middle interhemispheric variant of holoprosencephaly

Anti-natal
diagnosis of Syntelencephaly: Midline interhemispheric variant of holoprosencephaly. Anterior coronal USG image showing separate anterior frontal lobes
www.eurorad.org • CC by-nc-sa-4.0
Anti-natal
diagnosis of Syntelencephaly: Midline interhemispheric variant of holoprosencephaly. Coronal USG through mid section shows fused posterior frontal and anterior occipital lobes. Fused lateral ventricles and choroid plexus is also seen.
www.eurorad.org • CC by-nc-sa-4.0
Anti-natal
diagnosis of Syntelencephaly: Midline interhemispheric variant of holoprosencephaly. Anterior coronal MRI showing seperate frontal lobes
www.eurorad.org • CC by-nc-sa-4.0
Anti-natal
diagnosis of Syntelencephaly: Midline interhemispheric variant of holoprosencephaly. Posterior coronal USG image showing separate posterior occipital lobes
www.eurorad.org • CC by-nc-sa-4.0
Sinus
pericranii associated with syntelencephaly: a case report. Imaging findings of syntelencephly, craniosynostosis, and sinus pericranii in the present case. a T2-weighted head MRI at age 2 years and 4 months. Abnormal midline connection between the cerebral hemispheres of the posterior frontal lobes and cingulate gyrus are shown (black arrow). The basal ganglia and thalamus are separated bilaterally (black arrow head). b Head computed tomography findings at age 4 months. The cranial sutures were not fused (white arrows). Tortuous and dilated subcutaneous veins were observed in the parietal region (white arrow heads). c Head computed tomography findings at age 2 years and 5 months. Two parietal skull bone defects (white arrows) and coronal craniosynostosis are visible. Digital impression on the skull was not evident. d T1-weighted head MRI at age 2 years and 4 months. Sinus pericranii (white arrow) via the parietal bone defect can be seen. The white arrowheads indicate distension of the subcutaneous veins in the parietal region. Callosal hypoplasia and ectopic gray matter around the lateral cerebral ventricles can also be observed. The black arrow indicates the tight posterior fossa and slight descent of the caudal part of the cerebellum toward the foramen magnum. Agenesis of the body of the corpus callosum and continuity of the cingulate gyrus across the midline are also shown. e Color cranial Doppler ultrasound findings at age 2 years and 5 months. Blood flow in two abnormal blood vessels (sinus pericranii) through the parietal bone defects to the extracranial veins can be seen (white arrow). The subcutaneous veins show distension (white arrow heads). f Cerebral angiography confirmed that the abnormal blood vessels formed a communication between the superior sagittal sinus and parietal diploic and subcutaneous veins (white arrows). No obvious thrombi, dural sinus abnormalities, or other vascular malformations were observed. The subcutaneous veins show distension (white arrow heads). L → R, left–right view (upper); A → P, anterior–posterior view (lower)
bmcneurol.biomedcentral.com • CC-by-4.0
nicht verwechseln mit: Interdigitation der Gyri
Radiopaedia • CC-by-nc-sa 3.0 • de

Syntelencephaly, also known as middle interhemispheric variant (MIHV), is a mild subtype of holoprosencephaly that is characterized by an abnormal midline connection of the cerebral hemispheres between the posterior frontal and parietal regions.

Epidemiology

Syntelencephaly is a congenital malformation, with no known racial or gender predilection.

Clinical presentation

Patients with syntelencephaly present with a variety of deficits, particularly related to the involvement of the motor cortex. These include :

  • spasticity or hypotonia or dystonia
  • oromotor deficits affecting speech and feeding

Pathology

Unlike holoprosencephaly, to which syntelencephaly is believed to be related, the abnormality is usually confined to the posterior frontal and parietal lobes, often with the Sylvian fissure passing almost coronally over the vertex of the connected brain to join with the fissure from the other side.

Genetics

Mutations of the ZIC2 gene, on chromosome 13q32, thought to be important in regulating neural tube closure, have been implicated .

Associations

Recognized associations include :

Radiographic features

As with most cerebral structural congenital abnormalities, syntelencephaly is visible on all modalities, but in general is identified on antenatal ultrasound, and best characterized by MRI. Features that could be present are :

Treatment and prognosis

Unfortunately, as is the case with most congenital structural brain abnormalities, no specific treatment is available. The degree of neurological impairment is variable.

History and etymology

This entity was described by Barkovich and Quint in 1993.

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 present
Siehe auch:
und weiter:
Assoziationen und Differentialdiagnosen zu Syntelenzephalie:
Schizenzephalie
 
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