Shen et al. BMC Neurology (2016) 16:228
DOI 10.1186/s12883-016-0745-6

CASE REPORT

Open Access

Combined focal myoclonus and dystonia
secondary to a cerebellar hemorrhage:
a case report
Guangxun Shen1, Guangxian Nan1, Chae-Won Shin2, Hyeyoung Park3, Kwee-Yum Lee4 and Beomseok Jeon3*

Abstract
Background: Myoclonus is a clinical sign characterized by sudden, brief jerky, shock-like involuntary movements of
a muscle or group of muscles. Dystonia is defined as a syndrome of sustained muscle contractions, frequently
causing twisting and repetitive movements or abnormal postures. Cases of myoclonus or dystonia secondary to a
structural lesion in the cerebellum have been reported. However, there has never been a reported case of
combined myoclonus and dystonia secondary to a cerebellar lesion.
Case presentation: Herein, we report a 22-year-old female patient with sudden-onset myoclonic jerks, dystonic
posture and mild ataxia in the right upper extremity. At age 19, she experienced sudden headache with vomiting.
The neurological examination showed ataxia, myoclonus and dystonia in the right upper extremity. Brain images
demonstrated a hemorrhage in the right cerebellar hemisphere secondary to a cavernous malformation. After
resection of the hemorrhagic mass, headache with vomiting disappeared and ataxia improved, but myoclonus and
dystonia persisted.
Conclusions: It is the first report of combined focal myoclonus and dystonia secondary to a cerebellar lesion.
Keywords: Myoclonus, Dystonia, Cerebellar lesion, Magnetic resonance imaging, Electromyography

Background
Myoclonus is a clinical sign characterized by sudden,
brief jerky and shock-like involuntary movements of a
muscle or group of muscles. The main anatomical origins of the myoclonic jerks are known to be cortical,
subcortical, spinal, and peripheral. Although rare, several
cases of myoclonus secondary to a structural lesion in
the cerebellum have been reported. Therefore, it has
been speculated that cerebellum might be one of the
possible generators of myoclonus [1]. Progressive myoclonus was reported in a young child with a ganglioglioma in the region of the deep cerebellar white matter
and nuclei [2].
Dystonia is defined as a syndrome of sustained muscle
contractions, frequently resulting in twisting and repetitive movements or abnormal postures. Although most
* Correspondence: brain@snu.ac.kr
3
Department of Neurology, Seoul National University College of Medicine,
Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul 110-774,
Republic of Korea
Full list of author information is available at the end of the article

common structural lesions responsible for dystonia are
in basal ganglia, cerebellum is also considered to be important in dystonia [3, 4]. Dystonia secondary to a cerebellar lesion is rare, but several cases have been reported
in the literature. For example, focal limb dystonia was
demonstrated in a patient with a cerebellar mass [5].
Herein, we describe an unusual case of sudden-onset
combined focal myoclonus and dystonia secondary to a
cerebellar lesion.

Case presentation
A 22-year-old right-handed woman was referred for management of jerky movements and abnormal posturing of
the right hand that had developed since acute hemorrhage
in the right cerebellar hemisphere secondary to a cavernous malformation. At age 19, she developed an episode of
severe headache with vomiting, and poor coordination.
Examination revealed ataxia in her right upper extremity
along with jerks and abnormal posturing of her right hand
and fingers. Brain computed tomography (CT) and magnetic resonance imaging (MRI) showed a hemorrhage in

© The Author(s). 2016 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver
(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Shen et al. BMC Neurology (2016) 16:228

the right cerebellar hemisphere compressing the fourth
ventricle (Fig. 1a and b). No structure lesions were found
in the supratentorial region. Resection of the mass and
pathological examination confirmed the diagnosis of cavernous malformation. Her headache improved after surgery. However, mild ataxia in the right arm, abnormal
posturing of the hand and spontaneous and sudden jerks
of the right fingers persisted. Furthermore, the jerks were
unable to be suppressed voluntarily but disappeared during sleep. Alcohol intake did not seem to affect those abnormal movements, but anxiety and stress worsened the
symptoms.
Neurological examination at our clinic showed mild
dysmetria in the right upper extremity on the finger-tonose test. The right hand showed occasional brisk jerks
at rest which became more evident on maintaining posture, but were not provoked by touch. Abnormal posturing
of the fingers was noted, which was accentuated while outstretching. An abnormally tight grip was observed while
writing with a pencil. (See Additional file 1, a video footage
of the patient showing these features in more detail). The
patient presented symmetrical deep tendon reflex and intact proprioceptive sensation. No long-tract signs were
found. There were no changes in the severity of these

Page 2 of 4

involuntary movements during a 6-month trial of piracetam, biperiden, baclofen and clonazepam.
A 15-month follow-up MRI demonstrated a postoperative malacic lesion in the right cerebellar hemisphere
(Fig. 1c). Surface electromyography (EMG) recordings of
the right forearm while keeping outstretched illustrated the
typical features of myoclonus with synchronous bursts
(93–97 ms) of EMG activities in agonist and antagonist muscles (Fig. 2).

