Primary temporal horn-subarachnoid communication during trigonal tumor resection: an anatomical reconstruction technique.

Trapped temporal horn (TTH) may be present preoperatively in patients with lateral ventricular trigone tumors or develop after tumor resection. Although its clinical course is variable, persistent or progressive symptomatic TTH may require secondary cerebrospinal fluid (CSF) diversion or endoscopic treatment. We describe primary temporal horn-subarachnoid communication, an anatomical reconstruction technique performed during the index tumor operation to establish an alternative CSF outflow pathway from the temporal horn. We retrospectively reviewed seven patients with lateral ventricular trigone tumors who underwent primary temporal horn-subarachnoid communication during trigonal tumor resection. Four patients had established TTH preoperatively, whereas three had temporal horn dilatation without definite isolation. Depending on the anatomy encountered after tumor removal, tentorial edge fenestration (TEF) or choroidal fissure opening (CFO) was used to establish the communication. The communication was completed through the original transcortical operative corridor in all seven patients, without an additional cortical opening or separate surgical approach. Pre-existing TTH resolved after surgery in all four patients with established TTH, whereas none of the three patients with temporal horn dilatation without definite isolation developed postoperative TTH during follow-up. Primary temporal horn-subarachnoid communication may provide a feasible anatomical reconstruction option for selected patients with abnormal temporal horn anatomy undergoing trigonal tumor resection. Its most direct application is restorative in established TTH, whereas the indications and efficacy of prophylactic use require further evaluation.