Fig. 1.

A 50-year-old male, whose drainage system drained air immediately following MVD, underwent an additional surgery on the 13th postoperative day for a cerebellar abscess combined with meningitis and middle ear effusion. A : A loop of the posterior inferior cerebellar artery (arrow) offending the root exit zone of the right facial nerve in the supra-olivary fossette. B : The immediate postoperative computed tomography scan shows the site of the surgery and a portion of the closed-suction drainage (arrow). C : A follow-up evaluation using temporal bone computed tomography for middle ear effusion and fever shows an opened mastoid air cell (arrow) and air density near the wound on the second postoperative day. Fluid in the mastoid air cells can also be identified. D : Follow-up magnetic resonance imaging on the sixth postoperative day shows abnormal lesions with contrast enhancement near the bone flap (arrow) and in the middle of the right cerebellar hemisphere (arrowhead). The mass effect is caused by the cerebellar abscess slightly displacing the pons to the left.