2006

Case Reports / Journal of Clinical Neuroscience 21 (2014) 2006–2008

Conflicts of Interest/Disclosures
The authors declare that they have no financial or other conflicts of interest in relation to this research and its publication.
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http://dx.doi.org/10.1016/j.jocn.2014.05.009

Listeria monocytogenes brainstem infection (rhombencephalitis)
mimicking ischemic stroke
S. Marini a, A. Caruso b, M. Falcini b, P. Palumbo b, L. Pantoni c,⇑
a
b
c

Neuroscience Section, NeuroFARBA Department, University of Florence, Florence, Italy
Unità operativa degenza cerebrovascolare, Nuovo Ospedale di Prato, Italy
Stroke Unit and Neurology, Azienda Ospedaliero Universitaria Careggi, Largo Brambilla 3, Florence 50134, Italy

a r t i c l e

i n f o

Article history:
Received 24 January 2014
Accepted 10 March 2014

Keywords:
Brain abscess
Listeria monocytogenes
Rhombencephalitis
Stroke mimics

a b s t r a c t
The frequency of Listeria monocytogenes (Lm) infection of the central nervous system is increasing. We
report a patient recently treated with chemotherapeutic drugs for pulmonary adenocarcinoma who
suddenly developed hemiparesis, was initially diagnosed with stroke, and was then found to be affected
by Lm rhombencephalitis accompanied by a brain abscess. Lm meningoencephalitis mimicking ischemic
stroke is rare but must be considered, especially in specific patients.
Ó 2014 Elsevier Ltd. All rights reserved.

1. Introduction

2. Case report

Early diagnosis of stroke is becoming indispensable due to the
increasing use of thrombolytic therapy. During emergency
room evaluation, one must be aware that there are rare conditions
that might be falsely interpreted as ischemic stroke. These ‘‘stroke
mimics’’ are a heterogeneous group of non-vascular conditions,
including seizures, syncope, hypoglycemia, migraine with aura,
brain tumors, diverse encephalopathies (hypertensive, toxic,
metabolic, and infectious) and acute confusional states [1,2]. The
incidence of these conditions is reported to be around 30%
[1–3] in cases of focal brain deficits of apparently abrupt onset,
but their incidence and nature vary depending on the context.
Listeria monocytogenes (Lm) is a gram-positive bacillus that may
affect the central nervous system (CNS) causing meningitis, rhombencephalitis or brain abscess [4]. Lm is the third most frequent
cause of bacterial meningitis in patients aged >65 years [5] and is
an increasingly recognized agent of human infections, concomitant
with global changes in eating habits (specifically fast food
and ready-to-eat products). This has subsequently increased the
population at risk, including the elderly and immunocompromised
[6].

A 59-year-old woman was admitted to the emergency room for
the sudden loss of strength in her left arm and leg. The evening
before the hospital admission, she was slightly drowsy and complained of a very mild headache. She had a history of lung adenocarcinoma with vertebral bone metastases and pathological
fractures, diagnosed 1 year before and treated with cisplatin and
gemcitabine until 2 months previously. At the time of admission,
neurological examination showed a left upper motor neuron facial
nerve palsy and mild hemiparesis on the left side. The patient was
slightly lethargic but able to follow commands and there were no
signs of meningism. Her vital signs were within normal limits,
body temperature was normal and there were no abnormalities
on the blood tests. A cranial CT scan was unremarkable (Fig. 1).
She was not treated with thrombolysis because of the presumed
high hemorrhagic risk in a patient with multiple metastases. A first
work-up for stroke etiology, with blood test for hypercoagulability,
electrocardiogram, echocardiogram and carotid artery duplex scan
did not reveal significant alterations. During the next day, she
became febrile, her hemiparesis worsened, conjugate horizontal
eye deviation towards right appeared and the patient’s vigilance
level further deteriorated. Blood cultures were taken. A chest
radiograph demonstrated the known right lung tumor, but no signs
of an infective process. Blood test showed mild hyponatremia
(127 mEq/L), while the peripheral leukocyte count was within

⇑ Corresponding author. Tel.: +39 055 794 5519; fax: +39 055 429 8461.
E-mail address: pantoni@unifi.it (L. Pantoni).

Case Reports / Journal of Clinical Neuroscience 21 (2014) 2006–2008

2007

Fig. 1. Unenhanced axial brain CT scan showing no abnormality in the mesencephalon (A) or the internal capsule (B).

