Images in…

Sean Lance, 1 Tom Thomson2
1

Department of Medicine,
University of Otago Wellington,
Wellington, New Zealand
2
Hutt Valley District Health
Board, Lower Hutt, New Zealand
Correspondence to
Dr Sean Lance,
​Sean.​Lance@​ccdhb.​org.n​ z
Accepted 13 April 2019

© BMJ Publishing Group
Limited 2019. No commercial
re-use. See rights and
permissions. Published by BMJ.
To cite: Lance S,
Thomson T. BMJ Case
Rep 2019;12:e229876.
doi:10.1136/bcr-2019229876

Description

A 40-year-old man with a 5-day history of posterior
headache and neck discomfort presented with acute
onset severe ataxia when walking across the road
causing him to fall. There were no other neurological symptoms. On arrival to the emergency department, his National Institutes of Health Stroke Scale
(NIHSS) was assessed as zero due to lack of limb
ataxia. He was observed to have left beating horizontal nystagmus and jerky smooth pursuit. His
head impulse test was negative, and he was severely
ataxic on mobilisation with a tendency to fall to the
right.
His medical history was significant for migraine
for which he was on amitriptyline 30 mg once a day.
CT head excluded haemorrhage, and CT angiogram revealed a distal vertebral artery dissection
with a filling defect immediately proximal to the
intracranial extension of the artery consistent with
intravascular thrombus (figure 1). The dissected
portion of the artery is demonstrated by the change
in calibre from the narrow proximal portion to the
wider distal portion (compared with the usual situation where the vessel becomes smaller the more

Figure 1 Above: sagittal CT angiogram image showing
intravascular clot in left vertebral artery. Left below: left
vertebral artery dissection demonstrated by a change in
vessel calibre from narrow (proximal, dissected portion) to
fully patent (distal, non-dissected portion). Right below:
follow up CT angiogram 4 months later demonstrating
recanalisation of the left vertebral artery.

Figure 2 MRI sequences demonstrating acute
infarction of the cerebellar nodulus (hyperintense on
diffusion weighted imaging (DWI) (left image) with
corresponding hypointensity on apparent diffusion
coefficient (ADC) (right image)).
distal it travels). Despite an NIHSS of 0, his ataxia
was severe with potentially catastrophic functional impairment so he was thrombolysed with
alteplase 2 hours and 58 min following the onset of
symptoms.
An MRI performed the following day revealed
an acute infarct of the cerebellar nodulus (figure 2).
He showed rapid improvement and was
discharged home 48 hours after admission, mobilising independently.
Four months later, he was reviewed in clinic with
no ongoing neurological deficit. He had been able
to return to work as an administrator and was back
driving. Repeat CT angiography (figure 1) demonstrated recanalisation of the left vertebral artery.
Isolated infarcts involving the cerebellar nodulus
are rare and are challenging to diagnose. The
nodulus receives prominent vestibular sensory afferents, and so there is a significant risk of misdiagnosis
as typical cerebellar signs are often absent, with the
clinical presentation usually more consistent with a
vestibular disorder (vertigo and imbalance and the
absence of other cerebellar features).1 This, along
with the relative insensitivity of the NIHSS scoring
system to identify suitable patients presenting with
posterior circulation stroke syndromes for acute
stroke management, results in consistently lower
rates of thrombolysis and longer door to needle
times.2 Olivato et al described an approach (the
‘expanded NIHSS’ or ‘e-NIHSS’) which helps to
improve posterior circulation stroke sensitivity by
modifying the scoring of eye movements to include
nystagmus, facial palsy to include palate and tongue
deficits and limb ataxia to include postural stability.3
The majority of the literature on nodular infarction is restricted to case reports with a small (n=8
patients) observational study published in Stroke
in 2009 highlighting nodular infarction as a mimic

Lance S, Thomson T. BMJ Case Rep 2019;12:e229876. doi:10.1136/bcr-2019-229876

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BMJ Case Rep: first published as 10.1136/bcr-2019-229876 on 29 April 2019. Downloaded from http://casereports.bmj.com/ on April 18, 2024 by guest. Protected by copyright.

Cerebellar nodulus infarction secondary to vertebral
artery dissection

Images in…

►► The National Institutes of Health Stroke Score is insensitive

for posterior circulation strokes and so a careful assessment
of risk factors and clinical features is essential when
considering these patients for acute intervention—consider
additional examinations
►► When presenting with vertigo and/or ataxia, assessment of
gait is essential.
of peripheral vertigo.1 The key features identified in this paper
were the lack of other central features, with vertigo and imbalance most commonly reported. Additionally, features mimicking
peripheral vertigo were present including nystagmus ipsilateral to the lesion, with imbalance and falling contralateral to
the lesion.1 This observation is attributed to disruption of the
normal nodular inhibition on the vestibular nucleus and explains
the high risk of misdiagnosis in these patients.1
Our patient had presented with isolated imbalance, and in the
context of his lack of vascular risk factors, a diagnosis of peripheral vertigo seemed most likely. However, as noted, nodulus

stroke can present in a similar fashion, and the key aspect of
his case was the severe ataxia—so severe he could not stand
unaided—not usually such a significant feature in peripheral
vestibular disorders.
Our case also highlights the insensitivity of the traditional
NIHSS when assessing acute stroke and supports putting a larger
emphasis on assessing for significant functional impairment.
Contributors SL was the acute stroke registrar caring for this patient and TT was
the Stroke Physician providing acute and ongoing care. SL was the primary author
with TT providing advice and editing oversight.
Funding The authors have not declared a specific grant for this research from any
funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent for publication Obtained.
Provenance and peer review Not commissioned; externally peer reviewed.

References

1 Moon IS, Kim JS, Choi KD, et al. Isolated nodular infarction. Stroke 2009;40:487–91.
2 Merwick Á, Werring D. Posterior circulation ischaemic stroke. BMJ 2014;348:g3175.
3 Olivato S, Nizzoli S, Cavazzuti M, et al. e-NIHSS: an Expanded National Institutes of
Health Stroke Scale Weighted for Anterior and Posterior Circulation Strokes. J Stroke
Cerebrovasc Dis 2016;25:2953–7.

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Lance S, Thomson T. BMJ Case Rep 2019;12:e229876. doi:10.1136/bcr-2019-229876

BMJ Case Rep: first published as 10.1136/bcr-2019-229876 on 29 April 2019. Downloaded from http://casereports.bmj.com/ on April 18, 2024 by guest. Protected by copyright.

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