Transcript SYNTELENCEPHALY - Stanley Radiology

SYNTELENCEPHALYA lesser known
variant of
holoprosencephaly
Abstract ID: IRIA 1059
INTRODUCTION

Syntelencephaly - middle inter-hemispheric variant(MIH), is a
milder subtype of holoprosencephaly.

It is a congenital malformation with no gender or racial
predilection.

It is characterized by abnormal midline connection of the
cerebral hemispheres between the posterior frontal and
parietal lobe(1).
CASE REPORT
 19
year old male patient
 Presenting complaint : 4 episodes of seizure ,
Generalized tonic clonic type since one day
involving all four limbs.
--k/c/o seizure disorder for four years.
H/o developmental delay and mental retardation
since birth.
 General examination showed facial dysmorphism.
 Other system examination: NAD.
Examination (contd..)
CNS

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Higher function was
normal
Motor examination
revealed good neck
control.
Tone:
Upper limb: normal
Lower limb: increased
 Power:
4/5 through
out.
 Plantar response was
extensor bilaterally.
BACK GROUND
 Holoprosencephaly
have been classified
according to the system of DeMyer and coworkers
into alobar, semi lobar, and lobar forms(2).
 A fourth subtype, called the middle inter
hemispheric variant (MIH) of holoprosencephaly or
syntelencephaly, was first identified in 1993 by
Barkovich et al (3).
 Mutations of the ZIC2 gene on chromosome 13,
which plays a critical role in differentiation of the
roof plate of the developing embryo.
 The
affected children present with a variety of
deficits including spasticity, dystonia and
oromotor dysfunction affecting feeding and
speech.
 Seizures as well as mild cognitive and visual
impairment are noted in these children.
 On MR imaging, MIH is characterized by
abnormal fusion of the posterior frontal and
parietal regions of the cerebral hemispheres.
 There
is frequent incomplete cleavage of the
heads of the caudate nuclei and thalami, but the
hypothalamus and lentiform nuclei are wellseparated.
 Almost all patients with MIH have a single or
azygous anterior cerebral artery.
 There is a coronal configuration of the sylvian
fissures which are continuous across the cerebral
vertex.
 Frequent association with heterotopias and
malformations of cortical development have
been reported.(4)
Image 1: CT brain shows midline fusion of the right and left cerebral
lobe
Image 2: MRI brain T2 W image shows midline fusion the posterior
frontal and parietal region.
Image 1,2 and 3: MRI brain T1W Coronal and Sagittal section shows grey
matter heterotropia.
Image 1: MRI Brain T1W contrast shows agenesis of body and splenium
of corpus callosum.
Image 2: MRI Brain T2W FLAIR shows absent septum pellucidum with
fusion of bilateral lateral ventricles.
Image 1,2 and 3: MRI Brain T2W FLAIR Contrast Coronal and sagittal
image's shows no evidence of abnormal enhancement.
Angiogram and 3D Source image shows Azygous Anterior cerebral artery
with absent Anterior communicating artery. Normal vertebral, basilar and
middle cerebral artery.
DIFFERENTIAL DIAGNOSIS
#
HOLOPROSENCEPHALY
 usually affects anterior and inferior parts of the
prosencephalon.
 more frequently associated with a dorsal cyst.
 cerebellar abnormalities are less common.
#
SCHIZENCEPHALY
 The coronal orientation of the sylvian fissures may
mimic bilateral schizencephaly, but no extension
to the ventricles is presently.
LEARNING OBJECTIVES
 Due
to differences in pattern of neuroanatomic
abnormalities in MIH, there is a very low incidence
of endocrinopathies, hypothalamic dysfunction,
and choreoathetosis, while there is a relative high
incidence of dorsal cysts and spasticity.
 Advances in neuroimaging have made possible
the differentiation of different subtypes hence
allowing accurate diagnosis and predicting the
overall outcome with greater certainty.
REFERENCES
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1. Fujimoto S, Togari H, Banno T, Wada Y. Syntelencephaly
associated with connected transhemispheric cleft of focal
cortical dysplasia. Pediatr Neurol 1999;20:387–398

2. DeMyer W, Zeman W. Alobar holoprosencephaly
(arhinencephaly) with median cleft lip and palate: clinical,
nosologic, and electroencephalographic considerations.
Confin Neurol 1963;23:1-36.

3.Fujimoto S, Togari H, Banno T, Wada Y. Syntelencephaly
associated with connected transhemispheric cleft of focal
cortical dysplasia. Pediatr Neurol 1999;20:397-389

4. Barkovich AJ, Quint DJ. Middle interhemispheric fusion:
an unusual variant of holoprosencephaly. AJNR Am J
Neuroradiol . 1993; 14: 431-440.