Endoscopic fenestration of an acquired arachnoid cyst causing a trapped lateral ventricle: Two-dimensional operative video.

BACKGROUND

Arachnoid cysts are commonly congenital but they can also be acquired in the setting of surgery, trauma, hemorrhage, or infection. The pathophysiology of arachnoid cysts may involve adhesive arachnoiditis secondary to arachnoid tissue injury, leading to cerebrospinal fluid accumulation. While often asymptomatic, arachnoid cysts can produce symptoms due to mass effect or hydrocephalus. Intraventricular or periventricular cysts can lead to ventricular entrapment.

CASE DESCRIPTION: In this video, we present a case of a 28-year-old female patient who developed an intraventricular arachnoid cyst following resection of a Grade I meningioma. This led to left lateral ventricular entrapment and associated hemianopia, headache, nausea, and fatigue. The arachnoid cyst was managed with endoscopic fenestration with the aid of stereotactic neuronavigation. The operative video reveals multiple veils of adhered arachnoid firmly associated with choroid plexus as well as with the lateral walls of the ventricle. Using blunt instruments, bipolar cautery, endoscopic microscissors, and a Fogarty balloon, a wide communication between the body of the lateral ventricle and the trapped temporal horn and atrium was achieved. The patient experienced complete resolution of preoperative symptoms. Follow-up imaging revealed interval reduction in the size of the left lateral ventricle without evidence of cyst recurrence. The patient consented to the procedure, and the Institutional Review Board approval was not required as all identifiable patient information is removed.

CONCLUSION

While there are no significant differences in clinical or radiologic outcomes between different surgical strategies in managing arachnoid cysts, endoscopic cyst fenestration offers a balance between definitive treatment and avoidance of shunt dependence.