Files
statdx/docs_md/articles/irregular-lateral-ventricles_f42ce651-9877-480b-90d8-665be656b33f.md
2025-10-20 08:40:33 +01:00

360 lines
35 KiB
Markdown

---
title: "Irregular Lateral Ventricles"
docid: "f42ce651-9877-480b-90d8-665be656b33f"
authors:
- key: "1fa14dfd-71ea-4960-908e-e720313bc63a"
value: "Santhosh Gaddikeri, MD"
- key: "30ce27b2-237f-4aff-a88f-65ead356335b"
value: "Marinos Kontzialis, MD"
breadcrumbs:
-
name: "Brain"
slug: "brain"
treeNodeId: "6d8829f1-14d7-45af-8675-255189aa526a"
-
name: "Differential Diagnosis"
slug: "differential-diagnosis"
treeNodeId: "a7fdd139-664e-4bb8-8d18-400e4733ff60"
-
name: "Ventricles, Periventricular Regions"
slug: "ventricles-periventricular-regions"
treeNodeId: "353c434a-a6fc-4ef1-8786-d30a1988a4dc"
-
name: "Generic Imaging Patterns"
slug: "generic-imaging-patterns"
treeNodeId: "969c31a2-ef56-4fc3-9125-05857cf9aac3"
-
name: "Irregular Lateral Ventricles"
slug: "irregular-lateral-ventricles"
treeNodeId: null
category: "Brain"
documentVersionId: "2594bf27-49d6-4896-8859-f9eee7b4228c"
imageCount: 42
lastUpdated: "02/15/23"
pageDescription: "Irregular Lateral Ventricles"
pageKeywords: "Brain, Differential Diagnosis, Ventricles, Periventricular Regions, Generic Imaging Patterns, Irregular Lateral Ventricles"
pageTitle: "Irregular Lateral Ventricles | STATdx"
enhancedTitle: "Irregular Lateral Ventricles"
type: "DDX"
references: true
breadcrumbs:
- "Brain"
- "Differential Diagnosis"
- "Ventricles, Periventricular Regions"
- "Generic Imaging Patterns"
- "Irregular Lateral Ventricles"
---
# ESSENTIAL INFORMATION
- ## Key Differential Diagnosis Issues
- Irregular ventricles may be result of obstruction, chronic volume loss, &/or congenital deformities
- Obstruction: Mass effect, ballooned-appearing ventricles, and transependymal CSF migration
- Volume loss: Ventricle irregularity with brain parenchymal loss
- Congenital: Look for associated findings (colpocephaly, subependymal nodules)
- Ventricular deformities may become permanent despite relief of obstruction due to parenchymal atrophy or acquired ventricular noncompliance
- Enhancement may help differentiate etiologies
- ## Helpful Clues for Common Diagnoses
- **CSF Shunts and Complications**
- Common complications include shunt obstruction/breakage, infection, overdrainage
- Acquired ventricular noncompliance may result in ventricle deformity
- Small, "slit" ventricles → noncompliant ventricle syndrome, chronic overdrainage
- **Surgical Defects**
- Often evident from prior shunt tract or burr hole
- Overlying skull or scalp may show defect
- Deformity is chronic
- **Periventricular Leukomalacia**
- Selective vulnerability of periventricular white matter of preterm neonate
- Injury in late 2nd or early 3rd trimester
- Thinning of posterior body of corpus callosum, enlargement and irregularity of lateral ventricular walls
- Colpocephaly: Atrium/occipital horns dilated
- Related to spastic cerebral palsy
- **Cerebral Infarction, Chronic**
- Vascular territory wedge-shaped area of encephalomalacia
- Results in compensatory or ex vacuo dilation of regional ventricle due to volume loss
- **Multiple Sclerosis**
- Multiple periventricular/perivenular and callososeptal T2 hyperintensities
- Confluent lesions in severe disease lead to atrophy and irregular ventricular margins
- **Porencephalic Cyst**
- Congenital porencephalic cysts result from intrauterine vascular or infectious injury
- Acquired cysts are secondary to injury later in life from trauma, surgery, ischemia, or infection
- CSF intensity cysts with smooth walls and T2-hyperintense surrounding gliotic changes (no gray matter lining walls as in open-lip schizencephaly)
- Usually communicate directly with ventricular system
- ## Helpful Clues for Less Common Diagnoses
- **Chiari 2**
- Pointed anterior horns, colpocephaly
- Small, crowded posterior fossa, widening of tentorial incisura, towering cerebellum, tectal beaking, downward herniation of cerebellar vermian tissue through foramen magnum
- Associated with lumbar myelomeningocele
- Hydrocephalus and other midline malformations
- **Heterotopic Gray Matter**
- Subependymal heterotopia: Subependymal nodules follow gray matter signal and protrude into ventricles; no enhancement
- Focal/multifocal asymmetric gray matter indentation of ventricle
