hyperaesthetic ataxic syndrome

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Chun-An Cheng, et al.J Med Sci 2003;23(6):337-342
http://jms.ndmctsgh.edu.tw/2306337.pdf
Copyright © 2003 JMS
Received: February 18, 2003; Revised: May 7, 2003;Accepted:
May 13, 2003.
*
Corresponding author: Jiann-Chyun Lin, Department of
Neurology, Tri-Service General Hospital, 325, Cheng-Kung
Road Section 2, Taipei 114, Taiwan, Republic of China. Tel:
+886-2-87927173; Fax: +886-2-87927174; e-mail:neurojcl
@mail.ndmctsgh.edu.tw
Hypesthetic-Ataxic-Hemiparesis Syndrome Following Thalamic Infarct
Chun-An Cheng, Jiunn-Tay Lee, Yaw-Don Hsu,
and Jiann-Chyun Lin*
Department of Neurology, Tri-Service General Hospital, National Defense Medical Center,
Taipei, Taiwan, Republic of China
Thalamic lesions give rise to a variety of clinical syndromes including neuropsychological dysfunction, sensory deficits as
well as hemiataxia. Ataxic hemiparesis syndrome following thalamic infarct is infrequent. Herein, we describe 3 patients who
exhibited acute onset of ataxic hemiparesis contralateral to a thalamic infarct. All patients presented apparent dysmetria and
ipsilateral hemiparesis. They also had paresthesia, hypesthesia and hypalgesia over hand and face ipsilateral to the ataxic
limbs. The proprioception was normal in all patients. Magnetic resonance imaging showed lacunar infarction at the ventral
lateral nucleus of the thalamus. Magnetic resonance angiography demonstrated occlusion or stenosis at the P2 segment of the
posterior cerebral artery in 2 patients. The hemiataxia, hemiparesis, and hypesthesia resolved within 2 months after the disease
onset in all patients. Our cases demonstrate that lacunar thalamic infarct may present with hypesthesia, hemiataxia, and
hemiparesis on the same side of the body, and the outcome is usually good. The mechanisms of the development of
hypesthesia, hemiataxia, and hemiparesis in these patients are discussed.
Key words: ataxic hemiparesis, thalamic infarct
INTRODUCTION
Ataxic hemiparesis syndrome features a combination of
hemiparesis and cerebellar ataxia on the same side of the
body, but implies neither localization nor pathological
process. Fisher and Cole in 1965 coined the term of ataxic
hemiparesis after pathologic studies of 3 cases, which
revealed infarct cavities in the basis pons on the side
contralateral to the pyramidal and cerebellar signs1
. Ataxic
hemiparesis has also been described as a result of lesions
in midbrain2
, posterior limb of internal capsules3,4
, corona
radiata5,6
, and the head of caudate nucleus7
, but may also be
rarely caused by a lesion in the thalamus8
. The syndrome
is now recognized as one of the lacunar syndrome9
. Yet,
pontine hemorrhage10,11
, leukemic infiltration2
, tumor and
possibly demyelinating disease12
could also be a cause of
ataxic hemiparesis. Numerous reports have expanded the
spectrum of clinical symptoms and signs associated with
ataxic hemiparesis. Included are accompanying contralat-
eral trigeminal weakness12
and partial or complete ipsilat-
eral hemihypesthesia13-16
. Hypesthetic ataxic hemiparesis
syndrome is rarely reported14-16
. We describe 3 cases of
hypesthetic hemiataxia with brief pyradmial signs in which
magnetic resonance imaging (MRI) showed an infarct in
the contralateral ventrolateral nucleus of the thalamus.
CASES REPORT
Patient 1
A 71-year-old right-handed man had hypertension with
regular treatment for years. He suddenly developed weak-
ness of left limbs and unstable gait. The general examina-
tion revealed a blood pressure of 174/100mmHg, pulse rate
of 85/min, and respiration rate of 18/min. He was alert,
oriented, and he had no headache. The cranial nerves and
fundi examination were normal. The clumsy hand of left
upper limb was noted. There was noticeable dysdia-
dochokinesia, rebound, and dysmetria on heel-knee-shin
and finger-nose tests on the left limbs but normal on the
right side. The muscle power of right upper limb was
mildly decreased. The sensory examination found pares-
thesia over left hand. The computed tomography (CT) scan
(Fig. 1A) and MRI (Fig. 1B) of the brain described lacunar
infarction of ventral lateral nucleus of right thalamus. The
magnetic resonance angiography (MRA) revealed occlu-
sion of left posterior cerebral artery at the P2 segment, and
decreased blood flow and braches of the right middle
cerebral artery (Fig. 1C). Antiplatelet and physical therapy

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Ataxic hemiparesis and thalamus
were given and the hemiparesis resovled 3 days after the
onset. Hemiataxia and hemihypesthesia disappeared 1
month later.
