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Clinical Postcard

Delusional misidentification of inanimate objects,
persons, and places after a left orbitofrontal cortex
injury
Miki Tanabe a, Michitaka Funayama b,*, Yota Narizuka a,
Asuka Nakajima a, Isamu Matsukawa a and Tomoyuki Nakamura a
a
b

Department of Rehabilitation, Ashikaga Red Cross Hospital, Tochigi, Japan
Department of Neuropsychiatry, Ashikaga Red Cross Hospital, Tochigi, Japan

article info
Article history:
Received 4 August 2018
Reviewed 8 August 2018
Revised 9 August 2018
Accepted 24 August 2018
Published online xxx
Keywords:
Delusional misidentification
Inanimate objects
Personal misidentification
Orbitofrontal cortex

Delusional misidentification, a condition in which a patient
consistently misidentifies persons and places, rarely involves
inanimate objects. Only two previous reports have described
delusional misidentification of inanimate objects, which was
caused by traumatic brain injury in one case (Abbate et al., 2012)
and by delusional disorders in the other (Castillo & Berman,
1994). A neural basis was suggested in the case presented by
Abbate et al. (2012), as the individual had right temporal lobe
damage, although there must also have been diffuse axonal
injury due to the nature of the traumatic brain injury. Here
we describe a patient who presented with remarkable delusional misidentification of inanimate objects along with

misidentification of persons and places after focal left orbitofrontal cortex damage due to subarachnoid hemorrhage.
The patient was a 61-year-old right-handed man with 12
years of education. He had no past history of neurological or
psychiatric diseases. He suffered rupture of an anterior
communicating artery aneurysm (Hunt and Kosnik Ⅲ), which
was clipped. A ventriculoperitoneal shunt was placed to treat
hydrocephalus. He was admitted to a rehabilitation unit 2
months post-onset, where, although he was alert, he
frequently confabulated and tried to go to work or acted as if
he was working. Because of substantial behavioral symptoms,
he was then moved to the neuropsychiatric unit, where he
continued to receive physical, occupational, and linguistic
rehabilitation.
Upon neurological examination, he showed no palsy or
sensory deficits, and his daily activities in the hospital were
almost independent. He scored 33/36 on Raven's Colored
Progressive Matrices (compared with 29.2 ± 5.4 in 60 sec for
normal controls) (Sugishita & Yamazaki, 1993), suggesting
he had normal intelligence. In contrast, he scored only 3/12
on the Japanese version of the Rivermead Behavioural
Memory Test (cut-off score of 7 for 60 sec) (Watanuki, Hara,
Miyamori, & Etoh, 2002) and 12/18 on the Japanese version
of the Frontal Assessment Battery (compared with 14.6 ± .9
in 60 sec for normal controls) (Kugo et al., 2007), which reflected his episodic memory deficits and frontal dysfunction. His performance on the logical memory of Wechsler
Memory Scale-Revised (Sugishita, 2001) was <2% in comparison with the percentiles for the healthy groups, in
which he confabulated that eggs were broken by a traffic

* Corresponding author. Department of Neuropsychiatry, Ashikaga Red Cross Hospital, Tochigi, 3260843, Japan.
E-mail address: mctkfnym@gmail.com (M. Funayama).
https://doi.org/10.1016/j.cortex.2018.08.021
0010-9452/© 2018 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Tanabe, M., et al., Delusional misidentification of inanimate objects, persons, and places after a left
orbitofrontal cortex injury, Cortex (2018), https://doi.org/10.1016/j.cortex.2018.08.021

2

c o r t e x x x x ( 2 0 1 8 ) 1 e3

accident, rather than a truck loaded with eggs being broken.
In the Frontal Assessment Battery, the subtests in which he
showed a deficit were ‘conceptualization’, ‘mental flexibility’, and ‘motor programming’; in each of these he scored
only one point out of three. Although he spoke fluently,
was able to repeat a sentence correctly, and was able to
comprehend complex command sentences for the most
part, he sometimes showed word-finding difficulties along
with occasional relevant verbal paraphasias, e.g., coffee for
tea or ship for anchor. His overall linguistic score was 8 out
of 10 on the Standard Language Test of Aphasia in Japanese
(Hasegawa, Kishi, Shigeno, Tanemura, & Kusunoki, 1985),
which reflected a poor result on the naming subcategory (12
correct answers out of 20 trials). For praxis, he performed
perfectly on the Standard Performance Test for Apraxia,
which includes use of eight everyday objects, e.g., a toothbrush or a hammer, (Iwata, 2003), suggesting that he did not
show apraxia. These results indicate that even though he
might have committed semantic errors on naming tasks
due to misidentification of objects, he could use everyday
objects at least in an experimental situation. During his
stay in the hospital, however, he often showed confabulation and misidentification of persons and places. He often
said that he was in his shop after he opened the door to his
room in the unit. On one occasion, he confabulated that
someone stole his favorite car from the parking lot in the
hospital. Sometimes he misidentified rehabilitation staff as
his niece or his younger sister, with whom he was very
close. His confabulations occurred daily, whereas misidentification of individuals occurred about once a week.
Computed tomography of his brain demonstrated a lowdensity area in the left orbitofrontal cortex and frontal
pole (Fig. 1).
In contrast to his apraxia test results in an experimental
situation, the patient frequently misidentified inanimate
objects, particularly tools during his stay in the hospital. For
example, he used nail clippers as scissors, and he actually
cut the hairline along his neck with the nail clippers. He used
a toothbrush with toothpaste and tried to shave his beard. He
tried to take outlets off the wall in his room because he
thought they were closets. On another occasion, he called
the wall in his room a refrigerator and said that he put his
snacks in it. Likewise, he told an occupational staff to pass
him his skin lotion from the sink in his room, which he

