Serial Research Of The Changes Of Brain, Brainstem, And Cranial Nerves Caused By Vertebro-basilar Artery Abnormality Evaluated By 3.0T MRI

Objective: To investigate the influence of vertebro-basilar artery abnormality on the brain, configuration and orientation of the brainstem, and cranial nerves by 3.0T MRI, and the role of MRI and MRA in the diagnosis of vertebro-basilar artery abnormality.Methods: 218 consecutive patients(141 male, 77 female) with vertebro-basilar artery abnormality(tortuosity, hypoplasia, stegnosis, occlusion, etc), who were diagnosed by clinic and MRA or CTA, were selected from the Second Hospital of Hebei Medical University between October 2006 and August 2007 as case group, the mean age of the subject population was 59.97 years±13.15 with a range of 16~90 years. The patients had different symptoms and signs; the appearance of the brain was normal or ischemic. Clinical data was recorded. 218 healthy volunteers were selected as control group, there was no significant difference between the two groups in age and sex. All subjects in the case group and in control group were examined by MRI and MRA. The MRI and MRA images were observed by Signa Excite HD 3.0T high field MR scanner (GE Medical System, U.S.A) with a 8-channel array head coil. Axial T2-weighted fast spin echo (FSE) images (PROP, TR 5100 ms, TE 118 ms), axial and sagital T1-weighted fluid attenuated inversion recovery (FLAIR) images (TR 1750~3196ms, TE 7.9~8.9ms, TI 920~960ms), and axial T2-weighted fluid attenuated inversion recovery (FLAIR) images (TR 10002 ms, TE 115 ms, TI 2300 ms) were obtained by using 5 mm thick slices with a 1.0 mm gap; the matrix was 512×256; the field of view was 240mm×240mm; the number of excitation was 1. Magnetic Resonance Angiography (MRA) was performed by using a 3D-TOF sequence (TR 20ms, TE 3.2ms) and the thickness of the slice was 1.0 mm. The appearance of the brain and abnormality of the arteries were classified into different categories. The course of vertebro-basilar artery, the relationship of the artery and brainstem, and the rotated brainstem (the line between anterior median fissure/basilar sulcus and posterior median sulcus in equal or more than 5 degrees clockwise or counter-clockwise with respect to the line between nasal tip and internal occipital protuberance) were classified into different grades. Images were reviewed concurrently by two skilled radiologists with double blind test. With the sequence including axial T2- FSE, assisted by axial T2-FLAIR, axial and sagittal T1-FLAIR, the appearance of the brain, the course of vertebro-basilar artery, the relationship of the artery and brainstem, the degree of the rotated brainstem, the dilation of the ventricular system, and the abnormity of paranasal sinus were observed and recorded. With MIP reorganized images assisted by source images, the type of vertebro-basilar artery abnormity, the condition of the posterior communicating artery(PCA), and the abnormality of anterior circulation were observed. Statistical testing was performed by usingχ~2 contingency tables and there was significant difference when P<0.05.Results:The brain parenchyma of 143 subjects in the case group presented ischemic changes, but the brain parenchyma was normal in the control group. In the case group, the number of the left vertebral arteries which crossed the median line was more than right vertebral arteries (χ~2=4.261, P=0.039); the number of the basilar arteries displaced toward right and left was 97 and 58 respectively; in approximate 46% of the subjects the two vertebral arteries were equal, of the remaining 54%, about 72% had a left vertebral artery larger than the right, and about 28% had a right vertebral artery larger than the left, there was significant relationship between the diameter of the vertebral artery and the displacement of the basilar artery (χ~2=69.489, P=0.000), the contingency coefficient C=0.97. In the control group, only 10 right vertebral arteries and 26 left vertebral arteries crossed the midline, the number of the basilar arteries displaced toward right and left were 6 and 4 respectively; in 90% of the volunteers the two vertebral arteries were equal, of the remaining 10%, about 91% had a left vertebral artery larger than the right, and about 9% had a right vertebral artery larger than the left. The number of the vertebral artery and basilar artery displaced in case group was more than that in the control group, so there was significant difference between the two groups (right vertebral artery:χ~2=60.398, P=0.000; left vertebral