Unusual presentation of more common disease/injury

Case report

Stroke of the inferiomedial temporal lobe causing
word agnosia
Hardi Hassan,1 Huq Ehsanula,2 Mahendra Pattanshetti2
1

University Hospitals Coventry
and Warwickshire NHS Trust,
Coventry, UK
2
Maidstone and Tunbridge Wells
NHS Trust, Tunbridge Wells, UK
Correspondence to
Dr Hardi Hassan,
​hardi_​galali@​hotmail.​com
Accepted 20 June 2017

SUMMARY
A 69-year-old man presented with sudden loss of ability
to recognise written words and remember the meaning
of words and names. He could not name the town he
lived in nor name his children. It was difficult for him to
remember the meaning of concrete and abstract nouns.
His speech fluency and understanding of casual talks
were normal. He remembered that he had a conversation
with his family that morning, but not the exact content.
He was referred to the transient ischaemic attack clinic
by his general practitioner as he scored low on the
abbreviated mental test score. He underwent a brain
MRI scan (T2 weighted, diffusion weighted and fluidattenuated inversion recovery) which showed an acute
infarction in the left medial temporal region affecting the
fusiform and parahippocampal gyri. He also noticed that
it was easier to retrieve numbers, for example, his mobile
number. He recovered on waking up the next day.

Background
This was a rare and elusive presentation for a
stroke. It involved the posterior choroidal artery
territory, presenting with purely cognitive issues. It
was noticed, in this particular case, that retrieving
memorised numbers was easier than names. This
is an opportunity to study the function of the left
inferiomedial aspect of the temporal lobe (involving
parts of the fusiform and parahippocampus gyri)
and its involvement in the processing of word
meaning and cognition.

Case presentation

To cite: Hassan H,
Ehsanula H, Pattanshetti M.
BMJ Case Rep Published
Online First: [please
include Day Month Year].
doi:10.1136/bcr-2015214184

A 69-year-old right-handed man had a 4-day history
of early morning mild headaches. On the morning
of his presentation, he was reading a book when
suddenly noticed that he could not remember or
make out the meaning of the written words. His
wife noticed that he could not understand language
involving names of objects and people. When his
symptoms continued, he decided to see his general
practitioner who recorded amnesia to names, but
not numbers. For example, he was not able to recall
the name of the city and the road where he lived and
could not recall his children’s names despite recognising them by their faces. He could not process
their names even when mentioned to him. However,
he noticed that he could easily remember numbers
such as his mobile number. Symptoms improved
by the end of the day, and he awoke the following
day feeling back to normal. His speech was not
affected with regard to grammar and fluency. He

had no other bodily symptoms and no disturbance
of vision.
He was seen in the transient ischaemic attack
(TIA) clinic the following day, and a brain MRI scan
showed an acute left inferiomedial temporal lobe
infarction affecting the parahippocampus and fusiform gyrus. His subsequent investigations showed
no obvious embolic cause for the stroke.
He was well and performing back to his normal
self both cognitively and physically on follow-up
4 weeks later. He received clopidogrel, simvastatin
and blood pressure management for secondary
prevention.

Investigations
The MRI brain scan showed an acute infarction
in the left parahippocampal gyrus extending to
the fusiform gyrus. This was apparent on the
T2-weighted (T2W) images (figure 1), diffusion-weighted imaging (figure 2) and fluid-attenuated inversion recovery (figure 3). They were
in the territory of the posterior choroidal artery.
Scans of the cervical arteries, echocardiogram
and 48-hour Holter monitor showed no obvious
cause for an embolic stroke. His cholesterol was
6 mmol/L; low-density lipoprotein, 3.6 mmol/L;
and high-density lipoprotein, 3.5 mmol/L, with
normal thyroid-stimulating hormone, full blood
count, renal function and liver function.

Differential diagnosis
After discussing the symptoms, it was believed that
they did not fulfil the criteria for a transient global
amnesia or a seizure activity. A brain MRI scan
was arranged as the diagnosis, and brain territory
was not clear from the history. The sudden onset
of symptoms raised the possibility of a vascular
event, together with the impaired language skills
without a change in his behaviour or level of
consciousness.

Treatment
This man was duly started on secondary prevention
measures for ischaemic strokes, which included
perindopril, simvastatin and clopidogrel.