- **Tuberous Sclerosis Complex**
- Subependymal nodules lining ventricles characteristic
- Mostly along striothalamic groove
- Calcify with increasing age
- < 1.3 cm
- Cortical and subcortical tubers are usually multifocal ± mild mass effect
- Tubers most easily seen on FLAIR
- Rarely, tubers may calcify or enhance
- White matter radial migration lines
- Cyst-like white matter lesions (cystoid brain degeneration)
- Enhancing mass with rapid growth at foramen of Monro = subependymal giant cell astrocytoma
- **Metastases, Intracranial, Other**
- CSF seeding of primary CNS tumors, lymphoma, or systemic malignancy may cause irregular ventricles
- Intraventricular metastases = 0.9-4.6% of cerebral metastases
- Adults: Renal, colon, lung
- Children: Neuroblastoma, Wilms tumor, retinoblastoma
- May result in ventricular nodules, which can deform ventricles
- Lateral ventricles most common location
- Avid enhancement ± vasogenic edema in adjacent parenchyma
- **Intraventricular Webs or Adhesions**
- May be congenital or acquired (prior hemorrhage, infection, or tumor)
- Contours of ventricles may be rounded or balloon-like due to obstructive symptoms
- Contrast ventriculography or cine CSF can be helpful to assess for evidence of physiological flow obstruction
- Heavily weighted T2 sequences, such as FIESTA/CISS, helpful
- **CMV, Congenital**
- Microcephaly
- Periventricular calcifications 40-70%
- Migrational abnormalities: Lissencephaly, pachygyria, polymicrogyria, schizencephaly
- Delayed myelination, dysmyelination
- Cerebral + cerebellar volume loss
- Periventricular cysts, ventriculomegaly, ventricular adhesions, lenticulostriate vasculopathy
- **Schizencephaly**
- Transmantle cleft lined by gray matter
- Open lip (large defect), closed lip (small defect)
- Dimple in wall of ventricle when defect small/closed
- Up to 50% bilateral
- When bilateral, 60% are open lipped on both sides
- ## Helpful Clues for Rare Diagnoses
- **Hemimegalencephaly**
- Hamartomatous overgrowth of part/all of hemisphere
- Lateral ventricle ipsilateral to enlarged hemisphere is usually bizarre-shaped and typically enlarged
- Involved hemisphere may eventually atrophy from chronic seizures
- **Holoprosencephaly**
- Congenital structural forebrain anomalies defined by degree of frontal lobe fusion
- All types have absent septum pellucidum and frontal lobe fusion anomaly
- Alobar
- Single midline forebrain
- Single primitive monoventricle, often incompletely covered posteriorly by brain (dorsal cyst)
- Semilobar
- Frontal lobes > 50% fused
- Thalami and hypothalamus may be fused
- Interhemispheric fissure and falx cerebri may be present posteriorly
- Facial malformations mild or absent
- Lobar: Anterior lateral ventricle may be deficient
- Interhemispheric fissure present along most of midline
- Only most inferior frontal lobes fused
- Thalami almost/completely separated
- Callosal dysgenesis (genu, rostrum)
- **Holoprosencephaly Variants**
- Middle interhemispheric variant of holoprosencephaly
- Lack of separation in posterior frontal and parietal areas
- Dorsal cyst in 40%
- Callosal dysgenesis (body)
- ## Alternative Differential Approaches
- Gadolinium studies can differentiate among causes of ependymal nodules
- Nonenhancing subependymal nodules may represent gray matter heterotopia or tuberous sclerosis nodules
- Gray matter heterotopias follow gray matter signal/density
- Tuberous sclerosis nodules follow white matter signal or are calcified
- Enhancing nodules suggest ependymal tumor seeding
## References
# Selected References
1. [Balasubramaniam C: Shunt complications - staying out of trouble. Neurol India. 69(Supplement):S495-501, 2021](http://www.ncbi.nlm.nih.gov/pubmed/?term=35103008%5Bpmid%5D)
1. [Society for Maternal-Fetal Medicine (SMFM) et al: Holoprosencephaly. Am J Obstet Gynecol. 223(6):B13-6, 2020](http://www.ncbi.nlm.nih.gov/pubmed/?term=33168217%5Bpmid%5D)
1. [Gotardo JW et al: Impact of peri-intraventricular haemorrhage and periventricular leukomalacia in the neurodevelopment of preterms: a systematic review and meta-analysis. PLoS One. 14(10):e0223427, 2019](http://www.ncbi.nlm.nih.gov/pubmed/?term=31600248%5Bpmid%5D)
1. [Winter TC et al: Holoprosencephaly: a survey of the entity, with embryology and fetal imaging. Radiographics. 35(1):275-90, 2015](http://www.ncbi.nlm.nih.gov/pubmed/?term=25590404%5Bpmid%5D)
