PSYN-09710; No of Pages 8
Psychiatry Research: Neuroimaging xxx (2011) xxx–xxx
Contents lists available at ScienceDirect
Psychiatry Research: Neuroimaging
j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / p s yc h r e s n s
Shape alterations in the striatum in chorea-acanthocytosis
Mark Walterfang a,⁎, Jeffrey Chee Leong Looi b, Martin Styner c, Ruth H. Walker c, Adrian Danek c,
Marc Neithammer c, Andrew Evans c, Katya Kotschet c, Guilherme R. Rodrigues c,
Andrew Hughes c, Dennis Velakoulis c
a
Neuropsychiatry Unit, Level 2, John Cade Building, Royal Melbourne Hospital 3050, Australia
Research Centre for the Neurosciences of Ageing, Academic Unit of Psychological Medicine, School of Clinical Medicine, Australian National University Medical School, Canberra Hospital,
Canberra, Australia
c
Department of Neurology, James J. Peters Veterans Affairs Medical Center, Bronx, NY 10468, USA and Department of Neurology, Mount Sinai School of Medicine, New York, NY 10029, USA
b
a r t i c l e
i n f o
Article history:
Received 6 March 2010
Received in revised form 21 October 2010
Accepted 21 October 2010
Available online xxxx
Keywords:
Neuroacanthocytosis
Chorea-acanthocytosis
Chorea
Caudate
Striatum
Neurodegeneration
a b s t r a c t
Chorea-acanthocytosis (ChAc) is an uncommon autosomal recessive disorder due to mutations of the VPS13A
gene, which encodes for the membrane protein chorein. ChAc presents with progressive limb and orobuccal
chorea, but there is often a marked dysexecutive syndrome. ChAc may first present with neuropsychiatric
disturbance such as obsessive–compulsive disorder (OCD), suggesting a particular role for disruption to
striatal structures involved in non-motor frontostriatal loops, such as the head of the caudate nucleus. Two
previous studies have suggested a marked reduction in volume in the caudate nucleus and putamen, but did
not examine morphometric change. We investigated morphometric change in 13 patients with genetically or
biochemically confirmed ChAc and 26 age- and gender-matched controls. Subjects underwent magnetic
resonance imaging and manual segmentation of the caudate nucleus and putamen, and shape analysis using a
non-parametric spherical harmonic technique. Both structures showed significant and marked reductions in
volume compared with controls, with reduction greatest in the caudate nucleus. Both structures showed
significant shape differences, particularly in the head of the caudate nucleus. No significant correlation was
shown between duration of illness and striatal volume or shape, suggesting that much structural change may
have already taken place at the time of symptom onset. Our results suggest that striatal neuron loss may occur
early in the disease process, and follows a dorsal–ventral gradient that may correlate with early
neuropsychiatric and cognitive presentations of the disease.
© 2010 Elsevier Ireland Ltd. All rights reserved.
1. Introduction
The neuroacanthocytoses are a group of disorders that present with
neurological and psychiatric manifestations, and acanthocytes, spiculated red blood cells. Chorea-acanthocytosis (ChAc; MIM 200150) is an
autosomal recessive disorder associated with mutations or deletions
in the VPS13A gene on chromosome 9q. This gene codes for the
membrane protein chorein (Ueno et al., 2001b; Rampoldi et al., 2002),
which is strongly expressed in the brain (Dobson-Stone et al., 2002).
Loss of function of chorein appears to affect basal ganglia neurons,
especially those in the caudate and putamen (Bader et al., 2008).
Onset of neurological disturbance in ChAc is usually between ages 25
and 45, commonly with limb chorea that may be indistinguishable
from Huntington's disease (Dobson-Stone et al., 2002), but also with
distinctive lingual feeding dystonia (Bader et al., 2010). Identification
and sequencing of the VPS13A gene (Rampoldi et al., 2001; Ueno et al.,
2001a) have enabled definitive diagnosis of ChAc and differentiation
⁎ Corresponding author. Tel.: + 61 393428750; fax: + 61 393428483.
E-mail address: mark.walterfang@mh.org.au (M. Walterfang).
from related neuroacanthocytosis syndromes such as McLeod syndrome (Danek et al., 2005). Diagnosis has been facilitated by the
development of a Western blot screening test for decreased or absent
levels of chorein (Dobson-Stone et al., 2004).