Patient 2
A 75-year-old right-handed man had hypertension and
type 2 diabetes mellitus for 5 years. He had one episode of
ischemic stroke with dysarthria and good re-
covery 1 year ago. He suddenly developed
slurred speech, clumsiness and weakness of
right limbs. The general examination revealed
a blood pressure of 160/88 mmHg, regular
pulse rate of 68/min, and respiration rate of
18/min. Neurologic examination showed scan-
ning speech, and mild right central facial
palsy. Power in right limbs was decreased to
MRC: 4. The sensory examination revealed
decreased pain and temperature sensation over
lateral part of right face, and right fingers.
There was apparent ataxia and dysmetria on
heel-knee-shin and finger-nose tests on the
right limbs but normal on the left side. The
MRI of brain showed acute lacunar infarction
of the ventral lateral nucleus of left thalamus (Fig. 2A-C)
and small vessel disease (Fig. 2D). Extracranial neuro-
sonography showed heterogenous artherosclerotic changes
in left common carotid and internal carotid arteries with
percent diameter stenosis about 30-50 %. Transcranial
doppler sonography showed no detection of right vertebral
artery and basilar artery. He was treated with antiplatelet
and physical therapy. The hemiparesis resolved 4 days
after the onset. Hemihypesthesia and hemiataxia subsided
2 months later.
Patient 3
A 33-year-old woman was admitted for sudden onset of
weakness of right limbs and numbness over right face for
2 hours. She did not have hypertension or diabetes mellitus.
On admission, the blood pressure was 130/72mmHg, pulse
rate was 74/min, respiration rate was 20/min, and body
temperature was 36.8 o
C. Neurological examination showed
unsteadiness, wide-base gait, dysmetria on finger to nose
and heel to knee to shin tests and hemiparesis (MRC: 4/5)
on the right limbs. Sensation examination showed hypes-
thesia and hypalgesia over right border of the tongue and
perioral region. The MRI of the brain revealed acute infarction
of the ventrolateral part of left thalamus. MRA showed
decreased flow of the left posterior cerebral artery and
narrowing of its caliber at P2 segment with decreased
number of distal braches. Serial examinations including
echocardiogram, tumor markers, immunologic survey,
protein C, protein S and antithrombin III showed no
abnormal findings. She received intravenous pentoxyfyllin
and oral aspirin therapy during hospitalization. Right hemi-
paresis recovered on the 4th admission day. Hypesthesia
and hemiataxia also resolved 6 weeks later.
Fig. 1 Neuroimage study of the brain showing infarct of right
ventrolateral thalamus. CT scan showing hypodense
lesion at the ventrolateral part of right thalamus, and
periventricular lucency at the frontal horn (A). MR scan
showing lacunar hyperdense lesion in the ventrolateral
part of right thalamus, and small vessel disease on FLAIR
image (B). MRA revealing occlusion of right posterior
cerebral artery (arrow) at the P2 segment, and decreased
blood flow and branches of the right middle cerebral
artery (C).
C
BA

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Chun-An Cheng, et al.
DISCUSSION
Ataxia is a disorder of mobility characterized by im-
paired coordination of motor response with relative pres-
ervation of isometric motor strength. It is classically im-
puted to lesions involving the cerebellar system or the
sensory pathways that control the movement. Incoordina-
tion of limbs as a result of a thalamic lesion was recognized
by Dejerin and Roussy in 190617
. Ataxia from a thalamic
lesion represents either sensory deafferentation18
or cer-
ebellar dysfunction16
. All our 3 patients displayed obvious
incoordination of the limbs contralateral to the thalamic
infarct, dysmetria, dysdiadochokinesia, and
the performance of movement was not
improved under visual guidance.Moreover,
they had no proprioceptive impairment. We
therefore suggest that ataxic movement in
these patients was caused by cerebellar
dysfunction rather than sensory de-
afferentation.
The infarcts in our patients were located
in the ventrolateral parts of the thalamus,
with involvement of the ventral lateral
nucleus. Ventral lateral nucleus receives
fibers from the contralateral cerebellar
dentate nucleus (the dentatoru-brothalamic
projection). From the ventral lateral nu-
cleus, fibers run to the sensorimotor
cortex19
. Damage of the dentatorubrotha-
lamic projection to the ventral lateral
nucleus by the lesion rostral to the decus-
sation of the superior cerebellar peduncle
or damage to the ventral lateral nucleus
itself results in hemiataxia of the contralat-
eral limbs19
. Cerebellar ataxia in our pa-
tients was most likely caused by interrup-
tion of the dentatorubrothalamocortical
fibers at the level of the injured ventral
lateral nucleus.
