Etiological Diagnosis For Hemifacial Spasm By Combined Applcation Of3D-TOF And3D-FIESTA Seouences Of Skull Nase Thin Layer

Objective:This article focuses on finding arteries responsible for hemifacial spasm, discussing the relationships between the responsible arteries and facial nerves, and thus identifying the main types of the responsible arteries by analysis of3D-TOF and3D-FIESTA sequence in3.0T MR.Methods:The3D-TOF and3D-FIESTA sequence in3.0T MR for163hemifacial spasm(HFS) patients and107non-hemifacial spasm patients were retrospectively analysed. The affected sides of hemifacial spasm patients consisted the case group, and the unaffected sides and both sides of non-facial spasm patients consisted the control group. The MRI images of facial nerve root were studied. The relationship between facial nerve root and its surrounding vessels, the composition of responsible arteries and the probable responsible types with high occurrences were investigated. The following five types of relationship were classified:type1-no surrouding artery, type2-far away surrouding artery, type3-close surrouding artery, type4-contacted surrouding artery and type5-compressive surrouding artery. Type1,2and3were regarded as negative and type4and5were regarded as positive. Results:MRI images of all the540sides showed clear facial nerve root and surrounding structures. Among the166sides (3patients with spasm on both sides) in the case group,29sides were classified into type5(17.5%) and97sides were classified into type4(58.4%), while among the160healthy sides of hemifacial spasm patients, no sides were classified into type5and33sides were classified into type4(20.6%). For the214sides of non-hemifacial spasm patients, no sides were classified into type5and41sides were classified into type4(19.1%). There is no statistic significant difference between control group and non-HFS group regarding artery composition, but the difference between case group and control group (unaffected sides and both sides of non-facial spasm patients) was statistically significant (P<0.05). AICA accounted38.9%of the responsible arteries; PICA accounted35.7%, VA accounted19.0%and VA combined with other arteries accounted the left4%. The occurrence of hemifacial spasm in the sides with VA contacting or compressing were compared with that in the sides with PICA or AICA contacting or compressing. The occurrence in the27sides with VA contacting or compressing was88.9%(24/27), the occurrence in the71sides with PICA contacting or compressing was63.4%(63.4%) and the occurrence in the94sides with AICA contacting or compressing was51.2%(49/94).Conclusion:The3-D TOF and FIESTA sequence of MRI provide us a better view of facial nerve and its surrounding sturcture, especially the correlation between artery and facial nerve. Clinical use of this sequence help to confirm the pathogen of HFS, make decision to decompressive operation and evaluate the prognosis.The subgroup analysis shows that compression of VA cause HFS more easily and severely, which may predict a poor prognosis after the decompressive operation.