Histopathologically, the relatively rare ChAc cases with confirmed
VPS13A mutations have shown marked striatal neuronal loss with
reactive astrocytic gliosis, particularly in the head of the caudate
nucleus, with the globus pallidus less affected; and with minimal
changes in the thalamus and substantia nigra, with the cortex almost
universally spared (Bader et al., 2008). Magnetic resonance imaging
(MRI) findings in established ChAc cases mirror these findings, showing
marked striatal atrophy in the absence of significant cortical atrophy
(Hardie et al., 1991; Kutcher et al., 1999; Walterfang et al., 2008).
The functional consequences of these changes in the striatum are
the characteristic choreiform movements, thought to be the result of
disruption of motor loops in the putamen and pallidum (Danek et al.,
2005), and behavioural and neuropsychiatric symptoms. The involvement of non-motor frontostriatal loops that run through the caudate
nucleus, in particular, may be responsible for the characteristic
executive impairment seen in the illness (Hardie et al., 1991; Danek
et al., 2005). Patients with ChAc have very high rates of obsessive–
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doi:10.1016/j.pscychresns.2010.10.006
Please cite this article as: Walterfang, M., et al., Shape alterations in the striatum in chorea-acanthocytosis, Psychiatry Research:
Neuroimaging (2011), doi:10.1016/j.pscychresns.2010.10.006
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M. Walterfang et al. / Psychiatry Research: Neuroimaging xxx (2011) xxx–xxx
compulsive disorder (Walterfang et al., 2008), unique for any
neurodegenerative condition, suggesting disruption to the caudate's
central role in the function of the lateral orbitofrontal loop (LOFL) in
subserving the choice of behavioural actions relevant to emotional
and cognitive inputs from frontal cortex (Chamberlain et al., 2005).
Aside from case reports, only two systematic analyses of striatal
volume have been undertaken in ChAc patients. Henkel et al. used a
voxel-based morphometry (VBM) approach to compare six ChAc
patients to 15 age-matched controls, and showed a focal and
symmetrical atrophy of the caudate nucleus, but no reduction in
any other brain region, including in the putamen (Henkel et al., 2006).
Huppertz et al. expanded the dataset to nine ChAc patients, and
utilised the normalization component of the VBM approach of Henkel
et al. to create caudate and putamen masks from a large control group
average to determine normalized volume of these structures. They
demonstrated a significant volumetric reduction in both structures,
and showed complete separation of ChAc patients and controls on
measures of caudate volume (Huppertz et al., 2008). However, the
methodology of these studies did not extend beyond analysing the
total volume of striatal structures in ChAc. One study analysed striatal
volume in three brothers with McLeod syndrome (a related
neuroacanthocytosis syndrome) and 20 matched controls, and
showed that patients' striatal volumes were significantly reduced
compared with those of controls, with caudate nuclei showing a trend
towards significant volume reduction over a 7-year follow-up period
(Valko et al., 2010).
We sought to confirm and extend upon the findings of Huppertz
et al. (2008) with an expanded dataset, using a standardized and
validated traditional manual tracing methodology for each structure,
followed by a morphometric analysis to determine whether the shape
or morphology of the caudate and putamen differed between ChAc
patients and controls. This allowed us to explore whether there are
regional neuroanatomical changes to striatal structures in ChAc that
may relate to the characteristic symptoms of the illness. Our
hypothesis was that the caudate nucleus would be disproportionately
affected, and that we would find a predilection for involvement of the
head of the caudate nucleus, in particular regions that form a crucial
component of the LOFL, in the patient group.
2. Materials and methods
2.1. Subjects
Patients with ChAc (n = 13) were recruited from multiple centres
worldwide, including the United Kingdom, Europe, North and South
America, and Australia. Patients 1–8 include the six patients described
in the previously published VBM study (Henkel et al., 2006) and
patients 1–7 reported by Huppertz et al. (2008). Patient 9 has been
previously described by Robertson et al. (2008a) and Walterfang et al.
(2008a), and patient 11 corresponds to case 2 of Rodrigues et al.