artery:χ~2=54.461, P=0.000; basilar artery:χ~2=205.007, P=0.000). In the case group, 103 subjects presented artery contacting medulla oblongata, the number of the artery contacting left, right, or both sides of the medulla oblongata were 37, 45 and 21 respectively. There were 5 subjects presented artery contacting pons, the number of the artery contacting left and right of the pons were 2 and 3 respectively. There was no significant difference between male and female (χ~2=1.122, P=0.289). Of the 108 subjects whose artery contacting brainstem, 61% (n=66) presented ischemic cerebrovascular disease. In the control group, 52 subjects presented artery contacting medulla oblongata and the number of the artery contacting left, right, or both sides of the medulla oblongata were 14, 24 and 14 respectively; there was no artery contacting pons. The number and degree of the contacting in case group were more than that in the control group, and there was significant difference between the two groups (χ~2=26.037, P=0.000). There was no rotated brainstem in the control group. In the case group, the number of the rotated medulla oblongata was 102, of which 63% rotated counter-clockwise and 37% rotated clockwise; the number of the rotated pons was 5, of which 20% rotated counter-clockwise and 80% rotated clockwise. The number of the rotated medulla oblongata or pons was 107, but only 103 subjects presented rotated brainstem, three subjects presented pons rotated clockwise with medulla oblongata rotated counter-clockwise, one subject presented pons and medulla oblongata rotated counter-clockwise together. The number of theⅠ,ⅡandⅢgrade of the rotated brainstem were 36, 47 and 24 respectively. Of the 103 subjects with the rotated brainstem, 68% (n=70) presented ischemic cerebrovascular disease. There was no significant difference between rotated grading and ischemic cerebrovascular disease (χ~2=4.180 ,P=0.124). Among the 38 clockwise rotated medulla oblongata, 31 right vertebral arteries crossed the midline; 14 right vertebral arteries were larger than left; 18 arteries contacted right of the medulla oblongata. Among the 64 counter-clockwise rotated medulla oblongata, 53 left vertebral arteries crossed the midline; 45 left vertebral arteries were larger than right; 16 arteries contacted left of the medulla oblongata. There was significant relationship between vertebral artery across median line and rotated brainstem (χ~2=19.467, P=0.000), the contingency coefficient C=0.89. There was significant relationship between diameter of vertebral artery and rotated brainstem (χ~2=17.357, P=0.000), the contingency coefficient C=0.76. There was no significant difference in rotated brainstem between male and female (χ~2=0.012,P=0.914). There was no significant difference between rotated brainstem and dilation of the ventricular system (χ~2=0.118,P=0.731). On MRA images of the case group, it was frequent to see the tortuosity, stegnosis, or artherosclerosis of the artery, but it was relatively seldom to see the occlusion, thickening, or absence of the artery; there were three fenestration of the basilar arteries; 87 subjects presented artherosclerosis of the anterior circulation; the number of the PCA opened was 101. In the control group, there were only a few tortuous vertebro-basilar arteries and three fenestration of the basilar arteries; anterior circulation was normal; the number of the PCA opened was 62. The number of the tortuous vertebro-basilar artery in the case group was more than that in the control group, there was significant difference between the two groups (vertebral artery:χ~2=92.171, P=0.000; basilar artery:χ~2=95.671, P=0.000). The number of the PCA opened in the case group was more than that in the control group, there was significant difference between the two groups (χ~2=11.477, P=0.001). Nasosinusitis in the case group was significantly more and severer than that in the control group, there was significant difference between the two groups (χ~2=45.281,P=0.000).Conclusions: Vertebro-basilar artery abnormality is a common disease and there are many types. Tortuous vertebro-basilar artery is one of the common types of the vertebro-basilar artery abnormality as well as the main cause of the oppression and rotation of the brainstem. Artery oppresses brainstem, cranial nerves, or cranial nerves pulled by rotated brainstem may provoke related clinical symptoms and signs. 3.0T MRI and MRA can provide detailed anatomy information and important evidence of etiopathogenisis, diagnosis and treatment for vertebro-basilar artery disease.