1. [Smith AB et al: From the radiologic pathology archives: intraventricular neoplasms: radiologic-pathologic correlation. Radiographics. 33(1):21-43, 2013](http://www.ncbi.nlm.nih.gov/pubmed/?term=23322825%5Bpmid%5D)
1. [Osborn AG et al: Intracranial cysts: radiologic-pathologic correlation and imaging approach. Radiology. 239(3):650-64, 2006](http://www.ncbi.nlm.nih.gov/pubmed/?term=16714456%5Bpmid%5D)
1. [Melhem ER et al: Periventricular leukomalacia: relationship between lateral ventricular volume on brain MR images and severity of cognitive and motor impairment. Radiology. 214(1):199-204, 2000](http://www.ncbi.nlm.nih.gov/pubmed/?term=10644124%5Bpmid%5D)
## Images
### Selected Images
![Axial T2 MR in a patient with chronic shunting demonstrates slit-like irregular lateral ventricles <img src='img/arrows/CS.png'/> due to noncompliance from chronic drainage.](images/app.statdx.com_image_thumbnail_d27bb8c7-8ff5-46dc-a0ef-68850de500d4_annotated_true_size_900_quality_90_20b437c9_20251018T165133Z.jpg)
**CSF Shunts and Complications**
*Axial T2 MR in a patient with chronic shunting demonstrates slit-like irregular lateral ventricles <img src='img/arrows/CS.png'/> due to noncompliance from chronic drainage.*
![Axial FLAIR MR demonstrates a large surgical defect in the left frontal lobe <img src='img/arrows/CS.png'/> due to prior tumor resection communicating with the left lateral ventricle <img src='img/arrows/CO.png'/>, which appears irregular.](images/app.statdx.com_image_thumbnail_8880f9eb-b099-4000-9e1e-48961ce97d43_annotated_true_size_900_quality_90_2ce848f4_20251018T165133Z.jpg)
**Surgical Defects**
*Axial FLAIR MR demonstrates a large surgical defect in the left frontal lobe <img src='img/arrows/CS.png'/> due to prior tumor resection communicating with the left lateral ventricle <img src='img/arrows/CO.png'/>, which appears irregular.*
![Axial T2 MR in a 5-year-old boy with spastic cerebral palsy demonstrates irregular lateral ventricles <img src='img/arrows/CO.png'/> with paucity of white matter and periventricular hyperintensities <img src='img/arrows/CS.png'/>, consistent with periventricular leukomalacia.](images/app.statdx.com_image_thumbnail_9c9a7a2f-9e6b-4a73-8333-221f3fe6ed9c_annotated_true_size_900_quality_90_fc040ce9_20251018T165133Z.jpg)
**Periventricular Leukomalacia**
*Axial T2 MR in a 5-year-old boy with spastic cerebral palsy demonstrates irregular lateral ventricles <img src='img/arrows/CO.png'/> with paucity of white matter and periventricular hyperintensities <img src='img/arrows/CS.png'/>, consistent with periventricular leukomalacia.*
![Axial T2 MR demonstrates encephalomalacia in the left occipital lobe <img src='img/arrows/CO.png'/> with ex vacuo dilation of left occipital horn <img src='img/arrows/CS.png'/> due to PCA territory chronic infarct.](1e04b9f4-77c2-4080-86ac-47fcf2378c38)
**Cerebral Infarction, Chronic**
*Axial T2 MR demonstrates encephalomalacia in the left occipital lobe <img src='img/arrows/CO.png'/> with ex vacuo dilation of left occipital horn <img src='img/arrows/CS.png'/> due to PCA territory chronic infarct.*
![Axial T2 MR in a patient with primary progressive MS demonstrates extensive white matter hyperintensities <img src='img/arrows/CS.png'/> with asymmetric parenchymal volume loss and ex vacuo dilation of lateral ventricles <img src='img/arrows/CO.png'/>.](696938c6-acff-4981-a198-bb3859a4b58d)
**Multiple Sclerosis**
*Axial T2 MR in a patient with primary progressive MS demonstrates extensive white matter hyperintensities <img src='img/arrows/CS.png'/> with asymmetric parenchymal volume loss and ex vacuo dilation of lateral ventricles <img src='img/arrows/CO.png'/>.*
![Axial T2 MR demonstrates a right occipital lobe, smooth-walled, cystic encephalomalacia <img src='img/arrows/CO.png'/> lined by white matter <img src='img/arrows/CS.png'/> and communicating with the lateral ventricle, consistent with porencephalic cyst.](2a419e56-b484-4c51-91b1-c0157549c29a)
**Porencephalic Cyst**
*Axial T2 MR demonstrates a right occipital lobe, smooth-walled, cystic encephalomalacia <img src='img/arrows/CO.png'/> lined by white matter <img src='img/arrows/CS.png'/> and communicating with the lateral ventricle, consistent with porencephalic cyst.*