(2008b). Patients 12 and 13 are two previously unpublished siblings
from Australia. Molecular genetic diagnosis was confirmed by
mutations in the VPS13A gene, abnormally reduced chorein expression by Western blot, or both. In addition, 4/13 patients had
obsessive–compulsive symptoms or disorder, and 11/13 had executive dysfunction. Controls (n = 26) were matched two-for-one for age
and gender to the patient sample, and were selected from a large
database of healthy normal controls recruited by hospital and media
advertisements by the Melbourne Neuropsychiatry Centre.
2.2. MRI scanning
High-resolution volume-rendering 3D datasets of the whole head
were obtained for all subjects for the purpose of manual volumetry.
All control subjects were scanned on a 1.5T General Electric Signa MRI
scanner (GE, Milwaukee, USA) at the Royal Melbourne Hospital,
Melbourne. Images were acquired in the axial plane using a T1
weighted, 3D Spoiled Gradient Recalled Echo (SPGR) protocol (slice
thickness = 1.5mm, in plane resolution = 0.9375 mm×0.9375 mm).
ChAc subjects 1–9 were also scanned on a 1.5T General Electric Signa
scanner, using a similar SPGR sequence; patient 10 was scanned on a
1.5T Siemens Magnetom Vision Plus and patients 11–13 on a 1.5T
Siemens Avanto, using a T1 weighted, 3D Magnetized Prepared RApid
Gradient Echo (MPRAGE) protocol (slice thickness = 1 mm, in plane
resolution = 1 mm × 1 mm). As ChAc patients were scanned on
different machines, the signal-to-noise ratio (SNR) was calculated
for each scan using regions-of-interest in left prefrontal white matter
(WM) and in the image background (BG). SNR was calculated as the
mean of the WM signal divided by the standard deviation of the BG
signal. The SNR between controls (0.0447 ± 0.0123) and ChAc
patients (0.0509 ± 0.0246) was not significantly different (p = 0.307).
2.3. Image processing
Images were transferred to an Intel Apple MacBook Pro computer
running OSX 10.5 (Apple Inc, Cupertino, CA, USA), and were checked
manually for gross structural abnormalities prior to analysis. The
software ANALYZE 9.0 (Mayo BIR, Rochester, MN, USA) was used for
image analysis. Images were rescaled to isotropic format
(1 × 1 × 1 mm3). Manual segmentation was axially performed using
a standardized view, rigidly aligned in the AC-PC plane. All brain scans
were analysed blindly to all clinical information by an experienced
rater (JCLL, Fig. 1). A standardized manual tracing protocol was used
to trace and quantify the volume of the caudate via tracing its axial
outline serially through successive images (Looi et al., 2008). Intrarater class correlation was established at 0.97 for this rater (Looi et al.,
2008). We then adapted a reference image-based protocol developed
previously for a study of the putamen in frontotemporal lobar
degeneration (Looi et al., 2009). Intra-rater class correlation was
0.93 for this rater (Looi et al., 2009). Inter-rater reliability with
another experienced tracer using this method was rated at 0.98 for the
caudate and 0.87 for the putamen (Looi et al., 2008; Looi et al., 2009).
Volumes obtained were normalized in relevant analyses by calculation of total intracranial volume (ICV). We then calculated Z-scores for
all subjects based on the mean and standard deviation volume
measures from the control group, as in a previous analysis of ChAc
patients (Huppertz et al., 2008). Total ICV was measured by a
stereological point counting technique manually tracing the intracranial volume, with every fourth slice traced. The starting point was
randomly chosen from the most anterior four brain slices. The
landmarks for delineation and protocol are based upon those
previously published (Eritaia et al., 2000).
