Neurocase
The Neural Basis of Cognition

ISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/nncs20

A case of prosopometamorphopsia caused by
infarction of the splenium of the corpus callosum
and major forceps
Katsuhiko Ogawa , Takayoshi Akimoto , Keiko Takahashi , Makoto Hara ,
Akihiko Morita , Satoshi Kamei , Hideto Nakajima , Midori Fujishiro , Yutaka
Suzuki , Masayoshi Soma , Elisa Shikata , Akinori Futamura & Mitsuru
Kawamura
To cite this article: Katsuhiko Ogawa , Takayoshi Akimoto , Keiko Takahashi , Makoto
Hara , Akihiko Morita , Satoshi Kamei , Hideto Nakajima , Midori Fujishiro , Yutaka Suzuki ,
Masayoshi Soma , Elisa Shikata , Akinori Futamura & Mitsuru Kawamura (2020): A case of
prosopometamorphopsia caused by infarction of the splenium of the corpus callosum and major
forceps, Neurocase, DOI: 10.1080/13554794.2020.1797819
To link to this article: https://doi.org/10.1080/13554794.2020.1797819

Published online: 27 Jul 2020.

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NEUROCASE
https://doi.org/10.1080/13554794.2020.1797819

A case of prosopometamorphopsia caused by infarction of the splenium of the
corpus callosum and major forceps
Katsuhiko Ogawaa, Takayoshi Akimotoa, Keiko Takahashia, Makoto Haraa, Akihiko Moritaa, Satoshi Kameia,
Hideto Nakajimaa, Midori Fujishirob, Yutaka Suzukic, Masayoshi Somac, Elisa Shikatad, Akinori Futamurae
and Mitsuru Kawamurae
a

Division of Neurology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan; bDivision of Diabetes and Metabolic Diseases,
Department of Medicine, Nihon University School of Medicine, Tokyo, Japan; cDivision of General Medicine, Department of Medicine, Nihon
University School of Medicine, Tokyo, Japan; dDepartment of Clinical Laboratory Medicine, Nihon University School of Medicine, Tokyo, Japan;
e
Department of Neurology, Showa University School of Medicine, Tokyo, Japan
ABSTRACT

ARTICLE HISTORY

An adult female complained of enlargement of right eyes in other people. Diffusion-weighted ima­
ging detected an abnormal high-intensity area in the region from the splenium of the corpus callosum to
the major forceps on the right side. The patient reported that right eyes appeared larger in size, which
suggested prosopometamorphopsia. Adichotic listening test identified left-ear deficit. Acombination of
prosopometamorphopsia and left-ear deficit was not identified in the reported patients.
Prosopometamorphopsia in most of the reported patients included the eye as did that in our patient.
This result suggested the importance of information on the eye in recognizing faces.

Received 3 March 2020
Accepted 14 July 2020

Introduction
Metamorphopsia is a phenomenon where visual objects appear to
be modified to the perceiver (Hishizawa et al., 2015; Lee, 2015;
Saito et al., 2014; Tokita & Tagawa, 2014; Uchiyama et al., 2012).
Metamorphopsia limited to features of faces is called prosopome­
tamorphopsia (Barghouthi & EI Husseini, 2018; Lee, 2015; McCarty
et al., 2017; Saito et al., 2014). Information from the faces of other
people includes expressions and the arrangement of facial com­
ponents such as eyes, nose, and mouth, and are highly important
for perceivers (Nagaishi et al., 2015). In the cerebrum, the ventral
occipitotemporal cortex plays a crucial role in processing informa­
tion from faces (Barghouthi & EI Husseini, 2018; Hishizawa et al.,
2015; Saito et al., 2014; Schroeder et al., 2017). The right cerebrum
is considered to be dominant in processing information from
faces; however, conveyance between each cerebrum through
the corpus callosum is necessary for the integration of information
from faces in each cerebrum to recognize faces precisely
(Hishizawa et al., 2015; Nagaishi et al., 2015; Saito et al., 2014).
Prosopometamorphopsia has been reported in patients with
lesions of the corpus callosum and nearby regions (Amano et al.,
2014; Barghouthi & EI Husseini, 2018; Cho et al., 2011; Ebata et al.,
1991; Funatsu et al., 2017; Ganssauge et al., 2012; Hishizawa et al.,
2015; Imai et al., 1995; Katsura et al., 2010; Kobayashi et al., 2013;
Lee, 2015; McCarty et al., 2017; Nagaishi et al., 2015; Saito et al.,
2014; Schroeder et al., 2017; Tokita & Tagawa, 2014; Uchiyama
et al., 2012). We report here a female patient who showed proso­
pometamorphopsia in addition to left-ear deficit, which is
a symptom of disconnection syndrome (Kasahata et al., 1999;
Landry & Fuente, 2017; Otsuki., 2009; Van der Knaap & van der

CONTACT Katsuhiko Ogawa

ogawa.katsuhiko@nihon-u.ac.jp

© 2020 Informa UK Limited, trading as Taylor & Francis Group

KEYWORDS

Prosopometamorphopsia;
the splenium of the corpus
callosum; the major forceps;
infarction; left-ear deficit

Ham, 2011), caused by infarction of a region from the splenium of
the corpus callosum to the major forceps.