![Axial NECT demonstrates irregular lateral ventricles <img src='img/arrows/CO.png'/> with a right frontal lobe shunt catheter <img src='img/arrows/CS.png'/>. Note diffuse calvarial thickening <img src='img/arrows/CC.png'/> due to chronic shunting. Images of posterior fossa revealed small posterior fossa and other stigmata of Chiari 2 malformation (not shown).](918faead-f7fc-49d0-b0db-ad6d896501a9)
**Chiari 2**
*Axial NECT demonstrates irregular lateral ventricles <img src='img/arrows/CO.png'/> with a right frontal lobe shunt catheter <img src='img/arrows/CS.png'/>. Note diffuse calvarial thickening <img src='img/arrows/CC.png'/> due to chronic shunting. Images of posterior fossa revealed small posterior fossa and other stigmata of Chiari 2 malformation (not shown).*
![Axial T2 MR demonstrates nodular gray matter heterotopia <img src='img/arrows/CS.png'/> along the ependymal lining of bilateral occipital horns.](8eb6070b-371d-4980-af73-d3f71628661a)
**Heterotopic Gray Matter**
*Axial T2 MR demonstrates nodular gray matter heterotopia <img src='img/arrows/CS.png'/> along the ependymal lining of bilateral occipital horns.*
![Axial 3D T1 MPRAGE in a patient with known tuberous sclerosis demonstrates multiple subependymal nodules <img src='img/arrows/CS.png'/>. Also note tiny cysts in white matter <img src='img/arrows/CO.png'/>. Cortical/ subcortical tubers and white matter radial migration lines were seen (not shown).](92d8e135-15c5-4c7f-8210-fdcd830ae6b8)
**Tuberous Sclerosis Complex**
*Axial 3D T1 MPRAGE in a patient with known tuberous sclerosis demonstrates multiple subependymal nodules <img src='img/arrows/CS.png'/>. Also note tiny cysts in white matter <img src='img/arrows/CO.png'/>. Cortical/ subcortical tubers and white matter radial migration lines were seen (not shown).*
![Axial T1 C+ MR in a patient with metastatic lung cancer demonstrates multiple heterogeneously enhancing metastatic lesions in bilateral periventricular regions <img src='img/arrows/CS.png'/>.](cb26dd77-411b-4e6c-848b-269ad104eac2)
**Metastases, Intracranial, Other**
*Axial T1 C+ MR in a patient with metastatic lung cancer demonstrates multiple heterogeneously enhancing metastatic lesions in bilateral periventricular regions <img src='img/arrows/CS.png'/>.*
![Axial 3D T2 HASTE MR in a neonate demonstrates multiple septa/webs in both lateral ventricles <img src='img/arrows/CS.png'/>. Also note asymmetrically dilated, irregular lateral ventricles <img src='img/arrows/CC.png'/>. Encephalomalacia in the right parietooccipital region <img src='img/arrows/CO.png'/> is due to antenatal insult.](4670b1bf-fbaf-4453-9587-496db01a5658)
**Intraventricular Webs or Adhesions**
*Axial 3D T2 HASTE MR in a neonate demonstrates multiple septa/webs in both lateral ventricles <img src='img/arrows/CS.png'/>. Also note asymmetrically dilated, irregular lateral ventricles <img src='img/arrows/CC.png'/>. Encephalomalacia in the right parietooccipital region <img src='img/arrows/CO.png'/> is due to antenatal insult.*
![Axial NECT in a 2-year-old with a known congenital CMV infection demonstrates moderately dilated irregular lateral ventricles <img src='img/arrows/CS.png'/> as well as periventricular and deep white matter calcifications <img src='img/arrows/CC.png'/>. Note lissencephalic gyral pattern <img src='img/arrows/CO.png'/>.](a2c56b9b-f5ae-439d-a188-f63b50a7c07a)
**CMV, Congenital**
*Axial NECT in a 2-year-old with a known congenital CMV infection demonstrates moderately dilated irregular lateral ventricles <img src='img/arrows/CS.png'/> as well as periventricular and deep white matter calcifications <img src='img/arrows/CC.png'/>. Note lissencephalic gyral pattern <img src='img/arrows/CO.png'/>.*
![Axial 3D T1 MR demonstrates open-lip schizencephaly with a seam connecting ependymal to pial surface <img src='img/arrows/CS.png'/>. Note gray matter lining the cystic area <img src='img/arrows/CO.png'/>, differentiating it from a porencephalic cyst.](2946249f-8a43-47bd-8ae2-c72415856ca0)
**Schizencephaly**
*Axial 3D T1 MR demonstrates open-lip schizencephaly with a seam connecting ependymal to pial surface <img src='img/arrows/CS.png'/>. Note gray matter lining the cystic area <img src='img/arrows/CO.png'/>, differentiating it from a porencephalic cyst.*