2.4. Shape analysis
Shape analysis was undertaken in a semi-automated fashion using
the University of North Carolina shape analysis toolkit (Styner et al.,
2006; Paniagua et al., 2009), a technique that has been used in a range
of studies in neuropsychiatric illness (Styner et al., 2004; Zhao et al.,
2008; Levitt et al., 2009). Segmented 3D label maps are initially
processed to ensure that interior holes are filled, followed by
morphological closing and minimal smoothing. These are then
subjected to spherical harmonic shape description (SPHARM-PDM),
with reconstructed boundary surfaces of all segmentations mapped
onto the unit sphere and described via a set of coefficients weighting
spherical harmonic basis functions. The correspondence between
surfaces is established by a parameter-based rotation based on firstorder expansion of the spherical harmonics. All surfaces are then
uniformly sampled into sets of 1002 surface points each. These
surfaces are aligned to a study-averaged template for each structure
(left and right caudate and putamen) using rigid-body Procrustes
alignment (Bookstein, 1997), with normalization for head size
Please cite this article as: Walterfang, M., et al., Shape alterations in the striatum in chorea-acanthocytosis, Psychiatry Research:
Neuroimaging (2011), doi:10.1016/j.pscychresns.2010.10.006
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Fig. 1. Representation of orientation of caudate (red) and putamen (blue) shapes on coronal, sagittal and horizontal view of a healthy control brain. It is not possible to visualize both
the caudate and putamen in the sagittal view; thus, in this view only the putamen is shown.
corrected for using ICV via a scaling factor, fi, where fi = (Mean (ICV)/
ICVi)1/3 .
2.5. Statistical analysis
Analysis for between-group differences in continuous demographic variables was undertaken with independent t-tests. Individual
striatal volumes were compared using analysis of covariance
(ANCOVA), covarying for ICV. To analyze a differential effect of side
(left and right) and structure (caudate and putamen) between groups,
we undertook a repeated-measures analysis of covariance (RMANCOVA) using side and structure as within-subject factors, covarying for ICV. To examine the effect of duration of illness, we examined
Spearman's correlation coefficient. To compare structural shape
between ChAc patients and controls, we computed the local Hotelling
T2 two-sample mean difference, and corrected for multiple comparisons using false discovery rate (FDR) (Genovese et al., 2002). We
generated mean difference magnitude displacement maps and
significance maps of the local p-values in raw format, and corrected
for multiple comparisons. We also computed an overall, global shape
difference summarizing the group differences across surface maps via
averaging. Correlation with illness variables was performed locally
based on Spearman's rank-order correlation of the projection of the
surface points onto the group average surface normal. Raw and
corrected p-values were calculated as per group differences, and
displacement and significance maps were generated.
3. Results
at the caudate level, and all but patients 12 and 13, two sisters, in the
putamen. RM-ANCOVA showed a main effect of group (p b 0.0001)
and a structure-by-group interaction (F = 7.735, p b 0.01), but no sideby-group (F = 0.038, p = 0.845), structure-by-side (F = 0.161,
p = 0.691) or structure-by-side-by-group interaction (F = 0.043,
p = 0.846). There were no significant correlations between duration
of illness and left (r = −0.190, p = 0.950) or right (r = − 0.036,
p = 0.950) caudate volume, nor for left (r = −0.157, p = 0.608) or
right (r = −0.246, p = 0.419) putamen volume. There was no effect of
scanner type (GE vs. Siemens) on volume.
3.3. Shape analysis
Shape analysis demonstrated significant changes in both structures. An overall shape difference between groups was shown for the
left caudate (p b 0.0001), right caudate (p b 0.0001), left putamen
(p b 0.0001) and right putamen (p b 0.0001). In the caudate, regional
shape differences were seen in both left and right caudates (Fig. 4),
with the most significant findings occurring in the caudate head. In
the left putamen, significant changes were seen in the dorsolateral
and ventral regions, and in the right putamen in the area of the
dorsomedial and lateral regions (Fig. 5). There was no significant
correlation between duration of illness and changes in the caudate
(Fig. 6) or the putamen (Fig. 7).
Table 1
Demographic and symptom data of ChAc group. Patients 1–7 correspond with patients
1–7 from Huppertz et al. (2008). Patient 9 was described in Robertson et al. (2008b)
and patient 11 in Rodrigues et al. (2008a).
3.1. Demographic and symptom data
The characteristics of the patient group are presented in Table 1,
and between-group comparisons of demographic and volumetric
data in Table 2. The patient group was not significantly different in age
(t = −0.418, p = 0.680) and was identical in gender mix. The mean
duration of illness in the patient group was 12.57 ± 6.87 years.
