipient of grants from the University of Buenos Aires and the National Alliance of Research in
Schizophrenia and Depression.
The authors are indebted to Professor Robert G. Robinson for his invaluable advice on preparing
the manuscript.
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(Received April 18, 1988. Revised October 11, 1988. Accepted October 21, 1988)