Conclusion
Our patient presented with sudden-onset shock-like
jerks in her right fingers, superimposed on more sustained abnormality of posture in the right hand with
mild ataxia in the right arm. Surface EMG recordings
confirmed the jerks as myoclonus, which were synchronous and short-lasting activities in agonist and antagonist
muscles. Dystonic posturing of the right hand was evident in clinical examination (Additional file 1). It is
most likely that the cerebellar lesion is responsible for
both myoclonus and dystonia in our case based on the
following reasons: 1) The onset of the myoclonus and
dystonia coincided with onset of ataxia; 2) The lesion

Fig. 1 Brain images. Axial CT scan at the onset of the symptoms demonstrated a hemorrhagic mass in the right cerebellar hemisphere and the
fourth ventricle compressed by the mass (a). Axial T2-weighted MRI demonstrated heterogeneous low signal intensity of the mass (44 × 37 mm)
with high signal intensity in the periphery (b). Axial T1-weighted MRI at 15-month follow-up after resection demonstrated a post-operative
malacic lesion in the right cerebellar hemisphere (c)

Shen et al. BMC Neurology (2016) 16:228

Page 3 of 4

Fig. 2 Surface EMG. EMG recordings of the right upper extremity while maintaining a posture demonstrate two consecutive jerks (93–97 ms),
showing synchronous bursts in agonist and antagonist muscles. PRO: pronator teres muscle; SUPI: supinator muscle; DI. EXT: extensor digitorum
communis muscle; DI. FLE: flexor digitorum profundus muscle; CA. EXT: extensor carpi ulnaris muscle; CA. FLE: flexor carpi radialis muscle

of the right cerebellar hemisphere was demonstrated
on the brain CT and MRI; and 3) Involuntary movements were ipsilateral to the cerebellar lesion.
Cerebellum as a structure in cerebro-cerebellar loops,
participates in motor control by means of sensorimotor
integration - the process whereby sensory input is integrated by the central nervous system and used for assisting motor program execution [6, 7].
Even though there have been reports of dystonia in
cerebellar lesion, the pathophysiology is not entirely
clear. However, there are suggestions that abnormal
cerebellar learning and functional interactions between cerebellar and basal ganglia circuits may play a
role [8, 9].
Role of cerebellum in myoclonus is also not clear.
However, there are several reported cases of cortical
myoclonus in patients with cerebellar pathology,
which are documented by neurophysiology and pathology [10]. This paradoxical absence of cortical pathology and cortical myoclonus in patients with
cerebellar pathology has promoted the authors to suggest that enhanced excitability of the sensorimotor
cortex may arise as a distant effect of cerebellar pathology [10]. This has further been explored in the review by Ganos et al. [11].
Our case is unique in that the hemorrhage in the right
cerebellar hemisphere and subsequent surgical operation
result in myoclonus and dystonia at the same time, and
it further supports the role of cerebellum in the generation of myoclonus and dystonia.
In conclusion, the findings in our patient support that
movement disorders resulting from lesions of the cerebellum may include myoclonus and dystonia.

Additional file
Additional file 1: A 22-year-old woman with focal myoclonus and
dystonia in the right upper extremity. No myoclonus is noted at rest or
triggered by external stimuli. Postural myoclonus of the right hand is
prominent and her right fingers show dystonic posturing when she
outstretches the arms and rotates the wrist. The abnormal posturing
of hand also interferes with a writing task. The patient shows normal
gait. (MP4 32.1 mb)
Abbreviations
CT: Computed tomography; EMG: Electromyography; MRI: Magnetic
resonance imaging
Acknowledgments
We thank the patient and her family for their consents to publish the case
report and the accompanying video segment.
Funding
We receive no funding support.
Availability of data and materials
All data and material (Additional file 1: video) supporting our findings are
contained within the manuscript.
Authors’ contributions
GS examined the patient and drafted the manuscript. GN evaluated the
neuroimaging findings and provided critical clinical opinions. CWS and HP
helped with collection and analysis of EMG and clinical data. KYL helped
with English-editing of the manuscript. BJ conceived the case and is accountable
for the integrity of the entire work. All authors read and approved the final
manuscript.
Competing interests
The author (s) declared no conflicts of interest with respect to the research,
authorship, funding, and/or publication of this article.
Consent for publication
Written informed consent was obtained from the patient and patient’s mother
for publication of this case report and accompanying images. A copy of the
written consent is available for review by the Editor-in-Chief of this journal.

Shen et al. BMC Neurology (2016) 16:228

Page 4 of 4

Ethics approval and consent to participate
The patient has given her consent for this case report.
Author details
1
Department of Neurology, China-Japan Union Hospital of Jilin University,
Changchun, China. 2Department of Neurology, SNU-SMG Boramae Medical
Center, Seoul, Republic of Korea. 3Department of Neurology, Seoul National
University College of Medicine, Seoul National University Hospital, 101
Daehak-ro, Jongno-gu, Seoul 110-774, Republic of Korea. 4School of
Medicine, University of Queensland, Brisbane, QLD 4072, Australia.
Received: 12 July 2016 Accepted: 8 November 2016

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