Neurally mediated syncope associated with small cell lung cancer: a case report and review.

We encountered a case of limited-disease small cell lung cancer with episodic syncope. The frequency of the syncopal attacks increased with the increase in the tumor size, thus a relationship was suspected to exist between the SCLC and syncope. Syncope was evaluated by history taking, 24-hour ECG monitoring, and coronary angiography. As orthostatic hypotension and cardiac disease could be excluded, we finally diagnosed this case as neurally mediated syncope. Serum tests for anti-Hu and anti-Yo antibodies were negative. A temporary pacemaker was inserted for sick sinus syndrome. This patient showed good response to the chemotherapy. No further syncopal attacks were observed after the second course of chemotherapy. Here, in addition we review four cases of SCLC with episodic syncope. Interestingly, in all cases, the tumor was located in the left hilum in close vicinity of the afferent vagal nerve (C-fibers) and mechano-receptor. Therefore, we thought that the mechanism underlying the syncope was mechano-receptor hypersensitivity.