Case description
A 73-year-old right-handed woman noted an acute onset of the
right eyes of other people appearing larger than left eyes and
was admitted to our hospital the next day. Hypertension and
ventricular arrhythmia had been recorded in her past history.
On admission, she was hypertensive (178/93 mmHg) and afeb­
rile (36.5°C). Heart rate was regular at 73 beats per minute.
General internal findings were normal. On neurological exam­
ination, she was alert and conscious and showed good orienta­
tion with regard to names, places, and dates. There were no
abnormalities in the cranial nerves including the visual field and
eye movements, muscle strength or coordination of the four
extremities, deep tendon reflexes of the four extremities, or
standing and gait. Babinski’s sign was negative, as was
a sensory disturbance. For high order functions, a visual per­
ception test for agnosia noted no abnormality of fundamental
functions of visual sensations, topographical orientation, or
cognition of objects, faces, colors, symbols, visual fields. In
sketches of the faces of other people with both eyes, the right
eye was sketched at an enlarged scale compared with the
normal left eye (Figure 1). The right eye was also seen similarly
with one eye. The enlargement of the right eye disappeared
with the presentation of the lateral side of the face. The degree
of enlargement remained unchanged with the presentation of
various proportions of the white of the eye and the iris. On the
analysis of disconnection syndrome, alexia of the left visual
field was not detected. A dichotic listening test was performed

2

K. OGAWA ET AL.

Figure 1. Sketch of faces of other persons. The right eyes of other persons were
visualized with an enlarged size compared with the normal left eye. (Rt = right).

Figure 3. Brain diffusion-weighted magnetic resonance imaging. An abnormal
high-intensity area was shown in the region from the splenium of the corpus
callosum to the major forceps on the right side.

(160 mg/day) and the edaravone (60 mg/day) was performed
in 14 days. Prosopmetamophosia gradually subsided and dis­
appeared at the tenth hospitalized day after admission. After
the therapy of the two drugs, oral administration of aspirin
(100 mg/day) was performed.
Figure 2. Dichotic listening test. A set of three successive numbers was presented
through headphones as unilateral stimuli for 30 trials, then bilateral simultaneous
stimuli were supplied the same time for 30 trials. With the unilateral stimuli, the
rate of the correct answers was perfect (100%) in each ear. With the bilateral
simultaneous stimuli, the correct answer was supplied at a rate of 93% for the
right ear; however, for the left ear the rate was as low as 10%. This result
suggested the presence of left-ear deficit.

as well (Figure 2). One stimulation consisted of the sounds of
three successive numbers. Unilateral stimuli were presented in
each ear (contralateral side; noise) for 30 trials each. Bilateral
simultaneous stimuli were then applied for 30 trials. The answer
rate of each ear for the unilateral stimuli was 100%. With the
bilateral simultaneous stimuli, the answer rate for the left ear
was decreased to 10%, whereas that of the right ear remained
at a high rate of 93%. This result suggested the presence of leftear deficit (Figure 2). Routine blood hematology and biochem­
istry were normal except for a mild increase of cholinesterase.
The cardiac ultrasonography and electrocardiogram were nor­
mal. The carotid artery ultrasonography showed mild athero­
sclerosis of the bilateral internal carotid arteries, not
accompanying stenosis. Diffusion-weighted magnetic reso­
nance imaging (MRI) on admission showed a small highintensity area in the region from the splenium of the corpus
callosum to the major forceps on the right side (Figure 3). The
head magnetic resonance angiography was normal. Based on
the MRI finding, the patient was diagnosed as having cerebral
infarction. Intravenous administration of the ozagrel sodium

