588

SHORT REPORT

Unilateral globus pallidus internus stimulation improves
delayed onset post-traumatic cervical dystonia with an
ipsilateral focal basal ganglia lesion
J W Chang, J Y Choi, B W Lee, U J Kang, S S Chung
.............................................................................................................................

J Neurol Neurosurg Psychiatry 2002;73:588–590

Treatment with unilateral left globus pallidus internus (GPi)
deep brain stimulation is reported in a patient with severe
delayed onset post-traumatic cervical dystonia. He had
sustained severe head trauma at the age of 17 and had
developed a mild right hemiparesis. Three years after the
head injury, cervical dystonia with head turning to the left
side developed. Magnetic resonance imaging (MRI)
showed a discrete GPi lesion on the left side. At the age of
23, he underwent unilateral left GPi deep brain
stimulation. He experienced immediate but short lasting
benefit from the microlesioning effect of the electrode.
With activation of deep brain stimulation, there was
significant improvement of the cervical dystonia, persisting
for 12 months of follow up. This case underlines the
importance of the globus pallidus internus in the
generation and amelioration of cervical dystonia.

T

he pathophysiology of cervical dystonia is not well understood, and the mechanism of improvement associated
with stereotactic surgical procedures is not clear either.1–3
The rationale for globus pallidus internus (GPi) stimulation in
dystonia is partly based on the observation of an improvement
in L-DOPA induced involuntary movements by pallidotomy or
pallidal stimulation in patients with Parkinson’s disease.
Although a role of the GPi in the pathogenesis of dystonia is
strongly suspected, presumably acting through alteration of
thalamic inhibition,4 focal traumatic lesions of the GPi have
only rarely been reported to produce secondary dystonia.
In this paper, we describe a patient who sustained a motor
vehicle accident that eventually led to a focally restricted
lesion of the GPi with cervical dystonia, which was
successfully treated by unilateral GPi stimulation.

deficits, but had a mild right sided hemiparesis. His gait was
hemiparetic, and he had mild dysarthria. His head was turned
towards the left side. When lying on his back, he was able to
turn his head to the neutral position by using trick manoeuvres:
he could follow the movement of his right finger visually and
turn his head toward the midline; he was also able to turn his
head by lightly contacting his face with his palm.
Neuroimaging
Initial computed tomography (CT) of the brain obtained after
the car accident showed a traumatic subarachnoid haemorrhage in the quadrigeminal cistern and contusional haemorrhage in the left basal ganglia (fig 1A). Brain magnetic
resonance imaging (MRI) done five days after the initial
injury showed diffuse brain oedema around the left basal
ganglia and right thalamus (fig 1B). Six years after the initial
injury, brain MRI revealed a confined and small lesion in the
left GPi (fig 1C). Brain CT obtained after electrode implantation for deep brain stimulation showed that the electrode was
positioned in the left posteroventral GPi just medial and anterior to the lesion (fig 1D).

A 23 year old man sustained a severe closed head injury in a
car accident at the age of 17. He had a right hemiparesis and
was obtunded for several weeks before recovering slowly over
the next few months. Three years after the initial head injury,
cervical dystonia developed, and this progressed in severity for
six months. The cervical dystonia did not improve with medical treatment, which included clonazepam, L-DOPA, baclofen,
and trihexyphenidyl. Two years later, he was treated with
botulinum toxin injections to the neck, but there was only a
transient ameliorating effect. There was no family history of
movement disorders. The patient was referred to our
institution for further evaluation and management.

