Abstract: Objective To summarize the clinical features and surgical outcomes of idiopathic trigeminal neuralgia (TN) caused by sole arterial and venous compression.Methods Between Jan 2010 and Dec 2016,335 TN patients caused by sole arterial and venous compression were applied to microvascular decompression (MVD) treatment in our department.The patient data were retrospectively analyzed.Results Compared to arterial compression,V3 branch of the trigeminal nerve was more frequently involved,while V1 was rarely affected in venous compression (P<0.05).The most frequently offending vessel was the superior cerebellar artery (SCA,87.8%) in arterial compression and the transverse pontine vein (TPV,80.6%) in venous compression.The most common compression site was the root entry zone (REZ,78.6%) for arterial compression and cisternal (74.2%) for venous compression.Compared to arterial compression,the neuro-vascular compression grade was significantly lower in venous compression (P<0.05); the short-term outcomes were relatively worse in the venous compression group (P<0.05); however,the long-term outcomes were similar (P>0.05).No statistical differences were established regarding the rate of postoperative complications and recurrence between both groups(P>0.05).Conclusions Our results suggest that venous compression is more prone to involve V3 distribution of the trigeminal nerve.3D-TOF-MRA is preferred in identifying venous compression.MVD is still effective and safe for TN caused by venous compression and only small intraneural veins could be sacrificed.A relative long-term follow-up (1 year) is mandatory to monitor delayed pain relief and recurrence.

Key words: trigeminal neuralgia, microvascular decompression, arterial compression, venous compression, prognosis