Discussion
The corpus callosum is divided into the genu, truncus, and
splenium from the anatomical perspective (Otsuki., 2009).
Function-anatomically, the corpus callosum is divided into the
anterior third, anterior midbody, posterior midbody, isthmus,
and splenium (Otsuki., 2009). The splenium is mainly supplied
with the posterior pericallosal artery originating from the pos­
terior cerebral artery (Goto, 1986). The small infarct was
detected in the distribution of the posterior pericallosal artery
in the patient; however, the results of its location and the
neurological symptoms were inconsistent with the character­
istics of small-artery occlusion in the “Trial of Org 10172 in
Acute Stroke Treatment (TOAST)” classification (Adams et al.,
1993). Thus, the etiology of infarction in the patient was
grouped into the stroke of undetermined etiology in the
TOAST classification (Adams et al., 1993) because the cause of
infarction was indefinite.
Metamorphopsia is a condition in which the size, contour,
shape, color, depth, direction, or number in objects are altered
for perceivers (Hishizawa et al., 2015; Lee, 2015; Saito et al., 2014;
Tokita & Tagawa, 2014; Uchiyama et al., 2012).
Prosopometamorphopsia is a metamorphopsia that is limited to
faces (Barghouthi & EI Husseini, 2018; Lee, 2015; McCarty et al.,
2017; Saito et al., 2014). The ventral occipitotemporal cortex, which
is called the core system (Lee, 2015), is crucial to facial recognition
(Barghouthi & EI Husseini, 2018; Hishizawa et al., 2015; Saito et al.,

NEUROCASE

2014; Schroeder et al., 2017). The core system consists of three
regions; i.e., the occipital face area, the fusiform face area, and faceselective regions in the posterior superior temporal sulcus (Lee,
2015), and plays a central role in the processing facial recognition
(Hishizawa et al., 2015; Lee, 2015; Saito et al., 2014; Schroeder et al.,
2017). Recent studies suggested that information on faces in each
cerebrum is necessitated in the process of facial recognition with
no association with the dominance of the cerebrum and handed­
ness (Nagaishi et al., 2015; Tokita & Tagawa, 2014). Based on this
explanation, information on the right part of the face is predomi­
nantly projected to the right cerebrum (Funatsu et al., 2017;
Nagaishi et al., 2015; Saito et al., 2014). On the other hand, informa­
tion on the left part of the face is predominantly projected to the
left cerebrum (Funatsu et al., 2017; Nagaishi et al., 2015; Saito et al.,
2014). Information on faces in the core system is projected to the
other cerebrum through the corpus callosum and then integrated
to recognize faces (Lee, 2015; Steinmann et al., 2014). In prosopo­
metamorphopsia caused by lesions in the corpus callosum and
nearby regions (Amano et al., 2014; Barghouthi & EI Husseini, 2018;
Cho et al., 2011; Ebata et al., 1991; Funatsu et al., 2017; Ganssauge
et al., 2012; Hishizawa et al., 2015; Imai et al., 1995; Katsura et al.,
2010; Kobayashi et al., 2013; Lee, 2015; McCarty et al., 2017;
Nagaishi et al., 2015; Saito et al., 2014; Schroeder et al., 2017;
Tokita & Tagawa, 2014; Uchiyama et al., 2012), disruption of facial
information in each cerebrum is considered as the cause of proso­
pometamorphopsia (Funatsu et al., 2017; Hishizawa et al., 2015;
Lee, 2015; Nagaishi et al., 2015; Saito et al., 2014; Tokita & Tagawa,
2014). Thus, prosopometamorphopsia of the right-sided face is
caused by a lesion in the right cerebrum (Saito et al., 2014;
Uchiyama et al., 2012), and that of the left-sided face is caused by
a lesion in the left cerebrum (Funatsu et al., 2017; Saito et al., 2014;
Uchiyama et al., 2012). Information on the face in each cerebrum
was considered to be impaired by a lesion in the splenium of the
corpus callosum, which leads to the incidence of prosopometa­
morphopsia in our patient. Prosopometamorphopsia caused by
lesions in the corpus callosum showed simple deformations com­
pared with that caused by lesions in the cerebrum in general
(Nagaishi et al., 2015; Uchiyama et al., 2012) and included deforma­
tion of the eyes in a high rate (Funatsu et al., 2017). In particular,
information on the region of eyes is considered to be highly
important in recognizing faces (Funatsu et al., 2017; Nagaishi
et al., 2015). Prosopometamorphopsia in our patient was
a simple deformation and was limited to the region of the eye.
The laterality of the lesion was consistent with that of prosopome­
tamorphopsia. These results were consistent with those of proso­
pometamorphopsia caused by lesions of the corpus callosum
(Funatsu et al., 2017; Nagaishi et al., 2015; Saito et al., 2014;
Uchiyama et al., 2012).
Eighteen patients have been reported who showed proso­
pometamorphopsia caused by lesions in the corpus callosum
and its nearby regions (Amano et al., 2014; Barghouthi & EI
Husseini, 2018; Cho et al., 2011; Ebata et al., 1991; Funatsu et al.,
2017; Ganssauge et al., 2012; Hishizawa et al., 2015; Imai et al.,
1995; Katsura et al., 2010; Kobayashi et al., 2013; Lee, 2015;
McCarty et al., 2017; Nagaishi et al., 2015; Saito et al., 2014;
Schroeder et al., 2017; Tokita & Tagawa, 2014; Uchiyama et al.,
2012). These 18 patients and our patient are listed in Table 1.
Overall, 13 patients were right-handed including our patient
(Barghouthi & EI Husseini, 2018; Cho et al., 2011; Ebata et al.,

