PDF File - Mahidol University

358
Abstracts
Proton MRS is an emerging technology that allows for the
quantitative non-invasive assessment of regional brain metabolic
activity. MRS has been used to study a wide variety of
pediatric neurometabolic disorders, tumors and demyelinating
diseases. It has also been used to assess prognosis after
acute brain injury (perinatal asphyxia, near drowning, etc.)
and it is useful in localizing focal epilepsies. Brain metabolites
assessed with MRS and often expressed as ratios
include: (1) N-acetyl aspartate (NAA) found in neurons; (2)
creatine and phosphocreatine (Cre) that reflect energy metabolism;
(3) choline-containing compounds (Cho) released
during membrane disruption; (4) presence of lactate indicating
a disturbance in cerebral energy metabolism; and (5)
glutamate/glutamine that is a reflection of asphyxial injury.
Markedly reduced levels of NAA and increased lactate have
been seen in patients who ultimately suffer severe long-term
neurologic disability. Usually this can be seen 3–5 days after
injury and is a diffuse phenomenon present in cerebral gray
and white matter. Patients with malignant tumors are likely to
have moderate to marked increases in choline and reduced
NAA whereas patients with lower grade tumors may show
milder abnormalities. MRS is also useful in evaluating children
with traumatic brain injury (TBI) as is a new MR technique
known as susceptibility weighted imaging which is
more sensitive in detecting hemorrhagic lesions associated
with diffuse axonal injury that also show very abnormal MRS
patterns that correlate with outcome. Multivoxel MRS allows
non-invasive sampling of many brain regions. It is likely that
as MRS technology continues to improve, its use for the
diagnosis of many nervous system disorders of children
will increase.
SY-05-5
Diffusion tensor imaging
A. Ohnuma
Division of Pediatric neurology, Miyagi Prefectural Takutoh
Rehabilitation Center for Children, Miyagi, Japan
The recent development of diffusion tensor imaging
(DTI) has made it possible to visualize anatomic details of
the human brain and to provide quantitative measures of
fiber tract integrity and orientation. The evidence of brain
plasticity was confirmed via DTI and FMRI in the intellectually
normal five subjects (aged 8–26 years) with unilateral
extensive brain lesions, which developed in the prenatal
(cortical dysplasia one and encephalo-clastic lesion two),
perinatal (encephalo-clastic lesion 1) and neonatal (intracranial
bleeding) stage. Fractional anisotropy (FA) images
included whole brain axial images and coronal pyramidal
tract images at the brainstem. FMRI during the motor task
was performed by the affected hand grasping. DTI depicted
markedly reduced FA of the pyramidal tract of the affected
hemisphere in two cases, moderately reduced in two and
bilateral normal in one. FMRI showed ipsilateral activations
in two cases, bilateral in one and contralateral in one. The
mode of the reorganization of the pyramidal tracts seemed
to depend on the stage of the development of the hemispherical
brain damages and the state of the residual brain tissues
of the affected hemisphere. DTI was also examined in the
cases with various kinds of white matter disorders, such as
Pelizaeus-Merzbacher disease, X-linked adrenoleukodystrophy,
metachromatic leukodystrophy, Cockayne
syndrome and Fukuyama type congenital muscular dystrophy,
in comparing with normal controls. Quantitative
measures of diffusivity and FA were useful for evaluating
the white matter status of these disorders.
SY-6
Channelopathies
SY-06-1
Mutations of sodium channels in GEFS 1 and SMEI
K. Yamakawa
Laboratory for Neurogenetics, RIKEN Brain Science Institute,
Japan
GEFS 1 , a clinical subset of febrile seizures (FS), is characterized
by frequent episodes beyond 6 years of age (FS 1 )
and various types of subsequent epilepsy. Recent evidences
have indicated that the neuronal voltage-gated sodium channels
(SCN1A, SCN2A, SCN1B) are responsible for GEFS 1 .
Some of mutant channels showed slowed inactivation that
may lead to the augment of sodium ion influx, cause hyperexcitability
of neurons, and finally result in epileptic
seizures. SCN1A has been also reported to be mutated in
severe myoclonic epilepsy in infancy (SMEI). SMEI is an
extremely intractable epilepsy; normal development before
onset; seizures beginning during 1st year of life in the form
of generalized or unilateral febrile clonic seizures; secondary
appearance of myoclonic seizures, and associates with
ataxia and mental decline. SCN1A mutations in SMEI were
heterozygous and de novo, and most of them are frameshift
or nonsense. Mutations in GEFS 1 are all missense mutations,
and these suggest the distinct pathologies of GEFS 1
and SMEI even if SCN1A is responsible for both diseases.
In my talk, I will summarize the SCN1A mutations of
GEFS 1 and SMEI and discuss the genotype-phenotype
correlation as well as the predicted molecular pathology
of these diseases.
SY-06-2
Benign familial neonatal convulsions
S. Hirose, A. Mitsudome
Department of Pediatrics, School of Medicine, Fukuoka
University, Fukuoka, Japan
Benign familial neonatal convulsions (BFNC) is monogenic
epilepsy inherited via an autosomal dominant trait and
characterized by clusters of generalized and partial seizures