Fig. 1 e Computed tomography of the patient's head at age
61. A low-density area was evident in the left orbitofrontal
lobe and the left frontal pole.

misidentified as a closet. He tried to pull a piece of disposable
paper towel from a hot water dispenser after he washed his
hands as if it was a paper towel storage box. He tried to unlock doors and lockers in his room or in the unit with his
toothbrush or his glasses in an attempt to go to his shop,
which he thought was located on the opposite side of those
doors and lockers. He sometimes realized his errors when he
was given feedback about these misidentifications from an
occupational therapist, although there were times when he
did not seem to consider this feedback. When an occupational therapist asked him to provide a name for the glasses
that he had just previously used as a key to open a door, he
mistakenly called the glasses a key. In the next moment,
when he was shown those objects by the occupational
therapist, he correctly gave the name of a key and of glasses,
respectively, and was able to use them correctly. Although
his misidentification of tools and their related uses were
noted every day while he was in his room, this behavior
disappeared when he was instructed to use the tools for a
task by an occupational therapist, suggesting that his deficit
differs from apraxia. For the most part, he also used those
tools correctly while he was with other patients and after he
was moved to a room for two patients. His misidentification
of tools remained when he was discharged from the hospital
to a nursing home 7 months post-onset. Confabulation and
misidentification of persons and places then continued,
albeit to a lesser degree. In summary, his misidentifications
and confabulations occurred frequently when he was in his
room, which might have allowed him to remain in his own
world, without acknowledging the reality of the external
world. In contrast, his misidentifications often disappeared
when he was provided external reality cues via other
patients.
This case is unique with respect to the patient's
remarkable misidentification of tools, which were replaced
by a completely different kind of tool. In previous reports
on delusional misidentification of inanimate objects, the
original objects were replaced by an older or lower-quality
one of the same kind, e.g., a new item of jewelry would be
replaced by an older or lower-quality one (Abbate et al.,
2012; Castillo & Berman, 1994). In contrast, in this case,
the individual replaced one tool with a different kind of
tool, e.g., nail clippers being used as scissors. Delusional
misidentification has been associated with frontal lobe lesions, particularly the right frontal lobe (Alexander, Stuss,
& Benson, 1979; Feinberg & Roane, 2005). The lesion in
the patient described here is in the left frontal lobe, which
differs from previous lesions (Alexander et al., 1979;
Feinberg et al., 2005). This difference might reflect the
different kind of misidentification, i.e., tools and persons.
The former is closely associated with the left hemisphere
(Lambon Ralph, Jefferies, Patterson, & Rogers, 2007),
whereas the neural basis of an individual's semantic
memories has been found to reside in the right hemisphere
(Ellis, Young, & Critchley, 1989; Gorno-Tempini et al., 2004).
In addition, the orbitofrontal cortex, which is considered to
have a role in differentiating the mental world from the
external world (Burgess, 2007; Schiner, 2013), might
contribute to substantial misidentification that includes
tools, persons, and places. For example, if he wants to meet

Please cite this article in press as: Tanabe, M., et al., Delusional misidentification of inanimate objects, persons, and places after a left
orbitofrontal cortex injury, Cortex (2018), https://doi.org/10.1016/j.cortex.2018.08.021

c o r t e x x x x ( 2 0 1 8 ) 1 e3

his niece with whom he is close, he might falsely recognize
an occupational therapist as his niece, resulting in
misidentification of persons. If he wants to shave his beard
and yet has no shaving cream or shaver, he might use his
toothbrush to apply toothpaste like shaving cream, i.e.,
delusional misidentification of inanimate objects. When he
wants to go to work, he might think that the door in his
room leads to his office, and he might act as if he is
working in his laundry, reflecting misidentification of place
and confabulation, respectively. This case might shed some
light on the mechanisms behind delusional misidentification and, in particular, on misidentification of inanimate
objects.

Consent
Written informed consent was obtained from the patient and
the patient's wife.

Funding
No funding declared.

Competing interests
The authors declare that they have no competing interests.

Authors’ contributions
MT, MF, YN, and AN acquired case data, designed the study,
and drafted the manuscript. IM and TN supervised the study.

Acknowledgements
We express our sincere thanks to the patient and his family
members.

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Please cite this article in press as: Tanabe, M., et al., Delusional misidentification of inanimate objects, persons, and places after a left
orbitofrontal cortex injury, Cortex (2018), https://doi.org/10.1016/j.cortex.2018.08.021