3

1991; Funatsu et al., 2017; Hishizawa et al., 2015; Katsura et al.,
2010; Kobayashi et al., 2013; Lee, 2015; McCarty et al., 2017;
Nagaishi et al., 2015; Tokita & Tagawa, 2014), and 1 patient was
left handed (handedness not reported for the other 5 patients)
(Saito et al., 2014). Diagnosis of lesions was infarction in 16
patients including our patient (Amano et al., 2014; Barghouthi &
EI Husseini, 2018; Cho et al., 2011; Funatsu et al., 2017;
Hishizawa et al., 2015; Imai et al., 1995; Katsura et al., 2010;
Lee, 2015; McCarty et al., 2017; Nagaishi et al., 2015; Saito et al.,
2014; Schroeder et al., 2017; Tokita & Tagawa, 2014; Uchiyama
et al., 2012), resection of arteriovenous malformation in one
patient (Ganssauge et al., 2012), hemorrhage in one patient
(Ebata et al., 1991), and hypoglycemia in one patient
(Kobayashi et al., 2013). Lesions were located on the right side
in nine patients including our patient (Cho et al., 2011; Funatsu
et al., 2017; Hishizawa et al., 2015; Nagaishi et al., 2015; Saito
et al., 2014; Schroeder et al., 2017; Tokita & Tagawa, 2014), and
the left side in nine patients (Amano et al., 2014; Barghouthi &
EI Husseini, 2018; Cho et al., 2011; Ganssauge et al., 2012; Imai
et al., 1995; Katsura et al., 2010; Lee, 2015; McCarty et al., 2017;
Uchiyama et al., 2012). The lesion in one patient with hypogly­
cemia involved the bilateral splenium (Kobayashi et al., 2013).
The lesions involved in the splenium in 13 patients including
our patient (Amano et al., 2014; Barghouthi & EI Husseini, 2018;
Cho et al., 2011; Funatsu et al., 2017; Hishizawa et al., 2015;
Katsura et al., 2010; Kobayashi et al., 2013; Lee, 2015; McCarty
et al., 2017; Nagaishi et al., 2015; Saito et al., 2014) and the
retrosplenium in four patients (Ganssauge et al., 2012; Imai
et al., 1995; Tokita & Tagawa, 2014; Uchiyama et al., 2012). The
lesion in one patient involved either (Ebata et al., 1991), and
that in one patient was located in the major forceps and did not
involve the splenium or the retrosplenium (Schroeder et al.,
2017). No patients had noted prosopagnosia or visual field
defects. Prosopometamorphopsia was present in the lateral
side in 18 patients (Amano et al., 2014; Barghouthi & EI
Husseini, 2018; Cho et al., 2011; Ebata et al., 1991; Funatsu
et al., 2017; Ganssauge et al., 2012; Hishizawa et al., 2015; Imai
et al., 1995; Katsura et al., 2010; Kobayashi et al., 2013; Lee, 2015;
Nagaishi et al., 2015; Saito et al., 2014; Schroeder et al., 2017;
Tokita & Tagawa, 2014; Uchiyama et al., 2012); otherwise, later­
ality of prosopometamorphopsia that was limited to the mouth
was not shown in one patient (McCarty et al., 2017). In compar­
ison with each laterality of prosopometamorphopsia and the
lesion, the laterality was the same in 12 patients including our
patient (Lee, 2015; Uchiyama et al., 2012; Saito et al., 2014;
Barghouthi & EI Husseini, 2018; Nagaishi et al., 2015;
Schroeder et al., 2017; Ebata et al., 1991; Imai et al., 1995; Cho
et al., 2011; Ganssauge et al.; Amano et al., 2014) and opposite
in 5 patients (Cho et al., 2011; Funatsu et al., 2017; Hishizawa
et al., 2015; Katsura et al., 2010; Tokita & Tagawa, 2014). For the
form of prosopometamorphopsia, various types of deformation
were exhibited in all 19 patients (Table 1); however, other types
were infrequent and included brightness in 2 patients
(Ganssauge et al., 2012; Imai et al., 1995) and doubling in 1
patient (Nagaishi et al., 2015). These results on the laterality and
contents of prosopometamorphopsia were consistent with the
previously reported characteristics (Funatsu et al., 2017; Lee,
2015; Nagaishi et al., 2015; Uchiyama et al., 2012). For the extent
of prosopometamorphopsia, the region of the eye was

rt

n.d.
rt

rt
rt

rt

53/m

68/f

57/m

29/f

61/f

75/m

67/m
78/f

70/f

52/f

62/m

58/f

66/f
67/f

73/f

Ganssauge et al. (2012)

