The importance of preserving the deep cerebral venous outflow has been recognized in microvascular decompression for trigeminal neuralgia; however, few reports have described the details of complications arising from the sacrifice of the superior petrosal vein (SPV). During the procedure in a 77-year-old woman, some tributaries of the SPV complex were sacrificed to achieve microvascular decompression for right trigeminal neuralgia. Postoperatively, the patient was conscious and pain free; however, on postoperative day 1 she developed headache and nausea followed by a decreased level of consciousness. MRI revealed an extensive venous infarction in the right cerebellum. Sacrifice of the SPV may lead to serious, potentially life-threatening complications. Neurosurgeons should pay close attention to the management of the SPV to reduce the risk of venous complications.