3.2. Volumetric data
Whilst ICV was 9% smaller in the ChAc group, this was not
significant (t = − 1.692, p = 0.107). However, individual striatal
structures were all significantly smaller in the ChAc group, by 55–
60% (Figs. 2 and 3, Table 2). All structures were significant at
p b 0.0001. A Z-score of −2 separated all ChAc patients from controls
P1
P2
P3
P4
P5
P6
P7
P8
P9
P10
P11
P12
P13
Age at scan (years) Gender
Disease duration (years) Diagnostic methoda
30
42
35
26
36
40
44
36
38
40
59
42
46
39.07 ± 7.92
6
18
8
6
7
18
7
5
17
11
30
9
12
12.57 ± 6.87
F
M
M
M
M
F
M
M
F
M
F
F
F
(7M/6F)
VPS13A
VPS13A
VPS13A
VPS13A
VPS13A
VPS13A
VPS13A
Chorein
Chorein
Chorein
Chorein
Chorein
Chorein
a
“VPS13A” indicates that mutation was found on genetic screening. “Chorein”
indicates that diagnosis was made by Western blot.
Please cite this article as: Walterfang, M., et al., Shape alterations in the striatum in chorea-acanthocytosis, Psychiatry Research:
Neuroimaging (2011), doi:10.1016/j.pscychresns.2010.10.006
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M. Walterfang et al. / Psychiatry Research: Neuroimaging xxx (2011) xxx–xxx
Table 2
Between-group comparisons on demographic and intracranial variables. t = value of tstatistic. F = value of F statistic where df = degrees of freedom.
Age (years)
Gender (M/F)
Intracranial volume
(×103 mm3)
Left caudate
volume (mm3)
Right caudate
volume (mm3)
Left putamen
volume (mm3)
Right putamen
volume (mm3)
Patients
Controls
t/F (df)
p
38.02 ± 6.94
7/6
1478 ± 146
39.07 ± 7.92
14/12
1594 ± 233
− 0.418 (37)
–
− 1.692 (37)
–
1527 ± 499
4344 ± 573
154.51 (38)
b 0.0001
1547 ± 549
4360 ± 542
152.09 (38)
b 0.0001
1631 ± 649
3913 ± 616
78.36 (38)
b 0.0001
1703 ± 730
3945 ± 672
58.13 (38)
b 0.0001
0.680
0.107
4. Discussion
We have corroborated and extended the findings of two previous
studies examining striatal volume in ChAc (Henkel et al., 2006;
Huppertz et al., 2008), demonstrating in the largest cohort to date that
both caudate and putaminal volumes are markedly reduced bilaterally
in ChAc. This reduction in volume was greater for the caudate nuclei
than for the putamen. Additionally, we showed that there was a
significant morphometric difference for both structures between
controls and ChAc cases, suggesting that each structure is not
uniformly reduced. Significance maps showed that this was most
notable for the head of the caudate nucleus, and for the dorsal aspect
of the putamen.
The original VBM study suggested that volumetric reductions were
confined to the head of the caudate nucleus in a small cohort of six
ChAc patients compared with 15 controls (Henkel et al., 2006). We
showed that caudate changes occurred in other regions beyond the
head, including the tail. Our findings showing marked putaminal
changes contrast to those of one other study using regional volumetry,
which showed significant, but less marked, volumetric reductions in
the putamen in ChAc (Huppertz et al., 2008). The lack of detection of
reduction beyond the caudate head and in the putamen in a VBM-style
approach may indicate an under-powered sample size (Whitwell,
2009).
The study by Huppertz et al. used similar VBM-style principles to
the Henkel et al. study, and compared a larger cohort of nine ChAc
patients with 257 controls. In this study all subjects' brains were
normalized to a standard template, and then multiplied by a binary
mask created by manual tracing of caudate and putamen on each side
of a normalized average of a further 120 controls, to result in volume
measures. Whilst this approach addressed the power issue inherent in
the original study by use of a very large, presumably unmatched,
healthy control sample, this method again presumes accurate
registration of subcortical structures and that the whole putamen
and caudate in each subject are contained within the grey matter
mask. Nonetheless, the results of the current study are similar in the
degree of volumetric reduction observed in the Huppertz et al. (2008)
cohort, and we showed a similar separation of patients from controls.