Uchiyama et al. (2012)

Kobayashi et al. (2013)

Saito et al. (2014)

Tokita and Tagawa
(2014)
Amano et al. (2014)
Nagaishi et al. (2015)

Hishizawa et al. (2015)

Lee (2015)

McCarty et al. (2017)

Schroeder et al. (2017)

Funatsu et al. (2017)
Barghouthi and EI
Husseini (2018)
Our case

rt entire face (back-shifted,
deformed)
lt eye (adducted)
lt eye (moved to the outside and
upward)
rt eye (enlarged)

lt upper face including eye
(unnatural)
rt entire face (distorted, drooped,
shortened)
lt eye and eyebrow (dropped,
micropsia)
lt jaw and outer canthus (distorted)
rt eye (micropsia, macropsia,
doubled), eyebrow (cut off, blink), nostril
(micropsia), corner of
mouth (raised)
lt eye and corner of mouth (hung
up)
lt eye (micropsia), lip and cheek
(swollen)
mouth (distorted, enlarged)

−

−
−

−

−

−

−

−
rt side of objects
(doubled,
deepened)

−

−

lt side of objects
(stretched
outward)
−

−

−

lt side of objects
and
numbers
(blurred)
−
−

objects (contents)
−

other
metamorphopsia

−

−
−

−

−

−

−

−
−

−

−

−

−

−

−

−
−

−

prosopopagnosia
−

−

−
−

slightly
distorted
central
field**
−

−

−

−
−

−

−

−

−

−

−

−
−

−

visual field
defect
−

−

−

−

−
−

−

−

disconnection
syndrome

−

−
−

−

TGA (3 years
before)

−

−

−
−

left-ear deficit

−
−

−

alexia (letter
/number)

−

−

−
−

infarction
infarction

infarction

diagnosis of
lesions
hemorrhage

rt splenium to
major forceps

rt posterior CG,
major forceps
rt splenium
lt splenium

lt splenium

lt splenium

rt splenium

lt splenium
rt splenium

infarction

infarction
infarction

infarction

infarction

infarction

infarction

infarction
infarction

infarction

hypoglycemia
infarction

lt retrosplenium to o/t resection of
junction
AVM
lt retrosplenium
infarction

rt area and midline of infarction
splenium

lt splenium
lt splenium

locations of
lesions
rt retrosplenium
to splenium
boundary of lt CG
and retrosplenium

oversight (lt letters, rt lines alexia of lt visual bil splenium
and figures
field
−
−
rt splenium to
major forceps
−
−
rt retrosplenium

−

−

−

−
−

other neurological
findings
loss of superficial
sensation in lt face*
−

The impaired side including metamorphopsia describing the laterality of the object or person. Abbreviations; AVM: arteriovenous malformation, bil: bilateral, CG: cingulate gyrus, CC: corpus callosum, f: female, lt: left, m: male, n.d.:
not described, o/t: occipitotemporal, rt: right, TGA: transient global amnesia. * This symptom was caused by an old putaminal hemorrhage on the right side. ** This symptom was associated with tortuosity of the optic nerves.

n.d.

rt

rt

rt

lt

rt

n.d.

n.d.

rt

rt entire face (distorted)
lt eye (elongated outward), nose
and mouth (bent downward)
lt eyelid (swollen), nose (bent
downward), facial outline (bulged
and writhed)
lt eye (distortion, micropsia,
brightened)
lt entire face (stretched outward)

Cho et al. (2011)

rt
rt

67/f
58/f

Katsura et al. (2010)
Cho et al. (2011)

Imai et al. (1995)

prosopometamorphopsia
age/ handedsex
ness
region (contents)
60/f
rt
rt entire face (micropsia), facial
outline (distortion)
51/f
n.d.
lt entire face (dropped and
darkened)

authors
(years)
Ebata et al. (1991)

Table 1. Nineteen patients with prosopometamorphopsia caused by lesions in the corpus callosum and its nearby regions.

