Acta Neurochir (2015) 157:1519–1523
DOI 10.1007/s00701-015-2504-7

CASE REPORT - FUNCTIONAL

A single thalamic target for deep brain stimulation to treat
hemi-body pain syndrome
A. Rezaei Haddad 1,2 & I. Ughratdar 1 & K. Ashkan 1

Received: 1 March 2015 / Accepted: 29 June 2015 / Published online: 10 July 2015
# Springer-Verlag Wien 2015

Abstract
Background Patients experiencing hemi-body pain represent
a difficult problem when using the thalamus as a DBS target
given its anatomical topology.
Methods A 50-year-old HIV positive male underwent a right
unilateral thalamic DBS to treat his severe left hemi-body
central post-stroke pain following years of unsuccessful medication therapy.
Results The final active contact of the electrode corresponded
to stimulation of the nucleus ventrocaudalis parvocellularis
internis, which has provided prolonged pain relief.
Conclusion To our knowledge this was the first time this pattern of pain was treated by a single thalamic DBS electrode,
suggesting stimulation in this region may be a feasible target
for achieving relief from chronic severe hemi-body pain.
Keywords Hemi-body pain . DBS . Central post-stroke pain

Introduction
Deep brain stimulation (DBS) has been well established as an
effective treatment for movement disorders such as
Parkinson’s disease and essential tremor [7, 8]. Modern

* A. Rezaei Haddad
ali.rhaddad@me.com
1

Department of Neurosurgery, Kings College Hospital, Denmark Hill,
London SE5 9RS, UK

2

Warwick Medical School, The University of Warwick, Gibbet Hill,
Coventry CV4 7AL, UK

functional neurosurgical intervention for chronic pain syndromes dates back to the mid-1960s when Mazars et al., as a
result of their pioneering research on stimulation of the thalamic relay nucleus, paved the way for chronic stimulation in
patients by the early 1970s [21, 22]. However results from two
trials in the 1970s revealed only as few as 18 % of the patients
with initial favourable response maintained pain relief at
2 years [5]. As a result, skepticism about the efficacy of
DBS hindered further research and uptake of this intervention.
In the last decade however there has been a resurgence of the
technique following a number of reports that have confirmed a
good response to DBS in carefully selected patients [26].
Various DBS targets, including the ventroposterior (VP)
thalamus, septal area, periventricular gray matter (PVG) and
periaqueductal gray matter (PAG), have been utilised [12, 27,
28]. Given the frequent use and experience with the thalamus
as a target for movement disorders such as tremor, it remains
the preferred choice for many DBS surgeons including in our
unit. In the case of thalamic DBS, the underlying mechanisms
of action for the analgesic effects is unclear, but stimulation of
the thalamocortical pathways, alteration of thalamic activity
and interference of the pain relay pathway between the thalamus and cortex are believed to be responsible [18, 26, 31, 33].
Given the topological arrangement in the thalamus, patients
suffering from thalamic syndrome with hemi-body pain represent a specific problem. The ventral posterolateral nucleus
(VPL) and ventral posteromedial nucleus (VPM) serve as the
somatosensory relay nuclei of the thalamus, where the latter is
mainly involved with the general sensation of the head and
upper extremities, while the former receives sensory input
from the dorsal columns and spinothalamic tracts from the
lower extremities [13, 20]. Therefore, treating hemi-body pain
with a single DBS electrode proves challenging and of course
the strategy of inserting multiple electrodes carries the risk of
increased surgical morbidity and haemorrhage [37].

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Acta Neurochir (2015) 157:1519–1523

Here, we describe a 50-year-old HIV positive male who
suffered from a series of thalamic strokes and subsequently
developed severe hemi-body pain. This case provided the opportunity to identify whether a single DBS target could alleviate the hemi-body pain experienced by the patient.

