[Clinical and operative findings in patients with trigeminal neuralgia caused by brain tumors].

Trigeminal neuralgia (TN) is occasionally caused by cerebellopontine angle (CPA) tumors. Among 243 patients presenting with TN who had been operated on in our institute, 25 (10.3%) were caused by CPA tumors, which consisted of 11 epidermoid, 9 acoustic tumors, and 5 meningiomas. Cases with TN caused by tumors were clinically investigated in comparison with those of idiopathic TN. No significant differences were found concerning sex and the affected side between patient groups with tumors and without tumors. Patients with tumors were significantly younger than those without tumors (p = 0.04). In about 30% of patients of both groups, the trigeminal division of pain extended to two or more branches. In more than half of patients with epidermoid, the affected trigeminal distribution was two or more branches Operative findings demonstrated that the trigeminal nerve was compressed by surrounding vessels in 12 of 25 patients with tumors. The encasement of the trigeminal nerve by the tumor was most frequent affecting pattern in epidermoids, while acoustic tumors and meningiomas tended to compress and distort the nerve. TN disappeared in all patients with tumors at discharge. 5 patients with epidermoid experienced recurrence of TN during the follow-up period. In 4 of them, no tumor regrowth was detected at the time of TN recurrence. The mechanism of TN recurrence without tumor regrowth remains unclear, but may be explained by the arachnoid adhesion around the trigeminal nerve, as described in the previous report.