Arachnoid cysts of the posterior fossa

BACKGROUND The surgical indications and management of posterior fossa arachnoid cysts (AC) are still controversial. Different surgical techniques and management have already been suggested for arachnoid cysts of the posterior fossa. AC involving the posterior fossa and especially the cerebellopontine angle may carry a high surgical morbidity because of the involvement of important ne urovascular structures (e.g., brain stem and cranial nerves). Only long-ter m follow-up will determine the best surgical technique for such lesions, METHODS Between 1990 and 1996 a total of 12 patients underwent surgery for arachnoi d cysts involving the posterior fossa, In seven cases AC were located withi n the cerebellopontine angle (CPA), in three cases in the CPA with major ex tension dorsal to the brainstem, and in two cases at the CPA extending into the internal auditory canal. RESULTS A suboccipital retrosigmoid approach was performed in all patients. Radical resection of the cyst could be accomplished in all but one case, There was no mortality. Major postoperative morbidity was present in one case becaus e of an intraoperative air embolism in the semisitting position and strong adherence of the cyst wall to the surrounding neurovascular structures. Lon g-term follow-up (mean, 3.3 years) revealed improvement of most preoperativ e symptoms. CONCLUSION Open surgery and radical removal of the AC located at the posterior fossa, based an our retrospective analysis, provide very good long-term postoperat ive results. The suboccipital approach provides a good and safe exposure of vascular structures and cranial nerves in the CPA and allows radical resec tion of the cyst, reducing the chance of recurrence. (C) 1999 by Elsevier S cience Inc.