Objective:Toevaluateunusualpossiblecausesandclinicalpresentationsofhemifacialspasm(HFS).Methods:Theauthorsreviewed1642casesofHFS.Assessmentswerebasedonclinicalfeatures,3-dimensionaltime-of-flightmagneticresonanceangiography,andsurgicalfmdings.Causesotherthanneurovascularcompressionattherootexitzoneofthefacialnervewereinvestigatedandunusualclinicalpresentationswerenoted.Results:Nine(0.5%)patientshadasecondarycausativestructurallesion,7patientshadatumor,andtheremaining2hadavascularmalformation.Directcompressionbydolichoectaticvertebrobasilararterywasnotedin
