Absent septum pellucidum
An absent septum pellucidum may rarely be an isolated finding, or more commonly be seen in association with a variety of conditions.
On this page:
Epidemiology
The septum pellucidum is partly or entirely absent in 2 or 3 individuals per 100,000 in the general population.
Pathology
An absent septum pellucidum may be developmental or acquired secondary to another pathological process 1,2.
Cavum septum pellucidum is always visualized between 18 and 37 weeks and within a biparietal diameter of 44 to 88 mm. Failure to detect the cavum septum pellucidum within this time interval requires further investigation. However, the absence of cavum septum pellucidum on the ultrasound exam prior to 18 weeks or later than 37 weeks is considered a normal finding.
Developmental
Acquired
Radiographic features
Non-visualization of the septum pellucidum with direct communication of the frontal horns. Additionally, the following characteristics may be seen 3:
- boxing/squaring off of the frontal horns
- inferior pointing frontal horns
- abnormally inferiorly positioned fornix (coronal views)
Related Radiopaedia articles
Malformations of the central nervous system
-
malformations of cortical development
- abnormal cell proliferation or apoptosis
- abnormal brain size
-
microcephaly
- with normal to simplified cortical pattern
- microcephaly with lissencephaly
- microcephaly with extensive polymicrogyria
- macrocephalies (megalencephaly/macrocephaly)
-
microcephaly
- abnormal cell proliferation
- non-neoplastic
- cortical hamartomas of tuberous sclerosis
- hemimegalencephaly
-
focal cortical dysplasia (Type I and Type IIb)
- Palmini classification (2004)
- Barkovich classification (2005)
- Blumcke classification (2011)
- neoplastic
- non-neoplastic
- abnormal neuronal migration
- lissencephaly
- lissencephaly type I: subcortical band heterotopia spectrum (band heterotopia): undermigration
- lissencephaly type II (cobblestone complex)
- heterotopia: ectopic migration
- subependymal heterotopia
- subcortical heterotopia (not including band heterotopia)
- marginal glioneuronal heterotopia
- lissencephaly
- abnormal cortical organization
- mild malformations of cortical development (previously microdysgenesis)
-
polymicrogyria and schizencephaly
- bilateral polymicrogyria syndromes
- schizencephaly
- focal cortical dysplasia (Type IIa)
- abnormal brain size
- not otherwise classified
- malformations secondary to inborn errors of metabolism
- mitochondrial and pyruvate metabolic disorders
- peroxisomal disorders
- other unclassified malformations
- malformations secondary to inborn errors of metabolism
- abnormal cell proliferation or apoptosis
-
midline abnormalities of the brain
- absent septum pellucidum
- cephaloceles
-
midline nasal region lesions
- nasal dermoid
- nasal glioma
- nasal dermal sinus
- cerebral hemispheres
-
holoprosencephaly/septo-optic dysplasia spectrum
- septo-optic dysplasia
- lobar holoprosencephaly
- semilobar holoprosencephaly
- alobar holoprosencephaly
- middle interhemispheric variant/syntelencephaly
-
holoprosencephaly/septo-optic dysplasia spectrum
- corpus callosum
- intracranial lipoma
-
malformations of the cerebellum
- cerebellar hypoplasia
- focal hypoplasia
- generalized hypoplasia
- with enlarged fourth ventricle
- normal fourth ventricle
- with normal pons
- with small pons
- normal foliation
- pontocerebellar hypoplasias of Barth, types I and II
- cerebellar hypoplasias, not otherwise specified
- normal foliation
- cerebellar dysplasia
- focal dysplasia
- isolated vermian dysplasia
- molar tooth malformations including Joubert syndrome
- rhombencephalosynapsis
- isolated hemispheric dysplasia
- focal cerebellar cortical dysplasias/heterotopia
- Lhermitte-Duclos-Cowden syndrome
- isolated vermian dysplasia
- generalized dysplasia
- congenital muscular dystrophies
- cytomegalovirus
- lissencephaly with RELN mutation
- lissencephaly with agenesis of corpus callosum and cerebellar dysplasia
- associated with diffuse cerebral polymicrogyria
- diffusely abnormal foliation
- focal dysplasia
- cerebellar hypoplasia
- malformations of the brainstem
Unable to process the form. Check for errors and try again.