Operation
A Leksell stereotactic frame was used to implant an electrode
into the GPi. A tentative target was determined using customised software, which automatically calculated the target from
the magnetic resonance image. The tentative target was set at
21 mm lateral to and 3 mm below the intercommissural line
and 2 mm anterior to the midcommissural point. Microelectrode confirmation at the GPi target was undertaken as previously described.5 Conventional single and multiunit extracellular recordings were made with a gold and platinum plated
tungsten electrode insulated with Parylene-C. The mean
discharge rate of neurones in both segments of the globus
pallidus was considerably lower than that reported in
idiopathic Parkinson’s disease in previous studies6 7 (data not
shown).
The final target was just medial and anterior to the lesion in
the left GPi. A local anaesthetic was given and a precoronal
burr hole was made on the right side 2.5 cm lateral to the
midline. A deep brain stimulation electrode (Medtronics,
Minneapolis, Minnesota, USA) was then inserted into the target using a guiding cannula. Electrical stimulations were performed to assess the proximity of the internal capsule and the
optic tract. These stimulations resulted in a mild decrease in
EMG activity in the right sternocleidomastoid muscle (fig 2).
The electrode was fixed to the burr hole, connected to the IPG
(Itrel II, model 7424; Medtronics), and implanted in a
subcutaneous pouch in the left subclavicular region under
general anaesthesia.

Examination
On admission at the age of 23, the patient’s general condition
was unremarkable. He was fully oriented, without memory

Postoperative course
Immediately after the operation, the patient was able to turn
his head to the midline without any sensory tricks while lying

CASE REPORT

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Globus pallidus stimulation for cervical dystonia

589

Figure 1 Brain imaging studies throughout the patient’s clinical course. (A) Initial brain computed tomography (CT), showing a traumatic
subarachnoid hemorrhage in the quadrigeminal cistern and contusional hemorrhage in the left basal ganglia. (B) Magnetic resonance imaging
(MRI) obtained five days after the initial injury, showing diffuse brain oedema around the left basal ganglia and right thalamus. (C) MRI images
obtained six years after the initial injury showing a small confined lesion in the left sided GPi. (D) Postoperative CT showing appropriate
positioning of the electrode.

on his back. However, his ability to turn his head to the midline
while standing or sitting did not improve. Seven days after
implantation of the stimulating electrode, the initial improvement of head turning ceased. One month after implantation,
deep brain stimulation was begun and the patient again
showed improvement in head turning. His head turning ability
then improved gradually up to six months after the operation.
The initial setting of the stimulation parameters was as follows: amplitude 2 V, pulse width 180 µs, frequency 160 Hz.
The patient was able to turn his head to the midline voluntarily without sensory tricks while lying on his back. In addition,
he could now turn his head to the midline while standing or
sitting, although with considerable effort and slowness.
Three months after electrode implantation, the cervical
dystonia was stable. We explored various IPG parameters, but
no further improvement in symptoms was observed over 12
months of postoperative follow up. Functionally, the patient
could enjoy watching television and eat without too much
effort, which he could not do before the surgery. There were no
adverse effects associated with the operation.

DISCUSSION
Post-traumatic movement disorders secondary to severe head
injuries have been reported in 22.6% of surviving patients.8
Movement disorders were described as being transient in
10.4% and persistent in 12.2% during a mean follow up period
of 3.9 years. Dystonia was observed in 4.1% of these patients.
Hemidystonia is the most common presentation of dystonia
caused by brain trauma, and is typically manifested by a
delayed onset. In most cases of dystonia, contralateral lesions
are found in the caudate, putamen, or thalamus.8 9 The clinical
features of delayed onset post-traumatic cervical dystonia are
indistinguishable from those of idiopathic cervical dystonia in
terms of the gradual progression of symptoms and signs and
the development of sensory tricks and activation manoeuvres.
Both conditions are distinct from acute onset post-traumatic
cervical dystonia.3
Most cases of delayed dystonia secondary to various
acquired conditions have been associated with pathological
lesions in the putamen, and cases that have been attributed to
lesions of the globus pallidus have been extremely rare.

Figure 2 Electromyographic activity in the sternocleidomastoid muscle (SCM) on both sides while the patient was sitting with his neck in its
natural position of almost 90° turned to the left side (before and after deep brain stimulation).

