SP 44-Relationship between neuroimaging classification and

Relationship between Neuroimaging Classification and Hypertonia
Patterns in a Cerebral Palsy Population
James Rice
1,2
MD ,
Remo Russo MD
1,2
PhD ,
Felicity Baker
1
BPhty ,
Nick Rice
3
MD
1 Paediatric
Rehabilitation Department, Women’s and Children’s Hospital, Adelaide, SA; 2 Flinders University School of Medicine, Adelaide, SA;
3 Radiology Department, Royal Adelaide Hospital, Adelaide SA; AUSTRALIA.
Objective
Results
Cerebral Palsy (CP) can be classified in different ways according to impairmentand functional-based components, all of which are valuable in describing a
child’s abilities. It is recognized that different patterns of abnormal tone such as
dystonia and spasticity can co-exist in CP even when a single motor type
descriptor such as “spastic” is used. This study aimed to investigate the
relationship between brain lesions, as assessed by magnetic resonance
imaging (MRI) pattern, and motor subtypes, including patterns of hypertonia
directly measured in a clinical setting in children with CP.
Seventy-four percent (100/135) of subjects had MRI scans available for
assessment. WMI was observed in 45% of scans, GMI in 25% (including 9% with
focal vascular insults), miscellaneous findings in 12%, normal in 10% and
maldevelopments in 8%. There were no significant associations between level of
motor severity by GMFCS and imaging pattern, although there was a trend towards
an association between milder motor phenotypes (GMFCS I-II) and both WMI and
normal imaging patterns. In WMI 91% had spasticity subtypes, most commonly
diplegia followed by hemiplegia and quadriplegia. In the upper limbs of children with
WMI, as measured by application of the HAT, pure dystonia was observed in 40%,
mixed tone (both spasticity and dystonia) in 26%, normal findings in 32% and pure
spasticity in 1%.
In the lower limbs of children with WMI, pure dystonia and normal findings were
uncommon (6% and 4%) with most having mixed tone (77%) or pure spasticity
(13%). Dystonia severity (by BAD score) in WMI was universally in the slight/mild
range. In GMI, spastic hemiplegia and dyskinesia were the most common
subtypes, followed by spastic quadriplegia. On upper limb assessment in GMI
dystonia was observed either alone or in combination with spasticity in 76%; pure
spasticity was infrequent (10%), with similar findings in the lower limbs. Dystonia
severity scores in GMI were mostly in the nil/slight range with a lesser proportion in
the moderate/severe range.
Design
Cross-sectional, population-based cohort study. Participants and setting:
Children with CP ages 2-18 years attending a tertiary children’s hospital.
Method
One hundred and thirty five subjects were recruited; 78 male, 57 female; mean
age at assessment 8.7 years (SD 5.0); 94% were on the state CP Register.
According to motor subtype, 84% had spasticity, 15% dyskinesia and 1% ataxia.
Hypertonia was differentiated in each limb by application of the Hypertonia
Assessment Tool (HAT) by a research Physiotherapist, with severity of dystonia
and spasticity measured using the Barry Albright Dystonia (BAD) and Modified
Ashworth Score scales respectively (1). Each subject’s most recent MRI was
reviewed and classified by a Radiologist blinded to clinical information using the
Surveillance of CP in Europe (SCPE) neuroimaging classification: 1)
maldevelopments; 2) white matter injury (WMI); 3) grey matter injury (GMI);
including focal vascular insults; 4) miscellaneous; and 5) normal.
HAT Upper limbs (n=84)
Spastic
Dystonic
Mixed
Normal
Spastic
Dystonic
Mixed
Normal
Figure 3: Abnormal tone patterns observed in limbs in White Matter Injury
observed by Reid et al in a larger Australian population (2). Within the group, WMI and
GMI were the most common imaging abnormality patterns. Motor severity by GMFCS
level was influenced by the recruitment method used, rather than reflecting the
background geographic population which has a high proportion of cases of mild CP.
WMI
While WMI findings were mostly associated with the spasticity motor phenotype,
dystonia was frequently identified on examination using the HAT in both upper and
lower limbs. Although this generally measured as slight/mild according to the BAD
score, it may influence function, such as in children with spastic diplegia who are noted
to have difficulties with bimanual function. This is not well recognised or understood in
those children typically considered to have spastic CP.
GMI
Normal
Misc
GMI
WMI
Maldevel
Sp
hemiplegia
Sp diplegia
Sp Quad
Ataxia
Dyskinesia
Figure 2: Relationship between neuroimaging pattern and motor type
Discussion
Figure 1: Brain development and timing of lesions. From: www.scpenetwork.eu
HAT lower limbs (n=84)
This study found that the majority of subjects (90%) had abnormal MRI scans,
consistent with similar studies. Despite some differences in recruitment
methodology, the distribution of pattern abnormalities is very similar to that
Contact details:
[email protected]
In this pattern, spasticity typically co-existed with dystonia, regardless of overall motor
subtype category. Although it may be assumed that damage to structures such as
basal ganglia may associate with a more significant degree of dystonia, this was an
inconsistent finding.
This study should inform both future research into the co-existence of abnormal tone
patterns in CP and the development of classification methods to reduce hypertonia
pattern ambiguity in motor subtype classification.
References:
1. Jethwa A, Mink J, MacArthur C, Knights S, Fehlings T, Fehlings D. Development of the
Hypertonia Assessment Tool (HAT): a discriminative tool for hypertonia in children. Dev Med Child
Neurol 2009; 52: e83-e87.
2. Reid S, Dagia C, Ditchfield M, Carlin J, Meehan E, Reddihough D. An Australian population
study of factors associated with MRI patterns in cerebral palsy. Dev Med Child Neurol 2014;
56: 178–184.
Acknowledgement: This study was funded by a research grant from Allergan Australia Pty Ltd.

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