CASE REPORT
Korean J Stroke 2012;14(3):163-165 http://dx.doi.org/10.5853/kjs.2012.14.3.163
A Case of Atypical Isolated Nodular Infarction: Nystagmus with a Reverse Direction Kang Min Park, Kyong Jin Shin, Sam Yeol Ha, Jin Se Park, and Sung Eun Kim Department of Neurology, Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea
A cerebral infarction involving the nodulus usually produce contralateral lateropulsion and ipsilateral spontaneous nystagmus to the lesion. Here, we report a case of atypical isolated nodular infarction showed ipsilateral lateropulsion and contralateral spontaneous nystagmus to the lesion with a normal head impulse test. A right-handed 70-year-old man developed sudden vertigo with an unsteady gait. Neurologic examination revealed spontaneous left-beating nystagmus with a torsional component. He also displayed imbalance of walking and axial lateropulsion to the right side. Head impulse test was normal. Magnetic resonance imaging indicated acute infarction in the right nodulus on diffusion-weighted images. (Korean J Stroke 2012;14:163-165) KEY WORDS: Cerebral infarction; Nodulus; Vestibular neuritis
Introduction
tion with keeping in mind that most of the cerebellar infarction is accompanied by other neurologic focal signs such as dysarthria,
The flocculonodular lobe consists of the nodulus and the floc-
diplopia, ophthalmoparesis, and limb ataxia.4,5 In addition, one
culus.1 The blood supply of nodulus is the medial branch of the
important clinical discriminant between cerebellar infarction and
posterior inferior cerebellar artery. Nodular infarction is usually
vestibular neuritis is head impulse test.2 The head impulse test is
accompanied by ischemic lesions in other areas, and isolated
only positive in vestibular neuritis.6
nodular infarction is very rare.2 The patients with isolated nodu-
Here, we report a case of atypical isolated nodular infarction
lar infarction can present with vertigo and imbalance without
showed ipsilateral lateropulsion and contralateral spontaneous
other neurological deficits, and usually show contralateral latero-
nystagmus to the lesion with a normal head impulse test.
2
pulsion and ipsilateral spontaneous nystagmus to the lesion.
Acute onset of vertigo, nausea, vomiting, and spontaneous horizontal-torsional unidirectional nystagmus combined with falling to the side opposite to nystagmus are well known signs of 3
Case Report A right-handed 70-year-old man developed sudden onset of
the vestibular neuritis. These symptoms may be also produced
vertigo with an unsteady gait one day before the admission in
by certain types of cerebellar infarction, and these cases lead us
our hospital. He also suffered from nausea and vomiting. The
to confuse. It is usually possible to distinguish the cerebellar in-
symptom was not paroxysmal, but lasting all day. He denied tin-
farction from vestibular neuritis by careful neurologic examina-
nitus, hearing loss, speech disturbance, sensory disturbance, and
Received: September 6, 2012 / Revised: October 25, 2012 Accepted: November 23, 2012 Address for correspondence: Sung Eun Kim, MD, PhD Department of Neurology, Haeundae Paik Hospital, Inje University College of Medicine, 875 Haeundae-ro, Haeundae-gu, Busan 612-896, Korea Tel: +82-51-797-1190, Fax: +82-51-797-1190 E-mail:
[email protected] Copyright ⓒ 2012 Korean Stroke society
muscle weakness. He had been prescribed an antihypertensive agent because of hypertension. Neurologic examination revealed spontaneous left-beating horizontal nystagmus with a torsional component in the primary and any eccentric positions. The amplitude of nystagmus was not reduced by fixation. The velocity of nystagmus was not increased or decreased with gaze shift. ISSN 1229-4101
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Isolated Nodular Infarction
A
B
C
D
FIGURE 1. Diffusion-weighted axial magnetic resonance imaging (MRI) shows acute infarction in the right nodulus (arrow).
