IMAGES IN NEUROLOGY

Ataxic Hemiparesis
The Benefit of Acute Multiparametric Magnetic Resonance Imaging

A

76-YEAR-OLD HYPERtensive man was admitted with an acute
left ataxic hemiparesis. Neurological examination found a left-sided hemiparesis and cerebellar ataxia without
proprioceptive impairment (admission National Institute of Health
Stroke Scale score = 4). Diffusionweighted imaging disclosed a lacunar ischemic lesion within the right
ventroposterolateral thalamic nucleus
and an equivocal signal within the
right cerebral peduncle. No significant cerebellar or temporo-occipital
involvement was observed. Basilar
and right posterior cerebral artery occlusions were found on magnetic
resonance angiography. Perfusionweighted imaging was performed
with gradient-echo echoplanar
imaging using the bolus passage-ofcontrast method. The time-to-peak
map, generated from the concentration time curve, confirmed an extensive perfusion delay in posterior fossa
and right posterior cerebral artery territory, with a nearly complete diffusion-weighted imaging–perfusionweighted imaging mismatch
(Figure). The patient was treated
with intravenous tissue plasminogen activator, administered 155 minutes after symptom onset. Outcome
was favorable, with only mild left upper limb ataxia. The patient was discharged on day 3 (National Institute
of Health Stroke Scale score=1).

COMMENT
The present case of ataxic hemiparesis was likely related to a thalamic lacunar lesion, with damage of the efferent neocerebellum fibers crossing
the ventroposterolateral nucleus and
of the adjacent corticospinal tract.1 Althoughdiffusion-weightedimagingrevealed possible involvement of the
rightcerebralpeduncle,isolatedataxic
hemiparesis related to crus cerebri infarct is exceptional,2 and third nerve
palsyandotherthalamomesencephalic
symptoms are usually associated.
Ataxichemiparesisusuallyhasabenign course and may seldom reveal a
basilar occlusion. In patients with lacunar syndromes, neuroimaging is essential to exclude lesions other than
lacunar infarctions due to small-vessel
disease.3 Thispatientfurtherillustrates
that lesions compatible with a single
perforating artery occlusion on structural imaging can be related to a largearterydisease.Magneticresonanceangiography and perfusion-weighted
imaging data proved critical to assess
the mechanism underlying a seemingly benign lacunar stroke. Keeping
in mind the “herald hemiparesis” that
Fisher described,4 complete vascular
imaging is warranted in all patients
with lacunar infarcts.
Tae-Hee Cho, MD
Marc Hermier, MD, PhD
Laurent Derex, MD, PhD
Paul Trouillas, MD, PhD
Norbert Nighoghossian, MD, PhD

(REPRINTED) ARCH NEUROL / VOL 67 (NO. 1), JAN 2010
116

Correspondence: Dr Nighoghossian, Hôpital Neurologique Pierre
Wertheimer, 59 Blvd Pinel, 69677
Lyon CEDEX, France (norbert
.nighoghossian@chu-lyon.fr).
Author Contributions: All authors
had full access to all of the data in
the study and take responsibility for
the integrity of the data and the accuracy of the data analysis. Study
concept and design: Cho and Nighoghossian. Acquisition of data: Cho,
Hermier, Derex, Trouillas, and
Nighoghossian. Analysis and interpretation of data: Cho, Hermier,
Derex, Trouillas, and Nighoghossian. Drafting of the manuscript: Cho
and Nighoghossian. Critical revision of the manuscript for important
intellectual content: Cho, Hermier,
Derex, Trouillas, and Nighoghossian. Study supervision: Cho, Hermier, Derex, Trouillas, and Nighoghossian.
Financial Disclosure: None reported.
REFERENCES
1. Boiten J, Lodder J. Ataxic hemiparesis following thalamic infarction. Stroke. 1990;21(2):339-340.
2. Nighoghossian N, Trouillas P, Riche G, Getenet JC,
Neuschwander P. Midbrain ataxia related to crus
cerebri infarct [letter to the editor]. Cerebrovasc Dis.
1995;5(1):61.
3. Gerraty RP, Parsons MW, Barber PA, et al. Examining the lacunar hypothesis with diffusion and perfusion magnetic resonance imaging. Stroke. 2002;
33(8):2019-2024.
4. Fisher CM. The “herald hemiparesis” of basilar artery
occlusion. Arch Neurol. 1988;45(12):1301-1303.

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A

B

C

Figure. Magnetic resonance imaging in a 76-year-old hypertensive man with an acute left ataxic hemiparesis. A, Diffusion-weighted imaging disclosed a right
thalamic lacunar infarct (arrow) and a subtle hyperintensity within the right cerebral peduncle (arrowhead). B, Three-dimensional time-of-flight magnetic
resonance imaging revealed basilar thrombosis and occlusion of the proximal segment of the right posterior cerebral artery. C, A large perfusion delay in the
posterior fossa and right posterior cerebral artery was confirmed on the time-to-peak map.

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