American Journal of Emergency Medicine xxx (2014) xxx–xxx

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American Journal of Emergency Medicine
journal homepage: www.elsevier.com/locate/ajem

Case Report

Isolated rotational nystagmus may be the only clue to the early diagnosis of
dorsolateral medullary infarction☆,☆☆,★
Abstract
The medulla contains complex nervous structures related to motor,
sensory, coordination, and visceral autonomic functions. The medullary
infarctions cause various symptoms and signs depending on the
location of the lesion. Lateral medullary infarction is caused by a
vascular event in the territory of the posterior inferior cerebellar artery
or the vertebral artery [1]. We report a case of a patient with falling
tendency and whirling sensation. He reported no facial drop, arm drift,
slurred speech, difficulty of swallowing, or weakness of his limbs. The
neurologic examination revealed no decreased muscle power, dysarthria, dysphagia, or other relevant neurologic deficits. Urgent noncontrast brain computed tomography detected no acute hemorrhage or
ischemic lesion. On admission, the oculomotor examination revealed
conjugated rotational nystagmus with clockwise direction. The magnetic resonance imaging of the brain demonstrated acute infarct in the
medulla oblongata approximately 0.8 × 0.5 cm. The infarct appears
bright on diffusion-weighted images (Fig.). A diagnosis of dorsolateral
medulla infarction was established, and the patient was started on a
therapy of 100 mg aspirin once daily. After standard therapies, the
patient's recovery was uneventful.
We wanted to emphasize the importance of thorough history and
neurologic examination focused on cerebellar and posterior circulation functions performed in real time, which are keys to the diagnostic
workup for patients who present with acute-onset vertigo. It is critical
to establish the precise diagnosis and determination of which patients
require urgent neuroimaging and acute stroke therapies. With
standard therapies and poststroke rehabilitation, the recovery of
patients with lateral medullary infarction (LMI) remains favorable.
A 64-year-old man presented to the emergency department (ED)
due to falling tendency to the left side and whirling sensation since
this morning. His medical history was relevant for hypertension, for
which he had no antihypertensive drugs for years. He reported no
facial drop, arm drift, slurred speech, difficulty of swallowing, or
weakness of his limbs. On examination, he appeared distressed sitting
on the wheelchair. The patient had marked truncal ataxia, with a
tendency to fall to the left and was unable to ambulate. His vital signs
were as follows: blood pressure of 229/109 mm Hg, heart rate of 73
beats per minute, and respiratory rate of 20 breaths per minute. He
was afebrile. Serum biochemistry showed hyperglycemic level

☆ Author contributions: Dr Chun-Hsiang Tseng: concept and drafting. Dr Wen-Yi
Chiu: literature search, concept, drafting, and revision of article.
☆☆ The authors report no disclosures relevant to the manuscript.
★ The authors report no conflicts of interest relevant to the manuscript.