4
K. OGAWA ET AL.

NEUROCASE

included in 17 patients including our patient (Barghouthi & EI
Husseini, 2018; Cho et al., 2011; Ebata et al., 1991; Funatsu et al.,
2017; Ganssauge et al., 2012; Hishizawa et al., 2015; Imai et al.,
1995; Katsura et al., 2010; Kobayashi et al., 2013; Lee, 2015;
Nagaishi et al., 2015; Saito et al., 2014; Schroeder et al., 2017;
Tokita & Tagawa, 2014; Uchiyama et al., 2012). In particular, sole
involvement of the eye was shown in five patients including
our patient (Barghouthi & EI Husseini, 2018; Funatsu et al., 2017;
Ganssauge et al., 2012; Tokita & Tagawa, 2014). This result
suggested the importance of information from the region of
eyes in recognizing faces (Funatsu et al., 2017; Hishizawa et al.,
2015; Nagaishi et al., 2015).
Disconnection syndrome is caused by lesions in the cor­
pus callosum (Kasahata et al., 1999; Otsuki., 2009). Lesions in
the splenium of the corpus callosum often cause alexia and
anomia of the left visual field and left-ear deficit (Kasahata
et al., 1999; Landry & Fuente, 2017; Otsuki., 2009; Van der
Knaap & van der Ham, 2011). Left-ear deficit indicates the
presence of verbal extinction of the left ear and is also called
the right-ear advantage (Van der Knaap & van der Ham,
2011). This phenomenon is confirmed by a dichotic listening
test (Landry & Fuente, 2017; Otsuki., 2009). In the 19 patients
(Table 1), 2 patients noted alexia (Kobayashi et al., 2013;
McCarty et al., 2017). Alexia in one patient was noted in
the left visual field (Kobayashi et al., 2013), although the
visual field of alexia in another patient was not identified
(McCarty et al., 2017). A combination of prosopometamor­
phopsia and left-ear deficit was identified in our patient
alone among the 19 patients (Table 1). In the auditory path­
way (Figure 4) (England & Wakely., 1991), the hair cells in the
cochlea are innervated by bipolar neurons whose cell bodies
are located in the spiral ganglion (England & Wakely., 1991).
Neurofibers of bipolar neurons run in the cochlear division of
the vestibulocochlear nerve (VIII) in the pontomedullary junc­
tion. On entering the brainstem, the neurofibers separate
into the dorsal cochlear nucleus and the ventral cochlear
nucleus. Some neurofibers from the two nuclei ascend in
the lateral lemniscus through the superior olivary nucleus
on the ipsilateral side and then approach the inferior collicu­
lus. On the other hand, other neurofibers from the ventral
cochlear nucleus decussate through the trapezoid body and
join the decussated neurofibers from the dorsal cochlear
nucleus. These joined neurofibers ascend in the lateral lem­
niscus, and then approach the inferior colliculus. From the
nucleus of the inferior colliculus, neurofibers approach the
medial geniculate body through the brachium of the inferior
colliculus, and then the next neurofibers in the auditory
radiation finally approach the primary auditory cortex. Some
neurofibers decussate at the level of the nuclei of the lateral
lemniscus and the inferior colliculus (England & Wakely.,
1991). Accordingly, each auditory cortex receives auditory
information from the bilateral ears (England & Wakely.,
1991). Furthermore, each primary auditory cortex is con­
nected to one another through the posterior third, isthmus,
and splenium in the corpus callosum (Figure 4) (England &
Wakely., 1991; Otsuki., 2009). With unilateral sound stimuli,
auditory information is processed bilaterally; however, with

5

Figure 4. The auditory pathway from the cochlea (modified from the original
figure by England MA and Wakely J (England & Wakely., 1991)). The first
neurofibers arising from the cochlea approach the ventral and dorsal cochlear
nuclei in the pontomedullary junction. Part of the neurofibers from the two nuclei
ascend in the ipsilateral lateral lemniscus. The other neurofibers from the two
nuclei decussate in the pontomedullary junction and ascend in the contralateral
lateral lemniscus. The neurofibers on both sides approach the primary auditory
cortex through the inferior colliculus and the medial geniculate body. Each of the
primary auditory cortex receives neurofibers from the opposite cortex through
the corpus callosum. Some neurofibers decussate at the nuclei of the lateral
lemniscus and the inferior colliculus.

