====== Subependymal pseudocyst ======


Subependymal [[cyst]]s may either be postnatally acquired posthemorrhagic cysts or may be congenital (germinolytic). The congenital cysts may result from infection, ischemic injury, or hemorrhage.
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[[Subependymal pseudocyst]]s, or [[subependymal germinolytic cyst]]s, were described by Banker and Larroche in 1962
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When apparently isolated SEPC are observed at prenatal US, further investigations should be performed under the following circumstances: (1) SEPC great axis ≥ 9 mm; (2) SEPC adjacent to the occipital and temporal horns; (3) SEPC located posterior to the caudothalamic notch; (4) SEPC with atypical morphology
((Esteban H, Blondiaux E, Audureau E, Sileo C, Moutard ML, Gelot A, Jouannic JM, Ducou le Pointe H, Garel C. Prenatal features of isolated subependymal pseudocysts associated with adverse pregnancy outcome. Ultrasound Obstet Gynecol. 2015 Dec;46(6):678-87. doi: 10.1002/uog.14820. Epub 2015 Nov 8. PMID: 25684100.)).
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Differentiation of non-haemorrhagic from post-haemorrhagic germinolysis is necessary to clarify the aetiology and pathogenesis of non-haemorrhagic pseudocysts. Caudothalamic germinolysis possibly is the result of infection with stenotic intima proliferation following vasculitis. The results are thalamostriatal vasculopathy and germinal necrosis. Anterior plexus cysts might be the result of folding faults of the ependyma in the growth period of the choroid plexus. Pseudocysts lateral of the frontal horns should not be mistaken for ventricular ligaments
((van Baalen A, Versmold H. Nichthämorrhagische subependymale Pseudozysten: sonografische, histologische und pathogenetische Variabilität [Non-haemorrhagic subependymal pseudocysts: ultrasonographic, histological and pathogenetic variability]. Ultraschall Med. 2007 Jun;28(3):296-300. German. doi: 10.1055/s-2006-926805. Epub 2006 May 19. PMID: 16710814.)).