(random serum glucose level of 253 mg/dL) and normal sodium,
potassium, and renal function. The neurologic examination revealed
no decreased muscle power, dysarthria, dysphagia, or other relevant
neurologic deficits. Urgent noncontrast brain computed tomography
(CT) detected no acute hemorrhage or ischemic lesion.
The patient was transferred and admitted to the neurology inpatient
service. On admission, the oculomotor examination revealed conjugated rotational nystagmus with clockwise direction. The magnetic
resonance imaging (MRI) of the brain demonstrated acute infarct in
the medulla oblongata approximately 0.8 × 0.5 cm. The infarct appears
bright on diffusion-weighted images (Fig.). The MRI angiography of
circle of Willis reveals tortuosity and irregular caliber of bilateral
internal carotid arteries and right middle cerebral artery, which may be
atherosclerotic change. A diagnosis of dorsolateral medulla infarction
was established, and the patient was started on a therapy of 100 mg
aspirin once daily. After rehabilitation program, ataxia of his extremities
subsided, but mild numbness remained before discharge. The patient
was seen in outpatient regular follow-up in a half year, and these
symptoms gradually subsided.
Lateral medullary infarction is an uncommon disorder, accounting
for approximately 2.5% or less of all cases of cerebral infarction. Lateral
medullary infarction is also known as Wallenberg syndrome and
presents with facial sensory disturbance, cerebellar ataxia, Horner
syndrome, and paralysis of the soft palate and pharynx on the side of
the lesion [2,3]. It is crucial to differentiate dorsolateral medullary
infarction from peripheral vertigo, but the most sensitive signs in
early phase remain unclear. Nevertheless, in a cerebellar or brainstem
ischemia, vertigo can be the only symptom [4].
The Cincinnati Prehospital Stroke Scale is an effective tool to
identify stroke, requiring only 30 to 60 seconds at emergency units
[5]. However, the Cincinnati Pre-hospital Stroke Scale is not
susceptible in patients with LMI. In some cases, the primary cranial
imaging does not show any abnormalities, and patients with
cerebral ischemia with a diagnosis of peripheral vertigo are
misdiagnosed [4].
In our case, the oculomotor examination detected nystagmus with
clockwise (contralesional beating, rightward) rotational nystagmus,
and the diagnosis of LMI was confirmed. Isolated rotational nystagmus may be the only clue to the early diagnosis of dorsolateral
medulla infarction in this patient. The direction of the spontaneous
nystagmus in the first days after infarction is consistent with
combined stimulation of the horizontal and posterior semicircular
canals on the contralesion side [6]. It is useful to help us localize the
brain lesion.
Dizziness, vertigo, and imbalance are common presenting
symptoms in the ED, accounting for approximately 7.5 million
annually in the United States. The complaint of imbalance or difficulty

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Please cite this article as: Tseng C-H, Isolated rotational nystagmus may be the only clue to the early diagnosis of dorsolateral medullary
infarction, Am J Emerg Med (2014), http://dx.doi.org/10.1016/j.ajem.2013.12.039

2

C.-H. Tseng, / American Journal of Emergency Medicine xxx (2014) xxx–xxx

tion functions performed in real time, which are keys to the diagnostic
workup for patients who present with acute-onset vertigo. It is critical
to establish the precise diagnosis and determination of which patients
require urgent neuroimaging and acute stroke therapies [10]. Repeat
cranial imaging is indicated if vertigo does not improve under
standard therapy [4]. With standard therapies and poststroke
rehabilitation, the recovery of patients with LMI remains favorable [3].
Chun-Hsiang Tseng MD
Department of Orthopaedics
Taoyuan Armed Forces General Hospital
Taoyuan, Taiwan
Wen-Yi Chiu MD
Department of Family Medicine
Zouying Branch of Kaohsiung Armed Forces General Hospital
Kaohsiung, Taiwan
Department of Internal Medicine
Kaohsiung Armed Forces General Hospital
Kaohsiung, Taiwan
E-mail address: hanrogyi@gmail.com
Fig. The dorsolateral medulla oblongata infarct appears bright on diffusion-weighted
images.

walking has been shown to be a predictor for stroke in patients with
dizziness [7].
It is important to distinguish patients with central infarct from
those with benign peripheral causes because patients with a
misdiagnosis will have bad outcomes. In 1 case series, half of the
patients with misdiagnosed medullary infarctions were younger than
50 years, the overall mortality rate was 40%, and half of the survivors,
approximately 50%, had disabling deficits [8].
Brain CT scans are widely used in the emergency units, but it has
poor sensitivity for brain ischemia or infarction, especially in the
posterior fossa. Acute posterior circulation infarction can present with
nonspecific clinical findings and a normal brain CT. Magnetic
resonance imaging is the imaging test of choice, but it has several
practical limitations, including its poor real-time availability in the
emergent setting [9]. Magnetic resonance imaging still remains the
criterion standard test for the diagnosis of acute stroke, with an
overall sensitivity of 83% and specificity of 96%. However, the
sensitivity of MRI within 48 hours of symptom onset falls to 72% in
the subset of patients with brainstem infarction [10].
We wanted to emphasize the importance of thorough history and
neurologic examination focused on cerebellar and posterior circula-

http://dx.doi.org/10.1016/j.ajem.2013.12.039

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Please cite this article as: Tseng C-H, Isolated rotational nystagmus may be the only clue to the early diagnosis of dorsolateral medullary
infarction, Am J Emerg Med (2014), http://dx.doi.org/10.1016/j.ajem.2013.12.039