the bilateral simultaneous stimuli, the contralateral (decus­
sated) auditory pathway becomes dominant because the
ipsilateral auditory pathway is suppressed (Otsuki., 2009;
Van der Knaap & van der Ham, 2011). Furthermore, with
the bilateral simultaneous stimuli of different verbal sounds,
the left cerebrum becomes dominant because the left cere­
brum possesses the function to discriminate verbal sounds
(Otsuki., 2009; Van der Knaap & van der Ham, 2011). In this
process, verbal sounds from the right ear are easy to discri­
minate because they enter the left primary auditory cortex
directly (Otsuki., 2009; Van der Knaap & van der Ham, 2011).
On the other hand, verbal sounds from the left ear enter the
right primary auditory cortex, then they next approach the
left primary auditory cortex through the corpus callosum.
However, in cases with dysfunction of the corpus callosum,
it is hard for verbal sounds from the left ear to approach the
left cerebrum because there is little conveyance in the corpus
callosum (Otsuki., 2009; Van der Knaap & van der Ham, 2011).
As a result, left-ear deficit can occur. In our patient, the
conveyance of verbal sounds from the left ear was consid­
ered to be inhibited in the right part of the splenium of the
corpus callosum, which caused left-ear deficit.
In conclusion, the highly importance of information from eyes
was indicated in recognizing faces. Prosopometamorphopsia
limited to the eye like our patient also supported this considera­
tion. Left-ear deficit was identified, based on a dichotic listening

6

K. OGAWA ET AL.

test. These two symptoms suggested dysfunction of conveyance
between each cerebrum through the corpus callosum.

Disclosure statement
The authors state they have no Conflicts of Interest (COI) to disclosure.

References
Adams, H. P., Jr., Bendixen, B. H., Kappelle, L. J., Biller, J., Love, B. B., Gordon, D. L.,
& Marsh, E. E., 3rd. (1993). Classification of subtype of acute ischemic stroke.
Stroke, 24, 35–41. https://doi.org/10.1161/01.STR.24.1.35
Amano, S., Katsura, N., & Yamagata, M. (2014). Two patients of metamor­
phopsia caused by brain infarction [Dictionary of the Japanese
language]. Acta Medica Hachinohe (Journal of Hachinohe Japanese Red
Cross Hospital), 11, 17–22.
Barghouthi, T., & EI Husseini, N. (2018). Prosopometamorphopsia secondary
to a left splenium of the corpus callosum infarct. BMJ Case Reports, 2018.
https://doi.org/10.1136/bcr-2018-224735
Cho, J. Y., Moon, S. Y., Hong, K. S., Cho, Y. J., Kim, S. C., Hwang, S. I., Seo, S. Y.,
Kim, J. E., & Park, H. K. (2011). Teaching neuroimages: Unilateral proso­
pometamorphopsia as a dominant hemisphere-specific disconnection
sign. Neurology, 76, e110. https://doi.org/10.1212/WNL.
0c013e31821d74a0
Ebata, S., Ogawa, M., Tanaka, Y., Mizuno, Y., & Yoshida, M. (1991). Apparent
reduction in the size of one side of the face associated with a small
retrosplenial haemorrhage. Journal of Neurology, Neurosurgery, and
Psychiatry, 54, 68–70. https://doi.org/10.1136/jnnp.54.1.68
England, M. A., & Wakely., J. (1991). Hearing: A colour atlas of the brain &
spinal cord. Wolfe Publishing Ltd.
Funatsu, N., Hayakawa, M., Tokuda, N., & Toyoda, K. (2017). Transient
prosopometamorphopsia restricted to the left eye caused by ischemia
at the right splenium of the corpus callosum. Internal Medicine, 56,
2933–2935. https://doi.org/10.2169/internalmedicine.8295-16
Ganssauge, M., Papageorgiou, E., & Schiefer, U. (2012). Facial dysmorphop­
sia: A notable variant of the “thin man” phenomenon ? Graefe’s Archive
for Clinical and Experimental Ophthalmology, 250, 1491–1497. https://doi.
org/10.1007/s00417-012-1958-z
Goto, N. (1986). Cerebral arteries. Anatomy of the brain vessels [Dictionary of
the Japanese language]. Medical Tribune.
Hishizawa, M., Tachibana, N., & Hamano, T. (2015). A case of left hemifacial
metamorphopsia by a right retrosplenial infarction [Dictionary of the
Japanese language]. Rinsho Shinkeigaku (Clinical Neurology) (Journal of
Japanese Society of Neurology), 55, 87–90. (with English abstract).
Imai, N., Nohira, O., Miyata, K., Okabe, T., & Hamaguchi, K. (1995). A case of
metamorphopsia caused by a very localized spotty infarct [Dictionary of
the Japanese language]. Rinsho Shinkeigaku (Clinical Neurology) (Journal
of Japanese Society of Neurology), 35, 302–305. (with English abstract).
Kasahata, N., Kawamura, M., Shiota, J., & Mizobuchi, A. (1999). Disturbance
of color naming, alexia of the visual field and left ear extinction caused
by tumor lesion in splenium of corpus callosum [Dictionary of the
Japanese language]. Shitsugosho Kenkyu (Journal of Japan Society for
Higher Brain Dysfunction), 19, 122–127. (with English abstract).
Katsura, N., Konno, K., & Yamagata, M. (2010). A case of corpus callosum
infarction with unilateral facial metamorphopsia [Dictionary of the
Japanese language]. Nihon Naika Gakkai Zasshi (Journal of Japanese

