Neurological Sciences
https://doi.org/10.1007/s10072-018-3282-9

LETTER TO THE EDITOR

Cerebral arteriovenous malformation presenting as isolated bilateral
pupil-sparing oculomotor, pseudoabducens palsy, and hemiataxia
I-Hsu Chen 1 & Yi-Hui Lin 1 & Meng-Ni Wu 1 & Chiou-Lian Lai 1,2,3 & Li-Min Liou 1,2
Received: 18 December 2017 / Accepted: 8 February 2018
# Springer-Verlag Italia S.r.l., part of Springer Nature 2018

Dear Editor:
Most cases of pseudoabducens palsy, which is defined as a
failure of ocular abduction not due to dysfunction of the sixth
nerve or its nucleus (but due to an impaired inhibitory descending supranuclear pathway of convergence activity), are
associated with diencephalon-mesencephalic infarction [1, 2].
Most pupil-sparing oculomotor palsy is usually attributed to
microvascular ischemia, such as diabetes, hypertension, and
dyslipidemia. We reported a rare case of cerebral arteriovenous malformation (AVM) presenting with bilateral pupilsparing oculomotor palsy and pseudoabducens palsy. A 30year-old woman was admitted to our department for progressive binocular diplopia, subtle left side clumsiness, and gait
disorder since 2010. Diplopia was found in all directions.
When in a neutral position, both eyes slightly deviated to
medial-lower side. There was no fever, headache, stiff neck,
or diurnal change. Neurological examination reveals partial
paralysis of all the extraocular muscles (EOM) except the
bilateral superior oblique muscles. The pupil sizes were normal, symmetric, and reactive. There was no ptosis. Bilateral
partial oculomotor palsy and abducens palsy are suspected on
the clinical ground. While the horizontal vestibulo-ocular reflex (VOR) could be stimulated with an oculocephalic maneuver, vertical VOR could not. Testing of coordination revealed
subtle left hemiataxia. The gait was mildly broad-based.
Thyroid functions were within normal limits. Cranial

* Li-Min Liou
lioulm11@gmail.com
1

Department of Neurology, Kaohsiung Medical University Hospital,
Kaohsiung Medical University, No. 100, Ziyou 1st Rd., Sanmin
District, Kaohsiung City 807, Taiwan, Republic of China

2

Department of Neurology, School of Medicine, College of Medicine,
Kaohsiung Medical University, Kaohsiung, Taiwan

3

Department of Neurology, Kaohsiung Municipal Hsiao-Kang
Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan

magnetic resonance imaging revealed cerebral AVM from
the midbrain to the rostral pons without hemorrhage (Fig. 1).

Discussion
While most AVMs would present with concurrent problems of
intracranial hemorrhage, seizure, or headache, we report a
case of cerebral AVM located from the midbrain to the rostral
pons presenting with Bisolated^ left hemiataxia, bilateral oculomotor, and Babducens palsy,^ which actually is
pseudoabducens palsy without these concurrent problems.
Pseudoabducens palsy is rarely reported in patients with
AVM.
Abducens palsy may have supranuclear, nuclear, or
infranuclear causes. Pseudoabducens palsy is mostly seen
in patients with infarctions of the diencephalonmesencephalic area [1, 2]. Nuclear causes of abducens palsy should be accompanied by facial palsy because of their
special anatomical relationship in the pons. Unlike typical
nuclear or infranuclear abducens palsy, supranuclear
abducens palsy (pseudoabducens palsy) presents with preserved abduction during horizontal VOR testing with an
oculocephalic maneuver [2]. In our case, no facial palsy
was found and horizontal VOR was preserved.
Supranuclear abducens palsy (pseudoabducens palsy) may
have accounted for the presentation in our case [2]. Lesions
along the inhibitory convergence pathway, which courses
from the frontal cortex to the thalamus and then decussates
in the subthalamic region, could cause pseudoabducens palsy, due to elevated tone of the medial rectus during lateral
gaze [1, 2]. The lesions of AVM with pseudoabducens
palsy were smaller than we initially localized (Fig. 1).
While complete oculomotor palsy with pupil sparing is
usually benign and attributed to microvascular ischemia, pupil
involvement indicates a compressive lesion because parasympathetic fibers are at the periphery of the oculomotor nerve
from the experience of treatment of ICA-PCom aneurysms

Neurol Sci

Fig. 1 Axial T1-FLAIR (a, b, c) and T2-FLAIR (d, e, f) MRI images
showed the cerebral AVM at the midbrain to the rostral pons (arrows).
Ventral view of the location of the AVM, cranial nucleus, and nerve in the

brain stem (g). Lateral view of the location of the AVM, cranial nucleus,
and nerve in the brain stem (h)

[3]. However, partial oculomotor palsy with pupil-sparing
may be sometimes related to compressive lesions because of
the shape of the aneurysm, early disease phase, or compression at different points (without critical parasympathetic compression) [3]. These can explain why the oculomotor palsy in
our case does not have pupil involvement (Fig. 1).
Cerebral AVMs are uncommon, with a prevalence of about
0.1%. Brain stem AVM, which accounts 10–15%, is even
rarer because most AVMs are located superficially and are
primarily supplied by the anterior carotid circulation [4].
These also support the rarity of bilateral oculomotor and
pseudoabducens palsy in our case with brain stem AVM
(Fig. 1).
While AVMs usually manifest with intracranial hemorrhage,
followed by seizure and headache [5], Bisolated^ neurologic
deficits are rarely reported with an incidence of only 7% in
patients with AVM [5]. While the most frequent isolated neurologic deficit is hypesthesia, followed by hemiparesis, cognitive impairment, paresthesia, dysarthria, and hemiataxia, our
case presents with a rare phenomenon of bilateral pupilsparing oculomotor and pseudoabducens palsy and subtle
hemiataxia. The risk factors for isolated neurologic deficits
are increasing age, female, brain stem location, and venous
ectasia [5], which are compatible with the findings in our case
(Fig. 1). In summary, cerebral AVM can present with isolated
bilateral pupil-sparing oculomotor, pseudoabducens palsy, and

hemiataxia without concurrent intracerebral hemorrhage, seizure, or headache. The lesions of AVM with pseudoabducens
palsy may be smaller than we initially thought.

Compliance with ethical standards
Conflict of interest The authors declare that they have no conflict of
interest.

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