Unusual presentation of more common disease/injury

CASE REPORT

Aphasia due to isolated infarction of the corpus
callosum
Sami Saba, Sonja Blum
Department of Neurology,
NYU, New York, New York,
USA
Correspondence to
Dr Sonja Blum,
Sonja.blum@nyumc.org

SUMMARY
A 63-year-old man with an isolated infarction of the
corpus callosum developed expressive aphasia in
addition to the deficits traditionally associated with a
disconnection syndrome.

Accepted 25 May 2014

BACKGROUND
We report a case of isolated corpus callosum infarction, made unusual by the presence of expressive
aphasia in addition to the deficits traditionally associated with a disconnection syndrome.1 2 We
review the speech deficits which have been
reported following corpus callosum lesions, such as
dysarthria and stuttering, and consider possible
anatomical underpinnings of aphasia following a
callosal lesion.

CASE PRESENTATION
A 63-year-old right-handed man with a medical
history significant for coronary artery disease and
prior myocardial infarction experienced two episodes of systemic hypotension in the days after coronary
artery
bypass
surgery.
Afterwards,
neurological examination was notable for poor initiation of speech, decreased verbal fluency, wordfinding difficulty, impaired repetition, dysprosody
and hypophonia, but with intact comprehension.
He also exhibited many aspects of the callosal disconnection syndrome, including left hemifield paralexia, left ideomotor apraxia, left-hand agraphia,
left tactile anomia, intermanual conflict, left visual
extinction, left tactile extinction, blinded finger
anomia and bilateral agraphaesthesia. He exhibited
anosognosia for all deficits except for a vague
notion of ‘problem speaking’.

To cite: Saba S, Blum S.
BMJ Case Rep Published
online: [ please include Day
Month Year] doi:10.1136/
bcr-2014-204316

INVESTIGATIONS
MRI of the brain revealed acute ischaemia (indicated by the presence of hyperintense signal on
diffusion-weighted imaging sequence with correlated apparent diffusion coefficient (ADC) hypointensity) in part of the genu and almost the entirety
of the right body of the corpus callosum (figure 1),
in addition to two punctate areas of diffusion
restriction in the right medial frontal lobe and right
precentral gyrus. The rostrum and splenium of the
corpus callosum were minimally affected, and cortical language areas were intact. Magnetic resonance angiography of the head and neck was
significant for diffuse intracranial atherosclerosis
with extensive stenosis of multiple intracranial
vessels. Specifically, there was narrowing of the
supraclinoid segment of the right internal carotid
artery, with narrow and irregular calibre of the
proximal A1 segment and incomplete visualisation
of the distal A1 of the right anterior cerebral artery
(ACA). Thus the proposed mechanism of injury
was hypoperfusion in the territory of the severely
stenosed right ACA, namely in its right pericallosal
artery territory, during the two episodes of systemic
hypotension following coronary bypass surgery.

TREATMENT
The patient spent 2 weeks in an inpatient neurorehabilitation unit undergoing daily physical, occupational and speech therapy. Care was taken to
provide specialised therapeutic strategies, including
double simultaneous presentation of visual and
tactile stimuli, that catered to his specific deficits.
These included training in visual scanning, attentional training and perceptual retraining that are
conventionally used in patients with unilateral
neglect.3

Figure 1 MRI of the brain showing restricted diffusion in the right body of the corpus callosum, with relative sparing
of the genu and the splenium.

Saba S, et al. BMJ Case Rep 2014. doi:10.1136/bcr-2014-204316

1

Unusual presentation of more common disease/injury
OUTCOME AND FOLLOW-UP
Over the subsequent weeks, there was significant improvement
in all of the patient’s symptoms. At 4 weeks after the onset of
the initial neurological deficit, verbal fluency and repetition had
improved, as had the ideomotor apraxia, intermanual conflict
and left hemipseudoneglect. However, the paucity of spontaneous speech, hypophonia and dysprosody remained.

DISCUSSION
Peculiar speech abnormalities have been described following
corpus callosum infarction/injury, including stuttering.4 French
accent5 dysarthria6 and verbal aspontaneity.7 Aphasia as a
symptom of corpus callosum infarction is rare. In one series,
only 4 of 36 patients with callosal infarcts had decreased verbal
fluency, but these all had left-sided lesions, and all but one of
these had significant cortical involvement as well.8 In another
series of 48 consecutive patients with anterior cerebral artery
infarctions, transcortical motor aphasia was found in 10 of 30
patients with left-sided infarcts and 1 of 16 with a right-sided
infarct, all of whom had involvement of the supplementary
motor area or the subcortical white matter underlying it.9
A recent report described a case of expressive aphasia following
infarct of the right body of the corpus callosum, associated with
dysprosody and hypophonia.10 The proposed mechanism of
aphasia was transcallosal diaschisis in the primary language
cortex, which was supported by a relative hypoperfusion of the
left frontotemporal junction on single-photon emission CT,
despite normal MRI appearance of that area. In our patient
with aphasia and no structural abnormalities in the primary language areas of the left hemisphere or the supplementary motor
area in either hemisphere, a similar mechanism can be hypothesised. Alternatively, the aetiology of the language deficit may be
due to damage to fibres from the inferior frontal lobe language
area which pass through the genu and rostrum of the corpus callosum.11 However, the genu and splenium were relatively
spared, making this less likely.
Many of the deficits observed in our patient were manifestations of a verbal–motor disconnection: verbal commands that
are comprehended by the left hemisphere are unable to cross
into the right hemisphere to direct the appropriate movements
of the left hand.12 Aspects of recovery over the period of weeks
following the infarct suggest that the right hemisphere regained
access to language comprehension. This may occur through the
pathways that cross through the splenium, which was spared in
this patient, or through strengthening of subcallosal interhemispheric pathways.13 Through observation of another patient
with an infarct of the body and the splenium with expressive
aphasia that rapidly improved, it has been postulated that
semantic memory of objects and shapes is bilaterally

represented, and may only require training to gain access to
these faculties.14

Learning points
▸ Isolated infarction of the corpus callosum is rare.
▸ Expressive aphasia may be part of the callosal disconnection
syndrome.
▸ Most deficits following callosal injury improve significantly
and rapidly with therapy.

Contributors SS prepared initial draft of case report and SB was involved in
editing of case report and choice of images.
Competing interests None.
Patient consent Obtained.
Provenance and peer review Not commissioned; externally peer reviewed.

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Saba S, et al. BMJ Case Rep 2014. doi:10.1136/bcr-2014-204316