![Axial T2 MR demonstrates absent septum <img src='img/arrows/CS.png'/> with absent posterior body of corpus callosum. Also seen was abnormal bilateral sylvian fissure with ventricle orientation and midline fusion (not shown), consistent with syntelencephaly, a.k.a. middle interhemispheric variant holoprosencephaly.](8bbc4ba5-5a4f-43f5-ba8b-69dd4fa8af36)
**Holoprosencephaly Variants**
*Axial T2 MR demonstrates absent septum <img src='img/arrows/CS.png'/> with absent posterior body of corpus callosum. Also seen was abnormal bilateral sylvian fissure with ventricle orientation and midline fusion (not shown), consistent with syntelencephaly, a.k.a. middle interhemispheric variant holoprosencephaly.*
### Additional Images
![Axial NECT shows a right frontal ventricular drain that traverses the right ventricle but is not decompressing the left lateral ventricle, which remains irregularly enlarged <img src='img/arrows/WC.png'/>.](images/app.statdx.com_image_thumbnail_2926513c-8a66-47ff-9091-463f9a854993_annotated_true_size_900_quality_90_63045a79_20251018T165133Z.jpg)
**CSF Shunts and Complications**
*Axial NECT shows a right frontal ventricular drain that traverses the right ventricle but is not decompressing the left lateral ventricle, which remains irregularly enlarged <img src='img/arrows/WC.png'/>.*
![Axial T2 MR shows irregular enlargement of the left occipital horn <img src='img/arrows/WS.png'/> due to left temporal and occipital surgical defect and encephalomalacia from tumor removal in this location.](images/app.statdx.com_image_thumbnail_81d90381-93ef-4fd9-804f-98f39faf22d8_annotated_true_size_900_quality_90_3f67ffb9_20251018T165133Z.jpg)
**Surgical Defects**
*Axial T2 MR shows irregular enlargement of the left occipital horn <img src='img/arrows/WS.png'/> due to left temporal and occipital surgical defect and encephalomalacia from tumor removal in this location.*
![Axial T2 MR shows classic &quot;wavy&quot; or undulating contours of the lateral ventricles <img src='img/arrows/WS.png'/> in addition to colpocephaly (enlargement of the posterior portions of lateral ventricles). Colpocephaly reflects the predominantly posterior volume loss.](images/app.statdx.com_image_thumbnail_c7d04410-a691-42e3-9428-d55060a26d68_annotated_true_size_900_quality_90_5996778f_20251018T165133Z.jpg)
**Periventricular Leukomalacia**
*Axial T2 MR shows classic &quot;wavy&quot; or undulating contours of the lateral ventricles <img src='img/arrows/WS.png'/> in addition to colpocephaly (enlargement of the posterior portions of lateral ventricles). Colpocephaly reflects the predominantly posterior volume loss.*
![Axial NECT shows irregular enlargement of the left frontal horn <img src='img/arrows/WO.png'/> due to focal regional parenchymal volume loss in this patient with remote MCA infarct.](2f456604-123a-498e-a877-660381509108)
**Cerebral Infarction, Chronic**
*Axial NECT shows irregular enlargement of the left frontal horn <img src='img/arrows/WO.png'/> due to focal regional parenchymal volume loss in this patient with remote MCA infarct.*
![Axial T1 FS MR shows multifocal nodularity along ependymal margins of both lateral ventricles <img src='img/arrows/WS.png'/>. These nodules follow gray matter signal on all sequences and do not enhance or change over time.](f1496ad0-85d2-45aa-a05b-4f49fd882c3b)
**Heterotopic Gray Matter**
*Axial T1 FS MR shows multifocal nodularity along ependymal margins of both lateral ventricles <img src='img/arrows/WS.png'/>. These nodules follow gray matter signal on all sequences and do not enhance or change over time.*
![Axial NECT shows irregularly dilated occipital horns <img src='img/arrows/WS.png'/> with interdigitation of parietal and occipital parenchyma across midline <img src='img/arrows/WC.png'/> due to a falx deficiency.](5a2506e9-70d3-46f0-a725-26e1b13fa20f)
**Chiari 2**
*Axial NECT shows irregularly dilated occipital horns <img src='img/arrows/WS.png'/> with interdigitation of parietal and occipital parenchyma across midline <img src='img/arrows/WC.png'/> due to a falx deficiency.*
![Coronal T2 MR shows dysgenetic corpus callosum, small posterior fossa, and interdigitation of gyri <img src='img/arrows/WS.png'/> from deficient falx, best seen post shunting. Cerebellum &quot;towers&quot; through the tentorial notch.](d3885609-d163-4bb5-8179-ba8901e78c3a)
