Paraphysial cysts were first tentatively identified as such by Sjövall1 in 1909, but since that time the etiology in reported cases of these "colloid cysts of the third ventricle" has received either neglect2 or only irresolute attention. This might possibly be due to the fact that the cysts are comparatively rare (only forty-seven being reported in the literature of the past three quarters of a century, with but nine successful removals) or to the evident facility with which they may be confused pathologically with cystic degeneration of the choroid plexus when given only perfunctory consideration.3 Both preoperative diagnosis and curative therapeusis being now possible, the origin and adequate identification of these cysts should no longer remain shrouded in doubt.
The boundaries of the third ventricle, as the rostral portion of the primitive neural tube, have been the ancient proving ground for many phylogenic experiments and
McLEAN AJ. PARAPHYSIAL CYSTS. Arch NeurPsych. 1936;36(3):485-513. doi:10.1001/archneurpsyc.1936.02260090038002