Microscopic fenestration of a posterior fossa arachnoid cyst with cranial nerve compression by fully anatomical suboccipital mini-craniotomy: How I do it

Background Posterior fossa arachnoid cysts may cause cranial nerve dysfunction as well as brainstem or vascular compression due to mass effect in a narrow compartment. Optimal surgical management remains debated, particularly regarding the indications to surgery versus conservative management, fenestration or shunting. Methods We describe a fully anatomical microsurgical fenestration of a posterior fossa arachnoid cyst causing lower cranial nerve compression, performed through a midline suboccipital mini-craniotomy. The technique emphasizes direct visual identification of neurovascular structures and wide cisternal communication. Conclusions An anatomical suboccipital approach, performed without neuronavigation or intraoperative neuromonitoring, allows safe and effective decompression of posterior fossa arachnoid cysts with lower cranial nerve involvement. Microsurgical fenestration with meticulous dissection guided by direct anatomical landmarks provides durable, low-morbidity symptom relief.