**Chiari 2**
*Coronal T2 MR shows dysgenetic corpus callosum, small posterior fossa, and interdigitation of gyri <img src='img/arrows/WS.png'/> from deficient falx, best seen post shunting. Cerebellum &quot;towers&quot; through the tentorial notch.*
![Axial T2 MR shows multiple calcified subependymal nodules (SEN) <img src='img/arrows/WS.png'/> lining ventricles. Note also subcortical tubers <img src='img/arrows/WC.png'/>. SEN calcify much more commonly than cortical/subcortical tubers. ~ 50% of SEN are calcified by 10 years.](cd3b3a2b-1a19-4a9b-a8db-db235f939c8c)
**Tuberous Sclerosis Complex**
*Axial T2 MR shows multiple calcified subependymal nodules (SEN) <img src='img/arrows/WS.png'/> lining ventricles. Note also subcortical tubers <img src='img/arrows/WC.png'/>. SEN calcify much more commonly than cortical/subcortical tubers. ~ 50% of SEN are calcified by 10 years.*
![Axial T2 MR shows small, subependymal nodules <img src='img/arrows/WS.png'/>, which indent lateral ventricle margins. Unlike gray matter heterotopia, these follow WM signal or are calcified.](009fab60-a9d4-4283-aba1-b86b3717cb0a)
**Tuberous Sclerosis Complex**
*Axial T2 MR shows small, subependymal nodules <img src='img/arrows/WS.png'/>, which indent lateral ventricle margins. Unlike gray matter heterotopia, these follow WM signal or are calcified.*
![Axial T1 MR shows nodular ependymal thickening with an enhancing rind of tissue along the entire ventricular ependyma <img src='img/arrows/WS.png'/>. While infection &amp; primary malignant brain neoplasms such as GBM, germinoma, and lymphoma commonly spread along ventricular ependyma, this is a recognized but uncommon site for tumor deposits from extracranial primary tumors (melanoma in this case).](3602f90f-46e4-4ebe-b9a2-8f72def57b1f)
**Metastases, Intracranial, Other**
*Axial T1 MR shows nodular ependymal thickening with an enhancing rind of tissue along the entire ventricular ependyma <img src='img/arrows/WS.png'/>. While infection &amp; primary malignant brain neoplasms such as GBM, germinoma, and lymphoma commonly spread along ventricular ependyma, this is a recognized but uncommon site for tumor deposits from extracranial primary tumors (melanoma in this case).*
![Axial T2 MR shows a small dimple on the lateral ventricular wall, which &quot;points&quot; to the site of a fused pial-ependymal seam <img src='img/arrows/BS.png'/>. The aperture of the cleft is lined by gray matter <img src='img/arrows/WO.png'/> in this closed-lip schizencephaly.](05bee719-bf55-496d-8865-8bae802bbf01)
**Schizencephaly**
*Axial T2 MR shows a small dimple on the lateral ventricular wall, which &quot;points&quot; to the site of a fused pial-ependymal seam <img src='img/arrows/BS.png'/>. The aperture of the cleft is lined by gray matter <img src='img/arrows/WO.png'/> in this closed-lip schizencephaly.*
![Axial T2 MR shows cortical dysplasia and open-lip schizencephaly <img src='img/arrows/WS.png'/>. Schizencephaly is closed-lip with a fused, gray matter-lined pial-ependymal seam or open-lip with large, gray matter-lined and fluid-filled CSF clefts.](544584c2-74ba-4f36-8701-7b6f8d26db3c)
**Schizencephaly**
*Axial T2 MR shows cortical dysplasia and open-lip schizencephaly <img src='img/arrows/WS.png'/>. Schizencephaly is closed-lip with a fused, gray matter-lined pial-ependymal seam or open-lip with large, gray matter-lined and fluid-filled CSF clefts.*
![Axial NECT shows focal outpouchings of CSF from both lateral ventricles <img src='img/arrows/WS.png'/> with a CSF cleft extending from lateral ventricles to the subpial surface. The pial-ependymal seam is lined by gray matter.](2bc44bf5-bc94-467d-84f9-8de71b93d08b)
**Schizencephaly**
*Axial NECT shows focal outpouchings of CSF from both lateral ventricles <img src='img/arrows/WS.png'/> with a CSF cleft extending from lateral ventricles to the subpial surface. The pial-ependymal seam is lined by gray matter.*
![Axial NECT shows septum pellucidum and anterior falx absence. Frontal horns are hypoplastic. A band of parenchyma crosses midline <img src='img/arrows/WS.png'/>. Mild frontal lobe fusion anomalies, as seen here, are typical of lobar holoprosencephaly.](fd55a6d3-31b8-4659-8163-ae8f4b2a3fae)
**Holoprosencephaly**
*Axial NECT shows septum pellucidum and anterior falx absence. Frontal horns are hypoplastic. A band of parenchyma crosses midline <img src='img/arrows/WS.png'/>. Mild frontal lobe fusion anomalies, as seen here, are typical of lobar holoprosencephaly.*
