Endolymphatic hydrops with absence of vein in paravestibular canaliculus.

Unilateral endolymphatic hydrops is described associated with absence of the vein in the paravestibular canaliculus (PVC), and with decreased vascularity of the vestibular aqueduct and endolymphatic sac. The venous return from the vestibule was normal as far as the junction of the branches forming the PVC vein. At this junction, a blind venous loop was formed with no continuation of venous drainage through the PVC. This probably represents a developmental anomaly. The decreased vascularity of the endolymphatic sac may be related to the absence of the PVC vein. However, anatomical and functional relationships of these vessels are not clear and need further study. Perisac fibrosis and endosteal bone formation are possibly secondary to the decrease in vascularity. A large chronic rupture of the inferior saccule wall probably accounts for the absence of vertigo and the relatively mild degree of cochlear endolymphatic hydrops.