Large arachnoid granulation protruding into the transverse sinus: A probable cause of intermittent otologic symptoms.

A 69-year-old woman suffered attacks of hearing disturbance and vertigo for seven years. Her otologic and ophthalmological examinations did not show any significant findings. Cerebral magnetic resonance imaging revealed a cystic mass in the left cerebellar convexity. Computed tomography demonstrated a contrast defect of the distal left transverse sinus. Magnetic resonance imaging revealed a cyst protruding into the transverse sinus, and enlarging in the supine. Cerebral angiography demonstrated a congestive venous flow in the left transverse sinus, at the upstream of the cyst. At rest, the venous sinus pressure was 13 cm H2O at the upstream of the cyst and 8 cm H2O at the downstream. When the patient held a breath, the upstream pressure increased to 37 cm H2O, while the maximal downstream pressure was 22 cm H2O. A large AG protruding into the cranial dural sinus may cause intermittent venous congestion and associated otologic symptoms. Movements accompanied by a transient decrease in cardiac venous return and changes in head position can attribute to an enlargement of such AG.