There was no periodic alternating nystagmus. Head impulse test
infarction in the right nodulus on diffusion-weighted images
was normal. He could stand alone, but he was unable to stand
(Figure 1), and no abnormal finding was detected in other parts
with the feet together. He also fell to the right on walking if he
of the brain including brainstem and cerebellum. Computer-
was not supported. His range of movement for the extraocular
ized tomography angiography showed no evidence of steno-
eye muscles was full, and did not show any problems in appen-
occlusive lesion or aneurysm in the intracranial and major neck
dicular coordinaton such as dysmetria and dysdiadochokinesia.
arteries. Transthoracic echocardiography and 24 hours holter
Otherwise, neurological examination was normal.
monitoring showed no abnormal finding. Videooculography
Laboratory studies including electrolyte profiles, glucose level,
(VOR) was done 4 days after onset of the symptoms. In VOR,
cholesterol level, and thyroid function test were within normal
saccades, smooth pursuit, and caloric tests were normal. In addi-
limits. Magnetic resonance imaging (MRI) indicated acute
tion, spontaneous nystagmus was also disappeared in VOR. He
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Korean J Stroke 2012;14:163-165
Kang Min Park, et al.
was treated with aspirin. His vertigo and imbalance of walking
in a certain condition.8-10 If GABA has an excitatory effect in our
improved gradually within a few days.
case, the ischemic lesion may cause that the nodulus cannot exert excitatory effect on the ipsilateral inferior vestibular nucleus,
Discussion
resulting in ipsilateral lateropulsion and contralateral spontaneous nystagmus.
Lesions involving cerebellum produce lateropulsion and
Our case showed no focal neurologic signs except nystagmus
nystagmus.7 These findings could be explained by vestibular
and lateropulsion, and mimicked vestibular neuritis. However,
dysfunction. The Purkinje cells in the cerebellum have an inhibi-
head impulse test was normal. Our case is compatible with the
tory influence on the ipsilateral fastigial nucleus, and the fastigial
fact that the normal head impulse test strongly suggests central
nucleus has an excitatory connection with the contralateral ves-
lesion in the patients with spontaneous nystagmus.2
tibular nucleus. Lesions in the vestibular nucleus result in ipsi-
In conclusion, we report a rare case of isolated nodular infarc-
lateral lateropulsion and contralateral spontaneous nystagmus.
tion which showed atypical nystagmus and lateropulsion with a
Therefore, dysfunction of the ipsilateral cerebellar Purkinje’s
normal head impulse test. Clinicians should always perform the
cells may disinhibit the ipsilateral fastigial nucleus, and conse-
head impulse test at bedside exam.
quently activate the contralateral vestibular nucleus, resulting in ipsilateral lateropulsion and contralateral spontaneous nystagmus. In contrast to other areas of the cerebellum, a lesion involving the nodulus resulted in contralateral lateropulsion and ipsilateral spontaneous nystagmus. The nodular Purkinje’s cell projects to areas in the inferior vestibular nucleus, and a lesion in the nodulus may disinhibit the ipsilateral inferior vestibular nucleus, resulting in contralateral lateropulsion and ipsilateral spontaneous nystagmus.7 However, one interesting thing is that our patient showed ipsilateral lateropulsion and contralateral spontaneous nystagmus. We don’t know the exact reason for this. One conceivable explanation is involving other cerebellar or brainstem lesion. Our patient underwent brain MRI within 24 hours after symptom onset, and we didn’t have follow up brain MRI. We could miss other lesion because of early brain MRI examination. Another possibility is that edema surrounding lesion may be related to damage of other vermal lesions such as uvula and tonsil. Last possibility is that the nodulus may have transiently excitatory connection with ipsilateral vestibular nucleus. The Purkinje’s cells in nodulus usually have an inhibitory effect on vestibular nucleus by γ-aminobutyric acid (GABA), but not always. There have been some reports that GABA can exert excitatory effect
Conflicts of Interest The authors have no financial conflicts of interest.
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