This may be, in part, due to the overlap between our sample and the
sample analysed in these two studies. The lack of a correlation between
duration of illness in our cohort is notable, however, and may be
indicative of the relatively reduced spread of volumes in ChAc, or reflect
the difficulty in ascertaining onset of illness when this may be related to
psychiatric as well as neurologic symptom onset (Walterfang et al.,
2008). Alternatively, it is possible that much of the neuron loss has
already occurred at the time of illness onset (Huppertz et al., 2008). This
can be contrasted to the findings in the McLeod disease study, which
showed striatal volume loss occurring with illness progression (Valko
et al., 2010).
Shape analysis of the caudate nucleus suggested a dorsal to ventral
gradient of atrophy, combined with a caudal to rostral pattern of
atrophy in patients with ChAc. These changes appear more pronounced on the left, although direct side-to-side comparisons of
shape were not undertaken. A dorsal–ventral pattern of atrophy has
been previously described in Huntington's disease (Douaud et al.,
2006), and suggests that ChAc shares a pattern of atrophy with other
neurodegenerative diseases affecting the caudate nucleus. The
marked loss of neurons in the tail of the caudate nucleus may be a
reflection of the relative thinness of this section in the normal state,
such that a moderate loss of neurons in this region would result in a
Fig. 2. Scatter plot of left and right caudate volumes (left) and Z-scores (right) according to group, showing significant separation of diagnostic groups and tight relationship between
contralateral volumes.
Please cite this article as: Walterfang, M., et al., Shape alterations in the striatum in chorea-acanthocytosis, Psychiatry Research:
Neuroimaging (2011), doi:10.1016/j.pscychresns.2010.10.006
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5
Fig. 3. Scatter plot of left and right putaminal volumes (left) and Z-scores (right) according to group, showing significant separation, but greater left–right variation in the control group.
marked apparent reduction and “foreshortening” of the caudate. The
significantly affected regions of the rostral aspect of the left caudate
nucleus receive inputs from the dorsolateral prefrontal cortex
(DLPFC), anterior cingulate/medial prefrontal (ACC) and rostral
motor cortex. The affected regions of the caudal left caudate nucleus
receive inputs from the premotor, DLPFC and orbitofrontal (OFC)
cortex (Haber et al., 2000; Haber, 2003; Leh et al., 2007; Draganski
et al., 2008; Utter and Basso, 2008). For the rostral aspect of the right
caudate nucleus, similar regions are involved as for the left, but to a
lesser extent, whilst little caudal involvement is evident.
The putamen demonstrated a caudal to rostral pattern of atrophy
in patients with ChAc, with atrophy greatest at the caudal end of the
putamen on both sides. There is little evidence of a dorsal to ventral
pattern of atrophy, as found in the caudate. As for the caudate nucleus,
the left putamen shows a greater differential change than the right. As
there was an interaction between group and side for these structures
Fig. 4. Left (top) and right (bottom) caudate changes, showing differences between ChAc patients and controls. On left, uncorrected raw p-value map; middle, FDR-corrected p-value
map; right, between-group displacement map. Legend to p-value map shows that regions with p N 0.05 are coloured blue, with significant values on a spectrum from green (p = 0.05)
to red (p = 0). Legend to displacement map shows displacement of the ChAc group from the control group in mm.
Please cite this article as: Walterfang, M., et al., Shape alterations in the striatum in chorea-acanthocytosis, Psychiatry Research:
Neuroimaging (2011), doi:10.1016/j.pscychresns.2010.10.006
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Fig. 5. Left (top) and right (bottom) putamen changes, showing differences between ChAc patients and controls. On left, uncorrected raw p-value map; middle, FDR-corrected pvalue map; right, between-group displacement map. Legend to p-value map shows that regions with p>0.05 are coloured blue, with significant values on a spectrum from green
(p=0.05) to red (p=0). Legend to displacement map shows displacement of the ChAc group from the control group in mm.
on measures of absolute volume, this suggests that shape rather than
volume changes may be greater on the left side. Similar to the caudate
nucleus, the putamen showed atrophy in regions receiving projections
from DLPFC, ACC and OFC (Haber, 2003). The relative caudal atrophy of
the putamen occurs in regions receiving inputs from the premotor and
motor cortex and the somatosensory and supplementary motor cortex.