Case report
History
A 50-year-old male suffered from four episodes of predominantly right hemispheric stroke over a 2-week period in 2004.
As an immediate consequence of the cerebrovascular accident, he developed severe left-sided weakness and pain. Although his physical symptoms recovered following 5 months
of rehabilitation, his central post-stroke pain (CPSP) persisted
despite trialing a variety of medications under several pain
management programmes. His pain was dysaesthetic in nature
and involved the lower part of his left face, neck and whole of
the left trunk including the left arm and leg. Pre-operatively
his medications included pregabalin, nitrazepam, nortriptyline, aspirin and dipyridamole. Given his HIV status, he was
also on anti-retroviral medication with a steady viral load of
40 copies/ml and a CD4 count of 1145 cells/μl. As his pain
severity had not improved over a 7-year period, described as
10/10 by the patient despite therapy, and had limited his capacity to perform normal daily tasks, a right-sided unilateral
thalamic DBS was offered and undertaken. An MRI brain
scan revealed established infarctions predominantly in the
right hemisphere involving the right thalamus, right posteromedial temporal and right antero-inferior occipital lobes, left
posterior insula and left corona radiata. There was no significant damage to the right VP thalamus (Fig. 1).
Surgical procedure
A right-sided unilateral thalamic DBS was performed in July 2011 under local anaesthetic. Stereotactic MRI images were
acquired with a Leksell G frame and surgical planning was
performed using the Medtronic Framelink® platform. Due to
the nature of the pain, the target was chosen at a point midway
between the atlas coordinates of the VPL and VPM. This
corresponded to 9.5 mm posterior to the mid-commissural
point, 13 mm lateral to the mid-sagittal plane at the level of
the inter-commissural line (Fig. 2). Intra-operative testing and
final implantation were achieved using a Medtronic 3389
DBS lead. No microelectrode recordings were performed, although dynamic impedance recordings were used to aid
targeting.
During the procedure, the anatomical target was refined via
test stimulation assessment in the awake state [2]. Test stimulation was initially performed 2 mm above the target and then

Fig. 1 T2-weighted magnetic resonance imaging showed no significant
damage to the right ventroposterior thalamus

incrementally at 2 mm intervals until 6 mm below the target.
The stimulating voltage was increased until pleasant paraesthesia in the distribution of the pain was experienced. The
threshold for side effects was verified up to 4.0 V. Optimal
results were achieved with stimulation at 4 mm below the
inter-commissural line with a voltage of 3.0 V, pulse width
of 60 μs and frequency of 40 Hz. Given the concerns about
reducing the infection risk given the patient’s HIV status, a
Medtronic Soletra battery was implanted in the same operative
session and medicated with intravenous prophylactic antibiotics for 5 days post-operatively in line with our previous
experience [11].
Image analysis by fusing the post-operative stereotactic CT
with the preoperative planning stereotactic MRI [24] confirmed the final position of the centre of the most effective
stimulating contact at 11 mm posterior to the midcommissural point, 12 mm lateral to the mid-sagittal plane
and 2.75 mm below the inter-commissural line. Superimposition of this target on the Schaltenbrand-Wahren atlas [29] located the active contact point at the nucleus ventrocaudalis
parvocellularis internis (Vcpci) (Fig. 2).
On the second day post-operatively, the battery was
switched on to a voltage of 1.0 V, pulse width of 60 μs and
frequency of 40 Hz with the patient reporting pain reduction
and comfortable paraesthesia in the distribution of the pain.
He was noted to have new mild unsteadiness, left
faciolingobrachial paraesthesia and reduced taste intensity in
the immediate post-operative phase. However these resolved
within a week and were not present on subsequent follow-up
visits or when increasing the voltage. He required a further
increase in the stimulating voltage over the next 3 months.
At long-term follow-up 38 months later, his stimulation
voltage was at 3.0 V. Contact 1 remained as the active contact

Acta Neurochir (2015) 157:1519–1523

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Fig. 2 Final position of the active
DBS electrode contact. Plate 43,
brain LXXVIII, myelin-stained
sagittal section 12.0 mm from the
midline, with ruled and labelled
acetate overlay from the
Schaltenbrand and Wahren atlas
edited to show the initial target
(circular symbol) and the final
position of the active contact
(square symbol) [29]

(unipolar stimulation). The patient reported that he had
discontinued taking his analgesic medications, namely
pregabalin, nitrazepam and nortriptyline. He rated his pain
as 6/10, a 40 % improvement, and as a consequence, the
patient reported that he was able to take part in many daily
activities that were not possible prior to surgery such as
exercising and shopping.

single electrode targeted at a point halfway between the VPL
and VPM corresponding with the active contact located in the
region of Vcpci.
The underlying mechanism may be related to current
spread to both the VPL and VPM, although this may also be
explained by the modulation of the Vcpci nucleus, where the
final active contact is believed to be located. Potential error
introduced as a result of fusing the pre-operative stereotactic
MRI, post-operative stereotactic CT and brain atlas should be

