Rhombencephalosynapsis is a rare
genetic brain abnormality of malformation of the
cerebellum. The
cerebellar vermis is either absent or only partially formed, and fusion is seen in varying degree between the
cerebellar hemispheres, fusion of the
middle cerebellar peduncles, and fusion of the
dentate nuclei.
Findings range from mild
truncal ataxia, to severe
cerebral palsy
Cerebral palsy (CP) is a group of movement disorders that appear in early childhood. Signs and symptoms vary among people and over time, but include poor coordination, spasticity, stiff muscles, Paresis, weak muscles, and tremors. There may b ...
.
Rhombencephalosynapsis is a constantly found feature of
Gomez-Lopez-Hernandez syndrome.
One case of which has shown a co-occurrence with
autism-spectrum disorder.
Presentation
Clinical indications range from mild truncal ataxia with unaffected cognitive abilities, to severe
cerebral palsy
Cerebral palsy (CP) is a group of movement disorders that appear in early childhood. Signs and symptoms vary among people and over time, but include poor coordination, spasticity, stiff muscles, Paresis, weak muscles, and tremors. There may b ...
and
intellectual disability.
Genetics
An association with mutations in the
''MN1'' gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
has been reported in cases of atypical rhomboencephalosynapsis.
Pathology
Rhombencephalosynapsis is a rare brain disorder of malformation of the cerebellum that may be detected on
ultrasound
Ultrasound is sound with frequency, frequencies greater than 20 Hertz, kilohertz. This frequency is the approximate upper audible hearing range, limit of human hearing in healthy young adults. The physical principles of acoustic waves apply ...
of the
fetus
A fetus or foetus (; : fetuses, foetuses, rarely feti or foeti) is the unborn offspring of a viviparous animal that develops from an embryo. Following the embryonic development, embryonic stage, the fetal stage of development takes place. Pren ...
. The vermis is either absent or partially formed. There is dorsal fusion of the cerebellar hemispheres, fusion of the
dentate nuclei, and fusion of the
middle cerebellar peduncles.
The degree of severity of this disorder is associated with the degree of maldevelopment of the cerebellar vermis.
commonly exists with the disorder, as does its often resulting
hydrocephalus.
In some cases additional abnormalities may be present, such as
ventriculomegaly (enlarged
ventricles), and
supratentorial abnormalities.
Diagnosis
Rhombencephalosynapsis can be detected on imaging of the fetus. It is one of the
triad of features characteristic of
Gomez-Lopez-Hernandez syndrome (GLHS). When detected, signs of GLHS ought to be looked for on post-natal review. Signs include partial
alopecia and some facial peculiarities.
It is thought that due to the co-occurrence of these two disorders they may have a common etiology.
As a feature of GLHS one case study has shown GLHS to co-occur with
autism spectrum disorder
Autism, also known as autism spectrum disorder (ASD), is a neurodevelopmental disorder characterized by differences or difficulties in social communication and interaction, a preference for predictability and routine, sensory processing di ...
.
Epidemiology
As of 2018 only 36 cases of GLHS have been reported.
History
The first case was reported by
Heinrich Obersteiner in 1914.
References
{{Congenital malformations and deformations of nervous system
Congenital disorders of nervous system