Fig. 2. T2-weighted axial brain MRI showing abnormal signal, mainly due to edema, in the hippocampus, throughout the right thalamus and right internal capsule.

normal limits and other analyses were otherwise unremarkable. A
brain MRI on the third day showed patchy regions of abnormal
signal in the right uncus and hippocampus, right thalamus and
internal capsule characterized by iso-intensity on T1-weighted
and hyper-intensity on T2-weighted and fluid attenuated
inversion recovery sequences (Fig. 2). After gadolinium injection
nodular and ring enhancing lesions of 2–7 mm diameter with
abscess-like appearances were detected in the right thalamus and
mesencephalon (Fig. 3). Faint right temporo-parietal meningeal
enhancement was also detectable. Finally, blood cultures taken
on the second day grew Lm and led to a diagnosis of Lm mesenrhombencephalitis. The patient was treated with intravenous
ampicillin for 4 weeks and gentamicin for 2 weeks. In a few days,
she recovered a normal state of awareness and consciousness and
her weakness improved within 2 weeks at which time she could
walk, albeit only with a support mainly because of her vertebral
disease.
3. Discussion
We finally diagnosed meningoencephalitis with cerebral
abscesses caused by Lm in our patient presenting with an acute
onset motor deficit. Neurolisteriosis may manifest in humans as

meningitis and meningoencephalitis, which are the most common
presentations, followed by brain abscesses and brainstem infection
(rhombencephalitis) [4]. Lm brain abscesses present with different
features compared to those caused by other pathogens, particularly
due to the location in unusual subcortical areas (such as thalamus,
pons or medulla) and concomitant meningitis [7]. One large
review of CNS listeriosis reported that predisposing factors were
immunosuppression, age >50 years and underlying conditions such
as malignancy or diabetes [8]. Blood cultures are positive in 85% of
cases, a frequency much higher than abscesses caused by other
agents [7] and, of note, Lm is more commonly isolated in blood culture than in cerebrospinal fluid [8]. Rhombencephalitis is caused by
the extension of the infection and inflammatory process to the
brainstem with predominant infiltration of the nuclei, tracts and
intraparenchymal parts of the corresponding cranial nerves [9].
Clinical signs classically appear in two phases: the first is characterized by nonspecific symptoms such as headache, malaise, nausea and vomiting; and the second by asymmetrical cranial nerve
deficits, cerebellar signs and hemiparesis or hemisensory defects
which can be concomitant to meningeal signs [4,10].
Regarding the available literature, our patient presented with
most of the typical characteristics of Lm brain abscess and rhombencephalitis, including the lack of fever or meningism [4]. The

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Case Reports / Journal of Clinical Neuroscience 21 (2014) 2006–2008

Fig. 3. T1-weighted axial gadolinium enhanced brain MRI showing ring enhancement in the sub-insular regions (A) and in the right thalamus, posterior mesencephalon and
mesial temporal lobe (B), with a meningeal enhancement at right temporo-parietal lobes.

patient also had an impaired immune system due to malignancy
and chemotherapy. Finally, her neuroimaging was quite typical
for Lm encephalitis [11].
Among stroke mimics, infectious diseases of the CNS represent a
minority but compared to other mimics that may be easier to diagnose (such as hypoglycemia and seizures), may be more difficult to
suspect and exclude, especially in the acute context. Otherwise, the
presence of clinical hints obliges the physician to consider these
hypotheses in the diagnostic workflow. In an observational study
of 790 consecutively admitted patients presenting with an ischemic attack in a stroke unit, the clues to search for an alternative
diagnosis were younger age and absence of stroke risk factors, transient pure or predominant hemisensory symptoms and longer
duration of symptoms [12]. Additional signs and symptoms to
watch for are the presence of minor meningeal symptoms and
signs such as mild headache, confusional state, nausea or vomiting
and fever which may appear during the first days of
hospitalization.
Our patient had few unusual presenting features which may
have induced a suspicion of other diseases in the emergency room.
Her headache had started hours before the onset of the motor deficit and the slight consciousness impairment may have pointed to a
meningoencephalitis. Additionally, a tumor may have a stroke-like
presentation; in this instance, malignant cerebral tumors are more
frequently the cause [1]. The immunocompromised condition of
our patient due to malignancy and chemotherapy was an additional suspicious element. In the presence of these factors it is
advisable to perform additional investigations such as enhanced
CT scan or MRI.
Differential diagnosis between meningoencephalitis and stroke
is commonly not difficult when meningism, elevated temperature
and altered routine laboratory parameters are present. But it can
be very challenging, especially in the case of sudden onset and normal CT scan. To our knowledge, this is the first case of listerial CNS
infection in which a clear and prodromal phase could not be identified and the patient suffered an entirely acute onset of symptoms
[13].
Our report emphasises the fact that CNS listeriosis should be
considered as part of the differential diagnosis in parenchymal
http://dx.doi.org/10.1016/j.jocn.2014.03.021

brain involvement in immunosuppressed patients, and in those
with simultaneously affected meninges and brain parenchyma
subcortical brain abscesses.
Conflicts of Interest/Disclosures
The authors declare that they have no financial or other conflicts
of interest in relation to this research and its publication.
Acknowledgements
This clinical case was presented at the University of Florence
School of Neurology (chairman Domenico Inzitari) weekly grand
rounds.
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