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Involvement of the GPi, particularly unilaterally, was most
unusual in reviews of reports from around the world.4 10 11
King et al described the delayed onset of hemidystonia and
hemiballismus following an isolated lesion of the GPi and
presumed that the cause of the symptom was partial
preservation of the Gpi.4 They suggested that the partial
involvement of the GPi may have provided the pathological
basis for the overall progression of the symptoms.
It is generally believed that dystonia results from the relay
of erroneous information from the thalamus to the premotor,
supplementary motor, and probably the primary motor cortices. This could be attributed to pathological changes at several
sites, including the putamen, the globus pallidus, the
thalamus itself, and rarely the caudate nucleus.4 It is not clear
why a lesion of the putamen is the most common anatomical
site producing dystonia.12 13 Experience with isolated lesions of
the globus pallidus has not only demonstrated that they may
cause dystonia, but has also shown that they may cause
parkinsonism, behavioural disorders, or no clinical
dysfunction.3 4 10
Lesioning or deep brain stimulation of the GPi has been
used successfully to treat both parkinsonian dyskinesia and
dystonia.6 7 14–18 The rationale for pallidotomy or pallidal stimulation in cases of Parkinson’s disease may be the removal of
excessive output from the GPi, which has been shown to occur
in this condition. On the other hand, a slower than normal firing rate in the GPi and a lower than normal thalamic
metabolic rate are noted in dystonia. Thus the mechanism of
the postoperative amelioration of dystonia after pallidal
stimulation has not been established, but may involve
abolition of the abnormal firing pattern rather than a simple
decrease of the increased firing rates.4 15
Experience with pallidal stimulation for focal dystonias
including cervical dystonia is very limited. Islekel et al reported
that a unilateral pallidal lesion or stimulation was an effective
method of treatment in focal dystonia.16 They emphasised that
the target must be the pallidum contralateral to the contracted
sternocloidomastoid muscle. Parkin and colleague presented
data to show that bilateral GPi stimulation led to a progressive
improvement over several months in the pain, voluntary head
movement, and abnormal posture caused by spasmodic
torticollis.18 Kulisevsky et al reported two patients with
idiopathic cervical dystonia with only mild motor improvement but marked amelioration of pain symptoms following
bilateral deep brain stimulation of the posteroventral GPi. The
wide dissociation between pain and motor improvement in
their patients suggested that dysfunction of motor and somatosensory circuits in dystonia did not always proceed in
parallel.19
Our patient improved after unilateral deep brain stimulation on the same side of the initial abnormal lesion, suggesting that abnormal neuronal activity resulted from the initial
lesion and was ameliorated by subsequent deep brain
stimulation in the adjacent area of the same structure.
Conclusions
We report the beneficial effect of deep brain stimulation in the
GPi in a patient with delayed onset post-traumatic cervical
dystonia. Consistent with the clinical features, which are
identical to those of idiopathic cervical dystonia, the response
to GPi stimulation suggests a common central pathogenic
mechanism and shared anatomical features between delayed
onset post-traumatic cervical dystonia and idiopathic cervical
dystonia. In addition, the unilateral nature of the lesion and

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Chang, Choi, Lee, et al

the unilateral placement of deep brain stimulation in the GPi
underlines the central importance of that structure in the
generation and amelioration of cervical dystonia.

ACKNOWLEDGEMENT
This study was supported by grant No R01–2000–000–00104–0 from
the basic research programme of the Korea Science and Engineering
Foundation.
.....................

Authors’ affiliations
J W Chang, B H Lee, J Y Choi, S S Chung, Department of
Neurosurgery and Medical Research Centre, Brain Korea 21 Project,
Yonsei University College of Medicine, Seoul, Korea
U J Kang, Department of Neurology, University of Chicago, Chicago,
Illinois, USA
Correspondence to: Professor J W Chang, Department of Neurosurgery,
Yonsei University College of Medicine, CPO Box 8044, Seoul, South
Korea; jchang@yumc.yonsei.ac.kr
Received 5 March 2002
In revised form 18 June 2002
Accepted 12 July 2002

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