Unusual association of diseases/symptoms

CASE REPORT

Urgent decisions and a tight spot: embolic infarction
of a herniated cerebellar tonsil
Ruth Mc Donagh,1 David Bradley,2 Joseph Augustine Harbison3
1

Department of Geriatrics,
St. James’s Hospital, Dublin,
Ireland
2
Department of Stroke,
St. James’s Hospital, Dublin,
Ireland
3
Department of Stroke and
Geriatrics, St. James’s Hospital,
Dublin, Ireland
Correspondence to
Professor Joseph Augustine
Harbison,
jharbiso@tcd.ie
Accepted 21 July 2016

SUMMARY
A previously well 30-year-old woman presented at 17:30
with a sudden onset of dizziness, ataxia and headache.
She was initially investigated with a CT scan of the brain
and lumbar puncture, which yielded no diagnosis.
Subsequent MR scan revealed multiple posterior
circulation infarcts, along with a previously undiagnosed
Arnold-Chiari 2 malformation with an associated syrinx
of her cervical and thoracic spine. The infarct involved
one of the herniated cerebellar tonsils. Oedema of an
infarct in the herniated tonsils caused compression of
the medulla at the foramen magnum, with associated
neurological symptoms including Lhermitte’s
phenomenon and headache on valsalva manoeuvre.
Owing to these symptoms a surgical decompression was
performed. The most likely aetiology of her stroke was
determined to be a paradoxical embolus via patent
foramen ovale.

BACKGROUND
Arnold-Chiari malformation is a common anatomical variant where the cerebellar tonsils herniate
into the foramen magnum. It is frequently associated with the development of a cervical syrinx
and occasionally with syringomyelia. In this report,
we describe a case where acute embolic infarction
of a tonsil in a young woman resulted in sudden
presentation of symptoms or cervical cord compression. This hazardous complication of the interaction between two relatively common neurological
problems has not been described.

cranial CT scan to look for evidence of stroke,
which was reported normal initially; however, a
later formal report suggested herniation of her cerebellar tonsils with a Chiari malformation (figure 1).
A lumbar puncture was performed to rule out subarachnoid haemorrhage given the acute onset of
headache which also precluded thrombolysis. The
cerebrospinal fluid examination was normal with no
evidence of infection or xanthochromia, with 47
red cells and normal protein. Opening pressure was
not recorded. A prospective diagnosis of cerebellar
stroke was made and she was transferred to the
stroke unit. She underwent MRI of her brain and
cervical spine, and cerebral angiography the following morning. On MR diffusion-weighted imaging
she was found to have multiple small acute infarcts
in the posterior thalamus and both cerebellar hemispheres (figures 2 and 3), all in a posterior circulation distribution. Medullary and cerebellar
herniation through the foramen magnum was
noted, representing an Arnold-Chiari type 2 malformation (figure 4). There was also a substantial
syrinx in the spinal cord extending from C2 to T2
(figure 4), the extent of which was surprising given
her relative lack of neurological signs. Radiology
findings did not support dissection, vasculitis or
fibromuscular dysplasia as potential aetiologies.

CASE PRESENTATION

To cite: Mc Donagh R,
Bradley D, Harbison JA. BMJ
Case Rep Published online:
[please include Day Month
Year] doi:10.1136/bcr-2016215299

A 30-year-old Caucasian woman presented to the
emergency department with sudden onset of dizziness and vomiting, followed by a headache. She
had never experienced a similar episode previously.
Her only medications were the combined contraceptive pill and occasional cyclizine for intermittent
nausea. She was a lifelong non-smoker, drank
alcohol occasionally and denied illicit drug use.
There was no relevant family history.
On examination, she had brisk reflexes throughout and demonstrated dysmetria with her left
upper limb. She had no tremor or nystagmus
reported. Her saccadic movements were normal.
Her gait was ataxic and her NIH Stroke Scale was
reported as 3. Examination of other systems was
normal.