Outcome and follow-up
He was discharged from hospital as all his symptoms resolved by the following day when seen in
the TIA clinic. He remained well with no further
symptoms on follow-up 4 weeks later.

Hassan H, et al. BMJ Case Rep 2017. doi:10.1136/bcr-2015-214184

1

Unusual presentation of more common disease/injury

Figure 3 T2 fluid-attenuated inversion recovery showing the
infarction in the left middle and anterior fusiform gyrus and the
parahippocampal gyrus.

Figure 1 T2-weighted MRI brain showing inferiomedial left temporal
lobe ischaemia.

Discussion

Speech and language mapping in the brain has been studied
extensively in patients with dysfunction of the temporal lobes
due to epilepsy or structural damage in this area due to trauma
or vascular causes such as stroke. Cognition disturbance also has
a significant impact on processing speech and functional MRI
has recently contributed significantly to our understanding of
the function of the inferiomedial temporal lobes.1–4
To date, our understanding of the fusiform gyrus confirms its
contribution in visual perception and recognition. The middle
and posterior parts are mostly involved in word recognition,
and impairment in this area causes alexia (inability to read) and
word agnosia.5 6 The left fusiform gyrus is also involved in global
aphasia with loss of repetition, agraphia (inability to write) and
alexia.7 8 However, the right fusiform gyrus, mainly mid and
posterior parts, is involved in facial recognition, and their functional impairment causes prosopagnosia (loss of facial recognition).9
On the other hand, anomia (inability to name objects) localises to the inferior temporal gyrus and/or parahippocampus.2

In cases with alexia and agraphia, it was noticed that when there
was anomia, the lesion extended laterally to the anterior part
of the middle temporal gyrus or medially toward the parahippocampus.10 Therefore, anomia can be the result of any disruption affecting the interconnection between the lateral temporal
surface and the inferiomedial aspect of the lobe. This disruption
is commonly caused by a vascular event and less frequently by
other causes such as epilepsy and neurodegeneration.11
In our case, we were intrigued to find that retrieval of numbers
seemed to be intact. This led us to understand that processing
numbers and the meaning of words involve different pathways
or lateralisation. That of words involves the parahippocampus
(causing the anomia in this patient) and the fusiform gyrus
(leading to word agnosia in this patient). However, processing
numbers is related to the parietal lobes.12 Human cognition
and language apply logic and arithmetic constantly involving
complex symbolic, non-symbolic and numerical sequence
retrievals and processing.4 13 Recall of numerical sequence and
calculation is used in cognitive assessments, and we think that
incorporating it in clinical assessments may help to predict the
cognitive outcome in diseases such as stroke. In our case, the
numerical processing and sequence retrieval were intact, and he
had full cognitive recovery.

Learning points
►► MRI diffusion-weighted imaging is a crucial investigative

tool and should be readily available to transient ischaemic
attack (TIA) clinics and acute stroke services. CT brain is
mostly useful in cases of haemorrhagic strokes.
►► This case shows the role of the left parahippocampus and
fusiform gyrus in processing language.
►► Both anterior and posterior choroidal artery territory
ischaemic events are often thrombotic and not embolic.
►► Disturbed language skill without a global brain dysfunction
is a reliable clinical sign of a structural brain lesion (included
in one of the cortical signs of strokes or TIAs).
►► Always think of a vascular event when faced with an acute
neurological deficit.
Acknowledgements The authors thank Dr Anthony Kenton and Dr Don Sims who
helped with editing the text and reviewing the content of this case report.
Contributors This case was assessed and managed by all the three contributors.
We all participated in the clinical assessment, investigations and delivering the
health care to the patient. We also consulted with each other when reporting this
case, as we found it unique and very elusive in the way it presented. This is an
original case, and after extensive literature research, we decided to report it to share
our knowledge and understanding in order to improve the care given to stroke and
TIA sufferers.

Figure 2 Diffusion-weighted image showing the acute infarction in
the left inferiomedial temporal lobe.
2

Competing interests None declared.
Patient consent Obtained.
Hassan H, et al. BMJ Case Rep 2017. doi:10.1136/bcr-2015-214184

Unusual presentation of more common disease/injury
Provenance and peer review Not commissioned; externally peer reviewed.
© BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) . All
rights reserved. No commercial use is permitted unless otherwise expressly granted.

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