Case Report

Dermatomal Sensory Manifestations in Lateral
Medullary Infarction
Hiroki Hongo, MD,* Yasutaka Tanaka, MD, PhD,† Yoshiaki Shimada, MD,*
Ryota Tanaka, MD, PhD,* Nobutaka Hattori, MD, PhD,* and Takao Urabe, MD, PhD†

A 61-year-old man who experienced a sudden onset of unstable gait followed by
nuchal pain was admitted to our department. The neurologic examination revealed
right-sided limb ataxia, right partial ptosis, and decreased sensation to 50% of the
normal side to pinprick and temperature stimuli on the left side below the level of
the T-6 dermatome. A lateral medullary infarction caused by spontaneous vertebral
artery dissection was diagnosed by magnetic resonance imaging and computed
tomography angiography. In conclusion, lateral medullary infarction is an important
entity to consider in the differential diagnosis of dermatomal sensory
manifestations. Key Words: Dermatomal sensory manifestation—lateral medullary
infarction.
Ó 2014 by National Stroke Association

A 61-year-old man with sudden onset of unstable gait
followed by nuchal pain was admitted to our department.
He had a history of poorly controlled dyslipidemia and
was previously a smoker. He had no history of major
trauma to the neck. The neurologic examination revealed
right-sided limb ataxia, right partial ptosis, and decreased
sensation to 50% of the normal side to pinprick and
temperature stimuli on the left side below the level of
the T-6 dermatome (Fig 1A).
Blood test results were normal except for a slight elevation of triglyceride and g-glutamyl transpeptidase levels.
Diffusion-weighted magnetic resonance imaging (MRI)

From the *Departments of Neurology at Juntendo University
School of Medicine; and †Juntendo University Urayasu Hospital,
Chiba, Japan.
Received August 10, 2012; revision received September 13, 2012;
accepted September 18, 2012.
Address correspondence to Yasutaka Tanaka, MD, PhD, Department of Neurology, Juntendo University Urayasu Hospital, Tomioka,
2-1-1, Urayasu city, Chiba, Japan. E-mail: 8123a@juntendo.ac.jp.
1052-3057/$ - see front matter
Ó 2014 by National Stroke Association
http://dx.doi.org/10.1016/j.jstrokecerebrovasdis.2012.09.011

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revealed a right lower lateral medullary infarction (LM;
Fig 1B). Computed tomography (CT) angiography revealed a string and pearl sign in the right vertebral artery.
A cervical and thoracic MRI was normal. The final diagnosis was LMI caused by spontaneous vertebral artery
dissection.

Discussion
The typical case of lateral medullary syndrome, which
is characterized by a superficial sensory deficit in the
ipsilateral face and contralateral body, ipsilateral Horner
syndrome, cerebellar ataxia, dysarthria, and dysphagia,
is known as Wallenberg syndrome.1 However, a patient
with LMI who presents with all features of typical Wallenberg syndrome is uncommon. Because the present case
was characterized by restricted contralateral sensory
loss below the level of the T-6 dermatome without trigeminal sensory dysfunction, spinal cord involvement was
initially suspected.
This dermatomal sensory loss can be explained by the
site of the lesion and the topographic arrangement of
sensory fibers in the spinothalamic tract of the lower

Journal of Stroke and Cerebrovascular Diseases, Vol. 23, No. 1 (January), 2014: pp 182-183

DERMATOMAL SENSORY MANIFESTATIONS IN LATERAL MEDULLARY INFARCTION

183

Figure 1. (A) Representation of the patient’s
superficial sensory deficit (shaded area). (B)
Diffusion-weighted magnetic resonance imaging
scan reveals a small infarct in the right lateral
medulla oblongata. (C) Schematic drawing of important medullary structures (right unilateral).
Shaded area indicates the infarct area.

medulla oblongata.2,3 The sensations from the sacral
area, leg, trunk, and arm are somatotopically arranged
in an orderly fashion from the superficial to the medial
direction. In the present case, the ischemic lesion was
thought to involve the quite superficial layers of the spinothalamic tract. Judging from the coexisting symptoms, the lesion was considered to be in the extremely
lateral and posterolateral area, involving part of the inferior cerebellar peduncle and not involving the more
medial and posterior area that includes the descending
trigeminal tract, the nucleus ambiguus, and the nucleus
gracilis (Fig 1C).

In conclusion, LMI is an important entity to consider
in the differential diagnosis of dermatomal sensory
manifestations.

References
1. Wilkins RH, Brody IA. Wallenberg’s syndrome. Arch
Neurol 1970;22:379-382.
2. Kim JS. Sensory symptoms in ipsilateral limbs/body due to
lateral medullary infarction. Neurology 2001;57:1230-1234.
3. Kim JS, Lee JH, Lee MC. Patterns of sensory dysfunction in
lateral medullary infarction. Clinical-MRI correlation.
Neurology 1997;49:1557-1563.