The atrophy described indicates potential widespread disruption of
all three major frontostriatal circuits (involving the DLPFC, ACC, and
OFC regions (Haber et al., 2000; Haber, 2003; Leh et al., 2007;
Draganski et al., 2008; Utter and Basso, 2008)) relevant to behaviour
and cognition (Tekin and Cummings, 2002; Bonelli and Cummings,
2007). These findings provide a structural basis for the clinical features
Fig. 6. Significance maps of correlations between duration of illness and shape of left (top) and right (bottom) caudates, showing uncorrected p-value maps (left), with FDRcorrected maps (middle) and Spearman's r map (right). Legend to p-value map shows that regions with p N 0.05 are coloured blue, with significant values on a spectrum from green
(p = 0.05) to red (p = 0).
Please cite this article as: Walterfang, M., et al., Shape alterations in the striatum in chorea-acanthocytosis, Psychiatry Research:
Neuroimaging (2011), doi:10.1016/j.pscychresns.2010.10.006
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7
Fig. 7. Significance maps of correlations between duration of illness and shape of left (top) and right (bottom) putamen, showing uncorrected p-value maps (left), with FDRcorrected maps (middle) and Spearman's r map (right). Legend to p-value map shows that regions with p N 0.05 are coloured blue, with significant values on a spectrum from green
(p = 0.05) to red (p = 0).
of ChAc, where the most common neuropsychiatric presentation is of
behavioural change consistent with a dysexecutive syndrome seen in
more than 50% of cases, and the frequent presentation of OCD (Hardie
et al., 1991; Walterfang et al., 2008).
the illness. Contemporaneous collection of neuropsychological and
clinical data will allow examination of correlations of such morphometry with clinical features, enhancing our understanding of the
pathophysiology of ChAc.
4.1. Limitations
Financial disclosures
Because of the exceptional rarity of the disorder, it was necessary
to acquire scans from different centres to facilitate analysis. Whilst all
were scanned at 1.5T field strength and the majority of scans utilised
SPGR sequences, scanner make differed amongst subjects, although
it had no effect on regional striatal volume.
Whilst the nature of our shape analysis is suggestive of a particular
pattern of atrophy, particularly affecting the caudate head and with
greater shape changes suggested on the left, it is possible that the
shape changes we see are a reflection of a process that occurs
relatively uniformly across the structure. Given that the caudate is a Cshaped structure with a bulbous head and long sweeping tail, a
marked uniform loss of volume due to cell death and gliosis may
result in a structure with a more uniform thickness than that seen in
healthy controls. Only longitudinal studies, ideally from an early or
presymptomatic stage, would be able to resolve these two possibilities, to confirm whether at different illness stages differing neuronal
populations are more vulnerable to disruption of normal chorein
function.
4.2. Conclusion
We have corroborated previous findings suggesting a marked loss
of volume in the caudate nucleus and putamen that allows almost
complete separation from healthy matched controls on volumetric
measures. Clear shape differences were present in ChAc patients
compared with controls, suggestive of a predilection for neuronal loss
of the head of the caudate nucleus. This may correlate with the
findings of very high rates of dysexecutive syndromes and obsessive–
compulsive symptomatology in this disorder. A lack of relationship
with duration of illness in a cohort of symptomatic patients suggests
that a significant volumetric loss may occur presymptomatically. We
suggest that prospective, longitudinal studies be conducted to
investigate morphometric change of the striatum over the course of
The authors declare they have no financial conflict of interest.
Acknowledgements
Dr Walterfang was supported by a grant from the Advocacy for
Neuroacanthocytosis Patients (www.naadvocacy.org). Dr Walterfang
takes responsibility for the integrity of the data and the accuracy of
the data analysis. Furthermore, Dr Styner's work was funded by the
UNC Neurodevelopmental Disorders Research Centre HD 03110, and
the NIH Roadmap Grant U54 EB005149-01, National Alliance for
Medical Image Computing. Dr. B. Bader performed the chorein
Western blot with the help of G. Kwiatkowski at the Zentrum für
Neuropathologie und Prionforschung, University of Munich (director:
Prof. Dr. H. Kretzschmar), financially supported by the Advocacy for
Neuroacanthocytosis Patients. Dr. Looi self-funded travel and accommodation for his contribution to this project at Melbourne Neuropsychiatry Centre.
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