![Axial T1 MR shows open-lip schizencephaly with large, gray matter-lined <img src='img/arrows/CS.png'/> and a fluid-filled CSF cleft. In addition, there is ventricular wall irregularity due to subependymal gray matter heterotopia bilaterally <img src='img/arrows/CO.png'/>.](b7d119f1-d67e-42cd-bbfa-21c225e8cb7d)
**Schizencephaly**
*Axial T1 MR shows open-lip schizencephaly with large, gray matter-lined <img src='img/arrows/CS.png'/> and a fluid-filled CSF cleft. In addition, there is ventricular wall irregularity due to subependymal gray matter heterotopia bilaterally <img src='img/arrows/CO.png'/>.*
![Coronal T2 MR demonstrates closed-lip schizencephaly. Abnormal, thick gray matter <img src='img/arrows/CS.png'/> lines the cleft extending to a dimple in the wall of the right lateral ventricle <img src='img/arrows/BS.png'/>.](55272009-ca22-4b9f-9162-af69d8a49014)
**Schizencephaly**
*Coronal T2 MR demonstrates closed-lip schizencephaly. Abnormal, thick gray matter <img src='img/arrows/CS.png'/> lines the cleft extending to a dimple in the wall of the right lateral ventricle <img src='img/arrows/BS.png'/>.*
![Axial CT shows multiple calcified subependymal nodules <img src='img/arrows/CS.png'/> lining the ventricles in a patient with tuberous sclerosis. The nodules calcify much more commonly than cortical/subcortical tubers. Note traumatic subarachnoid hemorrhage <img src='img/arrows/BS.png'/> in the left Sylvian fissure.](1253b6d1-a526-4e7f-8b3e-2c2744b25924)
**Tuberous Sclerosis Complex**
*Axial CT shows multiple calcified subependymal nodules <img src='img/arrows/CS.png'/> lining the ventricles in a patient with tuberous sclerosis. The nodules calcify much more commonly than cortical/subcortical tubers. Note traumatic subarachnoid hemorrhage <img src='img/arrows/BS.png'/> in the left Sylvian fissure.*
![Axial T2 MR shows multiple bilateral subependymal nodules of heterotopic gray matter <img src='img/arrows/CS.png'/> along the lateral ventricular margins. These nodules follow gray matter signal on all sequences.](8a3bcced-e3f1-4a17-8cc5-b9d76bb8e2d7)
**Heterotopic Gray Matter**
*Axial T2 MR shows multiple bilateral subependymal nodules of heterotopic gray matter <img src='img/arrows/CS.png'/> along the lateral ventricular margins. These nodules follow gray matter signal on all sequences.*
![Axial CT in a Chiari 2 patient shows typical irregular appearance of the ventricles. Note the left posterior shunt catheter <img src='img/arrows/CS.png'/>.](fefed345-c959-4896-b9b2-5ad4f10bae9a)
**Chiari 2**
*Axial CT in a Chiari 2 patient shows typical irregular appearance of the ventricles. Note the left posterior shunt catheter <img src='img/arrows/CS.png'/>.*
![Axial FLAIR MR demonstrates left posterior middle cerebral artery encephalomalacia <img src='img/arrows/CS.png'/> with mild ex vacuo dilatation of the left occipital horn and atrium <img src='img/arrows/CO.png'/>.](9f0d6726-27e8-4c3e-92a9-9aa52067d6cb)
**Cerebral Infarction, Chronic**
*Axial FLAIR MR demonstrates left posterior middle cerebral artery encephalomalacia <img src='img/arrows/CS.png'/> with mild ex vacuo dilatation of the left occipital horn and atrium <img src='img/arrows/CO.png'/>.*
![Axial T2 MR in periventricular leukomalacia shows asymmetric, posterior, periventricular white matter (WM) volume loss with irregular ventricular margins <img src='img/arrows/CS.png'/>. Periventricular leukomalacia, a.k.a. WM injury of prematurity, is a result of brain injury occurring before 33 weeks gestation and resulting in loss of periventricular WM.](c36e4c1d-b34f-41e9-a31c-aab2cb0df8bf)
**Periventricular Leukomalacia**
*Axial T2 MR in periventricular leukomalacia shows asymmetric, posterior, periventricular white matter (WM) volume loss with irregular ventricular margins <img src='img/arrows/CS.png'/>. Periventricular leukomalacia, a.k.a. WM injury of prematurity, is a result of brain injury occurring before 33 weeks gestation and resulting in loss of periventricular WM.*
![Axial FIESTA MR in a patient following left temporal bone surgery shows skull defect <img src='img/arrows/CS.png'/>, underlying encephalomalacia <img src='img/arrows/CO.png'/>, and ex vacuo dilatation of the left lateral ventricle <img src='img/arrows/BS.png'/>.](images/app.statdx.com_image_thumbnail_c51882c7-eec5-40d6-9cfa-982849a82c22_annotated_true_size_900_quality_90_c7bab1c9_20251018T165133Z.jpg)