INVESTIGATIONS
Full blood count, renal and liver profiles, and C
reactive protein were normal. She had an urgent

Figure 1 Neurological imaging of the patient. CT scan
on admission showing crowding in foramen magnum due
to herniation of cerebellar tonsils. Admission
non-contrast CT scan of the brain. Foramen magnum
appears crowded with no visible cerebrospinal fluid.

Mc Donagh R, et al. BMJ Case Rep 2016. doi:10.1136/bcr-2016-215299

1

Unusual association of diseases/symptoms

Figure 4 Sagittal T2 MR scans of the brainstem and cervical cord.
Syrinx present in cervical and upper thoracic cord. Cerebellar tonsil
shows evidence of infarction.
Figure 2 Axial diffusion-weighted imaging (DWI) MR showing areas
of acute infarction in both hemispheres of the cerebellum. DWI
sequence MR scan of the brain. Multiple small infarcts were visible in
both cerebellar hemispheres.

Physiological monitoring demonstrated that she remained in
sinus rhythm throughout her hospital stay.
The patient’s headache initially improved following admission; however, 2 days after admission she reported worsening of
her headache on sitting up and coughing. This was thought to
be concerning, as she had a lumbar puncture performed in the
context of an undiagnosed Arnold-Chiari malformation. Repeat
MR brain scan and review of her initial MRI showed acute
infarct within her herniated right cerebellar tonsil on both
fluid-attenuated inversion recovery (FLAIR) and diffusion-

Figure 3 Axial diffusion-weighted imaging MR from just above
foramen magnum showing acute infarct in the right inferior cerebellum.
2

weighted imaging (figures 5 and 6) thus increasing her risk of
spinal cord or medullary compression. She had no new focal
neurology at that time, but some hours later she described bilateral paraesthesiae in her upper limbs on laughing or neck
flexion, characteristic of Lhermitte’s phenomenon.

TREATMENT
She was reviewed by a neurosurgical service and underwent craniocervical decompression of the Chiari malformation. This was
uncomplicated and she was transferred back to our care to complete her workup on her symptoms having resolved.

Figure 5 Axial T2 fluid-attenuated inversion recovery MR scan
showing infarction of the right cerebellar tonsil.
Mc Donagh R, et al. BMJ Case Rep 2016. doi:10.1136/bcr-2016-215299

Unusual association of diseases/symptoms
serious caution or contraindication exists.3 MR is clearly the
investigation of choice in a case such as this, where a patient
presents with acute neurological signs suggestive of a potential
posterior circulation stroke.4 5 However, MR remains unavailable outside standard working hours in many hospitals.6
Eventually it was not the imaging findings that led us to her
diagnosis but the symptoms and signs she developed after
48 hours, probably when oedema of the infarcted tonsil had
progressed, resulting in compression of the posterior columns
and causing Lhermitte’s sign. This emphasises the continued
importance of clinical neurological history taking and examination in the era of hyperacute stroke.

Learning points
▸ Arnold-Chiari malformation is a relative contraindication to
lumbar puncture; however, it may be performed where it is
necessary to rule out a serious pathology, such as meningitis
or subarachnoid haemorrhage.3
▸ Urgent brain imaging and rapid neurological assessment of
suspected stroke is now the norm in most centres to
facilitate potential intervention. In circumstances of more
complex neurological presentations caution should be
exercised before engaging in more invasive investigations
such a lumbar puncture, with detailed neurological
examination and formal evaluation of brain imaging carried
out before the start.
▸ While historically stroke was characterised by signs that were
‘maximal at onset’, neurological deterioration occurs in 20–
30% of cases. It is important that patients are kept under
observation and fully re-evaluated if this occurs to identify
remediable causes. This may be one reason for the effect of
stroke unit care in reducing death and disability.7

Figure 6 Axial diffusion-weighted imaging MR at level of foramen
magnum showing hyperintensity of the right cerebellar tonsil consistent
with the infarct.

