Commentary

This article describes the rare occurrence of a distal anterior inferior cerebellar artery (AICA) aneurysm mimicking a cerebellopontine angle tumor. The authors have reviewed the subject thoroughly and have addressed several relevant issues that might arise.

As the authors state, several features of this case are atypical of an acoustic neuroma: clinical presentation with a seventh cranial nerve palsy, heterogenous signal on T1-weighted magnetic resonance images, and no enlargement of the internal auditory canal. It is easily understood why one would be swayed toward a metastatic lesion in the differential diagnosis and not consider preoperative angiography.

Once diagnosed at surgery, it would have been interesting to know how “dominant” the AICA was in this particular patient. For example, was it an AICA-posteroinferior cerebellar artery vessel? If so, I would have hesitated before trapping the aneurysm without revascularization. It is difficult to discern whether there may have been enough redundancy in the AICA to effect the end-to-end anastomosis that the authors would have liked to have performed. The small infarct in the middle cerebellar peduncle reminds me of the desirability of revascularizing certain vascular territories (when technically feasible with a relatively low morbidity rate) when trapping is considered.

In summary, this well-documented case is yet another example of one diagnosis mimicking another and of things not always being what they seem.