Society of Internal Medicine), 99, 1318–1320. (with English abstract).
https://doi.org/10.2169/naika.99.1318.
Kobayashi, K., Ikejiri, Y., Toma, K., Udaka, F., & Ojigashi, Y. (2013). A case of
callosal disconnection syndrome with lateralization of visibility by the
difference for vision object [Dictionary of the Japanese language]. Ninchi
Rihabiliteishon (Journal of Society of Cognitive Rehabilitation), 18, 10–18.
(with English abstract).
Landry, S. P., & Fuente, A. (2017). Dichotic listening deficit associated with
solvent exposure. Oto Neurotol, 38, e68–e74. https://doi.org/10.1097/
MAO.0000000000001445
Lee, C. M. (2015). Splenial corpus callosum infarction presenting with unilateral
prosopometamorphopsia: A case report. Dementia and Neurocognitive
Disorders, 14, 94–97. https://doi.org/10.12779/dnd.2015.14.2.94
McCarty, C. W., Gordon, G. M., Walker, A., Delio, P., Kolarczyk, R. A., &
Pieramici, D. J. (2017). Prosopometamorphopsia and alexia following
left splenial corpus callosum infarction: Case report and literature
review. eNeurologicalSci, 6, 1–3. https://doi.org/10.1016/j.ensci.2016.08.
002
Nagaishi, A., Narita, T., Gondo, Y., Nakane, S., Fukudome, T., & Matsuo, H.
(2015). Left-sided metamorphopsia of the face and simple objects
caused by an infarction at the right of the splenium of the corpus
callosum [Dictionary of the Japanese language]. Rinsho Shinkeigaku
(Clinical Neurology) (Journal of Japanese Society of Neurology), 55,
465–471. (with English abstract).
Otsuki., M. (2009). Neuropsychological impairment following callosal and
related lesions [Dictionary of the Japanese language]. Noushinkeigeka
(Japanese Journal of Neurosurgery) (Journal of IGAKU-SHOIN), 18,
179–186. (with English abstract).
Saito, Y., Matsunaga, A., Yamamura, O., Ikawa, M., Hamano, T., &
Yoneda, M. (2014). A case of left hemi-facial metamorphopsia
induced by infarction of the right side of the splenium of the
corpus callosum [Dictionary of the Japanese language]. Rinsho
Shinkeigaku (Clinical Neurology) (Journal of Japanese Society of
Neurology), 54, 637–642. (with English abstract).
Schroeder, C., Schroeder-Gold, C., Beherendt, V., Grüter, T., Lukas, C.,
Gold, R., & Krogias, C. (2017). Unilateral right prosopometamorphopsia
with positive “half-face-covering-test” after small occipitotemporal
stroke. Journal of the Neurological Sciences, 379, 247–248. https://doi.
org/10.1016/j.jns.2017.06.025
Steinmann, S., Leicht, G., & Mulert, C. (2014). Interhemispheric auditory
connectivity: Structure and function related to auditory verbal
hallucinations. Frontiers in Human Neuroscience, 8, 2014. https://doi.
org/10.3389/fnhum.2014.00055
Tokita, H., & Tagawa, K. (2014). A case of metamorphopsia and micropsia of
physiognomy caused by cerebral infarction in the right retrosplenial
region [Dictionary of the Japanese language]. Kouji Kinoukenkyu
(Higher Brain Functional Research) (Journal of Japan Society for Higher
Brain Dysfunction), 34, 260–263. (with English abstract).
Uchiyama, Y., Iwata, M., & Uchiyama, S. (2012). A case of metamor­
phopsia caused by a small infarction adjacent to the posterior
corpus callosum of the left side [Dictionary of the Japanese
language].
Shinkei
Shinrigaku
(Japanese
Journal
of
Neurophysiology) (Journal of Neurophysiology Association of Japan),
28, 229–235. (with English abstract).
van der Knaap, L. J., & van der Ham, I. J. (2011). How does the corpus
callosum mediate intrahemispheric transfer? A review. Behavioural
Brain Research, 223, 211–221. https://doi.org/10.1016/j.bbr.2011.04.
018