OUTCOME AND FOLLOW-UP
Postoperatively, our patient was discharged on antiplatelet treatment (aspirin 75 mg daily).
Subsequent contrast echocardiography revealed significant
flow across the interatrial septum without valsalva, consistent
with a large patent foramen ovale or atrial septal defect which is
presumed to be the most likely cause of her infarct.

DISCUSSION
This report is of an unusual interaction of two fairly common
neurological conditions resulting in a potentially very serious
consequence. The assessment of dizziness in the emergency
department is frequently challenging1 with particular difficulty
for the emergency staff in distinguishing between central and
peripheral causes. MR scanning is not easily available out of
ordinary working hours and in the context of the availability of
acute interventions for stroke decisions are often made quickly
on the basis of CT scans where structural subtleties like the presence of herniated cerebellar tonsils may often be missed.
Even following our patient’s MR scan it was only when she
developed new symptoms that the infarction of the tonsil was
recognised.
The failure to recognise the Arnold-Chiari malformation and
herniated tonsils led to the medical team on admission performing a lumbar puncture to rule out subarachnoid haemorrhage.
While there was no absolute contraindication to lumbar puncture, the identification of a Chiari malformation may have led
to a decision to defer the procedure in the context of no blood
having been seen on CT scan. Recent studies have suggested that
sensitivity CT may be approaching 100% if performed in the
first 6–12 hours after onset of symptoms of subarachnoid haemorrhage2 and thus lumbar puncture may not be necessary if a

Mc Donagh R, et al. BMJ Case Rep 2016. doi:10.1136/bcr-2016-215299

Contributors RMD, DB and JAH were all involved in diagnosing and managing
the patient. All contributed to the writing of the paper.
Competing interests None declared.
Patient consent Obtained.
Provenance and peer review Not commissioned; externally peer reviewed.

REFERENCES
1
2

3
4
5
6
7

Kerber KA. Vertigo and dizziness in the emergency department. Emerg Med Clin
North Am 2009;27:39–50, viii.
Perry JJ, Stiell IG, Sivilotti ML, et al. Sensitivity of computed tomography performed
within six hours of onset of headache for diagnosis of subarachnoid haemorrhage:
prospective cohort study. BMJ 2011;343:d4277.
Erbay SH, O’Callaghan MG, Bhadelia R. Is lumbar puncture contraindicated in
patients with Chiari I malformation? AJNR Am J Neuroradiol 2005;26:985.
Tatlisumak T. Is CT or MRI the method of choice for imaging patients with acute
stroke? Why should men divide if fate has united? Stroke 2002;33:2144–5.
Merwick Á, Werring D. Posterior circulation ischaemic stroke. BMJ 2014;348:g3175.
Hauptfleisch J, Meagher TM, King D, et al. Out-of-hours MRI provision in the UK
and models of service delivery. Clin Radiol 2013;68:e245–8.
Roquer J, Rodríguez-Campello A, Gomis M, et al. Acute stroke unit care and early
neurological deterioration in ischemic stroke. J Neurol 2008;255:1012–17.

3

Unusual association of diseases/symptoms
Copyright 2016 BMJ Publishing Group. All rights reserved. For permission to reuse any of this content visit
http://group.bmj.com/group/rights-licensing/permissions.
BMJ Case Report Fellows may re-use this article for personal use and teaching without any further permission.
Become a Fellow of BMJ Case Reports today and you can:
▸ Submit as many cases as you like
▸ Enjoy fast sympathetic peer review and rapid publication of accepted articles
▸ Access all the published articles
▸ Re-use any of the published material for personal use and teaching without further permission
For information on Institutional Fellowships contact consortiasales@bmjgroup.com
Visit casereports.bmj.com for more articles like this and to become a Fellow

4

Mc Donagh R, et al. BMJ Case Rep 2016. doi:10.1136/bcr-2016-215299