The corticospinal tract is not a part of
thalamus. At the thalamic level, dentate-
rubro-thalamo-cortical pathway is not far
from corticospinal tract residing in the
posterior limb of internal capsule. Hemi-
paresis in our patients was probably caused
by initial edema compressing the adjacent
corticospinal tract in the posterior limb of
internal capsule because MRI did not re-
veal involvement of the internal capsule.
The hemiparesis clearing much more rap-
idly than the hemiataxia supports this speculation.
Deficits in pain sensation were found to be the most
common pattern of thalamic sensory dysfunction, while
deficits in proprioceptive sensations were found to be the
least common15,16,20
. Our patients had sensory symptoms of
paresthesia on the face, particularly around the mouth, and
distal portion of the limbs contralateral to the thalamic
infarct. All somatosenory modalities are processed in the
ventral posterior nucleus of the thalamus contralateral to
the side of the body where they are perceived. Within the
nucleus there is a definite topographic distribution19
. A
large volume of the nucleus is dedicated to the mouth,
A B
C D
Fig. 2 MRI showing acute lacunar infarct of left thalamus. MR scan showing lacunar
hyperdenselesiononFLAIR(A)anddiffusion-weighted(B)images,hypodensity
on ADC (C) map in left thalamus, with involvement of the ventrolateral nucleus,
and small vessel disease on FLAIR image (D). Lacunar thalamic infarct with
edema compressing the adjacent posterior limb of internal capsule (arrow) was
demonstrated on FLAIR image (A).

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Ataxic hemiparesis and thalamus
tongue and distal portion of the extremities. Clinically,
small lesions of the thalamic may yield only contralateral
paresthesias that lack “objective” sensory loss when tested
at the bed side21
. Such paresthesias tend to occur on one
side of the face, particularly around the mouth, and in the
distal portions of the limbs (cheiro-oral distribution). Tha-
lamic pain is the best-known component of Dejerine and
Roussy’s thalamic syndrome17
. Cooper concluded that the
lesion responsible for thalamic pain must include a portion
of the internal capsule or part of the parietal lobe along with
the thalamic lesion22
. Our cases did not have a MR demon-
strable lesion outside the thalamus; nor did they have
“thalamic pain”.
“Cerebellar type” hemiataxia is present in about one-
fourth of patients with thalamic infarction16
. Hemiataxia
rarely occurred in isolation, being associated with hemi-
paresis (AH), hemihypesthesia (HH), or with both (hy-
pesthestic ataxia hemiparesis, HAH)16,23
. HAH has been
reported in lesion in the thalamus as wells as in the internal
capsule15
and parietal lobe24
. Previous study showed sen-
sory loss in a high percentage of otherwise typical AH
patients and a clear predilection from lesion of the poste-
rior limb of the internal capsule, commonly with thalamic
involvement15,16,23
. Melo et al. studied 17 acute stroke
patients with thalamic ataxia; 7 patients had HH, 8 patients
had HAH, and only 2 patients had AH. In the part of HAH,
5 patients have sensory loss in the entire hemibody involv-
ing light touch, pain, temperature, and proprioceptive
sense16
. Three patients had a purely subjective sensory
disturbance, involving the entire hemibody in 1 patient,
and limited to the face and arm in 1 patient, and to the leg
in 1 patient. Gorman et al. also found 9 of 45 (20%) patients
had sensory loss in ataxic hemiparesis23
. All involved the
internal capsule and thalamus except for 1 pontine lesion.
All 3 of our patients had acute onset of hemiataxia with
ipsilateral sensory disturbance (paresthesia without sen-
sory loss) and hemiparesis resulted from an infarction
simply affecting the lateral thalamus.
It has been reported that the most common presumed
etiology of HAH was small-vessel disease, followed by
cardioembolism16,23
. MRI of the brain showed cerebral
small vessel disease in Cases 1 and 2. Serial examinations
for the etiology of young stroke in Case 3 showed unre-
markable findings. Helgason et al. proposed anterior cho-
roidal artery territory infarction as the main cause of this
syndrome15
, and the thalamic geniculate territory infarc-
tion as a possible contributor, which was later confirmed
by Melo et al.16
Stenosis of posterior cerebral artery at the
P2 segment on the MRA in Cases 1 and 3 supports that
involvement of thalmogeniculate branch of posterior cere-
bral artery produced HAH. All our patients returned to
normal without residual neurological deficit. Previous
studies also suggested that good outcome of HAH syn-
drome following thalamic infarct was the rule1,16,23
. Our
patients and previous reports also showed that the hemi-
paresis and hemihypesthesia usually resolved before
hemiataxia16,23
.
In conclusion, our cases illustrate that the ventrolat-
eral nucleus of the thalamus takes part in the cerebellar
projection to the sensorimotor cortex, disruption of which
can induce the unusual lacunar syndrome of HAH. Such
cases of HAH may represent a clinicopathological entity
different from that resulting from pure capsular lesions.
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