Discussion
Here, we report marked effects of analgesia following DBS in
an HIV-positive patient with severe hemi-body pain caused by
a series of strokes. It was estimated that approximately 8 % of
patients who suffer from stroke progress to developing CPSP
[1]. Further, it is thought that a higher percentage will suffer
from this intractable pain if the stroke involves the pain processing and sensory relay pathways, such as the thalamus [15,
16]. The first line of treatment consists of medication therapy
[9]. Should these medications fail to alleviate the pain, DBS
may be indicated in a selected group of patients [26].
Given the topological arrangement of the thalamus, the
pain pattern presented in this case, where the left half of the
head, trunk, arm and leg were affected, would be difficult to
address by insertion of a single thalamic electrode. Traditionally the VPM (9 mm posterior to the mid-commissural point,
9 mm lateral to the mid-sagittal plane and 0–4 mm below the
inter-commissural line) is targeted for facial and upper limb
pain whilst the VPL (10 mm posterior to the mid-commissural
point, 16 mm lateral to the mid-sagittal plane and 0–4 mm
below the inter-commissural line) is targeted for lower limb
pain [34]. To our knowledge, this is the first description of a
patient with this pattern of severe hemi-body pain treated by a

Fig. 3 The position of the ventral posteroinferior nucleus. Drawn coronal
section, 11 mm posterior to the mid-commisural plane, based on the
Schaltenbrand and Wahren atlas [29], to show the position of the ventral
posteroinferior nucleus (shaded area) in relation to the ventral posterolateral and ventral posteromedial nuclei

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born in mind when interpreting the results here [24]. Nevertheless, the Vcpci nucleus is believed to be an important structure for gustatory function [17]. The fact that our patient reported altered taste intensity after DBS may hint at the involvement of this nucleus in the mechanism of his pain relief.
In fact, a study has reported that strong stimulation of the
Vcpci in humans resulted in stimulation of somatic sensation
as well, suggesting that gustatory relay pathways convey multiple sensations [17]. No studies to date have looked at the role
of Vcpci in pain suppression in humans; however, a link between increased taste sensation and chronic back pain has also
been reported, indicating that an interaction between pain and
taste pathways may exist [30].
The Vcpci nucleus is situated inferiorly to the ventralis
caudalis (VC) nuclei and includes the arcuate nucleus [29].
The lateral part of the Vcpci is known as the ventral
posteroinferior nucleus (VPI) and is surrounded by the VPL
and VPM (Fig. 3) [29]. The VPI in primates has been reported
to contain nociceptive neurons and receive projections from
the spinothalamic tract [6]. The arcuate nucleus is a major
source of endogenous beta-endorphin, an opioid peptide, in
the central nervous system [3], and activity in this nucleus has
been shown to be increased in response to chronic pain in
rodents [19, 23, 25]. In addition, a few studies have reported
that stimulation of the nucleus arcuate was accompanied by
the release of beta-endorphin and a reduction of pain sensation
in rodents [4, 32, 35, 36]. These results suggest that the arcuate
nucleus activity may serve as a secondary mechanism to provide analgesia in response to persistent pain that may partly
explain the pain relief noted in our patient following the DBS.
Although DBS for chronic pain has existed for over 6 decades, because of the invasive nature and risks associated with
the procedure, it is reserved for when conservative medical
treatment has failed. The variable outcomes in the literature
warrant further studies and identification of novel surgical
targets [10, 14].
Our results support further research to determine the mechanisms responsible for the beneficial effects of Vcpci complex
stimulation and to explore whether arcuate nucleus stimulation specifically can have analgesic effects in humans.

Acta Neurochir (2015) 157:1519–1523

pain. Further studies are required to validate our findings and
elucidate the underlying mechanisms of pain relief.
Conflicts of Interest All authors certify that they have no affiliations
with or involvement in any organization or entity with any financial
interest (such as honoraria; educational grants; participation in speakers’
bureaus; membership, employment, consultancies, stock ownership or
other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript.
Patient Consent The patient has consented to the submission of the
case report for submission to the journal.

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Conclusion
We report marked analgesic effects in a patient suffering from
post-stroke hemi-body pain following placement of a single
thalamic DBS electrode targeted at a point midway between
the VPL and VPM with the active contact in the region of
Vcpci. To our knowledge this was the first time this pattern
of severe hemi-body pain was treated by a single thalamic
DBS electrode, suggesting stimulation in this region may be
a feasible target for achieving relief from chronic hemi-body

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