Objective To explore the incidence of operation complications and clinical curative effect of microsurgical vascular decompression on treatment of patients with common cranial nerve diseases. Methods One hundred and sixty-six patients with hemifacial spasm and 45 patients with primary trigeminal neuralgia,admitted to our hospital from September 2006 to May 2011,were collected in our study; all the patients under,vent microvascular decompression via a posterior sigmoid sinus key hole approach.Complications were analyzed after surgery for trigeminal neuralgia and hemifacial spasm patients to find the difference on complications between these 2 diseases. And at least 3-month clinical follow-up after microvascular decompression surgery was carried out to note the differences on disappearance of cranial nerve symptoms between 3 d and 3 months after the surgery. Results Postoperative fever in the patients with hemifacial spasm and trigeminal neuralgia was seen in 51 and 14 patients,prosopoplegia in 7 and 1 patient,hearing impairment in 4 and 2 patients,incisional cerebrospinal fluid leakage in 5 and 2 patients, and intracranial infection in 3 and 2 patients, respectively. Symptom disappearance was noted in 109 patients with hemifacial spasm 3 d after the surgery and in 153 patients 3 months after surgery with a cure rate up to 92.2％; 44 patients with disappearance of symptoms during the 3rd d to the 3rd months of surgery had delayed healing. The symptom disappearance was observed in 40 patients with trigeminal neuralgia 3 d after the surgery and in 42 patients 3 months after the surgery,with a cure rate reaching 93.3％. Conclusion No significant difference in the incidence of operation complications is noted between patients with trigeminal neuralgia and hemifacial spasm treated by microvascular decompression via a posterior sigmoid sinus key hole approach; the surgery enjoys exact effectiveness; and postoperative patients with hemifacial spasm may gradually get recovery in a short term.