**Surgical Defects**
*Axial FIESTA MR in a patient following left temporal bone surgery shows skull defect <img src='img/arrows/CS.png'/>, underlying encephalomalacia <img src='img/arrows/CO.png'/>, and ex vacuo dilatation of the left lateral ventricle <img src='img/arrows/BS.png'/>.*
![Axial T1 MR demonstrates a right parietal shunt catheter with its tip <img src='img/arrows/CS.png'/> in the right frontal horn in a patient with congenital aqueductal stenosis. The right lateral ventricle is collapsed, while the 3rd <img src='img/arrows/CO.png'/> and left lateral ventricles <img src='img/arrows/CC.png'/> are moderately dilated.](images/app.statdx.com_image_thumbnail_b0b4ac10-a5f5-45c0-8e06-16b37ce8e9e0_annotated_true_size_900_quality_90_abb03b0b_20251018T165133Z.jpg)
**CSF Shunts and Complications**
*Axial T1 MR demonstrates a right parietal shunt catheter with its tip <img src='img/arrows/CS.png'/> in the right frontal horn in a patient with congenital aqueductal stenosis. The right lateral ventricle is collapsed, while the 3rd <img src='img/arrows/CO.png'/> and left lateral ventricles <img src='img/arrows/CC.png'/> are moderately dilated.*
![Axial CECT shows a low-density outpouching from the right lateral ventricle <img src='img/arrows/CS.png'/>. While a thin rim of cortex seems intact, the cyst nearly reaches brain surface and can be considered a porencephalic dilation or porencephalic lateral ventricle cyst.](90e2763f-d574-42bb-b173-33d8362e631b)
**Porencephalic Cyst**
*Axial CECT shows a low-density outpouching from the right lateral ventricle <img src='img/arrows/CS.png'/>. While a thin rim of cortex seems intact, the cyst nearly reaches brain surface and can be considered a porencephalic dilation or porencephalic lateral ventricle cyst.*
![Axial T2 MR shows near-complete coating of the ependymal lining of both lateral ventricles with tumor nodules <img src='img/arrows/CS.png'/> due to metastatic seeding of an anaplastic oligodendroglioma.](66f6ca25-e3b3-437c-8531-4faa19f2e26c)
**Metastases, Intracranial, Other**
*Axial T2 MR shows near-complete coating of the ependymal lining of both lateral ventricles with tumor nodules <img src='img/arrows/CS.png'/> due to metastatic seeding of an anaplastic oligodendroglioma.*
![Axial NECT shows periventricular calcification <img src='img/arrows/CS.png'/>, particularly along the caudostriatal groove, in the context of microcephaly and developmental delay. This strongly suggests congenital CMV infection. Note smooth ventricular margins, unlike calcified nodules in tuberous sclerosis complex.](27976562-e322-411d-b649-4edfd868c0da)
**CMV, Congenital**
*Axial NECT shows periventricular calcification <img src='img/arrows/CS.png'/>, particularly along the caudostriatal groove, in the context of microcephaly and developmental delay. This strongly suggests congenital CMV infection. Note smooth ventricular margins, unlike calcified nodules in tuberous sclerosis complex.*
![Axial T2 MR shows enlargement of left cerebral hemisphere accompanied by an irregular ipsilateral ventricle <img src='img/arrows/CS.png'/>. The body of the left hemispheric WM is bulky. Note left fornix <img src='img/arrows/CC.png'/> overgrowth.](6cf5c025-6a72-4fc7-8343-15d1240eec7b)
**Hemimegalencephaly**
*Axial T2 MR shows enlargement of left cerebral hemisphere accompanied by an irregular ipsilateral ventricle <img src='img/arrows/CS.png'/>. The body of the left hemispheric WM is bulky. Note left fornix <img src='img/arrows/CC.png'/> overgrowth.*
![Axial T1 MR shows a large, horseshoe-shaped monoventricle <img src='img/arrows/CC.png'/> with fused basal ganglia <img src='img/arrows/CS.png'/>. There is no interhemispheric fissure and no identifiable lobulation or formation of ventricular horns in this alobar holoprosencephaly.](88c3bc23-d2eb-443c-832b-37829eed0963)
**Holoprosencephaly**
*Axial T1 MR shows a large, horseshoe-shaped monoventricle <img src='img/arrows/CC.png'/> with fused basal ganglia <img src='img/arrows/CS.png'/>. There is no interhemispheric fissure and no identifiable lobulation or formation of ventricular horns in this alobar holoprosencephaly.*