Presentation
Giddiness. No hearing loss at present, however giddiness is too frequent. No tinnitus.
Patient Data
Prominent bony canal is seen in superior mastoid portion, which is likely to represent a dilated mastoid emissary vein. Also noted is, its continuity with another channel in close proximity to temporo-mandibular junction, which may represent remnant petrosquamosal sinus.
(Case courtesy: Sapthagiri Digital imaging center, bangalore, with special thanks to Dr. Ajit Reddy)
Left transverse sinus appears hypoplastic with atretic sigmoid sinus. Torcular herophili is sen to drain from dilated occipital sinus, which is seen in continuity with petrosal/petrosquamous sinus (difficult to differentiate), draining into dilated mastoid emissary vein.
Case Discussion
Dilated mastoid emissary vein is an incidental finding in this case, although its association with pulsatile tinnitus is well documented.
Reason behind dilated emissary vein in this case, is atresia of sigmoid sinus, leading to venous drainage diverted via occipital sinus, into the petrosquamous sinus channel, and through the mastoid emissary vein.