Tash R, DeMerritt J, Sze G, Leslie D
Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT 06510.
AJNR Am J Neuroradiol. 1991 Sep-Oct;12(5):839-42.
MR imaging was used to evaluate the relationship of the root exit zone of the seventh cranial nerve to surrounding vascular structures in 13 patients with clinically documented hemifacial spasm and in 70 asymptomatic patients. MR imaging clearly demonstrated the course of the seventh nerve from the root exit zone of the brainstem to the internal auditory canal and its relationship to the surrounding vertebrobasilar system. The presence of a vascular structure at the root exit zone of the seventh nerve was identified in all 13 patients with hemifacial spasm. In the 70 asymptomatic patients, examination of 140 seventh nerves revealed that 21% had contact by a vascular structure at the root exit zone of the seventh nerve. Our results indicate that although neurovascular contact may be asymptomatic, MR demonstration of a vascular structure at the root exit zone of the seventh cranial nerve in a patient with hemifacial spasm may implicate neurovascular compression as the cause of symptomatology. This finding may alter therapeutic management. Because of the inherent limitations of CT in the visualization of posterior fossa structures, MR imaging should be considered the initial screening procedure in the assessment of patients with hemifacial spasm.
采用磁共振成像（MR成像）评估13例临床确诊为面肌痉挛的患者以及70例无症状患者的第七颅神经根部出口区与周围血管结构的关系。MR成像清晰显示了第七神经从脑干根部出口区至内耳道的走行及其与周围椎基底系统的关系。在所有13例面肌痉挛患者中均发现第七神经根部出口区存在血管结构。在70例无症状患者中，对140条第七神经进行检查发现，21%的神经在第七神经根部出口区与血管结构有接触。我们的结果表明，虽然神经血管接触可能无症状，但在面肌痉挛患者中，MR显示第七颅神经根部出口区有血管结构可能意味着神经血管压迫是症状的原因。这一发现可能会改变治疗方案。由于CT在显示后颅窝结构方面存在固有局限性，在评估面肌痉挛患者时，应将MR成像视为初始筛查程序。
