Treatment of refractory giant suprasellar arachnoid cyst by endoscopic expansion of a fenestrated stoma

BACKGROUND: Although endoscopic ventriculo-cysto-cisternostomy is considered to be effective for suprasellar arachnoid cysts, we encountered a giant suprasellar arachnoid cyst that recurred despite surgery using this technique. CASE DESCRIPTION: The patient was a 9-month-old boy. Magnetic resonance imaging revealed a huge suprasellar arachnoid cyst extending from the suprasellar region to the anterior skull base and both middle cranial fossa. First, an endoscopic procedure was performed to open the cyst wall between the right ventricle and the cyst and between the cyst and the prepontine cistern. Although the cyst initially shrank, it recurred over the next 2 months, and hence, we performed another endoscopic surgery. At the second surgery, both the previously opened stomas were found to be occluded. To reopen the cyst wall between the ventricle and the cyst, multiple holes were made with monopolar electrodes, and forceps were used to connect the holes by grasping and twisting the cyst wall so that the stoma was much larger than at the previous surgery. Postoperatively, the cyst shrank and the patient’s head circumference stopped expanding. CONCLUSION: Following the treatment of large cysts, the stoma might become narrower as the cyst shrinks, resulting in obstruction. Using the technique reported here might prevent occlusion of large arachnoid cysts.